Service Manual

31
Two-Unit Operation The arrival of another VRS-equipped vehicle (unit B) into the coverage
area of unit A has no effect on unit A’s radio operation until unit B’s
VRS is enabled.
Unless there are portable transmissions occurring when unit B arrives,
unit B’s repeater transmits a Single Tone burst when its VRS option is
turned on. Unit B’s repeater priority counter initializes in delay state
zero, making unit B the priority unit. Unit A’s repeater/portable
receives unit B’s Single Tone transmission, which sets unit A’s repeater
to delay state one. See Figure 19. Transmissions from portable units in
the area now repeat through unit B. See Figure 20.
A portable radio’s transmissions (solid arrows in Figure 20) go to all
portable radios and VRSs in the area. Because unit B is the priority
repeater, it repeats the portable’s signal (open arrows in Figure 20) to
the base station and other mobile radios.
Unit A cannot countdown and repeat until the delay state one time
delay elapses. However, because unit A detects the mobile carrier of the
priority unit (open arrow in Figure 20) before the delay expires, the
priority counter does not begin the countdown. Unit A remains in
delay state one and does not repeat portable transmissions.
Figure 18. Single VRS Unit Operation
SINGLE TONE
BURST
UNIT A
“DELAY STATE ZERO”
PRIORITY UNIT
MAEPF-26079-O
Figure 19. Two-Unit VRS Operation
SINGLE TONE
BURST
UNIT A
“DELAY STATE ONE”
UNIT B
“DELAY STATE ZERO”
PRIORITY UNIT
MAEPF-26080-O