User's Manual

The following table shows the softpot ranges to achieve approximately -110dBm. The
actual value varies from radio to radio. The VRS transceiver ships from the factory with
the softpot set for -110dBm. In the event that this value needs to be re-set in the field, it
is recommended that a communications analyzer or similar piece of test equipment be
used to verify these settings.
Band Channel Spacing Approximate Softpot
Range for -110dBm
VHF 25kHz 56-63
VHF 12.5kHz 63
UHF R1 25kHz 44-52
UHF R1 12.5kHz 63
UHF R2 25kHz 43-46
UHF R2 12.5kHz 63
Other adjustments can be made using the Global Tuner, but it is recommended that all
other tuning be performed by a Motorola Service Center.
VRS750 Upgrade Kit
The VRS750 firmware can be reprogrammed/reflashed using the VRS750 Upgrade Kit.
In order to use the VRS750 Upgrade Kit the VRS750 should be connected to a desktop or
laptop PC via a COM port as indicated in Figure 12. The Flash adapter (NTN4056A)
should be placed between the VRS750 programming cable (3085031D02) and the SRIB.
When connecting the VRS750 to the SRIB via the Flash adapter, make sure that the
switch on the adapter is in the OFF position. With the ASTRO mobile powered on
and “PROG VRS” displayed on the control head, the upgrade can be started. Open the
VRS750 Upgrade Kit and click on the “PROGRAM” button. Follow the instructions
through to the completion of the Flash process. Upon completion, place the switch on the
Flash adapter back in the OFF position and disconnect the VRS750 from the
programming cable. For more detailed information on the flashing process, consult the
“read me” file for the Upgrade Kit.
Note: The VRS750 Upgrade Kit will request which baud rate to use when flashing the
first radio. For the VRS750 the baud rate should not exceed 38,400 bps.
5. Detailed VRS Operation
Multi-VRS Operation
The VRS is designed to accommodate multiple VRS units in the same area. This is
accomplished by each VRS maintaining a priority level or delay state. During either
portable-to-base or base-to-portable transmissions, only the highest priority VRS will