John R. wrote:
Mathew George wrote:
Hi all,
Can someone explain how we may build a FM/SW receiver using A/D D/A
converter in a sound card and minimal additional hardware? Somewhere I
have read that this is possible, in principle, but could not yet
gather info suitable for a novice.
I am attempting the same general thing. I am pretty sure you will need
a radio receiver that has an IF output. My AOR 8200 has a discriminator
output which I think is something different. In theory it has an IF
output also but have not seen anything showing how to use it.
John
Well, I´m sure you´ll have to decide on what you want, because great FM
sound by feeding something through a sound card isn´t sounding realistic.
You can not get more informations per second generally from a
soundcards´ output than you put in the input, roughly...
So you could detect and such signals which could be sampled from some
receiver if the bandwith would be limited to what a soundcard can
digitize, so without aliasing that would be 20kHz or maybe higher. The
intermedeate frequency in radios would be much higher, more megaherzes
A discriminator output may be applicable, but the processing of such a
signal into a FM decoded signal may not be what sr is usually used for.
In most cases the much higher sampling rate of the hardware device for
sr is needed to get a demodulatable signal I think, as well the
soundcard input may have not right impedances compared with radio boards.
Very low frequency signals could be AD converted by soundcard, or a
signal with small bandwidth mixed into the audio band.
Theo
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