RF basic P3

7/23/2019 RF basic P3

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RF basic P3

1. What is the analog and digital signal?What is pulsed RF signal? (Each burst can bereferred as Pulsed signal). what is bit,!"bol # baud ?what is the relation betweenbandwidth re$uire"ent and "odulation?rate?(bit%infor"ation,s!"bol%baud %trans"ission energ!,it can be an! nu"ber of bit)

!"bol rate%bit rate&n%bandwidth re$uired, n%log'(") if "%1 bits in *+ then n%

Modulation

Channelspacing(MHZ)

RadioMode

MinE1Mapping(Ch)

Max ETHBandwidth(Mbps)

MaxE1canbeassigned

EthBWavailablewhenMaxE1 inuse

P- /ighcapacit!

0 10 0

1*+

/igh

capacit! 0 '' 10 1

3' *+ /ighcapacit!

0 ' 13 0

*+ /ighcapacit!

0 33 1 '

1'2 *+ /ighcapacit!

0 3 12 1

' *+ /ighcapaci

t!

0 '1 0

uppose we need ''"bps speed or 10 E1 and we use 1*+ so our bandwidthre$uire"ent is!"bol rate%''&%."ega s!"bol,each bits s!"bol is carried in 1 c!cle so we need4100000%+ega c!cle or +h5.

'. /ow "an! signaling "ethod are in E1 co""unication? 66,6*

3. /ow data is co""unicated in E1?

The total symbol rate for GSM per symbol in GMSK produce

270.833 K symbolssecond. Thtransmission rate of the time sl22.8 Kbps.

The tim

is de"

transm

mana!

and tim1# for

si!nal

synch

n proc

then

establ

and it

know

frame

7/23/2019 RF basic P3


. What is constant en7elop?Wh! we need this?

. What t!pe of a"pli8er is used in 9+,+?Wh! we don:t use ad;acent ch?<ecause 9+- "odulation has a constant en7elope. non=linear a"p will not add an!distortion, a class 6 RF power a"pli8er is used to "a>i"i5e power ecienc! @head;acent channel "a! ha7e so"e additional distortion if the a"p is linear and dri7en to

saturatio.A+B33. What line coding is used in "obile co""unication?RC,DRC,Mancheste coding?What is

6 co"ponent?Wh! do we use DRC?what is spectral ecient coding? What do weunderstand b! spectral ecient?

DRC "ore spectrall! ecient than RC but oer poorer s!nchroni5ation because of large dcco"ponent. DRC is not used in audio a"p or phone lines due to the fact that these ' t!pesof circuits are dc blocGing.+anchester has no dc co"ponent and can be passed through *udio or phone lines.. /ow "an! $uanti5ation le7els are in nor"al telephon! ,9+? ',21' le7els

7/23/2019 RF basic P3


2. What is 7ocoders?what is the rate of *+R FR,/R? Bocoder is a wa7e for" sa"plescoder .9+ uses RPE=A@P codec.

. What is 7iterbi coder used for? @he recei7er begins a process in which it uses itsGnowledge of what happened the training se$uence to correct the speech data bits of thetrans"ission.

10. What are the inHuencing factors choosing "odulation techni$ue?a.Aow bit rate (8delit! or acceptable bit error probabilit!) Eb&D0 power ecienc!.b.Perfor"s well in "ultipathc.Fading conditionsd.Iccupies "ini"u" bandwidth( J energ! con8ned in allocated bandwidth) "eaningJ energ! within 1:rst order har"oni.e.6ost aecti7it!

The lo%er the sample codin! bits &the

lo%er the M'S&the hi!her the

con"olution codin! bits. The bits %etal(ed here are not the bits )uanti*ed

form speech %a"e form& bit fromcoders.

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RF basic P3