Hey thanks again for the help everyone. I ended up installing ubuntu 10.04 under Windows 7 through the VMWare Player as a virtual machine.
Unfortunately despite playing with the input levels I'm not really getting any good decodes. I'm trying to decode MotoTRBO (DMR). I tried listening to P25 as a control and would get about 5 minutes of noise and then one perfect 15 second long clear understandable decode, and then more minutes of noise. Results were even poorer with DMR, with no good decodes at all.
I'm guessing I'm just SOL with the limitations of the VM install and the sound card on my laptop "ES1371 [AudioPCI-97]" / "Realtek high definition audio," but if anyone had any further advice I'd be happy to give it a shot. Decode quality of the DMR audio signal should be VERY good, as the repeaters are close by.
I'm still using DSD on my Dell 1525. I had equally bad performance feeding discriminator audio into the ES1371 mic input vs feeding it into the mic input of a SB Live 24-bit external USB mic input. The reason I used mic input on the ES1371 is because that's all I had. The reason i used mic input on the SB Live 24-bit is because I knew the line-in levels were extremely low and nonadjustable in linux.
However, as a last ditch test I decided to switch from mic-in on the SB Live 24-bit external to the line-in. Sure enough, it was only showing INLVL 4%, BUT the decodes were significantly better. not perfect by any means. I question whether anyone is really getting 100% decodes on even strong signals.... but perhaps they are. At any rate, a buddy of mine explained a few reasons why the line input is better. It doesn't just have to do with the audio levels. I wish I could remember exactly the reasoning he gave, but he was right.
So, assuming your tap is of sufficient quality, then I would say to try your best to figure out a way to do line-in on your card. In fact, I will mess with things further tomorrow on my laptop and will see if there is any way to get line-in functional on the laptop.
Oh, another FYI -- and you're going to like this...
The ES1371, at least on my laptop, only has one mic input adjustment slider. If I use 'mic-in', then it also mixes the front jack mic-in with the built-in microphone audio. And there is no way to turn off / turn down the microphone audio for the internal microphone in linux.
If you have an internal microphone on your laptop, you're probably experiencing hte same problems. And you likely aren't finding anyway to disalbe it in Linux. However, I found a way to disable it. Dont' ask my why it works.
When in Windows, go in and find the internal microphone input. DISABLE it. So you'll have internal micrphone DISABLED and you'll have the front jack mic-in showing "plugged in" (i'm runningg vista, it may say something different in Win7).
Anyway, after disabling the internal microphone within Windows and hten booting up to Linux, I started to get some decoding and could decode things that I didn't have a chance of decoding when it was mixing the two mic input audio sources. It didn't work as well as LINE-IN on the SB worked, but it worked better than not disabling the internal mic in Windows before booting to Linux.
So you might want to give that a try.
After I do some more in depth testing of the built-in sound on the Dell tomorrow, I'll let you know what i find out.
But I suspect you'll never get as good a decode rate using the mic-in as you would using line-in.
I think you are also dealing with additional difficulties having employed VMWare Player to run your linux instance rather than running Linux as the core OS.
Mike
