lorrain
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John, I suggest a request concerning the display of SNR (Signal to Noise Ratio) and I have a question.
1/Request
We can have SNR (Signal to Noise Ratio) with REW by 3 ways.
Method 1 : classic way with 2 separated measures with and without the signal
Method 2 : REW give signal level in “RTA window” and Noise level in “Show distorsion” box with a technic of removing the fundamental and its harmonics.
SNR is done by the formula : SNR= Signal level(dBx) –Noise level (dBx) in dB
.
Method 3 : the selection of dBc option places the peak level of the input at 0 dBc. In this case N is - SNR. We have a full real time measure.
With the objective to have directly SNR without manipulation, is it possible to add SNR (unweighted and A weighted) in “Show distortion” box?
In audio measurement, SNR is very useful and becomes Dynamic Range with the highest signal allowed by the equipment under test.
If this request cannot be applied, it might be interesting to add some information in the documentation to explain how to get SNR in particular with dBc option.
2/Question
Signal level is present in “Show distortion” box and in “RTA Window” box but when the signal level is very low ou with no input signal (generator off), values are different.
Why the value in the "Show distortion" box does not always match with the value in "RTA window"? It is not a problem but I am surprised by this observation.
In this example below with generator off, we have -66,95 dB FS in “RTA window” (it is the noise level with generator off ) and -75,18 dB FS in “Show distortion” box.
Tanks
Eric
1/Request
We can have SNR (Signal to Noise Ratio) with REW by 3 ways.
Method 1 : classic way with 2 separated measures with and without the signal
Method 2 : REW give signal level in “RTA window” and Noise level in “Show distorsion” box with a technic of removing the fundamental and its harmonics.
SNR is done by the formula : SNR= Signal level(dBx) –Noise level (dBx) in dB
.
Method 3 : the selection of dBc option places the peak level of the input at 0 dBc. In this case N is - SNR. We have a full real time measure.
With the objective to have directly SNR without manipulation, is it possible to add SNR (unweighted and A weighted) in “Show distortion” box?
In audio measurement, SNR is very useful and becomes Dynamic Range with the highest signal allowed by the equipment under test.
If this request cannot be applied, it might be interesting to add some information in the documentation to explain how to get SNR in particular with dBc option.
2/Question
Signal level is present in “Show distortion” box and in “RTA Window” box but when the signal level is very low ou with no input signal (generator off), values are different.
Why the value in the "Show distortion" box does not always match with the value in "RTA window"? It is not a problem but I am surprised by this observation.
In this example below with generator off, we have -66,95 dB FS in “RTA window” (it is the noise level with generator off ) and -75,18 dB FS in “Show distortion” box.
Tanks
Eric
