Uniden uh078sx User Manual download pdf (Page 2)

Bush Search And Rescue Victoria

Radio System Types

There are two basic types of radio systems, conventional and trunking systems and

within conventional systems there are two modes: simplex and repeater operation.

Simplex – a conventional radio system

No reception -

shaded by hill

Poor reception

due to foliage

Good reception -

close by & line of sight

Good reception -

high on hill

Simplex

Operation

One channel - uses

the same transmit and

receive frequency

Remote Base

(if in place)

Search Base

 Simplex channels use a single frequency (f1) for transmit and receive and allow

direct communications between one radio and all other that are within range.

Simplex coverage is line of sight only. It will not go over hills and in the bush is

normally limited to 1-2km

 In a BSAR scenario simplex is used with UHF CB radios on a line search,

around the search base or to an adjacent search group

Remote Base

 A remote base is a simplex radio located at a high location linked back to the

search base, often by another radio channel

Repeater – a conventional radio system

 Repeater communication uses a channel with separate frequencies for transmit

and receive via a radio repeater located on a nearby high point

 From a BSAR perspective this could be a local Police repeater or a UHF CB

repeater channel (Ch 1-8)

 A repeater improves coverage range within an area by being located in a high

location

 All other radios within range of the repeater will hear all traffic

 When out of range of the repeater a radio cannot communicate with any nearby

radios as the radios transmit and receive of different frequencies eg all the hand

held radio transmit of f1 and receive of f2

 To check if you are in range of a repeater push the PTT for 2 seconds and listen

for the sound of a repeater tail ie the radio squelch/mute opens and the closes a

short time later

Competency Name Radio Procedure No C_003 Rev No V2

File Name bsar radio v2.6 aug10.doc Issue Date 01/08/10 Page 2 of 17

1 2 3 4 5 6 7 ... 16 17

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Uniden uh078sx User Manual Page 2

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