RF linked simulcast radio network

The best solution for wide area radio coverage

ABSTRACT

This presentation wish to explain the characteristic aspects of a simulcast radio

network. It will be considered only one broadcasting channel, RF linked, network,

but the same structure can be implemented for multichannel broadcasting.

Block diagrams of received signals up-link and transmited signals down-link

elaborations, togheter with an axplanation of the effects of amplitude, phase and delay

equalization, give a clear overview of network potential.

A simple propagation model simulation can help to correctly size network, which,

thanks to the “low” radio frequency band used, can cover a very wide geographical

area with a small number of repeaters. To further extend coverage area, a network

configuration including sub-master station will be explained.

Master, submaster and slave station appearance drawings and an example of a

network economic cost calculation will close this presentation.

Network – signal connections (1 ch)

Master

Fixed stationCH1

CH1

•The same RF channel over all Network => One communication per channel

•All stations directly connected to the network => Integrated communication sys

•Automatic roaming and hand-over => Easy to use

•Wide coverage area => easy to expand coverage by adding “slave” stations

•UHF narrow band interconnection channels => low infrastructure costs

•Functioning like single “big repeater” => automatic and simple conference call operation

Slave

Slave

Slave

Slave

Point-to –multipoint

link channels

CH1

Up-link signal path (example)

Radio Base Station MASTER

Receiver

160MHz

4W

Voter system

The real – time DSP voting selector chooses

the best signal (greater S/N) incoming from

the SLAVEs and sends it back to all the

SLAVE stations.

Control Center

160MHz

Receiver

450.000MHz

Receiver

450.025MHz

Transmitter

460.000MHz450.000MHz

Radio Base Station SLAVE

Transmitter

450.000MHz

DSP

Receiver

160.000MHz

Receiver

460.000MHz

Transmitter

164.600MHz

160.000MHz

450.025MHz

Slave

450.050MHz

SlaveReceiver

450.050MHz

Down-link signal path (example)

Radio Base Station MASTER

Receiver

160MHz

4W

Voter system

The DSP on the SLAVE stations perform

automatic carrier synchronisation, delay

compensation and audio equalization.

Control Center

164.600MHz

Receiver

450.000MHz

Receiver

450.025MHz

Transmitter

460.000MHz

460.000MHz

Radio Base Station SLAVE

Transmitter

450.000MHz

DSP

Receiver

160.000MHz

Receiver

460.000MHz

Transmitter

164.600MHz

164.600MHz

Slave

SlaveReceiver

450.050MHz

164.600MHz

What does “simulcast” mean?

All transmitters send the same information

signals on the same carrier frequency at

the same time

fc

fc

•The same RF channel over whole coverage area=> no channels change through

different repeaters, frequency saving

•Equivalent to a “big cell” single repeater => no special signalling like MPT1327 is

required (fully transparent to conventional mobile equipments).

•Automatic roaming and hand-over => Easy to use, fast set-up call

Network – down-link equalization

Transmitter

If the transmitted signals are

not accurately equalized in

amplitude, phase and delay

the mobile receiver will hear

a very noisy signal

9.492856

9.51896

Sj

400j1000

f c

.

0 5 10 15 20 25 30 35 4010

5

0

5

10

ms

Transmitter

delay to be compensatedon the station

TX1 (more delayed)

TX2

Transit delay

TX1TX 2

164.600MHz

Transmitter Receiver

460.000MHz

Network – down-link equalization

With the appropriate

equalization and

synchronisation the signals

“sounds” very good DSP

0 50 100 150 200 250 300

1

0.5

0

0.5

11.1

1.1−

si

3000 i

delay compensation

TX1 (more delayed)

TX2

Transmitter Transmitter

Transit delay

TX1TX 2

164.600MHz

Transmitter Receiver

460.000MHzDSP

10m 10m2m

Up to 20 Km Up to 20 Km

Up to 40 Km

Propagation model - 10m towers example

Antenna gain = 12dB

Base station antenna height = 10m

Mobile (train) antenna height = 2m

Frequency = 160MHz

RF Power = 10W / +40dBm

Horizon = 18.8 Km

5 10 15 20 25 30100

95

90

85

80

75

70

Km

dBm

p f0 i,( )

Horizon

ri

Coverage area / open channel

10 to 300 Km

(depending on heigth

of the antennas)

The coverage area depends on

the antenna’s height and on

the number of radio base

stations. It can spread from 10

to 300 Km or more.

The coverage area can be

easy adjusted to reach special

geometry (long valley, part of

lands, ... ).

The use of a single broadcast

channel permit an optimum

spectrum efficiency.

The coverage area may be

extended with the insertion of

other SLAVE / SUB-MASTER

base stationsThe communications are in “open channel”

(conference) mode over the entire coverage area .

This functionality ensures the best way to coordinate

emergency accidents (no “blinded trunking” ).

MASTER / SUB-MASTER / SLAVE

One Master station can receive

up to 8 Slave/Sub-Master

stations.

One Sub-Master station can

receive up to 8 Slave/Sub-Master

stations.

Master

Fixed stationCH1

CH1

Slave

Slave

Slave

Sub

Master

CH1

Slave

Slave

CH1

CH1

Base stations appearance

The base stations are very

compact and reuse the same

elementary units.

�

MUTE

SEL.

:

RADIO

LINE

POL DEVICE CHANNEL

:RX

UNLK 1

UNLK 2BUSY D

BUSY N

:

ON

PSM

Vout

Vin_OKVin_KO

:

TCS

PPSEEP

SYNC

DSP

RX

TXUNLK

MTCH

:

PWR RF HIGH

PWR RF LOW

PWR FAIL

ROS FAIL

TX

�

MUTE

- +

-SEL. +

:

RADIO

LINE

DEVICE CHANNEL

:

UNLK 1

UNLK 2BUSY D

BUSY N

:

UNLK 1

UNLK 2BUSY D

BUSY N

:

TCS

PPSEEP

SYNC

RX

TXUNLK

MTCH

: :

ON

Vout

Vin_OKVin_KO

:

TCS

PPSEEP

SYNC

RX

TXUNLK

MTCH

:

UNLK 1

UNLK 2BUSY D

BUSY N

:

PWR RF HIGH

PWR RF LOW

PWR FAIL

ROS FAIL

�

MUTE

- +

-SEL. +

:

RADIO

LINE

POL DEVICE CHANNEL

�

MUTE

- +

-SEL. +

:

RADIO

LINE

POL DEVICE CHANNEL

:

ON

PSM

Vout

Vin_OKVin_KO

:

TCS

PPSEEP

SYNC

DSP

RX

TXUNLK

MTCH

:RX

UNLK 1

UNLK 2BUSY D

BUSY N

:

PWR RF HIGH

PWR RF LOW

PWR FAIL

ROS FAIL

TX

:

PWR RF HIGH

PWR RF LOW

PWR FAIL

ROS FAIL

TX

:RX

UNLK 1

UNLK 2BUSY D

BUSY N

:

TCS

PPSEEP

SYNC

DSP

RX

TXUNLK

MTCH

:

ON

PSM

Vout

Vin_OKVin_KO

�

MUTE

- +

-SEL. +

:

RADIO

LINE

POL DEVICE CHANNEL

�

MUTE

- +

-SEL. +

:

RADIO

LINE

POL DEVICE CHANNEL

:

ON

PSM

Vout

Vin_OKVin_KO

:

TCS

PPSEEP

SYNC

DSP

RX

TXUNLK

MTCH

:RX

UNLK 1

UNLK 2BUSY D

BUSY N

:

PWR RF HIGH

PWR RF LOW

PWR FAIL

ROS FAIL

TX

:

PWR RF HIGH

PWR RF LOW

PWR FAIL

ROS FAIL

TX

:RX

UNLK 1

UNLK 2BUSY D

BUSY N

:

TCS

PPSEEP

SYNC

DSP

RX

TXUNLK

MTCH

:

ON

PSM

Vout

Vin_OKVin_KO

Sub

Master

Master

Slave

The Sub-Master station

integrate 3 full-duplex

transceivers

�

MUTE

- +

-SEL. +

:

RADIO

LINE

DEVICE CHANNEL

:

UNLK 1

UNLK 2BUSY D

BUSY N

:

UNLK 1

UNLK 2BUSY D

BUSY N

:

TCS

PPSEEP

SYNC

RX

TXUNLK

MTCH

: :

ON

Vout

Vin_OKVin_KO

:

TCS

PPSEEP

SYNC

RX

TXUNLK

MTCH

:

UNLK 1

UNLK 2BUSY D

BUSY N

:

PWR RF HIGH

PWR RF LOW

PWR FAIL

ROS FAIL