A few people may have noticed that the Artisan Radio SDR has been up and down for a few day. It now should be up for the next little while for both the FM station and the AM feed.
I've been moving things around in the studio, and attempting to get a reasonable antenna installation for the Talking Sign. Almost there.
The SDR acts differently with AM than with FM. On AM, you have to use direct sampling, which reduces sensitivity. And when the amplitude of the signal goes down, as in quiet spots, the noise level goes up. Almost like an AGC. I know that it needs a better AM antenna, and I can reduce the effects just by holding the antenna (and providing a better ground), but it still happens. On FM, you just get a quiet carrier.
There is little to no noise over-the-air on quiet spots for AM and FM. I'll be fooling around with gain and other things for AM some more, but it's a bit of a mystery right now.
It's actually a pleasure to listen to music on AM through the SDR. FM has better frequency response, of course, but the AM is still pretty good.
One of the big advantages of the AM SDR is bandwidth - it takes up less than 100kbps (Wide FM was around 250kbps). So many more users can be supported on the server side, and it won't impact the client side nearly as much.
I can't figure out why, but I prefer to listen to my little station on AM as opposed to on FM. Something about the reduced bandwidth and the more aggressive processing. I just like the sound!
I was listening to your AM signal through the SDR for a short while during Wilson Beach Radio. It sounds as if the signal is breaking up on peaks. Could the signal into the SDR be a bit too strong, causing it to overload? It's close, but something doesn't sound quite right.
Yeah, the SDR feed for AM is still not there yet. Too much noise getting into the signal, and overload when I place the SDR antenna close to the transmitting antenna. Plus the surge in noise during quieter spots in the programming.
I'll be trying out a few things this weekend, so it may be up and down a bit.