Motorola VRS750, Service Manual

Page: 46 / 104

34
Rptr PPI—Portable
Priority Interrupt
NOTE: When using Rptr PPI, the receiver squelch setting of
the portable must be programmed for CSQ (carrier
squelch).
<Rptr PPI> is CPS programmable. The main function of <Rptr PPI> is
to allow the portable to interrupt base-to-portable transmissions.
During VRS to portable transmissions, an interrupt is sent to the
transmitter every 2 seconds on conventional modes and 1 second on
trunking modes. (These times are CPS programmable and may be
changed to 500 ms for trunked modes or 500 ms for conventional
modes.) There is also a random time factor added to the base interval
to prevent two VRS units from interrupting at the same time. This
interrupt allows the receiver to monitor portable or other VRS activity
for approximately 6 ms. See the timing chart in Figure 23.
Figure 22. Priority Unit Reassignment
MAEPF-26083-O
VRS REPEATER
TRANSMITTER
PORTABLE
TRANSMITTER
WITHOUT “PL”
PORTABLE
TRANSMITTER
WITH “PL”
MOBILE
TRANSMITTER
ON
OFF
ON
OFF
ON
OFF
ON
OFF
~ 2 sec ~ 6 msec
Figure 23. Portable Priority Interrupt
UNIT B
DELAY UNITS 1 0
MAEPF-26084-O
REPEATER WAITS ONE DELAY UNIT, COUNTS DOWN (1,0),
AND BECOMES PRIORITY UNIT.
THE PRIORITY STATE COUNTER IN OTHER REPEATERS
ALSO COUNTS DOWN BY ONE DELAY UNIT.