What about using with the PC Radio Card which actaully recieves AM and FM radio signals?
Any capability to resolve the positive-going from the negative-going modulation peaks of a MW AM waveform must be done in the r-f domain. All of the active r-f circuits in this PC radio card are internal to it, and normally wouldn't be accessible to the card user.
The card would deliver demodulated program waveforms to the PC soundcard as audio streams, much as though the audio output of any AM/FM receiver was connected to the audio input jack of a PC.
Also -- most PCs generate a lot of r-f interference to sensitive receivers located near them due to switching power supply noise and all the digital signals present in the PC. Probably this would affect the useful S/N possible for the audio outputs of the card.
Real easy to see. I liked what you were playing, too.
Bruce, DOGRADIO
Ok, The $199 software occiliscope by REA measures and manages the tx high and low peaks via an interface to the transmitter with a little box which they market.
From the information on the REA website this looks promising, although for use at Part 15 AM power levels the cost is in the $400 area.
Probably a decent, used oscilloscope could be found that cost less than $400, but the software display of the REA package is a lot easier to read/interpret than the waveform of an AM signal on a CRT or solid-state display screen.
Note that the REA package does not produce asymmetrical modulation of AM signals, just measures it. Some other device in the audio input stream to the transmitter would be necessary to produce and control those asymmetric peaks.