Monday, June 27, 2011

FunCube Dongle and OSX, ie fun with python

So gnuradio seems to have a bug with CoreAudio right now, I cant use any SR higher then 44100 without getting errors. The funcube dongle has a fixed rate of 96000, no other option. So hence I cant use gnuradio with it, and basically thats all I want my funcube dongle for.

So instead of learning coreaudio to fix the bug I figured it would be fun to learn a little more about python and how wav files work and how gnuradio stores and transmits data.

Here is a small app I wrote that takes data from the funcube dongle (in int 16bit 2ch) and converts it to a 32bit float for gnuradio. Now I dont know python that well but I couldnt for the life of me find a function that did this, so I had to learn how float's were stored in a bitwise fashion then write my own function. Its ugly and slow, actually too slow, so I had to write a small app to make a cross reference include file with an array of the values converting int16 to float32

But whatever, it works :) now I can use my funcube dongle in osx again.

Ive included the record_tcp app that creates a server for gnuradio to connect to

and record_file that saves the output in both gnuradio .dat and .wav format

FunCube python

Wednesday, April 20, 2011

Two Watson antenna's. The 881 and 889

Long story short I ordered the 881 and I thought Canada Post lost it so being in a hurry I ordered the 889, both arrived the same day lol. Oh well so to compare them :)

The WSMA881 on 162.4mhz

The WSMA881 on 867mhz

The WSMA889 on 162.4mhz, there really is no difference here between the two antenna's

The WSMA889 on 876mhz here really shines when you shorten the antenna, because its telescopic from 5.5"-16". When left at full length it was no better nor worse. Shortened a little and it really took off as the superior of the two.

All the tests were done in my concrete basement with the scanner on the desk about 1ft away from the wall surrounded by electronics gear, a terrible environment for radio lol. But that was kind of the point, I didnt want a perfect environment to test it in, Im never in such a place so why test in one haha.

I want to thank Durham Radio for their excellent sales service. It looked like the 881 was lost in the mail and they got a 889 out to me next day on UPS I was really thankful for them.

Sunday, February 13, 2011

Friday, February 11, 2011

The Arduino controlling a Von Weise actuator arm

Use PWM I can control the speed and direction of the arm using serial cmd's through the Arduino, this will let me have full remote control of my dish without the need for a satellite receiver

Here is a picture of the setup plus my bench.

Here is the sample src.

Im using an Arduino UNO Mega along with a DFRobots motor controller

The power supply is a 36v 10a ps bought off ebay, there are hundreds of them on there and they're cheap too.

The actuator is a Von Weise V76-5

edit: Well something went horribly wrong lol

Still not 100% sure what happened, was playing with python and py-serial to make a little Qt app for this and sparks and smoke everywhere

36v @ 10amps sure has some kick hehe

Thursday, January 13, 2011

Icom PCR-100 IF output mod

I acquired a USRP N210 in December and love it. I was using an old Pro-2022 as my IF but it has alot of freq gaps, cant be controlled with the pc, plus other issues.

So I bought a PCR-100 off eBay for cheap and proceeded to read the service manual for it which can easily be found online. The service manual labels the parts really well, although my pcb rev is slightly different then the one in the manual its close enough.

I chose a spot right after the 2nd IF, right past a cap. Your going to need a cap anyways to filter the DC out, plus it had a through hole to make it easy to solder a wire too. (I see now recommends the same spot hehe)

Now if your only interested in 230khz of bandwidth (ie a softrock which has 192khz bw) then you may want to consider choosing farther down the line. Past the point I chose it goes to a NBFM or WBFM filter, then to another IF amp. You may want to choose that IF amp as a tap point, but I wanted alot more bw then that, I wanted to get as much as I possibly could from the Icom unit. Plus Ive got a IF buffer amp from Clifton Labs I will be eventually putting inline, so the extra gain isnt that important to me.

I took pictures as I went along, you can download them in high res here

As a note, I use qpcr1k in linux to control the PCR-100, which works well over X11 forwarding so my mac has access to it as well. I use gnuradio companion (grc) for the USRP N210. That USRP w/Gnuradio is an amazing combination, one heck of a SDR.

edit: 05 March 2011
Ive uploaded my Simple PCR app, all it does it turn the device on/off and tune a freq
edit the .py file to set your /dev/ttyUSB# or /dev/ttyS# your using to connect the computer to the pcr with