[amsat-bb] decoding Niwaka
normanlizeth at gmail.com
Thu Dec 20 21:37:04 PST 2012
In the process of rehabbing a dish and building a feedhorn for the
space segment at 5.8 GHz. Choosing a radio and a conversion scheme
that is both economical in the short term and with the ability to
reuse the radio at a later date has been an interesting journey.
The radio that I've found is the ADF 7020 development board. There are
several flavors of daughter cards for different licensed or ISM bands.
The particular flavor I'm considering using is the licensed band
(ham!) uhf radios (432).
Rather than reprint the data sheet, feel free to make google your
friend! Short synopsis is that it natively supports what looks like
more than a few common modes of demodulation for the type of data as
well as data rates compatible with satellite data downlinks.
Additionally, there is the capability to slew the frequency via
electronic frequency control OR via data in. Smells like an
application of an arduino playing DTE for an RS 232 connection. The
arduino can be driven by data from the dde interface from either
Orbitron or Satpc32!
Frequency conversion scheme will use a mixer and yig with a
synthesizer. This sounds like a difficult approach. Most of the heavy
lifting has been done by John Miles ke5fx. Driving the yig is quite
straight forward using either a parallel port or Arduino or such.
Mixer is a Hittite microwave dev board bought for 16 bux shipped on
epay. This is flat out the tiniest thing I've ever worked on. Pictures
to come!! Watch my flickr page.
The mixer should support both the data radio and a funcube dongle via
a mini circuits power divider.
The key is most of this gear is capable of being repurpoused to
Alexander, Graham and Bell when they're deployed.
Sorry as I've left out more than I've included, I'm afraid.
73 de Norm n3ykf
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