The RFD2305 is a calibrated noise source from RF Design.
The supplied calibration chart was keyed up in a tab delimited file for import to NFM to allow automatic interpolation of ENR at the frequency of measurement.
Because of the expected Noise Figure of the TS2000, the external 10dB
attenuator that is part of the calibrated RFD2305 was removed to obtain
a higher Y factor from the receiver. To make allowance for
that change, the value of Att1 is set to -10dB.
The abbreviated measurement procedure was:
The use of a measurement interval of 5s with receiver effective noise bandwidth of 1500Hz gives a noise measurement uncertainty of 0.1dB at 95% confidence (see Noise measurement uncertainty calculator), considerably better than would usually be obtained using a multimeter or audio millivoltmeter. Whilst in this case, the sensitivity of calculated Noise Figure to uncertainty in each noise measurement is relatively low, measurement of a LNA with 1dB noise Figure is quite sensitive to uncertainty in each noise measurement.
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