Freedom R8100 SERIES, Руководство оператора

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4.1.4 Off-The-Air Measurements
Place the R8100 in Monitor mode by pressing the Monitor front panel hard key. Press the RF Zone soft
key and set the Monitor Frequency and Modulation Type to match that of the 2-way radio or transmitter
under test. For best accuracy set the Bandwidth just wide enough to cover the channel spacing allocated
to the radio under test. In the R8100 Audio Zone set the High Pass Filter to 300 Hz and the Low Pass
Filter to 3 kHz.
Connect the supplied whip antenna to the R8100 ANTENNA port. Connect a dummy RF load or hook
the radio’s working antenna into the antenna port of the radio. Adjust the squelch control to ensure the
incoming radio signal will un-squelch the monitor. Otherwise rotate the knob fully counter-clockwise
(squelch off) and lower the volume if the background noise is excessive.
Key the radio or activate the transmitter being monitored. Deviation and frequency error measurements
require sufficient signal level to fully quiet the analyzer's receiver. Accuracy is best when the signal levels
are 10 dB or higher than the receiver’s quieting threshold. Read the signal level (“Input Lvl”), frequency
error (“Freq Error”), and deviation (“Deviation”) in the RF Zone section of the R8100 main screen.
4.2 FM Receiver Testing
The R8100 has extensive capability for evaluating the performance of FM receivers. However, detailed
instructions for the wide variety of receiver types are outside the scope of this manual. This section will
outline basic FM receiver testing and focus on fundamental items of importance such as receiver
sensitivity, frequency accuracy, audio distortion, and squelch sensitivity.
4.2.1 Basic FM Receiver Testing – initial setup
Refer to Figure 5.2.1-1. Connect the analyzer's RF I/O port to the RF input of the radio or receiver under
test. Connect the radio’s speaker/audio output to the analyzer's Meter In port. Access to the speaker/audio
output is often provided through a special interface connector on the radio used for testing purposes. Refer
to your radio’s service manual.
CAUTION
The analyzer’s Meter In port is unbalanced (ground referenced). On some radios grounding the speaker
output will damage the audio circuitry. Use an appropriate interface to measure balanced or DC powered
audio circuits with the Meter In port of the R8100. Typically this requires the use of an isolation
transformer which is an optional R8100 accessory.