GUANG ZHOU HAN TING INFORMATION TECHNOLOGY CO.LTD WWW.FMUSER.NET
USER’S MANUAL FOR CZH618F-1000/500C TRANSMITTER
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5.1.1 Audio Performance Test
a. Connect transmitter and test Instrument with cable according Figure 5-1.
b. Make audio analyzer output 400Hz, 0dBm;
c. Finely adjust audio output level until demodulation reaches 75KHz (100% modulated
）
;
d. Scan audio output frequency from 30Hz to 15kHz, record frequency response (< ±0.1dB)
and distortion (< 0.1%);
e. Scan audio output frequency from 30Hz to 15kHz, record stereo separation (typical >
50dB);
f. Set audio analyzer to 1kHz, exciter pre-emphasis to 50µs, demodulator to 50µs de-emphasis,
adjust audio analyzer power output until demodulation reaches 75KHz , record mono SNR(>75dB)
and stereo SNR (>70dB).
5.1.2 Carrier Frequency Accuracy Test
a. Connect the test instrument to transmitter according to Figure 5-2;
b. The test carrier frequency accuracy (±200Hz).
Transmitter
Wattmeter
Dummy
Load
Universal
Counter
Attenuator
Figure 5-2 connecting for carrier frequency test
Figure 5-1 connecting for audio analyse
Audio
Analyzer
FM
Demodulation
Transmitter
Wattmeter
Dummy
Load
RF
RF
RF
Audio
Audio
