What is the peak to rms ratio in NADC for the Agilent 8920, 8921?

The ratio of Peak to rms power for TDMA NADC PRBS modulation is 2.95 dB +- 0.05 dB. This number comes from several different experiments.

The first experiment results show that the DSP path and the peak power meter differed by 2.97 dB. This test was done with an NADC base station at four different power levels.

A second experiment involved using a sample of ideal NADC data. The data showed that the ratio was 2.93 dB.

The last experiment used several NADC Sources into an Agilent 8921 and an Agilent 438A. The ratio was 2.94 dB.

Averaging these three experiments gives a value of 2.95 dB. The +-0.05 dB confidence level is twice as large as any of the measured results, so this value could be at least a 95% confidence interval.

There are ways to miscalculate this ratio. If the signal has a large amount of origin offset (greater than -40 dBc), the ratio could be affected. We also noticed that the output sections of both the Agilent 8657D and the Agilent 8921D caused the peak to rms ratio to be compressed by approximately 0.1 dB. This would be expected from any amplifier that is not completely linear.

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