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Hardware
You'll need the following hardware, or something similar:
- AnalogToDigitalConverter:
Either ordinary PC sound hardware (for low bandwidth signals, under 40kHz),
fancy PC sound hardware (for medium bandwidth signals up to about 96kHz), or
for high bandwidth, a MeasurementComputing?
PCI-DAS4020/12 A/D card, about US$1300 [1]
- RfFrontEnd: Microtune 4937
cable modem tuner module [2]. You want
the double conversion device with the 5.75 MHz IF output for the US, or 7.125
MHz for most PAL countries.
- Some kind of board to mount the 4937. Microtune has an expensive and
inconvenient way to use the eval board. You can also build a better board by
hand using these schematics: http://comsec.com/4937-eval-board-schematic.pdf
- A suitable antenna. The right answer depends on your location. We used a
Radio Shack model 15-2151, 50" Boom Length, 18 Element Antenna (US$19.99). http://www.antennaweb.org/ has
suggestions, and also indicates the digital stations that are in your area and
the bearing to their transmitter.
(HdTv also needed to be able to
write 40 Mbytes/sec to hard drives, so see HowtoHdTv for the disk configuration
used there. Most GnuRadio users
won't be handling the same volume of data or computation, so won't need this.)
''The April 25 '03 issue of NTK (http://www.ntk.net/2003/04/25/)
mentions that EricBlossom
previewed a "$300 USB 2.0 GnuRadio
setup" at the recent Emerging Technology conference. Any details on this device?
''
-- Try the UniversalSoftwareRadioPeripheral,
Currently (2004-01-01) working in prototype.
- Gerald Youngblood's SDR-1000 hardware (http://www.flex-radio.com/) is now
shipping in limited quantities (as of May 2003). It provides a receive
bandwidth of up to 40kHz tunable from DC to 60MHz and is designed to work with
a PC sound card. It provides receive capabilities, as well as a 1 watt
transmitter for licensed amateur radio operators to use in the HF and 6M ham
bands.
Untested idea: The BT878 chip used on some analog TV cards has an additional
single channel 16 bit AD-converter for audio that can use a few fixed sample
rates between 119 and 448kHz (no, I did not forget a decimal point). It can be
used in Linux as an OSS device with the btaudio module (use analog=1 parameter)
or the snd-bt87x module of ALSA 1.0rc2 or later (use subdevice 1).
Btaudio does work with gnuradio. I had to comment out the code that attempts
to set the fragment size (btaudio does not currently support this) and the code
that attemps to set the number of channels in VrAudioSource?.h and
GrAudioSource?.h . After
making the relevent changes in VrAudioSource?.h and
audio_scope.cc I am able to use audio_scope to see a live spectrum display of
the input (on a unmodified tv tuner card this is the baseband audio output from
the tuner). The bt878 has three multiplexed audio inputs so the extras could be
used for narrow to medium bandwidth radio signals (vlf with no downconverter or
an IntermediateFrequency of
up to 120KHz).