Aeroflex 2946A Instructions d'exploitation télécharger pdf (Page 12)

OPERATING MANUAL 2945A

46882-311D 1-3

The AF generators, to provide a source of modulation for the transmitter under test.

The RF power meter, to measure the mean output power level of the transmitter.

The RF counter, to obtain the mean RF frequency of the transmitter output.

The modulation meter, to measure the modulation depth or the deviation level and to

provide a demodulated output signal. Single sideband transmissions can be demodulated

when the SSB option is implemented.

The AF counter, to measure the frequency of the demodulated signal.

The distortion meter, to obtain the signal to noise level, the modulation distortion percentage

or the modulation SINAD level of the transmitter.

The oscilloscope, to view the demodulated signal and to measure the modulation levels.

The tones generator, to modulate transmitters of systems using tone calling.

The tones decoder, to demodulate tones generated by the transmitter.

The AF amplifier and loudspeaker, to monitor the demodulated signal.

Cellular radio-telephones can be tested using the SYSTEMS mode. (See ’System testing’).

The spectrum analyzer facility, which is a separate operating mode (SPEC ANA), can be used to

study the sidebands and any harmonics produced by the transmitter, either by direct connection or

by off-air monitoring.

Receiver testing

Service Monitor

Under

Test

DEMODULATED AF SIGNAL

MODULATED RF TEST SIGNAL

C3241

Fig. 1-2 Receiver test setup

The receiver test procedure uses:-

The RF generator and the AF generators, to produce a transmission with defined parameters.

The AF voltmeter, to measure the level of the demodulated signal from the receiver.

The distortion meter, to obtain signal-to-noise ratio, SINAD levels and distortion percentage

figures.

The tone generator and tone detector, to produce and decode specialised calling tones to test

tone recognition circuits.

The oscilloscope, to view and measure the demodulated signal or other waveforms.

The RF signal from the Service Monitor is coupled to the receiver and the demodulated signal from

the receiver taken to the AF input of the Service Monitor. By measuring the levels of the AF signal

from the receiver, the sensitivity of the receiver can be checked. The distortion levels introduced

by the receiver can be measured.

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Aeroflex 2946A Instructions d'exploitation Page 12