Low frequency performance.
Posted: Fri Jun 01, 2007 9:23 pm
I have started this thread here rather in the Images & Sound section as it seems more appropriate.
Attached is another .wav file I created in software, it's a simple 12.5Hz square wave with the NBTV sync thrown in. (missing included).
Playing it back on the (very cheap) soundcard/motherboard here resulted in the waveform shown in the .jpg. Which was far better from a LF point of view than I ever expected. It's 'almost' DC coupled. It's of a complete frame of NBTV, you can see the missing sync.
I created two other files, one of complete black with just the syncs, and the same with white. There was a shift in the sync tips between these two files, but not like you would expect with AC coupling.
Either I just have hit lucky, or perhaps soundcards are generally like this?
Of course this is just the playback side, record section has yet to be used.
Steve A.
Thinking about it further, the 'almost' factor could be due to power supply regulation, there was no real load on the output, just the 10 megohm scope. But who knows how the D-A is configured?
The fact that the white part of the waveform is ruler straight (ignoring the overshoots) has got me quizzical.
Attached is another .wav file I created in software, it's a simple 12.5Hz square wave with the NBTV sync thrown in. (missing included).
Playing it back on the (very cheap) soundcard/motherboard here resulted in the waveform shown in the .jpg. Which was far better from a LF point of view than I ever expected. It's 'almost' DC coupled. It's of a complete frame of NBTV, you can see the missing sync.
I created two other files, one of complete black with just the syncs, and the same with white. There was a shift in the sync tips between these two files, but not like you would expect with AC coupling.
Either I just have hit lucky, or perhaps soundcards are generally like this?
Of course this is just the playback side, record section has yet to be used.
Steve A.
Thinking about it further, the 'almost' factor could be due to power supply regulation, there was no real load on the output, just the 10 megohm scope. But who knows how the D-A is configured?
The fact that the white part of the waveform is ruler straight (ignoring the overshoots) has got me quizzical.