Specifications

Table Of Contents
APPENDIX D: INSTALLATION DETAILS
Page 207 MRC-565 Packet Data Radio Operations & Maintenance
However, as the number of spikes increase, the effectiveness of the blanker is reduced. When
setting up a site always look at the IF test point with a scope to determine the level of the power
line noise interference. It is mandatory that power line noise be avoided for an optimum site. Try
to place the receiver antenna well away from power lines.
NOTE.
Power companies are required to properly maintain their power lines to reduce noise. Call
the local utility in case of severe noise.
Automobile Ignition Noise
Automobile ignition noise is generated by all gasoline engines and is a result of the high voltage
required to fire the spark plugs. Auto ignition noise is similar to power line noise with the
exception that it does not have the 8-10 ms period which is associated with power line noise.
Computer-Generated Interference
All computers and printers contain high-speed circuits that generate spurious signals throughout
the 37-50 MHz band. Interference will result if any of these signals couple into the antenna at
the MRC-565 receive frequency. To minimize this type of interference, try to keep the antenna
away from computers by at least 100 feet. The noise blanker will not suppress computer-
generated interference.
Signal Interference
This type of interference will occur whenever another transmitter is producing harmonics at the
receiver center frequency of the MRC-565. Antenna nulling and spatial separation can be used
to reduce this type on interference.
NOTE
With XTERMW installed (see Section 3.3), the STAT command can be used to determine
the site antenna noise levels. Ideally, the background noise levels should be less than –115
dBm.
DC Power Source
The MRC-565 requires a 12 (11.0-15.0) VDC power source. The average standby current at an
input voltage of 13.0 VDC is about 150 ma in a full operating mode (w/o GPS) without any low
power modes (LPM) enabled. When the unit transmits it requires about 25 amps for 100 msec.
An automobile battery provides an excellent power source. When operating from a battery with
Solar Panel Charger low power modes can be used to reduce current drain in receive mode.
If there is no AC power available a solar panel can be used to charge the battery. The size of the
solar panel is determined by the solar radiation available at the location of the site. In most
locations in the USA, a 40 watt solar panel will suffice. At higher elevations, where winter