Reply To: Noise figure measurement using an SA44B with Spike software

Andrew
Thank you for your comments.

No the problem is not related to image rejection, switching off ‘Spur Reject’ has no effect, still reading 3dB low.

The Spike measurement receiver utility (MRU) fails to synchronise to zero with white noise always reading a few dBs negative. The version 2.18 software in contrast synchronises fine with white noise.

I did a test using the Spike MRU where I inputted a pure sign wave, it synchronised fine and I then added a 6dB attenuator and got a reading of -5.981dB. So the Spike MRU works fine with a sign wave but not with noise even after you correct for the synchronisation offset.

I notice the Spike MRU lacks the options available in the old software e.g. bandwidth adjustment,FM and AM detection and gives unstable readings with noise suggesting it’s using a very narrow bandwidth. Is this the problem?

Richard