Author: Tom Zicarelli

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HAB APRS tracking

Notes on high altitude balloon tracking using APRS.

Byonics TT3 is another option – a separate APRS encoder, to be combined with GPS and transmitter, for example:

What are all the pieces I will need to make a complete TinyTrak APRS tracker?

  • You will need:
    • a TinyTrak3 or TinyTrak4 controller (The primary difference is that the TinyTrak4 can decode incoming stations, so you can monitor others if you connect a computer.)
    • a serial GPS recevier, such as our GPS2. (We sell both TinyTraks as a combo above with a GPS2.)
    • a radio/power interface cable to connect to the mic & speaker or data jacks of the 2 meter mobile or handheld radio you will use. (If you don’t have a radio, consider our Micro-Trak line which include the transmitter.)
    • a F-F null modem cable to connect the TinyTrak to your computer serial port for configuration, and possibily for operations for the TinyTrak4.
    • a USB to serial adapter if your computer doesn’t have a serial port.
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RTTY with Arduino

Transmitting on 434.650 MHz.

Successfully ran the configuration described in this article

By Anthony Stirk at UKHAS

http://ukhas.org.uk/guides:linkingarduinotontx2

Have only tried 50 baud – but the beacon ran for over an hour without errors. The receiving   setup was done on a Windows 7 computer:

  • Funcube (software defined radio)
  • FCHID (software to tune the Funcube)
  • Spectraview (demodulate signal from Funcube to SSB)
  • FLDigi (decode RTTY using custom setup)

The bandwidth of the RTTY signal was close to 900 instead of something more reasonable like 50. This can be adjusted by trying various resistor values in the voltage divider circuit.

Next steps include building antennas and increasing the baud rate.

 

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using a WiFi router as a closed local network

I set up a WiFi router today at school, with no internet connection to use for ssh logins to Raspberry Pi and OSC experiments with Arduino. It has the same SSID as my home router so it will be interesting to see what happens when I go from one place to the other. 

Update: Actually this works great. Have been using it for any situation that requires OSC.

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FM Midi Synthesizer with Pd on Raspberry Pi

Here’s a simple FM Midi synthesizer developed in pd running on a Raspberry Pi. The patch was written and tested on a Macbook, then the patch file is uploaded to RPi and run using pd-extended from the command line. For example the command to run this patch is:

pd-extended -nogui -noadc -midiindev 1 piSynth1.pd

[todo: upload patch to this site. Currently in tkzic/rpi/pd/piSynth1.pd]

[udpate]: when trying this again, a few problems came up:

  1. R-Pi didn’t recognize sound card/midi: Solution was to connect the sound card directly to the R-Pi USB port and connect the Midi controller via powered USB hub
  2. Sometimes pd-extended errors out with a device busy message. Seems to run ok if you press ctrl-c and repeat the pd-extended command line. I think this problem may be due to a previous process hanging – and not exiting cleanly

 

 

 

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Pd synth examples

notes

A collection of Pd synth patches that might run on Raspberry Pi.

 

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bluetooth with Raspberry-Pi

notes
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Raspberry Pi with Pd: audio test

notes

In an audio pass-through test using Pd, with a USB sound card (Griffin iMic), the maximum stereo sample rate before ‘breakup’ is 32000.In mono, it sounds “ok” at 44100. Latency seems low enough to use for music but I’m too sleepy to figure out the numbers.

I don’t know enough about Linux audio to say if the performance deficit is due to ALSA drivers, the sound card, background processes, pd, the CPU, or what?Anyway I ‘m guessing R-Pi will spawn interesting synths and lo-fi FX processors. They’re cheap enough you could use them in parallel.

Prediction: They’ll double the speed, and sell a million more by the end of the year. We’ll see a range of ‘Pi’ clones which run the same Linux distributions, but offer various speeds and IO options. It feels like the democratization of manufacturing has taken another huge leap.