I don't know what REW is doing to compute SNR, so can't really tell why the two are different.I used your suggestion and even went 5-24khz in multitone. Snr only went down from 124.8 to 124.6. In REW it is 122.5
Correct. The maximum # of harmonics determines what's shown on the display, not used in the computation. Noise is measured across the measurement frequency range. If you want Fs/2 then you'll need to specify it as the upper bound of the measurement bandwidth.@pkane so snr is computed in multitone using all noise and all harmonics in selected measurement range, not just max 15 harmonics plus noise?
It also does just the measurement range, not nyquist/2?
I can't say, @Moto. Multitone does a fairly straightforward calculation after removing the fundamental and harmonics from the result and then summing the remaining energy for the specified bandwidth. I don't know what REW does.@pkane does it make sense that snr in Multitone would be better than snr in REW given john’s clarification of REW’s computation of snr?
I can't say, @Moto. Multitone does a fairly straightforward calculation after removing the fundamental and harmonics from the result and then summing the remaining energy for the specified bandwidth. I don't know what REW does.
No, sorry if that wasn’t clear. Noise calculation excludes harmonics, and, of course, the fundamental.Maybe I misunderstood you earlier. I thought you said in the snr calculation that you used noise plus harmonics in the “noise” part of your computation.
Interesting. Then REW and Multitone should agree on snr. Odd that snr in Multitone is about 2db better than REW. Oh well.No, sorry if that wasn’t clear. Noise calculation excludes harmonics, and, of course, the fundamental.
Interesting. Then REW and Multitone should agree on snr. Odd that snr in Multitone is about 2db better than REW. Oh well.
On another note in 1.0.83 whenever I set the fft when just doing 1000hz sine measurement, it reverts to 256k. What would cause it ti do that?
I had just realized that and edited the post to delete that but you beat me to it with an answer!High sample rate will increase FFT size automatically.
Is there a chance we can have a "no PC shutdown" option during measurements?
I keep forgetting it!
No,that is another matter,I'm talking about the energy saving schemes,some like foobar prevent that (as an option).It's already available: use a better ASIO driver. As an option, you can also buy a new PC