
How to talk to a 36-year-old space probe with GNU Radio, a USRP and a big dish - liotier
http://www.jmalsbury.com/how-to-talk-to-a-36-year-old-space-probe-isee-3-with-gnu-radio-a-usrp-and-a-big-dish/
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pronoiac
Oh cool! They presented this at Dorkbot-SF a couple of weeks ago. A bit I
particularly liked was that, because of the relative speed of the probe, a
couple of km/sec, the frequencies sent and received had to be separately
adjusted. And also, Arecibo was broadcasting with enough power to _boil birds
that flew over it._

It's _cool space shit,_ is what I'm saying.

Edit: here's some video:
[https://www.youtube.com/watch?v=NTljlMH-0oM](https://www.youtube.com/watch?v=NTljlMH-0oM)

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smoyer
"Arecibo was broadcasting with enough power to boil birds that flew over it"

Birds that flew over the parabola of the antenna or birds that flew between
the focal point and the parabola? I can't imagine the amount of energy the
former would take (and the latter is impressive by itself)!

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spitfire
Same thing with the Mig-21 radar, and I presume other fighters. If they
powered it up on the ground, bird would drop.

During WWII, soldiers would stand in front of the radar to keep warm. This was
before health and safety.

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axman6
There's a darwin award for a security guard at (I think) a TV studio who
decided on christmas eve that work was too hard and instead spent the night
sleep in front of one of their microwave transmitters. I believe they found
him dead and cooked right through in the morning.

~~~
sp332
Did that actually happen? I know someone who worked at a shortwave (a.k.a.
microwave) radio station when that almost happened. They had to shut down the
transmitters occasionally to paint the radio towers, but someone had the
bright idea that they could just power down long enough for the painters to
climb on. Then, when they weren't grounded, they could power it back up during
the painting. They actually did a test run with chickens before it dawned on
anyone that they would be cooking anything up there!

~~~
ZoF
Why would they do a test run with chickens if it hadn't already dawned on them
to some degree?

~~~
sp332
They were worried about electrical problems, not radiation problems.

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wyager
Oh man. This is such a cool example of how open software platforms have made
the world more accessible. Imagine how hard it would have been to rig up that
modulation system from scratch 30 years ago.

Also, this article made me realize how you can do frequency
addition/multiplication on arbitrary signals via complex
multiplication/exponentiation! That part of the flow graph really confused me
for a bit. So cool!

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tommi
Some glossary to make it easier to read:

USRP, Universal Software Radio Perhipheral -
[https://en.wikipedia.org/wiki/Universal_Software_Radio_Perip...](https://en.wikipedia.org/wiki/Universal_Software_Radio_Peripheral)

SDR, Software Defined Radio - [https://en.wikipedia.org/wiki/Software-
defined_radio](https://en.wikipedia.org/wiki/Software-defined_radio)

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BuildTheRobots
Looks like we've already thrashed his server (oom errors); so here's a link to
a cached version for the lazy:
[http://webcache.googleusercontent.com/search?q=cache:Qhe6rYL...](http://webcache.googleusercontent.com/search?q=cache:Qhe6rYLO9rEJ:www.jmalsbury.com/how-
to-talk-to-a-36-year-old-space-probe-isee-3-with-gnu-radio-a-usrp-and-a-big-
dish/+&cd=1&hl=en&ct=clnk&gl=uk)

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frozenport
I got to get me one of those _Arecibo_ dishes! I'm still impressed that they
were able to get access to it.

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mellisarob
it was amazing the way they accessed it

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callesgg
The hole thing they are doing is very cool and they write and post allot of
stuff.

Unfortunately most of the text they post is quite boring and detail less.

It would be nice if they added someone new to the team that was a better
writer.

