I bought my EMU-0202 at the beginning of 2009, but it only worked at 44.1KHz. Now we've got it working at up to 96Khz in Linux, with an Alsa change forthcoming.

Here's the story: Shortly thereafter Creative released Mac USB drivers and I spent some time looking at the source and saw there were two ways to set the sampling rate: a "direct" method and a "clock" method. The "Extension Unit" code confused me, and I never got around to mapping between the Mac USB and the Linux USB stacks.

But just recently "mellowman" described a patch to get 48Khz sampling working. Over at UbuntuForums "v.stiff" reported success, and I then figured out the quirk to extend it to the full range. CannibalZerg either took my patch or figured it out alone, and we've all tested it and it works!

So I have got the EMU-0202 working at up to 96KHz on Linux. Others report the 192Khz sampling working on the EMU-0404, but the 0202 says you have to disable the input monitor before doing that, and it's not clear to me that that's working yet.

Why's this useful? Well, it lets me use my Quisk K3 LPPan package to see 96Khz of the band instead of 44KHz, a major improvement.

- posted by Leigh @ 05:22 z 0 comments

This morning I thought about a fun science experiment for kids: Use a laptop with a sound analysis program such as fldigi to use its FFT to measure the audio doppler shift from an oscillator carried aboard an oncoming bicycle or car. If you know the frequency of the audio source and the velocity of the vehicle, you can calculate the speed of sound. Then, having measured the speed of sound, you can use the laptop to sample and display the varying velocity of a vehicle. A GPS might be good for calibrating the initial vehicle velocity measurement.

Or, you could just skip the experiment and do it all in The Matrix.

- posted by Leigh @ 20:44 z 0 comments

This SA-10 has always had an intermittent buzz to it, and a low-level hum. I took it apart and didn't see any obviously blown capacitors, so I did a search and found a quick review article on the Realistic SA-10 Audio Amplifier by Joe Roberts. Joe points out that C108 is perhaps under-rated for its job, so I replaced it with a 50V one I had on hand. We'll see if that takes care of the intermittent buzz.

The power cord is a two-line one that goes directly to a transformer. The hum went away when I grounded the case, so I fashioned a third-wire for it and am now enjoying a bit of the old Ludwig van.

Labels: electronics

- posted by Leigh @ 19:25 z 0 comments

Grab the Python-rigcontrol package and install it, and then run k3fixtime

tar xzf python-rigcontrol-0.3.2.tar.gz
cd python-rigcontrol
sudo python setup.py install

- posted by Leigh @ 06:04 z 0 comments

Labels: DX

- posted by Leigh @ 17:58 z 0 comments

I bought an EMU-0202 sound device from Sweetwater. (Actually I got their demo model for $10 off.) The Sweetwater folks have been very attentive, and asked what my plans were. I told them Linux and amateur radio, and they didn't bat an eye, though their main business is of course music. They said they'd report my interest in Linux support to the manufacturer. Hopefully that will result in some official support for the ALSA developers on the project from EMU.

Briefly, I found that in Ubuntu 8.10, 48Khz stereo input works with certain bit formats, and 48Khz output as well. 96Khz is recognized, but just produces a bunch of aliases. 192Khz causes segfaults in the application. Also, the device can't be plugged in during boot as it causes a hang very early on.

Patrick W9PDS reports that he's had better luck using raw ALSA builds as described here, but it's a dicey non-packaged installation.

Update: 44.1Khz works; 48Khz does not. The Creative Drivers page claims that it now defaults to 44.1Khz even after a power reset. Maybe the OSS Mac drivers will help.

- posted by Leigh @ 21:02 z 0 comments

I've been using this Elecraft K3/K2 rig control program in Python for a few years, adding bits as I needed them. It's both a set of command line utilities and a small library. Also included is a rotor control package for the Idiom Press controller. A SteppIR command library is in the works (being re-coded from C).

I've recently packaged it up into a release; it may have some issues, but I decided to go ahead and release it anyway.

Next up: Web libraries, a REST based interface, and integration into QUISC (which I was on the verge of writing when I found someone else had already done it).

By the way, don't forget hamlib if you're doing C programming. This is a convenience package for me to experiment with Python control.

Update: now a Python module Download

Labels: Software

- posted by Leigh @ 04:45 z 0 comments