User Manual

Instruction Manual 19
Setting the Receiver Noise Floor
Based on the ambient noise level at the repeater site, it is desirable to determine the noise floor of the site
and to set the receiver appropriately. Setting the noise floor allows for the maximum dynamic range of the
receiver to be used in decoding the radio signals.
The steps for setting the receiver noise floor are:
1) Using the data logging capability of the repeater, establish the value for the noise floor based on
the receive antenna configuration.
2) Using the noise floor value and the table of noise floor values versus receive amplifier voltage
settings, select the proper receive amplifier voltage setting and adjust the receiver amplifier
voltage to the proper voltage value.
Voltage
(VDC)
Attenuation
(dB)
0.00 15.1
-0.10 14.8
-0.20 14.5
-0.30 13.9
-0.40 13.6
-0.50 13.4
-0.60 13.0
-0.70 12.7
-0.80 12.0
-0.90 11.6
-1.00 11.2
-1.10 10.7
-1.20 10.3
-1.30 9.2
-1.40 8.6
-1.50 8.1
-1.60 7.2
-1.70 6.5
-1.80 4.6
-1.90 3.6
-2.00 2.7
-2.10 1.8
-2.20 1.0
-2.30 0.2
-2.40 0.1
-2.50 0.0