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to give the rated audio output but if only Sinad sensitivity is being
measured a lower level is acceptable. The Sinad meter will now dis-
play the combined level of all the frequencies except 1000 Hz present
in the receiver’s output. These are the noise and distortion products.
With the high level input applied these will be low and the meter
deflection will be small indicating a high Sinad ratio. The RF input
level is now reduced until the meter reads 12 dB (the standard refer-
ence) and the RF level, μV or dBm, is the Sinad sensitivity for the
receiver.
The oscillator to produce the test tone may be included in the
meter and filters may be provided to comply with various weightings.
20.2.3 Audio signal generators
The instrument provides an output