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Another Amateur Radio Satellite
k4hg writes "Remember the US Naval Academy satellite with the measuring tape antennas?
Well, not only is it still alive after nearly four years in orbit (be sure to read the 2001 Slashdot articles to see who was right and wrong about it working at all!), but the latest satellite to come out of the same lab, called PCSat2, was installed Wednesday on the International Space Station. It is bolted to the space station on the P6 truss, but is otherwise independent, only benefiting from the high mass to drag ratio of the ISS to prolong orbital life. The satellite is alive and transmitting on amateur radio frequencies, I could hear it on a marginal elevation in the Florida Keys. When it come in range of a ground station with better coverage, the data will be viewable here in real time. This new system is in addition to the amateur radio station already operational on the ISS.
And yes, they used tape measure antennas again, you could see them deploy on Nasa TV!"
When the checkout is complete and the satellite is opened for general amateur use, it will also relay position between two points on the earth (which is the main function of the first PCSat).
The ISS is fairly easy to recieve, but due to it's low orbit it has a very small footprint meaning you only get about 7-10 minutes each pass when it will be in range.
:(
On the upside it's got a higher power transmitter than other Amateur radio sattelites so it's a lot easier to hear. I regularly listen to it with just an HT and stock rubber duck antenna. 145.800 is the frequency of interest but what you hear depends on what they're doing with it.
Most often it's in packet mode so all you'll hear are bursts of data. They aren't very melodic but they do stand out above the background noise so you can tell you're hearing it. It's 1200 baud packet and with something like a $45 TNC-X hooked to your audio you could decode it fairly easily. The packet transmissions are a combination of APRS for position reporting on the earth and the BBS for sharing messages.
From time to time it gets put into cross band repeat mode where it listens on 437.800 and then retransmits whatever it hears on 145.800 I made a contact through it in that mode just a few weeks ago using nothing more than a homebuilt "J-pole" I usually use for communications on earth based repeaters. (They're real easy antennas to build, just takes one 1/2" copper tee 1 1/2" elbow and 10' of 1/2" copper pipe, lots of sites on the net with plans for them.) For my uplink I thought I was using a 440mhz Jpole I had build but not yet installed but later found out I was using my directional Yagi I built for listening to weaker satelites - amazingly I had that very directional antenna pointing nowhere near the ISS but was still able to get a signal through it very easily.
The third mode the ISS radio may be in is just a normal radio with an astronaut on the other end. I've yet to be lucky enough to hear it in that mode
However the radio is also off from time to time since it's not a primary mission of the ISS. It's always off when they're on spacewalks to keep down RF exposure.
The website www.issfanclub.com is a great place to check and see what the current status is. They have an area where people submit what they've heard recently so you can see what mode it's in. Though for some reason the site isn't responding today.
Because of the ISS's small footprint just knowing it's over NA isn't usually good enough. You'll need a way to check it's actual current position. On Windows I use a package called Orbitron which is postcardware and works great. amsat.org has links to a bunch of other sat tracking programs as well as a tool for finding passes through their site. Also because the ISS tends to move around more than most sats you need to make sure that your keplerian elements are up to date. Those are what the tracking programs use to determine it's exact position. Most sats are fairly fixed in their orbits but the ISS is adjusted from time to time espically when docking with a shuttle or other supply ship.
--- Juggle juggle@hitesman.com
Once you get some idea of when the sat will be overhead, you can start tuning around the transmit frequency. You have to keep the squelch open, and it helps to have a continuous tuning receiver because it is easier to adjust for doppler shift. I wouldn't think the NASA communications between the ISS and ground control is open for the general public (looks like the ground control systems are not easily heard by a scanner anyway), but the HAM stuff is all just narrowband FM. Good luck.
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What changed under Obama? Nothing Good
Teaching someone how to track and listen to an orbiting spacecraft in a short post is pretty tricky - so yeah I figured some would stumble on a few of the more specialized terms. But I'm willing to keep helping since just a few months ago all of it was gibberish to me as well even though some of the questions lead me to believe I'm just responding to a troll.
/. quite a bit lately with the whole cell phones will fry your eyes and all the Wifi/WiMax/Bluetooth wireless stuff.
Just for reference when I say spacecraft I'm including unmaned satelites juts to prevent confusion before it starts....
-very small footprint
The footprint is the area of the earth visible to the orbiting spacecraft. The higher the spacecraft the more of the surface of the earth that will be line of sight to it at any given time. That dosn't necessarially mean the spacecraft can only see the area in it's footprint, but it does mean only those in the footprint can see (and talk to or recieve transmissions from) the spacecraft. The ISS is the lowest orbit of any spacecraft carrying amateur radio so it's got the smallest footprint. That means the window that you can hear it durring is shorter than any others - but it also means the signal is louder and easier to hear.
-HT and stock rubber duck antenna
HT = HandiTalkie. A small low power handheld radio. "Rubber Duck" is a cheap flexible antenna with little or no gain, basically the bare minimum to recieve a radio signal.
-in packet mode
-1200 baud packet
-$45 TNC-X
Packet is a form of digital communication. 1200 baud is the speed it runs at. A TNC is to radio basically what a modem is to a phone line, it converts audio to digital information and vice versa. The TNC-X is a pic (small microcontroller populary with hobbyists) based TNC that you can assemble yourself for very low cost. It has USB capabilities but relies on the computer it's attached to do to much of the "thinking" for it.
-APRS for position reporting
APRS is a a position reporting system. Kind of like the Garmin Rhino only a LOT more powerfull. It uses 1200 baud packet to encode information and transmit over the air where it is picked up by other amateurs.
-BBS for sharing messages
Seriously, what the heck are you doing reading slashdot (a BBS!) if you don't know what a BBS is. This is the point where the troll starts to show...
-homebuilt "J-pole"
As explained in my first post, it's an antenna you can build yourself. Once again the trollishness is getting pretty bad.
-directional Yagi
A Yagi is a certian type of antenna, google is your friend. They're very directional meaning that they transmit a very directed signal and likewise recieve from a limited area. Omni antennas you don't aim, directional you do.
-RF exposure
RF = Radio Frequency. Come on, RF exposure has been discussed on
-make sure that your keplerian elements are up to date
Keplerian elements are descriptions of a spacecrafts orbit. They're used to calculate the position of the spacecraft. Most tracking software have built in utilities to download them on a regular basis to make sure you know where a spacecraft will be.
--- Juggle juggle@hitesman.com
I've been watching the shuttle mission on the K6BEN amateur TV repeater near San Jose, which is on 421.25Mhz, the same as cable (not broadcast) channel 57, through my VCR and with a Yagi I made from a magazine article. The NASA Ames Amateur Radio Club is providing the feed with a 1.2GHz uplink to the repeater. They also have shuttle audio on two meters, and I can receive that with my VX-2R HT.
It has the useful purpose of being a place to go and stay. Getting up to LEO requires a lot of thrust and equipment, but take note of this highly recommended article: A rocket a day keeps the high costs away. If you can haul up large amounts of stuff, for a cheap price to LEO and the ISS, then everything else has already been solved, practically. I see the ISS as a solution to a problem that will come eventually.
True confidence comes not from realising you are as good as your peers, but that your peers are as bad as you are.
PCSat2 .Info page (with images)
You can kind of see it mounted on the ISS.
I'm a 2000 man.
More likely elevation as in "horizon at the bottom, zenith at the top." The higher the sat is above the horizon, the longer the pass, the shorter the radio path and the less atmospheric attenuation (for high UHF and above).
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