Projects/SDR

1. Name: Thomas Kleffel
2. Email address: tk at-or-so maintech.de
3. any special instructions | power adapter : European Standards, 220V | desired keyboard layout : US English
4. Quantity of machines desired: 1

Background

My company is doing active R&D in the area of SDR, building DVB modulators and related soft/hardware. Some of us (including me) got a ham radio license. We are running the DVB-T transmitter at the 24C3.

Basic Idea

The basic idea is to turn the OLPC into a radio receiver (or maybe even a transmitter) by adding some hardware. This is a very vague description because there are so many ways to use SDR. This is a (probably incomplete) list of Ideas:

• Classic Shortwave Radio Receiver with DSP enhancements
• Shortwave Spectrum "Browser"
• Receiver for "simple" small bandwidth data transmission modes like
  • Morsecode [[1]]
  • RTTY [[2]]
  • PSK31 [[3]]
  • ...
• Receiver for commercial radio services (Weather-Fax for example)
• Receiver for Digial Radio Mondial [[4]] (this will need some more external hardware, OLPC is not powerful enough to decode in software alone)
• Transmitting - This is difficult because of licensing issues and requires more external hardware. But it's not as complicated as one might think. Ham radio often simple, self built transceivers with low power to communicate over long distances [[5]].

Social impact - why I think it's good for OLPC

• Children could be encouraged to "play" with and explore a part of the HF spectrum
• Children would get access to a cheap radio which can (to some extend) be updated via software only
• Children could listen to ham radio broadcasts, develop interest in them and someday become a ham radio operator
• Children could stay connected and informed in remote areas without wifi access (requires transmitter)

Possible hardware devices

Disclaimer: The following list is non-exhaustive. It contains hardware that I have already worked with and/or read about.

• Gnuradio [[6]] - This is quite expensive and powerful hardware, but it's open source and using Python to connect it's software processing blocks. There is also a GUI [[7]] which looks like a part of TamTam. (I have access to this hardware)
• HPSDR [[8]] - Built by a ham radio group, very modular design, still expensive. The Idea to connect it to the OLPC already came up in their mailing list in the last few weeks.(I have access to this hardware)
• Softrock [[9]] - Affordable hardware, limited bandwidth. They're also developing a transceiver [[10]]. They also already had the OLPC-Idea.
• to be continued...

First Level Goals

• Connect Gnuradio and HPSDR to OLPC.
• Assess OLPC's processing power related to SDR - see what's possible and what not.
• Build a simple AM receiver (proof-of-concept)

Second Level Goals

• Demodulate some simple digital stuff (Morse code / RTTY)
• Write an activity to control a SDR receiver

Wild Dreams

• Build Hardware specific for OLPC
• Implement things like Chat or BBS over HF links