I am using Audio Weaver to make a DTMF tone, which I am using to test another system. I add together two sine waves as seen in the attached .awd. I take the headphone output to my scope. I reduce the amplitude of each sine wave in turn and I see just the other sine wave. The problem is that neither sine wave is at the frequency selected in my app. For example, 1209 Hz appears about 100 Hz low, and 852 Hz appears about 60 Hz low.
I get the same results for computers with different sound cards. I have confirmed that the sound cards are using the same sampling frequency as my app (48 kHz) and no enhancements are operating.
Any ideas what is going on? I was expecting to see whatever frequency I put on the sine generation dial.create_dtmf_one_sine.awd