Signal Generator Noise
Posted: Thu Oct 03, 2013 1:40 pmSignal Generator Noise
When viewing a sine wave output from the signal generator on a separate dedicated o-scope I notice a significant amount of high frequency noise imposed on the waveform. I also notice that the spectrum analyzer displays peaks at non harmonic frequencies of the signal generator output e.g. 1.5 KHz for a 1 KHz output. I don't see either of these results if I input a signal to my sound card from a separate signal generator. I am using the default THD settings. Are these findings anomalous? Can you suggest a cause and/or solution?
bonfis
Post at 12-6-2012 10:36
Yes, it is anomalous. It looks like a sound card hardware problem. Have you tried the software on another sound card?
virtins
Post at 22-6-2012 00:03
Just did today. Results are identical. Both sound cards show the same noise riding the sine wave. One card is an external EMU 0202 USB and the other a Turtle Beach PCI card. If its a hardware problem it's not in the sound card.
bonfis
Post at 4-7-2012 22:35
Another two possible causes of noise could be (1) the connection cable (2) How you connect the ground lead?
virtins
Post at 10-7-2012 09:31
The connection cables have been switch without any change in the noise. The scope connects directly to sound card output via a direct or X10 probe. No difference noted between the X10 and X1 probe settings. The probe ground connects to the sound card output cable shield.
bonfis
Post at 4-8-2012 08:31
When viewing a sine wave output from the signal generator on a separate dedicated o-scope I notice a significant amount of high frequency noise imposed on the waveform. I also notice that the spectrum analyzer displays peaks at non harmonic frequencies of the signal generator output e.g. 1.5 KHz for a 1 KHz output. I don't see either of these results if I input a signal to my sound card from a separate signal generator. I am using the default THD settings. Are these findings anomalous? Can you suggest a cause and/or solution?
bonfis
Post at 12-6-2012 10:36
Yes, it is anomalous. It looks like a sound card hardware problem. Have you tried the software on another sound card?
virtins
Post at 22-6-2012 00:03
Just did today. Results are identical. Both sound cards show the same noise riding the sine wave. One card is an external EMU 0202 USB and the other a Turtle Beach PCI card. If its a hardware problem it's not in the sound card.
bonfis
Post at 4-7-2012 22:35
Another two possible causes of noise could be (1) the connection cable (2) How you connect the ground lead?
virtins
Post at 10-7-2012 09:31
The connection cables have been switch without any change in the noise. The scope connects directly to sound card output via a direct or X10 probe. No difference noted between the X10 and X1 probe settings. The probe ground connects to the sound card output cable shield.
bonfis
Post at 4-8-2012 08:31