HP-PNESG-1_Using the HP ESG-D Series of RF Signal Generators and the HP 8922 GSM Test Set

8/14/2019 HP-PNESG-1_Using the HP ESG-D Series of RF Signal Generators and the HP 8922 GSM Test Set

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Using the HP ESG-D se ries of

RF s ignal gene rators an d theHP 8922 GSM Tes t S e t for

GSM App licatio n s

Product Note ESG-1


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page

1 . In tro du c ti on 3

2 . In t ro d u ct io n t o GS M 3

3. Generating a 0.3 GMSK modu lated burst s ignal 10

for GSM (GSM 900, DCS 1800 & PCS 1900) usin g

the HP ESG-D series s ign al generator

4 . D at a Ge n e ra ti on 15

4.1 Choosing Data Pa tt erns

4.2 Single / Cont inuous Data pat tern s

4.3 Data Dependencies

4.4 Generating long data pattern s,

such as a GSM superframe

5. Triggerin g a GSM frame 23

6 . Cus tom i zi ng the GSM Mode 26

7 . Adjacent Broadcas t Channe l Generati on 28

using the HP ESG-D ser ies s ignal gen erator

and the HP 8922 GSM Test Se t

8. Using the HP ESG-D series s ignal generator 31

and th e HP 8922 GSM Test Se t to carry out

GSM receive r tests

8.1 Receiver Co-Cha nn el Rejection

8.2 Receiver Adjacent Ch an nel Rejection

8.3 Receiver Intermodulation Rejection

9 . Conver ti ng ARFCNs i n t o abs o lu t e f requency 39

values for GSM systems

10. Glossary of terms 40

11. Top l ine Speci fi cat ions 41

12. Related Li terature 42

13. Warranty Information 42

14. Presales address l is t , Disc la imer 43

Table o f Contents


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The HP ESG series RF signal generators from Hewlett-Packard Company

provides pr ecise frequen cy and level contr ol, modulat ion (AM, FM, P ha se

Modulat ion an d Pu lse Modulat ion), a choice of frequen cy covera ge from

250 kHz to 1, 2, 3 or 4 GHz and an easy-to-use interface. The digital family,

the H P E SG-D series, adds versa tile I/Q digita l modulation capabilities and

six built-in communications standards (GSM, DECT, TETRA, NADC, PHS

an d PDC) are provided with th e optional IQ baseband genera tor (Options

UN3 & UN 4) . Accessible at t he t ouch of a but ton, these built-in commun ica-

tions personalities ar e easy to configure to meet u ser-defined test require-

ments. The HP ESG-D series provides operators measurement versatility by

offering a choice of inter nal or extern al da ta generat ion, a nd flexible framing,

timeslot a nd power burst profile configurat ion capabilities.

The pur pose of this product note is to show how to use the H P E SG-D series

signal generat ors to generate a digita lly modulated signa l for the Global

Syst em for Mobile Commu nicat ions (GSM). Deta ils will also be given on how

the HP ESG-D series signal generat ors can be used with th e HP 8922 GSM

Test Set for GSM applications.

The Global System for Mobile Communications (GSM) is the most successful

digital cellular system in operat ion today. Alth ough GSM origina ted in

Eu rope, it is quickly gaining world-wide acceptan ce and is being adopted as a

standa rd in ma ny countr ies.

GSM uses 0.3 Gauss ian Minimu m S hift Keying (0.3 GMSK) modulat ion a nd a

bit ra te of 270.833 kbits/second. The "tr ellis" diagr am , shown below, shows a

repr esenta tion of GMSK modulat ion. It shows time on th e X-axis and ph ase

on the Y-axis. This allows th e examina tions of th e pha se tr an sitions with

different symbols or bits.

GMSK is a special type of digita l FM. Ones and zer os are r epresent ed by shift-

ing the RF carrier by plus or m inus 67.708kHz. This frequency shift h as acorr esponding shift in ph ase (relative to the u nm odulated carr ier) which

conveys information.

1. Introduc tion

2. Introduction to GSM

Figure 1a.

Trell is diagram of GMSK.

Time

Phase


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Broadcast

Channel

BCH

Traffic

Channel

To

BSC

Abis

Interface

TCH BTS

Uplink

Down

link

GSM

GSM

GSM

Figure 2 .

Diagram o f GSM cell .

Figure 1b.

0.3 GMSK

Data

Frequency

Phase

+67.708 kHz

-67.708 kHz

270.833kB/s

+90 -90I

Q

If a long series of ones wer e sent , th e resu lt would be a series of positive

phas e tr ans itions of 90 degrees per bit. If a long series of zeros were sent ,

ther e would be a const an t declining phas e of 90 degrees per bit. Typically,

there would be intermediate tr ansmissions with r andom data.

The modulation spectrum is reduced by applying a Gaussian pre-modulation

filter. This slows down th e ra pid frequency tra nsitions which would other wise

sprea d energy into adjacent chan nels. When Ga ussian filtering is applied, the

phase makes slower direction changes and this prevents the phase trajectory

from m eeting its 90 degree tar get points. The exact pha se tr ajectory is very

tightly contr olled - the GSM s pecifications allow no more t ha n 5 degrees rm s

and 20 degrees peak deviation from th e ideal tr ajectory. The 0.3 ment ioned

above describes the bandwidth of the Ga ussian filter with relat ion t o the bit

ra te, and is m ore commonly called the fi lter alpha or th e bandwidth-by-

time produc t (BbT).

The GSM system consists of Mobile St ations (MS), both h and-held porta bles

and mobiles mounted in a car, which comm unicate with the Ba se Sta tionSystem (BSS) over th e RF a ir int erface. The BSS t ypically consists of a Ba se

Tran sceiver System (BTS) and a Base St ation Controller (BSC) which are

connected by a link called the Abis interface. The Abis interface is often a

microwave link, but can also be a cable or an optical fibre.


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The BTS is fitted with a n umber of tr an smitt er/receiver (or tr ans ceiver)

modules, th e num ber of which deter mines th e num ber of frequency chann els

tha t can be used in th e GSM cell. Its exact configur ation varies depending on

the num ber of users expected in the cell. All BTSs contin ually produce a

Broadcast Ch ann el (BCH). The BCH is like a beacon - it allows mobiles t o find

the GSM network. The BCH consists of various par ts for frequency corr ection,

synchronization, control and access. The BCH is received by all mobiles in the

cell, wheth er th ey are on a call or n ot.

Mobiles on a call use a TCH (Tr affic Cha nn el). The TCH is a tw o w ay chan-

nel used to exchan ge speech informat ion between t he mobile and base-stat ion.

Usin g Fr equen cy Division Mult iple Access (FDMA), informa tion is divided

into the uplink and downlink, depending on its direction of flow. The uplink is

for m obile tr an smission and t he downlink is for bas e stat ion tr ans mission.

With in each band th e cha nnel nu mbering scheme is the sa me, however, the

uplink a nd downlink bands ar e 45 MHz apart.

Each ba nd is t hen divided into 200 kHz chann els called Absolute Radio

Fr equency Chann el Number s (ARFCN). In addition to frequency division,

time is also divided into segments using Time Division Multiple Access

( TDMA).

51Frames

FCH Frames 0, 10, 20, 30, 40

SCH Frames 1, 11, 21, 31, 41

BCCH Frames 2-5CCCH Frames 6-9, 12-19

SDCCH Frames 22-29, 32-39

SACCH Frames 42-49

Frame 50 is idle

2 3 00 11

Figure 3 .

Diagram of BCH.


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Each ARFCN is shar ed between up to 8 mobiles. Since ther e are a ma ximum

of eight u sers per frequen cy, there a re eight timeslots (TS) per GSM frame.

Each t imeslot las ts 576.92s an d cont ains 156.25 bits of inform at ion,

alth ough only 148 of th ese bits are us ed for da ta. The r emain ing bits a re used

for "gua rd" time. The patt ern r epeats, giving th e users anoth er timeslot each

frame. Ther efore, each mobile (user) uses t he ARFCN for one t imeslot a nd

then wait s for its tu rn t o come round aga in in the next fram e.

The mobile tran smitt er tu rns on only dur ing its active timeslot. The require-

ment t o tr an smit in only one single timeslot an d stay idle dur ing the rema in-

ing seven timeslots results in very tight dema nds on th e switching on an d off

of the RF power. If a mobile station does not perform according to the specifi-

cations , it will distu rb other mobile sta tions in adjacent t imeslots a nd on

adjacent chan nels. The GSM specifications m ake su re a mobile's emissionsrema in in its a ssigned channel by specifying a power-versus-time t emplate,

shown in Figure 5. During the centra l, or "useful", part of the TDMA burst

(corresponding to 147 bits) when dat a is being tran smitt ed, the mobile has t o

cont rol its output t o within +/1dB of the mean value. This pulsed tran smis-

sion is not only defined for the mobile station but is also generally defined for

base stations.

+1.0 dB

1.0 dB

+4 dB

6 dB

30 dB

70 dB

6 dB

30 dB

70 dB

147 "Useful" Bits

542.72s

148 "Active" Bits, 546.42s

3 57 1 26 1 57 3

10s 8s 10s 10s 10s8s

Power

Time

Figure 5 .

GSM TDMA Burst

Figure 4 .

Diagram of ARFCNs.

1 2 3

45

6

3

4 5 6

70

1

2

Time

Frequency

Amplitude

ARFCN

Timeslot

Physical Channel is an

ARFCN and Timeslot

7


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The ETSI GSM 05.05 specifications also define the Adjacent Channel Power

(ACP) performan ce required by both m obile and ba se st at ions. The ACP spec-

ificat ions define the per form an ce required by the mobile and base st ations

outside their a ssigned chan nels. The ACP is usua lly defined at 1 chan nel

(200kHz), 2 cha nn el (400kHz), 3 chan nel (600kHz), etc. offset s from t he

assigned channel. Both t he modulation process and th e power ra mping up

and down (switching tran sients) affect th e outpu t RF spectru m. The required

ACP per form ance due t o these two effects is defined in t he E TSI GSM 05.05

specifications. The diagram and table below illust ra te th e excellent ACP

perform an ce available with th e HP ESG-D signa l generat or (configured with

Option UN3 or Option UN4). It can clear ly be seen from th e table th at th e

HP ESG-D complies with t he E TSI specificat ions.

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Table 1: Sum mary of HP ESG-D GSM ACP performan ce vs. ETSI GSM 05.05 recomm en datio ns

(ACP given in dBc, except where stated otherwise)

Spectrum due to modulation Spectrum due to switching

Offset from carrier (kHz) 200 400 600 1,200 200 400 600 1,200

ETSI spec.

(30 kHz measurementbandwidth)BS (at max power) 30 60 70 73 --- 57 67 74MS (at max power) 30 60 66 66 --- 23 dBm 26 dBm 32 dBm

HP ESG-D spec.

(30kHz measurementbandwidth) 37 71 81


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As ment ioned ear lier, eight time-slots ma ke up a GSM fra me. Fra mes ar e

th en grouped together t o ma ke multifram es. Speech mu ltifra mes (such as a

TCH) consist of 26 fra mes, while signaling data mult ifra mes (such as a BCH)

ar e ma de up of 51 fra mes. A superframe consists of 26 or 51 m ultifram es.

How are GSM, DCS1800 and P CS1900 different?GSM is a family of digital cellular systems. The term GSM can be used collec-

tively to describe the GSM900 and DCS1800 sta ndar ds. GSM900 is the origi-

na l GSM system, using frequencies in th e 900 MHz ban d an d is designed for

wide area cellular operat ion. DCS1800 is an a dapt ation of GSM900. Creat ing

DCS1800 involved widening th e bands assigned t o GSM and m oving them up

to 1.8 GHz. To avoid confusion, the chan nel nu mber s (ARFCN ) used for

GSM900 cha nnels r un from 1 to 124, and th e ARFCNs for DCS1800 ru n from

512 to 885. With wider frequency allocation, leading to more channels,

DCS1800 is able to cope with higher u ser dens ities. DCS1800 mobiles ar e

also designed for lower outpu t powers (up to 1W), so cell sizes have t o be

sma ller, meaning even higher densities. In all other respects, GSM900 and

DCS1800 are th e sam e. The GSM Phase I I specifications (a r evised an d re-

writt en sta nda rd) brings the two systems even closer. GSM900 gets addi-

tional bandwidth a nd chann els, called E-GSM (Extended ba nd GSM) and

lower power cont rol levels for mobiles, allowing micro-cell opera tion. These

two featur es allow increased user den sities in GSM systems. Ph ase II also

ma kes pr ovision for th e addit ion of new services on GSM a nd DCS1800.The a ddition of specific services such as dat a, fax an d dua l mode opera tion is

curren tly being defined in what is referred to as Ph ase II+. In th e USA, bands

have been released ar ound 2 GHz for a PCS (Personal Commun icat ions

System). The ready availability of GSM equipment a nd expertise ha s ma de

GSM at 1.9GHz very att ra ctive for m any operat ors. In t echnical term s

PCS1900 will be identical to DCS1800 except for frequency allocation and

power levels.

6.12s

3 1 1 326 bits 57 bits57 bits

Control

bit

Control

bit

Midamble Guard

Period

DataData

8.25

bits

Tail

bits

Tail

bits

120ms

4.615ms

576.92 s

Superframe

Multiframe

Frame

Timeslot(normal burst)

26 Frames

51 Multiframes

8 Timeslots

156.25 Bits

Figure 7 .

Diagrams of Frames,

mult i frames, superframes.


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Table 2: Sum mary of GSM system p aramete rs

Phase 1GSM900

Uplink Frequency 890 to 880 to 1710 to 1710 to 1850 toRange 915 MHz 915 MHz 1785 MHz 1785 MHz 1910 MHz

Downlink 935 to 925 to 1805 to 1805 to 1930 toFrequency Range 960 MHz 960 MHz 1880 MHz 1880 MHz 1990 MHz

Voice Coder 13 kBit/s Full Rate 13 kBit/s, 13 kBit/s Full Rate 13 kBit/s, 13 kBit/sBit Rate Half Rate 5.6 kBit/s Half Rate 5.6 kBit/s

TX/RX Spacing (Freq.) 45 MHz 45 MHz 95 MHz 95 MHz 80 MHz

Mobile Power 0 - 15 2 - 19 0 - 13 0 - 15 0 - 15, 30, 31Control Steps

Mobile Max Power 20W 8W/39 dBm 1W/30 dBm 4W/36 dBm 2W/33 dBm

(8W used)43 dBm/39 dBm

Mobile Min Power 20mW/13 dBm 3mW/5 dBm 1mW/30 dBm 1mW/0 dBm 1mW/0 dBm

Phase 2GSM900

Phase 1DCS1800

Phase 2DCS1800 PCS1900

ARFCN range 1 to 124 0 to 124 and 512 to 885 512 to 885 512 to 810975 to 1023

Channel Spacing 200 kHz Bits per Burst 156.25

Modulation Type 0.3 GMSK Useful Bits per Burst 147

Modulation Data Rate 270.833 kHz Frame Period 4.62s

Tx/Rx Time Spacing Three Timeslots Timeslot Period 576.9s

Slots per Frame 8 Bit Period 3.692s

General GSM Parameters

For more inform at ion on the GSM stand ar d, see th e list of relat ed liter atu re,

given in Section 12.

The following table is a summary of the GSM specifics:


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The HP ESG-D series signal generat ors ar e capable of genera ting 0.3 GMSK

signals requ ired for t he development and testin g of GSM commun ications

systems a nd t he components of these syst ems. 0.3 GMSK signa l generation is

achieved by using the HP E SG-D series signal generat or with t he inter nal I/Q

baseband generator (Options UN3 or UN4). The baseban d generat or also

provides signals tha t conform t o other commu nications standa rds su ch as

PHS, PDC, NADC, DECT and TETRA.

1. Turn t he signal generator on or press Preset (the green but ton on th e

lower left corner of the instr umen t).

2. Set th e desired RF outpu t frequency. The cur ren t RF output frequency is

always shown in the frequen cy ar ea of the display. Press t he Frequency front

pan el har dkey to chan ge the RF outpu t frequency. To enter a new value for

frequency, rotate t he front pa nel knob unt il the desired frequency is

displayed, use th e up an d down ar row keys, or ent er th e value using the

numer ic keypad and press the GHz, MHz, kHz, or Hz ter mina tor softkey.

For example, to set a n outpu t frequen cy of 880MHz:

Press Frequency.

Key in 880 using the numeric keypad.

Press the MHz softkey.

Many GSM users a re accustomed to thinking in term s of chann el (ARFCN)

numbers, rather than absolute frequency values. There are formulae which

can be used to convert ARFCNs t o the corr esponding absolut e frequency

values. These form ulae a re given in Section 9.

3. Set th e desired RF output power level.

The curren t RF outpu t power level is always shown in the am plitude ar ea of

th e display. Press this front pa nel har dkey to cha nge the RF output power. To

enter a new value for amplitude, rotate t he front panel knob until the desired

am plitude is displayed, use the up a nd down arr ow keys, or enter t he value

using the num eric keypad an d press the dB m, dB uV, dBu Vem f, mV, uV,

mVemfor uVemfterm inat or softkey.For example , to set u p an output power level of 0 dBm:

Press the Amplitude hardkey

Press 0 on the num eric keypad

Press the dBm softkey

4. Press the front panel Mode key.

Pressing the grey front pan el Mode key reveals a menu of softkeys. These

softkeys a llow furt her menu s to be a ccessed, for configur ing th e desired digi-

tal communications standards, in this case GS M.

5. P ress the GS M softkey.

Pr essing this softkey reveals a men u of softkeys for genera ting fram ed or

unframed GSM tr ansmissions.

6. Data Format Pattern Framed

Pr ess t his softkey to toggle between Data Format Pattern , to tra nsmit a

continuous stream or pa ttern of data, and Data Format Framed , to tra ns-

mit a pulsed RF GMSK signal in a GSM TDMA format .

Select Data Format Framed

3. Gen erati ng a 0.3 GMSK

modulated burst s ignal

for GSM (DCS 1800 & PCS

1900) using the HP ESG-Dseries s ignal generator


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The lower ha lf of the signal genera tor's display will now show a gr aph ic of the

GSM timeslot pat tern , as shown in the diagra m below.

The default sett ing of the signal generator is th at it tra nsmits a single frame

of data (Frame Repeat Single softkey). The HP E SG-D can also be set to

transmit frames of data continuously (Frame Repeat Cont softkey) .

The data sequences that can tra nsmitted ar e described in Section 4

"Data Generat ion".

7. Man ipulating the timeslot

The HP ESG-D series signal generat or allows the contents of each timeslot to

be defined.

Pressing the Configure Timeslot softkey revea ls a men u of choices for

configur ing th e timeslot. This softkey is inactive unt il Data Format Framed

is selected.

In t his menu , the user can select which timeslots to turn on and choose the

type of RF power burst desired. The subsequent m enus ar e then used to

configur e the dat a an d tra ining sequence fields.

As mentioned in the int roduction, th ere ar e 156.25 bits in each timeslot. The

HP ESG-D optional baseband generat or (option UN3/UN4) implement s th e

GSM scheme by ma king every four th timeslot (i.e. timeslot 0 & timeslot 4)

157 bit per iods long , and t he r emainin g timeslots in t he fram e (i.e. timeslots

1,2,3,5,6 & 7) 156 bit periods long. This implementation complies with the

ETSI GSM standard (GSM 05.10, version 4.9.0, section 5.7).

A similar implementation applies to Guard Time and Extended Guard Time

bits. Gua rd time (G) appear s in the visual represen ta tion of th e timeslot as a

8.25 bit field. In th e actual implement ation, the guar d time in timeslots 0 & 4

ar e 9 bits long, and th e rema ining timeslots contain 8 bit fields. Extended

Guard Time (EG ) appears in th e visual represen tat ion of Access timeslots as

a 68.25 bit field. In th e actual implement at ion, the gua rd t ime in timeslots

0&4 are 69 bits long, and th e rem aining t imeslots contain 68 bit fields (also

docum ent ed in th e GSM sta nda rd "GSM 05.10, version 4.9.0, Section 5.7").

1. Turning Timeslots Off and On

After t he Configure Timeslot softkey has been pr essed, press the

Timeslot # softkey. Any one of th e eight t imeslots can be selected by

using th e front pa nel knob, the u p and down ar row keys, by enter ing

the nu mber using the nu meric keypad, and pr essing the Enter

ter mina tor softkey. The selected t imeslot is activated by toggling

Times lot Off On to On . The visua l represen tat ion of the timeslot

pat tern should now show the selected timeslot tur ned on.

Figure 8 .

ESG-D GSM Timeslot Patte rn


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2. Settin g the Timeslot type

Having selected t he a ctive timeslots, the t imeslot t ype can be set for

th e active timeslot. Any of the 8 t imeslots can be set t o one of the

following types:

Normal A normal burst is the most common burst in the GSM system an d

is tra nsmitted in one timeslot either from the base st ation or t he

mobile sta tion. This burst type configur es the t imeslot a s a t ra ffic

chann el. To select this bu rst type for t he a ctive timeslot:

Press the Normal softkey.

The following figure s hows an example of display graph ics for a n ormal t imes-

lot. This sh ows each field of the timeslot as it is defined by the GSM sta ndar d.

Frequen cy Corr ection

Timing is a critical need in a GSM system. The base st at ion ha s to provide

th e mean s for a m obile station to synchr onize with th e mast er frequency of

th e system. To achieve synchronization th e base stat ion tr an smits a

frequency correction burst , during certain kn own int ervals. Thisfrequency correction bu rst is simply a fixed sequence of zeros for th e dur at ion

of one timeslot. In a GSM network, frequency corr ection bur sts occur every 10

fram es (Fr am e 0, Fr am e 10, Fr am e 20 etc. of a BCH signaling data mu lti-

fram e (see the FCH in F igure 3), and always occur in timeslot 0 (the base

sta tion always genera tes the BCH on t imeslot 0). To ma ximize th e flexibility

of the HP ESG-D series signal genera tor, however, any timeslot may be set to

th e frequency corr ection t ype. Also note t hat th e frequency corr ection burst

will be repeat ed every fra me, not every 10 fra mes, if the bu ilt-in da ta genera-

tor is u sed. To repeat every 10 fra mes, a long user-defined dat a sequ ence

could be genera ted an d loaded directly into the signal genera tor's patt ern

RAM (see Section 4.4 "Generating long data sequences").

To select t his bur st t ype for th e active timeslot:

Press the FCorr softkey.

Synchroniza t ion

The base sta tion sends signals on the BCH which contain some valuable

system pa ra meter s, such as those which ena ble the mobile to synchronize to

th e BS. The mobile, however, needs a defined t ra ining sequence before it can

demodulate a nd decode this informat ion. The base st at ion t ells the mobile

which tr aining sequence to use with th e synchronization burst . The

synchronization bur st ha s an extended mida mble (or tra ining sequence) with

a fixed sequence in order to give the mobile the "key" it needs to decode the

system par am eters. Like frequency correction chan nels, synchr onizat ion

chann els occur every 10 fram es (Fram e 1, Fr am e 11, Fr am e 21 etc. of a

signaling data m ultifram e - see the SCH in Figure 3), and t he bursts always

Figure 9 .

ESG-D GSM Norm al

Timeslot


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occur in timeslot 0 . To maximize the flexibility of the HP ESG-D series signal

generat or, however, any timeslot m ay be set to the synchronization type. The

synchronization burs t will be repeated every frame, not every 10 frames, if

the built-in data generat or is used. To repeat every 10 fra mes, a long data

sequence could be genera ted an d loaded directly int o th e signal genera tor'spattern RAM (see Section 4.4).

To select t his bur st t ype for t he a ctive timeslot:

Press the Sync softkey.

Random Access

Mobiles us e a random access burs t when tr ying to gain initial access to the

system. This burst t ype is shorter th an a normal burst, and is used by the

base sta tion to measur e the tim e delay a mobile's burs t is experiencing.


Press the Access softkey.

Dummy

In th e GSM system, the base stat ion mu st tr ansmit something in each times-

lot of the base channel. Even if these timeslots ar e not allocat ed to comm uni-

cation with an y mobiles, the base sta tion has to tra nsm it predefined dummy

bursts , specially defined for th is pur pose, in th e idle timeslots of the base

channel.


Press the D ummy softkey.

Custom

The custom t imeslot is pr ovided for u sers' flexibility, but it is not a sta ndar d

GSM timeslot type. A cust om timeslot is configur ed using a n in tern ally-gener-

ated da ta pat tern , a downloaded sequen ce of bits st ored in a us er file, or by

supplying external dat a.


Press the Custom softkey.

Once the desired t imeslot t ype has been selected, th e "Configure Timeslot"

menu will be displayed.

3. Configuring selected timeslot

The data and t ra ining sequence fields within a cert ain timeslot type may be

configur ed by the user. From within th e Configure Timeslot menu , select

the Configure ... softkey corresponding to the chosen timeslot type. For

example, to configure a norma l timeslot, the Configure Normal softkey

should be selected. The visual r epresent ation of the timeslot shows each field

of th e timeslot as it is defined by the GSM standa rd. Note tha t if the text in a

field is grey, the value in t his field cann ot be alter ed. However, if the t ext in a

field is black, the values in t his field can be changed. For example, in a

Norma l timeslot the data (E field - signifying encrypt ion bits), Stealing Flag(S) bits and t he tra ining sequence (TS ) values can be chan ged, but t he T

(Tail ) bits, and th e Guard (G) bits cann ot be altered. The fields th at can be

changed depend on the t ype of timeslot chosen. Note th at the FCorr timeslot

values can not be altered at a ll.

Selecting values for data

For Normal , Sync and Access Timeslots: Pressing th e E softkey from within

the Configure ... menu reveals a menu of choices for int erna l data genera-

tion (P N9, PN15, or a f ixed sequence of data) or t he u ser can choose to

supply his own dat a. The num ber of dat a bits in th e E field depends on th e

timeslot type chosen.


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For Custom Timeslots: The sam e choices as above are au tomat ically

displayed when th e Configure Custom softkey is pr essed.

The choices a vailable for dat a a re described in S ection 4.

The dat a values will be shown on the signal generat or's display,

below the gra phic of the curr ent t imeslot.

Sett ing values for the stea l ing bi ts

The st ealing bits ar e set t o indicate th e difference between speech

and cont rol data on a TCH. The S bits can t herefore only be set for

Normal timeslots.

Press the S softkey, and enter a '0' or '1' using the front panel kn ob, up

and down arr ow keys, or the num eric keypad, and press t he Enter

term inat or softkey.

Sett ing values for the tra ining sequence

The training sequence can be changed for the following timeslot typesonly: Normal , Sync and D ummy.

Press the TS softkey to change the 26-bit (64-bit for Sync) training

sequence. The preset hexadecimal value (when n ormal pr eset is selected)

for TS repr esents a color code according to the GSM st an dar d. A new

value ma y be entered, to simulat e different bas e sta tion codes, by

pressing this softkey.

The new value may be enter ed by using the front pa nel knob, up an d

down ar row keys, or th e num eric keypad and t he A,B ,C,D ,E , and F soft

keys, and pressing the Enter term inat or softkey. Note th at other color

code values us ed in GSM ar e specified in th e Help text .

Sett ing values for the Synchronization Sequence

The synchronization sequence can be alter ed for Access timeslot types

only. The synchronizat ion sequen ce has a s imilar function to the tr aining

sequence in other timeslot types .

Press the SS softkey t o chan ge the 41-bit synchronization sequence.

The preset hexadecimal value (when n ormal pr eset is selected) for SS

reflects t he GSM stan dar d, however a new value can be entered by

pressing th is softkey. A new value ma y be entered u sing the front pa nel

knob, up an d down ar row keys, or t he nu mer ic keypad an d the

A,B ,C,D ,E , and F softkeys, and press ing the Enter term inat or softkey.

Settin g values for Extende d Tail Bits

The extended t ail bits can be chan ged for Access tim eslot types only.

Press the ET softkey t o chan ge the 8-bit extended ta il bit sequence.

The preset hexadecimal value (when n ormal pr eset is selected) for E T

(extended t ail bits) reflects t he GSM stan dar d, however a new value may

be enter ed by pressing this softkey. A new value ma y be entered u sing

the front pa nel knob, up an d down ar row keys, or th e num eric keypad

and t he A,B,C,D,E, an d F softkeys, and press ing the En ter t erm inat or

softkey.

8. Retur n to the top level menu by pressing the Return front panel har dkey

twice.

9. The RF car rier is modulated only when Mod On/Offis set to On . To tu rn

GMSK modulation on, set GSM Off On to On .

10. Set RF On Off front panel har dkey to On . This makes th e GSM signal

available at the RF OUTPU T connector.


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15

The HP E SG-D series signal generat or offers a var iety of int erna lly generat ed

data patt erns (PN9, PN15, fixed 4-bit repeatin g sequences, set pat ter ns of

ones an d zeroes,) or you can choose to supply your own da ta (download a

binary file or input dat a u sing th e DATA INPUT connector). It is a lso possible

to continuously repeat th e chosen data pattern .

With H P E SG-D series signal generat ors equipped with Options UN3 or UN4,

the ba seband gener at or's clock can be intern ally or exter nally supplied, and

the external data clock can be set to a normal bit clock or a symbol clock for

the NADC, PHS, PDC an d TETRA format s. There a re severa l data /clock

combinat ions a vailable to the u ser a nd t he selections will affect t he input s

required and the outputs available.

For m ore informa tion on th e input an d output r equirements for da ta and

clock settin gs, see Tables 7-1 an d 7-2 in Section 7 "Operat ion" of th e HP E SG

User Guide.

4.1 Choosing Data Patterns

Th e Data softkey is available in th e GSM menu to select a da ta pa tter n for

unframed tr ansmission (Data Format Pattern is selected). The Data soft-

key is inactivat ed when Data Format Framed is selected for fram ed tra ns-

missions. If data genera tion for fra med tr ans missions is requir ed, the same

choices ar e available by pressing t he E softk ey, wit hin th e Configure

Timeslot Normal, Configure Timeslot Syn c , Configure Timeslot

Access menus, and from th e Configure Timeslot Custom menu, as

ment ioned in t he pr evious section.

P N9

Press the P N9 softkey to select t he P N9 pseudoran dom bit sequence. The

PN 9 sequence consists of 511 bits (29 1 bits) and complies with t he CCCIT

Recommendation 0.153 .

PN15

Press the PN15 softkey to select t he P N15 pseudoran dom bit sequence. The

PN 15 sequence consists of 32767 bits (215 1 bits) and complies with CCCIT

Recommendation 0.151.

Fixed 4 bit

Press the FIX4 softkey to select a 4-bit repea ting sequence . Ent er th e

desired 4-bit pat ter n using th e front pa nel knob, up an d down ar row keys, or

enter th e value using the nu meric keypad and press th e Enter terminator

softkey.

Other Patterns

Press the Other Patterns softkey to select da ta pat tern s of 1's and 0's. Data

pat ter ns of 4 1's followed by 4 0's, 8 1's followed by 8 0's , and so on, may bechosen.

External Data

Press the Ext softkey in the da ta s election menu (or in the E m enu for fra med

tr ans missions) to select extern al data . With Ex t selected, the dat a signal

should be supplied to the DATA INPUT connector.

The DATA connector expects a TTL signa l where a TTL high is a data 1 an d a

TTL low is equivalent to a dat a 0. The ma ximum da ta ra te is 1.152 Mbit/s.

The appr opriate dat a a nd symbol clocks must also be supplied to the front

pan el inpu ts DATA CLOCK an d SYMBOL SYNC.

4. Data Gen eration


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16

User Files

The HP ESG ser ies signal generat or allows user-specified data sequences to

be loaded int o the n on-volatile mem ory of the s ignal genera tor.

These dat a sequ ences, accessible through t he file cat alog featu re of the signal

generat or, ar e comm only used to:

insert a specific set of data into the data field of a tim eslot(s) of a built-in

commun ications st andar d.

simulat e some type of tr an smission between a base st at ion an d a mobile by

specifying the da ta of th e entire fra me.

Press the User File softkey t o display th e cata log of binary files stored in th e

signal generator's memory. A custom file may be selected from this catalog for

the u ser-specified data pa tt ern. Scroll thr ough the listed files until the

desired selection is highlighted, th en press the Select File softkey.

If you elect to supply your own da ta file for fram ed tr ans missions, it sh ould be

created t o exactly fill the da ta fields of an integer n um ber of timeslots (n*148

bits for a GSM Custom tim eslot a nd n*114 bits for a GSM Norma l timeslot .

The following diagram illust ra tes t hat different u ser files may be selected t o

fill the da ta fields of different timeslots. In t his exam ple, UserFile #1 is

selected t o fill cust om timeslot #0. The first 148 bits of data fill the da ta field

of the timeslot in Fr am e 1. The next 148 bits go on t o fill timeslot #0 in F ra me

2, Frame 3, and so on. A second userfile, UserFile #2, is selected to fill times-

lot #5, an d is also sequent ially loaded into timeslot #5 of every fram e un til the

end of th e file.

If the end of the file does not coincide with th e end of a fra me, dat a will be

truncated in one of the following ways:

1. Enough fram es will be generated to tran smit as mu ch of the data pattern

as will fit into complete fram es. The rema ining bits of th e data pat ter n (which

ar e too few to completely fill a fram e) are t ru ncated.

2. If two files of unequa l sizes are selected for different timeslots of the sam e

framed tr ansmission, enough fram es will be generat ed to tra nsmit a s mu ch of

the da ta pat tern of the lar gest file as will fit into complete fram es.

The rema ining bits of the da ta pa tt ern a re tr uncat ed. The smaller file will be

UserFile #1 UserFile #2

Frame #1 Frame #2 Frame #3.....

.....

.....

.....

.....

.....0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 etc.

................

................

................

148 bits

148 bits

148 bits

................

................

................

148 bits

148 bits

148 bits

Figure 10


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17

repeat ed as ma ny times as n ecessar y to completely fill these frames. Data will

be tru ncated for t he sm aller file to coincide with t he end of the last frame.

3. If a user 's file and a PN9 file are selected for different timeslots of the sa me

framed tra nsmission a nd th e user's file is shorter t han the P N9, 511 frames will

be generat ed to transm it the P N9 without t run cation. The end of the PN9 datawill coincide with the end of the 511th frame. The sma ller user 's file will be

repeat ed as ma ny times as n ecessar y to completely fill these 511 fra mes. Data

will be tru ncated for th e sma ller file to coincide with th e end of the last frame.

4. If a user's file and a PN9 file are selected for th e same fram ed tra nsm ission

and t he user 's file is longer th an t he PN9, enough frames will be generat ed to

tra nsmit a s much of the data pattern as will fit into complete frames.

The rem aining bits of the da ta patt ern (which ar e too few to completely fill a

frame) are tr uncated. The PN9 data will be repeated as ma ny times as neces-

sar y to completely fill these fram es, but th e PN9 sequen ce will be tru ncated if

necessary.

The following SCPI comm and downloads a da ta sequence into the HP ESG

series signal generator:

MMEM: DATA "FILEN AME", #ABC

where,

A = The num ber of numer ic digits in B, which specifies the a mount of dat a in C

B = The num ber of bytes of dat a in C

C = The dat a

For exam ple, to download a file, called "NEWDATAFI LE", with da ta bytes in

ASCII, the comman d :

MMEM: DATA "NE WDATAFILE", #1912SA4D7 89

gives the A, B and C fields the following meanings:

A = the number 1 ; specifies th at B conta ins a single digit.

B = the number 9 ; specifies tha t C contains 9 bytes of dat a.C = 12SA4D789 ; the ASCII represent at ion of th e data t ha t is downloaded to

the HP ESG.

In t he following examp le, th e file "NE WDATAFILE1", cont ain s 2 bytes of

ASCII data:

MMEM: DATA "NE WDATAFILE1", #2101 2&A%4D 789

gives the A, B and C fields the following meanings:

A = the number 2 ; specifies tha t B contains a double digit - in t his case 10 .

B = the number 10 ; specifies that C contains 10 bytes (in ASCII) of data

C = 12&A%4D 789 ; the ASCII repr esenta tion of the digita l demodulat ion dat a

tha t is downloaded to th e HP E SG.

If the dat a is downloaded usin g ASCII char acters (which represent one byte of

data per char acter), 19 bytes (152 bits) of data mus t be ent ered for Cus tom

timeslots in order tha t th e corr ect ASCII cha ra cter is form ed. Because th e

GSM cust om timeslot only really needs 148 bits of data, when t he HP ESG

loads t he us er file int o the tim eslot, it will drop the four least-significant bits of

the data sequence. A file of 18 bytes (represen ting 144 bits ) of data is too small

to completely fill the 148-bit d ata field. In t his case t he en tire file would be

tr uncat ed an d nothing would be modulated. By the s am e logic, 15 bytes

(120 bits) of data m ust be entered for a Norm al timeslot to complete th e fina l

ASCII char acter.


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The following SCPI comm an d can be used t o query a digita l demodulation

user file from t he file system :

MMEM:DATA? "fil enam e"

For example, using the comm and

MMEM:DATA? "NE WDATAFILE"

will retur n the dat a #1912SA4D789 in the sam e #ABC format a s used in the

earlier example.

The following exam ple progra m demonst ra tes how to genera te a pr ogra m to

send a file and da ta to the H P E SG-D signal generat or's Userfile directory.

This program example was creat ed in Rocky Mountain Basic version 6.0.

10 Sig_gen=719

20 LOCAL Sig_gen

30 CLEAR Sig_gen

40 CLEAR SCREEN

50 OUTP UT Sig_gen;"*RST"

60 OUTP UT Sig_gen;"MMEM:DATA ""Newda ta file"",#1912SA4D789"

70 END

Exam ple programs showing how to apply basic SCPI concepts , ar e given in

Chapt er 7 "Opera tion "Userfile Applicat ions"" of th e HP ESG User Gu ide.

Once the file ha s been tra nsferr ed to the HP ESG series signal generat or,

existing an d newly-tr ans ferred files can be reviewed using the signal genera -

tor's memory cat alog.

1. P ress the Util ity butt on located under MENUS .

Note: Press the Local button to place the instrument in the local mode.

2. Now pr ess Memory Catalog

3. P ress (All ) to review all the files in th e system.

4. Now press Binar y to review th e binar y files tha t exist.

To generat e a GSM t ra ffic multiframe, one would need t o genera te bit

sequences for ea ch timeslot of the mult ifra me, download them to user

files, then select the custom bur st m ode in GSM a nd ident ify which

user file to insert in each tim eslot. The length of each timeslot file

would have t o be :

148 bits x 26 frames = 3848 bits = 481 bytes

where,

148 = the nu mber of dat a bits in a GSM Cust om timeslot

(the other bits are gua rd tim e and do not need to be loaded) and ,26 = the num ber of frames in a t ra ffic mu ltiframe

The 3848 bits would be sequent ially loaded in the selected timeslot thr ough

the 26 frames.

To simulat e a contr ol mu ltiframe, such as a BCH, a user file containing:

148 bits x 51 fram es = 7548 bits = 944 bytes

where,

148 = the nu mber of data bits in a GSM Cust om timeslot

(the oth er bits ar e guard tim e and do not need to be loaded) an d,

51 = the num ber of frames in a signaling mult ifra me


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19

could be downloaded int o timeslot #0 of the GSM fram e. The actua l data in

the u serfile would have to represen t th e appropriat e inform at ion for a BCH

(i.e. the da ta sequence corresponding to a FCH in fra mes 0, 10, 20 ; SCH in

frames 1, 11, 21 ; and so on). Remember t hat th e BCH tran smits its u seful

inform at ion always in tim eslot #0 - dumm y data or, for example, user filesrepr esenting a TCH, could be selected for one or all of the other timeslots.

The size of userfile that may be downloaded depends on the a vailable memory

of the signa l generat or's file system . Curr ently, the ma ximum a mount of space

available in th e file system is about 128 kbytes. The mem ory available for

dat a files also shrinks if memory is also used for sa ved inst ru ment sta tes or

sweep list files. There is enough mem ory in t he file system t o genera te m any

multifram es using userfiles, but there a re constra ints on th e num ber of user-

files tha n can be downloaded t o Cust om timeslots in order to generat e a GSM

superframe.

A GSM superfram e conta ins 51 * 26 fra mes = 1326 fram es. Therefore for an y

par ticular t imeslot, a GSM Cust om file would requir e:

1326 * 148 bits = 196248 bits of informat ion for th at timeslot.

This requires a 25 kbtye user file. Remember t hat the m aximum am ount of

memory available in t he file system is 128 kbytes ,so only a m aximum of 5 of

these userfiles could be stored in th e file system.

Now, consider how much space 1326 GSM fra mes t ake u p in dat a genera tor

memory.

1326 * 156.25 bits/tim eslot * 8 timeslots per fr am e = 1.6575 Mbits

When dat a is writt en to RAM, 1 bit of data r equires 1byte of pat tern RAM,

ther efore a GSM super fram e would requir e 1.6575 Mbytes of RAM.

Option UN3 cont ains 1MBytes of dat a genera tor memory (or pat tern RAM)

wherea s Option UN4 offers 8MBytes. Only Option UN4 can th erefore be used

to generate th e data pa ttern used to create a GSM superfram e. This may be

achieved by car rying out a "direct write" of data to the da ta generat or

memory. Details on how to car ry out t his direct writ e of dat a a re given in

Section 4.4.

4.2 Single /Continuou s Data patterns

A choice of wheth er t o outpu t just one occur rence of the selected dat a, or t o

output a continuous stream of the data pattern is available.

Fr om the first-level GSM menu , set the Pattern Repeat Single Cont to

Pattern Repeat Single an d the signal genera tor will output a single occur -

rence of the chosen dat a. Note that Exter nal dat a cann ot be selected when

Pattern Repeat is set to Single . Select the tr igger event for t he output using

the Pattern Trigger softkey. This softkey r eveals a men u of choices for tr ig-gering an unframeddata pattern . The data can be triggered by the front

panel Trigger key, by an exter nal t rigger supplied to th e PATTERN TRIG-

GER rea r pa nel connector, or by a comm and sent over H P-IB.

The Pat tern Trigger softkey is inactive when Data Format Pattern Framed

is set to Framed. To trigger a one-shot pattern the tr igger must m ake a t ran -

sition from low to high, an d is sa mpled by th e rising edge of the da ta clock.

The HP E SG-D also has the capability of tr ans mitt ing fra med dat a cont inu-

ously or output ting a single fra me. If only one t imeslot is on, selecting a single

framed t ra nsm ission (Fra me Repeat S ingle) will outpu t t he following

sequences:


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20

4-Bit Pattern s (FIX4) - A single fram e is genera ted. The 4-bit

patt ern r epeats u ntil the dat a fields are completely filled.

Each trigger tra nsmits the same frame.

P N9 - A single fra me is genera ted. The da ta fields ar e filled with

the leading bits of the PN9 sequen ce. A tr igger causes t he fram e tobe tran smitt ed. The dat a fields of this fra me ar e then filled

sequent ially with th e next series of PN9 dat a bits. A tr igger causes

the fram e to be tra nsmitted. This process continues, tran smitting the

entir e PN9 sequence fra me by fra me. The last bit of the P N9

sequence in a data field is immediately followed by the first bit of a

second PN9 sequence.

P N 15 - A single fra me is genera ted. The da ta fields ar e filled with

the leading bits of the PN15 sequen ce. A tr igger causes t he

frame to be tr an smitt ed. The dat a fields of th is

frame ar e then filled

sequent ially with th e next series of PN15 data bits. A tr igger causes

the fram e to be tra nsmitted. This process continues, tran smitting the

entir e PN15 sequence frame by fram e. The bit of the PN15 sequence

in a data field is immediately followed by the first bit of a second

PN15 sequen ce.

User Fi le - The user's file should have th e appr opriate dat a t o fill

an int eger num ber of times lots. If not, the rem aining bits are

tr uncat ed. Depending on the size of th e file, more th an one

frame can possibly be genera ted.

External Data - Extern al dat a is clocked into the da ta fields of

the t imeslot. A single frame is genera ted.

Triggering sin gle fra mes of data is described in Section 5.

To output a contin uous str eam of data, Frame Repeat Single must be

toggled to Frame Repeat Cont . Selecting Cont with fram ed data causes the

frames t o be tra nsm itted cont inuously.

Note:

As with Section 1, th e top level GSM softkey menu m ust be retur ned to,

and GSM On must be turn ed set and RF tur ned on.

4.3 Data Dependen cies

There ar e some situa tions where certa in combinat ions of dat a pat tern s will

cause the da ta t o be tru ncated or discontin uous. A discontinuous pat ter n will

mak e BER test ing invalid, ther efore, it is very import an t t o be awar e of these

situations.

Any combination of external data and a PN15 data pattern will cause a

discontinuous P N15 patt ern.

Any combinat ion of user 's files and a P N15 data pa tter n will cause a

discontinuous P N15 patt ern.

4.4 Generating long data patte rns, such as a GSM supe rframe.

The HP E SG-D signal generat or (with Option UN3/UN4) offers the user t he

capability to generate long data patterns, and store them in the signal gener-


21/43

21

ator's pattern RAM.

The length of data sequence that can be stored in the pat ter n RAM depends

on the insta lled optional baseban d genera tor. Option UN3 pr ovides 1MB of

RAM and Opt ion UN4 offers 8MB. This tr an slates t o maximum lengths of

data sequences of 1Mbits a nd 8Mbits r espectively, becaus e each bit of data

requires 1Byte of RAM. This is becau se ther e are other par am eters, such as

whether RF power is to be switched on, that mus t be set for each bit of data .

This met hod of dat a gener at ion r esults in a flexible means of contr olling

every single data bit in a user-defined sequence.

The SCP I comm an d MEM:DATA:PRAM: BLOCK #0 < dat a_block >

(or MEM:DATA:PRAM: LIS T < uin t8 ,...,...> )

allows a block of ASCII da ta or a str ing of decima l values t o be written

directly to the dat a genera tor memory (patt ern RAM). This data t akes over

the bur st contr ol of the m odulating signal. The entire dat a genera tor memory

is cont rolled by th is comma nd. In other words, th e user is in cont rol of how

the m odulation is implemented. The featur es of the bu ilt-in comm unications

form at s, such as t imeslots a nd t imeslot t ypes, can no longer be u sed. To car ry

out a direct load of dat a int o the pat tern RAM, the desired comm unications

mode must be selected in order to set up the baseband generator a nd dat a

generat or clock r at es for t ha t m ode. For exam ple, if GSM tra nsm ission is

required, press Mode , GS M, GSM On , to set the clock rat e for GSM tr ans -

mission. This will ensure the dat a is tr ansmitt ed at t he correct ra te.

Note that when th e front pan el or SCPI u ser inter face of a mode resum es its

norma l opera tion, the user int erface is ta king back the contr ol of th e data

generat or m emory. This means t hat all previous user data written to the

patt ern RAM by the above comman d will be erased.

As mentioned ear lier, one byte of data is used for every data bit produced.

The pur pose of th ese bits is as follows :

Bit Pos ition Bit Valu e (in de cimal) UN3/UN4 valu e0 1 data value

1 2 0 a lways

2 4 burst cont rol

3 8 0 a lways

4 16 must always be set to 1

5 32 0 a lways

6 64 Event 1 cont rol

7 128 Pat tern Reset

Bit 0 ("data value") should be set to a 0 or 1 as requ ired for a da ta bit.

Bit 2 ("burs t cont rol") should be set t o a 0 for bur st off or 1 for bur st on.

All data values tha t requires bursted RF power out must have this bit on.

The "Event 1 cont rol" bit (Bit 6) should be set to a 0 or 1, as desired , to be

output a t th e EVENT 1 rea r pan el connector. "Pattern Reset" should be set to a 1 to reset the patt ern generation to the

star t, after t his entry is pr ocessed.

The user, ther efore, has complete contr ol over t he value of dat a bits t ra nsm it-

ted, wheth er RF power bur st is on, how long th e burs t will be on for, and


22/43

22

where to reset the patter n.

For example, to store a da ta value of 1, with burst contr ol on, the decimal

value of th e dat a would be 21.

To send a fixed 4 bit repeat ing sequence of 1100, with bur st on, th e value th e

comm and ma y look like th is:

MEM:DATA:PRAM:LIST 21,21,20,148

Each "block" represents the dat a bit an d all it 's parameters, and takes up

1Byte of RAM. Note th at t he last value in t he sequence, 148, sets t he Pat tern

Reset bit, so tha t th e data counters for the mem ory will reset a t th e beginning

of the 1100 sequence.As mentioned in Section 4.2, the da ta bits corr esponding to the 1326 frames

in a super frame could be genera ted an d loaded into the pat ter n RAM. There

ar e 1250 bits in a GSM fra me an d ther efore a su perfram e contains 1.6575

Mbits. This would require 1.6575MB of RAM, when using the direct load

meth od. In order t o have sufficient mem ory for generat ing a GSM superfram e,

Option UN4 (which has 8MB of pat tern RAM) must be inst alled. Unlike the

custom file method, all the bits in t he su perfram e mus t be specified - this

includes gua rd bits, cont rol bits a nd da ta bits. To genera te a continuous

super frame t he Pat ter n Reset bit should be set for th e last bit in the sequence,

so that t he data generat ion will star t again at the first bit of the superframe.

Bit Position

Setting

Bit Value

= 21 !

16 + 4 + 1

Event 1 Burst Data

7 6 5 4 3 2 1 0

0 0 0 1 0 1 0 1

always"1"

Figure 11.

Sett ing data values

1 Byte 1 Byte 1 Byte 1 Byte

"1" "1" "0" "0"

Pattern Reset Bit

was set to '1'

0 0 0 1 0 1 0 1 0 0 0 1 0 1 0 1 0 0 0 0 0 1 0 0 1 0 0 1 0 1 0 0

21 21 20 148 etc.

Pattern Reset Bit

Figure 12.

Blocks of data


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23

There a re several options available to the user to trigger a single GSM frame.

These ar e using th e Trigger key, triggering over th e bus, and t riggering the

frame externa lly.

Fr om the GSM mode:

Select Data Format Framed .Toggle Frame Repeat Single Cont to Frame Repeat Single .

Press the Frame Trigger softkey t o display the ra nge of options:

Trigger Key - Press the front panel Trigger hardkey to output one frame of dat a

Bus - Pr ess this softkey to tr igger th e single fram e over HP-IB

External - Pr ess this softkey to trigger a single fra me from an externa l

source. The fram e triggerpulse mu st be sent t o th e PATTERN

TRIG IN rea r pa nel BNC input connector. The HP ESG-D is

tr iggered when t he CMOS input tr ans itions from low to high,

then one frame of data is generated. The minimum trigger input

pulse width , high to low, is 100ns. The trigger edge is latched

and sampled by falling edge of data bit clock to synchronize

tr igger with bit t iming. At the end of the fra me, guard bits a re

generat ed unt il a new tr igger is received . If the tr igger

ar rives t oo ear ly (1.5 to 2.5 bit clock periods before th e end of a

frame), it will be ignored an d the n ext frame is delayed unt il the

next valid tr igger occurs. If th e tr igger occurs too lat e (between

N-1.5 to N-2.5 bit clocks a fter t he fra me ends ), then t he fram e

begins N bit clocks a fter t he pr evious frame ends. For exam ple ,

if the trigger occurs between 0.5 and 1.5 bit clock periods after

the fra me ends, i.e. N=1, then 1 add itiona l bit is inserted in

between frames (i.e. next frame begins 1 bit clock period after

previous fra me ends). For m ore inform at ion on fram e and

pat tern tr igger tim ing, see Section 7 of the E SG User Gu ide.

An applicat ion for th e externa l fra me tr igger featur e is in GSM Base Sta tion

manufacture. The BTS transmits its timing information on the downlink BCH,

including deta ils of the fra me t iming. The BCH is used t o comman d th e mobileand t ell it when to respond and sta rt commun icat ion with th e BTS. In Base

Sta tion testing, the HP ESG-D signa l genera tor (configured with th e optional

IQ baseband gener at or) can be used simulat e a mobile in order t o send a signa l

to the BTS t o verify correct BTS operation. The HP ESG-D must ther efore be

capable of sta rt ing its tr an smission at th e correct time relative to the BTS

tr ans mission, as would a 'real' mobile station. To achieve this, the HP ESG-D

can be configur ed to accept a frame tr igger (sett ing Frame Trigger External

and supplying BTS fra me clock to PATTERN TRIG IN r ear pan el connector)

from t he BTS, as sh own in the following diagram . This synchronizes the

HP ESG-D to the BTS.

BTS

Tx BTS

Rx

Frame Clock

Combiner

Pattern Trig In

RF OUTPUT

HP ESG-D

Figure 13.

Applicat ion of exte rnal

frame trigger

5. Trigge ring a

GSM Fram e


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24

If the BTS sends a t rigger at the sta rt of every fram e, and the HP ESG-D is

set up with an y of th e intern al data selections (PN9, PN15, FIX4, Other

Pat ter ns) , the ESG-D will send a fra me of th e chosen data every time it

receives the t rigger. Some Base St at ion t ests, however, may r equire a st rea m

of frames from the H P E SG-D to synchronize to a single trigger from th e BTS.In t his case, a us er file conta ining the appr opriate nu mber of bits for th e

num ber of fram es needed in the strea m could be used.

Settin g a trigger delay

A program ma ble delay, in bits, may be set in order to trigger the H P ES G-D

in a different timeslot. This featu re is only available when t riggering the

signal genera tor exter nally. The Tr igger Delay r esolut ion is one data bit clock

period.

To set t he extern al tr igger delay:

From the Frame Trigger men u, a s descr ibed above, select exter na l triggering:

Select th e Ex t softkey.

Se t Ext De lay Off On to On

Press the Ext Delay Bits softkey

Ent er th e desired delay using the front panel knob, up an d down

arr ow keys, or the n umeric keypad, and press th e Enter terminator

softkey. The ma ximum pr ogra mm able delay is 65,535 bits. Note t ha t

sett ing the t rigger delay to the frame bit count m inus t wo will allow

the frame to sta rt within +/- one h alf bit clock of trigger edge.

For exam ple, the GSM Fr am e bit count is 1250, th erefore sett ing the

delay to 1248 will allow th e fram e to st ar t with in h alf a bit clock of

the t rigger.

To tr igger th e HP E SG-D series signal generat or to start producing

frames contin ually.

Fr om the GSM mode:

Select Data Format Framed .

Toggle Frame Repeat Single Cont to Frame Repeat Cont .

Press the Frame Trigger softkey t o choose between t riggering using t he

front panel Trigger key, or over

HP-IB (Bu s softkey).

Synchroniz ing equipment to the HP ESG-D series s ignal gene rator

The HP E SG-D series signal generat or may also be used to tr igger other

equipment.

Fr om the first level GSM menu , press the More (1 of 2) softkey.

Press the Sync Out softkey t o display the menu of choices for output ting a

1-bit synchronization signal to th e EVENT 1 r ear pan el connector.

Begin Frame synchronization signal occurs a t t he beginningof t he GSM frame.

Begin Timeslot # synchronization signal occurs a t t he beginning

of th e selected GSM t imeslot. Any one of the 8

timeslots ma y be selected.

Timeslot All synchronization signal occurs a t t he beginning

of the ea ch timeslot in t he GSM fram e


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25

It is also possible to move the synchr onizat ion signa l forwar d or back from t he

beginnin g of the fra me or t imeslot.

Fr om the GSM first level menu , press the More (1 of 2) softkey.

Press the Sync Out Offset to set the num ber of bits of offset.

Enter the desired value using the numer ic keypad, the up and downar row keys, or th e front pa nel knob and pr ess the Enter terminator

softkey. The range of allowed values is 155 through +155 bits


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26

The HP ESG-D series signal generat or (with option UN3 or UN 4) provides the

flexibility t o modify the commun icat ions form at s pr ovided. For th e GSM per son-

ality, the modulation dat a r ate, the burst shape an d the Gau ssian Filter Factor

can all be modified. Note that adjustin g these factors mea ns th at t he signal

generat ed will no longer be a st an dar d GSM signa l. The display annu nciator

will cha nge from GSM:STANDARD to GSM:MODIFIED when an y of the

aforementioned attributes a re a ltered.

1. P ress the Mode front pa nel har dkey.

2. P ress the GS M softkey.

3. P ress the More (1 of 3) softkey a t th e bottom of the display.

A menu containing t he softkey options an d Modify Stan dard will be

displayed.

4. To alter th e data r ate or the filter alpha, press Modify Standard .

4.1 To adjust t he filter factor, press th e Filter softkey.

The choice of filter factor r an ges from 0.2 to 0.7, in 0.05

increment s. To enter a new value for filter alpha , rotate th e front

panel kn ob unt il the desired value is displayed, use the up a nd

down ar row keys, or ent er th e value using the num eric keypad.

The display should n ow include a s ymbol in t he F ilter field, to

indicate that it differs from th e GSM standa rd.

4.2 To adjust th e modulation data rat e, press the Bit Rate softkey.

A dat a r ate with in the r ange 163 kbit/s to 300 kbit/s may be

selected. To enter a new value for th e modulation data ra te,

rotat e the front pan el knob unt il the desired value is displayed,

use the up an d down a rrow keys, or ent er th e value using the

numeric keypad and press the kbs softkey. The disp lay sh ould

now include a s ymbol in th e Bit Rat e field, to indicate th at it

differs from the GSM sta ndar d.

Th e Restore Defau lt Filter BbT and the Restore Default Bit Rate softkeys

set th e filter factor and m odulation dat a ra te to the GSM stand ar d values of 0.3

an d 270.833 kbit/s res pectively.

5. To alter t he GSM Burs t Shape, press Burst Shape .

Within t his men u, the r ise and fall times of th e GSM burst m ay be modified.

The rise a nd fall of the bur st can also be delayed from th e default values.

This is useful for doing mar gin testing an d adding impairm ents t o existing

systems, an d for t he development of new system s.

5.1 To adjust th e rise an d fall times, press the Rise Time and Fall

Time softk eys r espectively.

To enter a new value for t he rise/fall time, rotate th e front pa nel knob until

the desired value is displayed, use th e up an d down ar row keys, or ent er th e

value using the nu meric keypad and press th e Enter softkey. Rise an d fall

times can be set in bit periods, with in the limits 0.2 to 30 bits.

6. Customizin g the

GSM Mod e


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27

Here, the rise time ha s been decreased from t he stan dard value, meaning that

the power level is ra mped u p too quickly, and th e bur st profile does not fit

within t he desired m ask. This could cause inter ference with other mobiles in

the cell.

5.2 To delay the rise or fall of th e GSM bur st , press t he

Rise Delay and Fall Delay softkeys r espectively. Delay tim es of up

to 10 bit clock periods can be set. To enter a new value for th e delay

time, rotat e the front pan el knob unt il the desired value is displayed,

use the up an d down a rrow keys, or ent er th e value using the

numer ic keypad and press the Enter softkey.

Here, a rise delay has been added to the burst . As can be seen, the

burs t pr ofile is now right at the lower limit of the ma sk. Any furt her

delay would r esult in the output power level being rea ched too late,

and useful bits of information could be lost.

Th e Restore Default Burst Shape softkey restores the burst shape values

to the r ise/fall tim es of 4.22 and 3.44 bit clock per iods and ris e/fall delays of

zero an d 4.38 clock periods.

+1.0 dB

1.0 dB

+4 dB

6 dB

30 dB

70 dB

6 dB

30 dB

70 dB

147 "Useful" Bits

542.72s


3 57 1 26 1 57 3

10s 8s 10s 10s 10s8s

Power

Time

Figure 14.

Adjust ing the rise t ime of a

GSM TDMA Pow er Bu rst

+1.0 dB

1.0 dB

+4 dB

6 dB

30 dB

70 dB

6 dB

30 dB

70 dB

147 "Useful" Bits

542.72s


3 57 1 26 1 57 3

10s 8s 10s

Rise Delay

10s 10s8s

Power

Time

Figure 15.

Adding rise delay to a GSM

TDMA Pow er Burst


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7. Adjacen t Broadc ast

Channel Generat ion

usin g HP ESG-D series

s ignal generator and theHP 8922 GSM Tes t Se t.

The pur pose of this section is to demonstr at e how the HP ESG-D series signal

generat or can be used with the HP 8922M GSM Mobile Test Set t o generat e

an Adjacent Broadcast Channel.

The HP 8922 fam ily of GSM MS Test Set s ar e integrat ed test solutions for t he

production a nd ser vicing of GSM radios. The HP 8922 used in th is product

note is designed for m anu factur ing, providing accur at e and r epeata ble

measurem ents for consistent t est r esults. The HP 8922M test set generally

follows th e procedur es as outlined in th e associat ed GSM recomm endat ions,

but does not necessar ily meet t he exact requirem ents or cover all ran ges,

limits or conditions requ ired for type appr oval t esting.

As mentioned in S ection 2, a ll Base St at ion Tr an sceivers (BTSs) continua lly

tr ans mit a Broadcast Cha nn el (BCH). The BCH is like a beacon - it allows

mobiles to find th e GSM net work. Th e BCH consists of var ious par ts for

frequency correction, synchronization, control and access. Its exact configura-

tion varies on the n um ber of user s expected in t he cell. The ARFCN u sed by

the BCH is different in each cell. The mobile ha s a list of these frequency

channels in the Base Allocation (BA) table, in order to know which BCH

frequencies to go out and measu re. The BA table is coded onto the BCH. The

BA ta ble will differ for GSM 900, DCS 1800 an d PCS 1900 system s. The BCH

is always received by all mobiles in a cell, wheth er t hey ar e on a call or not.

Ea ch m obile measur es th e power of the ser ving cell and t he a djacent cell's

BCH. Mobiles also measur e the st rengt h an d quality of the signa l being

received on the Traffic Channel. Measurements of Received Level (RxLev)

and Received Quality (RxQua l) are report ed back to the serving cell base

sta tion. RxQual r eport s can be ma pped onto bit-error r at io. The RxLev

num bers can be ma pped directly onto signal levels in dBm. As a m obile

roams a round, it continu ally measur es th ese power levels. If the mobile

moves far from t he se rving BTS, i.e. if th e RxLev becomes sufficient ly low on

th e ser ving cell, th e mobile will switch to an adja cent cell which is closer.

In th is section, two broadcast chan nels will be genera ted on different

ARFCNs, and sen t to a mobile, using the HP 8922M GSM Test Set a nd th eHP ESG-D series signal genera tor .The t wo BCHs will have different

Broadcast Colour Codes (BCCs) to allow the mobile to differentiate between

the HP 8922M BCH an d the H P E SG-D BCH.

A BCH at RF, corresponding to a certain ARFCN, will be sent to a mobile

using th e HP 8922M. Then BCH inform ation at ba seband will be generat ed

using th e 8922M GSM Test Set . This data will be modulated up to a

frequency corresponding to a different ARFCN u sing the HP ESG-D series

signal generat or and s ent t o the mobile. It will then be possible to verify tha t

the mobile can find both signals (or both BTSs).

There a re formulae given in Section 9 to convert ARFCNs int o absolute

frequency values. The deta ils for cell selection an d r eselection ar e given in

Chapter 20 of the GSM 11.10 Specifications.


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Connect t he HP 8922M MS Test Se t, the HP ESG-D Signal generator

and the mobi le under test

1. Connect th e HP 8922M, HP E SG-D an d the m obile to be tested, as

shown in Figure 16.

2. Power on th e HP 8922M, th e HP ESG-D series signa l generat or

and t he mobile.

Set up HP 8922M to send broadcast data to HP ESG-D signal gene rator

Th e H P 8922M has default sett ings to broadcast on frequen cy chann el ARFCN

20 with a n am plitude of -85dBm. Different sett ings for these par amet ers ma y

be chosen if desired, but this will n ot be covered in t his note. Remember th at

the in sert ion loss thr ough the power divider m ust be accounted for, as t his willaffect the a mplitude of the signal.

3. Fr om the front pan el, press the Cell Config hardkey.

4. Go to the BA (Base Allocat ion) Table. This is a t able th at is sent to

the mobile to let it know which BCH ARFCNs ar e active in its cell.

First of all position t he cur sor on th e "Activat ed" field, push t he k nob

and change to "Sett able". There ar e 124 possible cha nnels t hat can be

set. Position t he cursor t o the top left "0" an d push th e cursor contr ol

knob.

A channel may be selected by going to the corresponding

position in the ta ble, and s etting th e value to "1" .

For exam ple, to set chan nel 10 for GS M, "Position" would be

selected. The cursor cont rol knob would t hen be used to go

to the r ight ha nd column in th e first row. This position

(for chan nel 10) would be selected, an d a "1" set t o activate

this ARFCN. When editing is complete, "Done" and then

"Activate d" are s elected. This t ells th e mobile to look for a

BCH on ARFCN 10.

5. Use th e selection knob to go into the "Aux BCCH " menu

Select "Adjacent "

This tur ns th e Modulat ion In /Out Da ta a nd Clock to OUT - the

HP 8922M will send data to the HP ESG-D signal genera tor.

POWER

Data

Clock

Power Divider (HP 11636A)RF IN/OUT RF OUTPUT

HP 8922 M HP ESG-D10 MHz Out 10 MHz In

Figure 16.

Diagram of se t-up


30/43

30

Set up HP ESG-D signal generator

6. Press Frequency . Ent er "937MHz". This sets th e adjacent signal

to th e frequency chan nel ARFCN 10. Any ARFCN ma y be chosen,

provided it is different from th at set on HP 8922M

7. Press Ampl. Set t o the power level to a value different from tha ton the 8922M broadcast chan nel (i.e. 85dBm in t he default case).

The amplitude of the signal should be lar ger than the sensitivity

level of the mobile. For example, set t he a mplitude t o 100dBm.

In order t o ta ke into account th e insertion loss th rough th e power

divider, enter an am plitude offset in the Ampl menu. The typical

insert ion loss for a power divider is 6.2dB, therefore t he Amplitude

Offset should be set to 6.2dBm .

8. Press Mode.

Select GSM.

Select Data Format Pattern

Press the Data softkey

Select th e Ex t softkey. This means th at the dat a from the

8922M is the m odulation pr ovided.

Turn GSM On Offto GSM On .

9. Turn RF On Off to RF On .

Check that the mobi le can camp to both s ignals

10. Slowly decrea se the am plitude of th e signal of th e HP 8922M,

unt il it is much lower tha n th at of the HP ESG-D signal generat or.

The mobile should camp onto the signal from the s ignal generat or

becaus e its RxLev will be better. This can be verified by increasing

th e amplitude of signal from the HP ESG-D signal genera tor, and

checking tha t th e signa l stren gth on the m obile's display increases.

Lowering the am plitude of the signal genera tor should result in th e

displayed mobile signal level decreasing, until finally it will camp on

to the signal from the HP 8992M again.


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31

The receiver measu rements for r adios in th e GSM system m ake use Bit E rror

Rate (BER) techniques. A known pseudora ndom binar y sequence (PRBS) is

tr ans mitt ed to the m obile station which loops the received bits, after chann el

decoding, back to th e test equipmen t th rough its own tra nsm itter. The BER is

eva lua ted with in th e t est er (such as the HP 8922 GSM Mobile Station Test Set).In t he following sections, some key GSM mea sur ement s will be ma de using

th e HP 8922M GSM Mobile Sta tion Test Set a nd th e HP E SG-D series signal

generat or. Note th at t his is not a compr ehensive guide to the HP 8922M

Test Set, nor an in -depth stu dy of the GSM measur ement specifications.

For details of th ese area s, please refer to the HP 8922M documen ta tion and

th e relevant sections of the ETSI GSM specifications.

There a re formulae given in S ection 14 to convert ARFCNs into absolute

frequency values.

8.1 Receive r Co-Channe l Rejection

Co-cha nnel r ejection meas ur es a r eceiver's a bility to receive a wan ted m odu-

lated signal in th e presence of an unwan ted modulated signa l, both signals

being at th e same frequency. Bit error ra te is then measur ed to ensure the

receiver is r ejecting the un want ed signal. The test is described in detail in

the ETSI GSM Specifications 11.10 (Section 14.4)

The HP E SG-D series signal genera tor can be used as the un wanted source,

as it provides pr ecise 0.3GMSK modulation. The want ed signal can be gener -

ated using a test system such as the HP 8922M GSM MS Test Set.

Varia tions from t he GSM 11.10 Section 11.4.4 Test Recommen da tions

The HP 8922M does not us e the st anda rd t est signal "C1" for t he in-cha nnel

source. The sta nda rd test s ignal is a 1-0 pat tern with "dummy" bur sts for all

other t imeslots of the fra me. The HP 8922M uses a 1-0 data pa tt ern bu t does

not tra nsm it "dum my" burst s in all oth er timeslots. The HP 8922M can not

generat e a progress messa ge to the m obile station. This is a signaling

messa ge inst ead of speech. The HP 8922M does not simulat e fading.

An externa l fader, e.g. HP11759C, needs to be used with th e HP 8922M tomeet t he GSM recomm endat ion. The HP 8922M and HP ESG-D signa l gener-

at or can not test the m obile station in hopped mode, becaus e the E SG-D signal

generator cannot generate a hopping signal.

Co-Chann el Reject ion Measurem ent P rocedur e

POWER



Figure 17.

Diagram of test se t-up

8. Using the ESG-D se ries

s ignal generator and

the HP 8922 GSM Tes t

Set to carry out GSMMS receive r tests


32/43

32

Connect the HP 8922M MS Test S et, the HP ESG-D Signal

generator and the mobi le under test as sh own in Figur e 17.

1. Power on all equipment BUT ensur e the HP ESG-D signal genera

tor ha s RF On Offset to RF Off

Set u p the HP 8922M MS Test S et

2. Preset the HP 8922M. Press the Preset front panel ha rdkey.

3. Fr om the Cell Sta tus Screen, use th e cur sor control to scroll to

" To Screen, More".

4. Select "Cell Cont rol 2".

5. Fr om the Cell Cont rol 2 screen:

-Under "TCH Pa rm s" set th e following:

"TCH1"

Mode "Single"

ARFCN "60"

Check tha t "FS" is selected (this s hould be as it is

the default setting)

-Select "TCH Cont rol"

-Select "TCH1 Asgn"-Highlight "Execute

-Scroll to Audio Cnt l. Set "Loopback" to "FE"

(This turns Fr ame Era sure on)

-Set "Speech" to "PRBS "

-Set "PRBS Patt rn " to "10"

-Set "RF Gen" , "Amplitu de" to "85dBm" as d efined in t he

GSM specification. (Take into account the insertion loss

thr ough the power divider. For example, if the inser tion loss

for your power divider is 6.2dB, th e "Amplit ude" should be

set to 78.8 dBm to compensate for the loss. Alternatively,

the RF a mplitude offset field in t he HP 8922M I/O

configur ation could be set to account for th e loss thr ough

the divider.)

6. Check that the mobile is camped onto the signal from the HP 8922M.

7. Scroll to the lower right h and corn er men u, and select the

"BIT ERR 2" option. Under t he Bit E rr or Test screen "BIT ERR 2"

-Under "Meas Nu m 1","Type", select "ResTypeII ".

-Under "Bits t o Test", enter t he desired n umber of bits

accordin g to th e GSM specificat ions (see Table 14.14 on

Specifications 11.10). For exam ple, ent er "2,000,000".

-Under "Meas Nu m 2","Type", select "ResTypeIb".

-Under "Bits t o Test", enter t he desired n umber of bits

accordin g to th e GSM specificat ions (see Table 14.14 on

Specifications 11.10). For examp le, ent er "3,300,000".

-Un der "MS Loopba ck" ,"Loop Delay Speech Frms" set to "Auto".

Set up HP ESG-D signal generator

8. Press Frequency front pan el har dkey. Ent er "947MHz". This sets

th e inter fering signal to the sam e frequency channel as the in-cha nnel

signal (ARFCN 60)

9. P ress the Ampl front pan el ha rdkey. Set to "-94dBm" Compensa te

for t he inser tion loss th rough th e power divider by setting the

Amplitude Offset to 6.2dBm . This sets t he int erference signal t o 9dB

below the want ed signal, as specified in th e GSM recommendat ions.


33/43

33

10. Press Mode .

Select GS M.

Se t Data Format Pattern Framed to Data Format Pattern

Select r andom da ta e.g. set Data to P N9


11. Turn RF On Offto RF On .

12. Set up a call from the mobile.

On the HP 8922M:

13.Under "MeasCntl" select "Single" and "Run". This will perform

the bit error test.

Compa re th e results t o those shown in the Test Limits Table in th e

GSM 11.10 Sp ecifications.

To change channel numbers for ad di t ional m easurements

14. Fr om the HP 8922M Cell Cont rol 2 screen:

-Under "TCH Par ms" set th e following:

"TCH1"

Mode "Single"

ARFCN - Enter the n ew chann el number you wantto test.

-Select "TCH Cont rol"

-Select "TCH1 Asgn"

-Highlight "Execute

15. Set the HP ESG-D signal genera tor Frequency to the frequency

of t he new chann el.

16. Repeat st eps 9 and 15 to measure bit-error rat e.

8.2 Adjacen t Chann el Rejection

Adjacent Ch ann el Rejection or Adjacent Cha nnel Selectivity mea sur es th e

GSM receiver's ability to reject a n un wanted signa l tha t is one or two cha nnelspacings from th e receiver's n ominal frequency. This is pr obably the most

importa nt out -of-chann el test per form ed on radios. It determ ines how well

th e radio will perform when other r adios are operated in t he adjacent RF

chann els. The t est is described in deta il in the E TSI GSM Specifications 11.10

(Test 14.5)

Testing adjacent channel selectivity requires a n in-cha nnel signal genera tor

set to the nominal center frequency of the r eceiver. This is a chieved by using

an H P 8922M Test Set t o esta blish a call with th e mobile on th e cha nnel

und er test . A second signal generat or is used to simulate a n un wanted or out-

of-chan nel signal. It s frequen cy is set to +/ one or two chann el spacings from

th e receiver's nominal cent er frequency, and is modulated with r andom da ta.

The outpu t level of the out-of-chan nel signal genera tor is set to a h igher level

(defined by the GSM sta ndar ds) than t he in-cha nnel signal generat or.

The HP ESG-D series signal genera tor can be used as t he out-of-channel

source, as it provides precise 0.3GMSK modulation. A featu re of the HP ESG

series signal genera tor is th at ther e ar e two choices available for optimizing

phase noise to suit your applicat ion.The ph ase-lock loop bandwidth may be

set to optimize ph ase noise for offsets below (Mode 1) or above (Mode 2)

10kHz offsets. For out-of-channel m easu remen ts (as in t his case), Mode 2

should be selected. This is the m ode selected a fter norm al preset , but t he

mode selection procedure will be described for futur e r eference purposes.

Varia tions from th e GSM 11.10 Section 11.4.5 Test Recomm enda tions

As sta ted in Section 4.1, th e HP 8922M does not generat e the sta ndar d test

signal "C1" or simu late fading.

Adjacent Cha nnel Reject ion Measurement Procedure


34/43

Connect the HP 8922M MS Test S et, the HP ESG-D Signal

generator and the mobi le under test as show n in Figure 17

Power on all equipment BUT ensu re th e HP E SG-D signal generat or

has RF On Offset to RF Off

Set u p the HP 8922M MS Test S et

1. Preset the HP 8922M. Press the Pr eset front pan el har dkey.

2. From the Cell Statu s Screen, use the knob to scroll to Screen More

3. Select "Cell Cont rol 2".

4. Fr om the Cell Contr ol 2 screen:

-Under "TCH Par ms" set th e following:

"TCH1"

Mode "Single"ARFCN "60"

Check tha t "FS" is selected

(this should be as it is the default sett ing)

-Select "TCH Contr ol"

-Select "TCH1 Asgn"

-Highlight "Execute

-Scroll to Audio Cntl. Set "Loopback" to "FE"

(This turns Fr ame Era sure on)

-Set "Speech" to "PRBS "

-Set "PRBS Patt rn " to "10"

-Set "RF Gen" , "Amplitu de" to "85dBm" as d efined in t he

GSM specification. (Compensate for the insertion loss

th rough th e power divider).

5. Check that t he mobile is cam ped onto the HP 8922M.

6. Under t he Bit Err or Test screen "BIT ERR 2"

-Under "Meas Nu m 1","Type", select "ResTypeII".

-Under "Bits to Test", enter th e desired num ber of bits

accord ing to th e GSM specificat ions (see Table 14.21 on

Specificat ions 11.10). For exam ple, enter "600,000".

-Under "Meas Nu m 2","Type", select "ResTypeIb".

-Under "Bits to Test", enter th e desired num ber of bits

accord ing to th e GSM specificat ions (see Table 14.21 on

Specificat ions 11.10). For exam ple, enter "1,000,000".

-Under "MS Loopback","Loop Delay S peech Fr ms" se t

to "Auto".

Set up HP ESG-D signal gen erator

34

POWER



Optional Diagram of set-up

(same as Co-Channe l Setup

Figure 17)


35/43

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7. Press Freq front pan el har dkey. Ent er "947.2 MHz". This sets t he

inter fering signal to the carrier frequency plus 200kHz (i.e. ARFCN 61).

The procedure to select phase noise Mode 2, will now be described.

Press the Optimize Noise softkey.

Press the Mode 2 Optimize > 10kHz Offset softkey.

8. Press Ampl front pa nel ha rdkey. Set t o "76dBm". Take into

account t he inser tion loss th rough th e power divider by setting

Amplitude Offset to, say, 6.2dBm. This sets th e am plitude of the

out-of-chann el signal to 9dB above tha t of the in-cha nnel signa l, as

specified in t he GSM r ecomm endat ions.

9. Press Mode .

Select GS M.

Se t Data Format Pattern Framed to Data Format

Pattern .

Select a random data pattern . Set Data , PN9 .


10. Turn RF On Offto RF On .

11. Set up a call from t he mobile.

On the HP 8922M:

12. Und er "MeasCn tl" select "Single" an d "Run ". This w

Documents

HP-PNESG-1_Using the HP ESG-D Series of RF Signal Generators and the HP 8922 GSM Test Set