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Space Technology

Another Amateur Radio Satellite 140

Posted by samzenpus from the very-cool dept.
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!"
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Another Amateur Radio Satellite More

Another Amateur Radio Satellite

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  • Heh... (Score:2, Funny)

    by WindozeSux ( 857211 )
    Not only does this satellite transmit Amateur Radio waves, it measures the stars! :)

  • Ham nerds (Score:5, Funny)

    by QuantumG ( 50515 ) <qg@biodome.org> on Wednesday August 03, 2005 @10:17PM (#13237286) Homepage Journal
    Now I know how "normal" people feel when I start talking about code.

    • Re:Ham nerds (Score:2, Funny)

      by Kris_J ( 10111 ) *
      What's the Ham vs Computer vs whatever Nerds chain that's the equivalent of RPGers "greater than" LARPers "greater than" Furries?
    • I gave up talking about code years back, and the other night I realised why. I spent two or three hours coding a little utility to take strips of 24-bit icons (14 per row, fixed width & height), slice them up and save them out to individually named ICO files in the relevant skins folder. I'd do it manually, but this way I can generate 20 skins with a click of the mouse.

      I tried to explain, briefly, why I was happy it was all working, but it sounded so trivial in 25 words or less and the reaction was...
      • Well, they're right, if you'd just scripted the GIMP it would have taken you minutes.
        • Plus three hours to figure out the scripting ;-) (I'm an old dog... new tricks come hard these days.)

          I'll certainly look into it though. I use the Gimp already, just haven't delved into the script language.
      • I thought you gave up talking about code...

      • Re:Ham nerds (Score:3, Insightful)

        by Thuktun ( 221615 )
        I tried to explain, briefly, why I was happy it was all working, but it sounded so trivial in 25 words or less and the reaction was... three hours to cut up a bunch of pics?

        Geeks like us appreciate not having to do the same thing multiple times, particularly if it's mindless work. You avoided mindless work by creating something which you can reuse later to continue avoiding mindless work. Sounds fine to me!

  • Price? (Score:5, Interesting)

    by Atlantic Wall ( 847508 ) on Wednesday August 03, 2005 @10:21PM (#13237309)
    The thing may be cheap to build, but you can not just throw it up there like a kite, it needs a rocket to get it into orbit. the price does not reflect this cost.
    • Tell that to the amateur rocket enthusiasts, heh.

  • marginal elevation? (Score:5, Funny)

    by fenodyree ( 802102 ) on Wednesday August 03, 2005 @10:27PM (#13237326)
    Is there a type of elevation in the florida Keys _other_ than marginal?

    Marginal elevation: Elevation due to a stick of margarine. The low cholesterol alternative to butteral elevation.

    /*sarcasm*/

    • yeah (Score:2)

      by CiXeL ( 56313 )
      actually theres a really large trash heap you can get some elevation on.

      they have an interesting way of getting rid of trash here. they compress it and pile it up and then throw dirt over the top of it. it creates these MASSIVE pretty green hills as the natural tendency of any field or pile of dirt is to sprout grass.

      my coworker here refers to the big one in south of miami in cutler ridge as 'mount trashmore'
  • A school science experiment in the form of an amateur radio satellite. Shuttle to deliver it, ISS to 'hold it up', finally, the pair of them actually doing something useful....
    • As I understand it, real science on the ISS won't begin the Columbus Science Laboratory is added (if it's added), and, really, not until they can have six crew there on a permanent basis.

      But, frankly, it seems the history of science in LEO is pretty poor. Aside from using LEO as a convenient spot to look down upon the Earth or up at the stars, that is...

      Can any Slashdotters make a convincing case that science on the ISS is a vaguely good use of funds? In the sense of "the scientific payoff is likely wor

      • Re:Yeah... (Score:3, Informative)

        by fbjon ( 692006 )
        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 [fourmilab.ch]. 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.

      • Re:Yeah... (Score:3, Interesting)

        by Vo0k ( 760020 )
        Freefall research. Lots of processes give totally unexpected results without gravity. Some of them can be simulated in ballistic flight, but it lasts at most a few minutes. You can't examine gravity-less growth of plants, formation of crystals, diffusion of liquids and all kinds of processes that simply take time. Things that depend on gravity start often to behave in completely unexpected ways when the gravity is not present. We often have no idea what kind of profit would that give us, but it's like explo

        • Orbital microchip factory.

          Short pause to remember that when we started into space, one of the possible commercial exploitations that was mentioned was an orbital vacuum-tube factory.

          Anyone priced a 6146 lately?

        • Yeah, I want Intel's toxic waste or even "known space junk" raining down over my house. Good idea. Most of it might burn up in the atmosphere, but is that really any better, i.e. isn't burning toxic waste still toxic waste?
        • You can't examine gravity-less growth of plants, formation of crystals, diffusion of liquids and all kinds of processes that simply take time.

          "Gravity-less" is not correct. Even "microgravity" is a misnomer. "Micro-acceleration" would be a better term.
  • What are these amateur satellites for? I clicked on a link and I saw a bunch of entries like these:

    02:11:26:12 : W3ADO-1]BEACON,SGATE,qAo,N1GAU-15:T#014,066,058,05 8,087,213,11111111,0001,1

    Enlighten me, please...

    • Re:Stupid Question (Score:4, Informative)

      by k4hg ( 443029 ) on Wednesday August 03, 2005 @10:40PM (#13237384) Homepage
      That is telemetry, which gives the status of the satellite. PCSat2 is a material-science experiment, which monitors 70-odd different solar cells and how they respond to the environment of space. The solar cell performance data is sent via a separate amateur radio system.

      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).

    • More specifically, that is an APRS packet containing telemetry ... the APRS network primarily operates on 144.390 MHz. It's a tactical network of stations that send and repeat location-aware information. Primarily, amateur radio operators use it for regional mapping of other APRS stations and weather data.

      The original PCSat is an APRS satellite ... ie: it relays APRS packets to a wider area. The ISS has amateur radio equipment on board and it also was an APRS "digipeater". Sometimes the ISS astronauts g
      • You can see this telemetry converted into sensible numbers on the realtime telemetry page at http://www.pcsat2.info./ [www.pcsat2.info] This shows the operational characteristics of the PCSAT2 device and some of the basic characteristics of the MISSE5 solar cell experiment.
  • OK, I'm not a ham but I have a couple of scanners. My question is, how can I eavesdrop on the ISS and/or STS shuttle missions? Some web searching has led to 145.8000 and 146.6550 as the ISS and STS audio downlinks, respectively; however, monitoring them even when ISS is over North America doesn't get me anything.

    Are there other interesting frequencies, or does the ISS/STS have to be "exactly overhead" in order to pick up on their transmissions? I presume that if Houston is able to pick them up, I should be

    • Re:Q: How can we listen to ISS/Shuttle comms? (Score:5, Informative)

      by Juggle ( 9908 ) on Wednesday August 03, 2005 @10:59PM (#13237450) Homepage
      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.

      • very small footprint
        HT and stock rubber duck antenna
        in packet mode
        1200 baud packet
        $45 TNC-X
        APRS for position reporting
        BBS for sharing messages
        homebuilt "J-pole"
        directional Yagi
        RF exposure
        make sure that your keplerian elements are up to date

        Dude, I have no idea what any of that means.

        The bold one's my favorite, though.

        • Re:Q: How can we listen to ISS/Shuttle comms? (Score:5, Informative)

          by Juggle ( 9908 ) on Thursday August 04, 2005 @12:21AM (#13237736) Homepage
          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.

          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 /. quite a bit lately with the whole cell phones will fry your eyes and all the Wifi/WiMax/Bluetooth wireless stuff.

          -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.
          • Ah I wasn't trying to be a troll. I was at most trying to be mildly humorous for other people like me who don't understand it.

            I know what a BBS is, but I don't quite understand how a satellite would use a BBS for messages. Also, I don't really read into the stories that much, so I didn't really know what RF was.

            Thanks for taking the time to explain things. It makes more sense and I'm actually interested in it now.
            • Hopefully the bit about Packet and what a TNC is helps fill in what a BBS is doing on a satellite.

              Sometimes people forget that radio is usefull for more than just music and voice. You can also send data by encoding it someway.

              Think back to the days of dial-up BBSes, only one user at a time so you do a store and forward type of deal. On radio it's the same. Only one person can use a frequency at a time so you can either have a single conversation or use a BBS to store messages and let multiple people send
          • A TNC is completely superfluous.
            It is a technology developed over 20 years ago, at the time the typical radio amateur would have only a terminal or a very simple computer, and computers existed in very many variants so software development on home computers was a nightmare.
            To make packet work, someone developed a small embedded system with modem and firmware running the protocol, and connected it to a serial port of a computer that would only be a terminal.

            However, with the current state of the art you don'
            • Even in Linux this service is available, as part of the standard kernel.

              Really?! The Linux kernel has a built-in soft modem? I thought it just understood the higher-level packet protocols like AX.25. All I can find is: Device Drivers > Networking Support > Amateur Radio support > Packet Radio protocols > Amateur Radio AX.25 Level 2 protocol . If it's not in the kernel, is there a software TNC/modem package for Linux?

              • I believe AX.25 is what you are looking for.
              • The program that acts as a modem is called soundmodem. Its home is www.baycom.org/~tom/ham/soundmodem [baycom.org]. You run audio from your radio's earphone to the computer's line-in, and from the computer's line-out to the radio's mic/line-in. Soundmodem handles converting the data-audio signal conversion.
                The tricky part is getting the computer to actually turn on the mic (push the PTT button) on the radio before transmitting. This requires an interface between the computer's parallel or serial port, and the radio
              • As ThinkingGuy wrote, that part is called soundmodem. It is also in the standard kernel.
                You need the AX.25 protocol as well.

                When you have enabled the AX.25 protocol and the soundmodem, you can use various user-mode programs to display what you are receiving. In SuSE Linux, which I use, there are packages like ax25-tools and ax25-utils.
                • [soundmodem] is also in the standard kernel

                  It is? I grepped the kernel for soundmodem and only found one reference to it, in a file called hdlcdrv.c. The page for soundmodem suggests that it is a usermode program that integrates with the kernel AX25 stack. I'm confused...

                  • Apparently it has been removed in 2.6
                    In 2.4 it was part of the standard source but of course it usually was not enabled in .config.
                    Maybe they considered the audience too small...

                    But anyway, it is available for Linux.

                    In my own system I use a HDLC interface card that is driven by drivers/net/hamradio/scc.c and has external hardware modems, this was a solution popular between the TNC and the softwaremodem era. This driver is still in the 2.6 kernel, together with some others.
                    It scales a bit better because it

                    • The network has mostly died...

                      It's really a shame, because (/me just can't force himself to write "in this post 9/11 era")... well, because it is good to have a long-range, backup data network that can be driven by battery-powered portable devices and can route emergency position information across the nation (with VHF-HF digipeaters). It would be cool if packet had evolved into a parallel Internet, and hams could basically use the Internet (albeit at 9600 baud) anywhere near a digipeater.

          • 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. Handheld Transciever, that's the technical definition.
      • If you need a JPole here's the place to get one [martechsys.com]

    • Re:Q: How can we listen to ISS/Shuttle comms? (Score:4, Informative)

      by grumling ( 94709 ) on Wednesday August 03, 2005 @11:20PM (#13237511) Homepage
      You can, but it will require a little playing around with an antenna. It is unlikely you will be able to hear with a standard "rubber duck" antenna. I use one of these, made by Arrow Antennas [arrowantennas.com], for working Ham satellites. Then you need to figure out when the satelite will be in range. For example, AO-51 is in a polar orbit. It makes 2 passes per day. I have heard it with a 1/4 wave dipole on my HT, but not very well. The Arrow works much, much better. A good source of location data is the Heavens-Above [heavens-above.com] web site, but if you really get into satelite listening, you'll want to download a tracking program. I use STS Plus, mostly because it is freeware, but there are many others.

      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 [qsl.net]. 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 [klabs.org] anyway), but the HAM stuff is all just narrowband FM. Good luck.

    • Here is the CHEAP answer:
      YES

      You should have no trouble hearing the ISS, The Shuttle or any satellites using Ham Radio.

      How to do it

      You need to know when to listen. Yes you can get keps and computer software and learn how to use it, however it's real easy for average Joe to just go to http://www.heavens-above.com/ [heavens-above.com] and look it up. They tell you when and in what direction. ---It's great because you can see the ISS and other orbiting things too.

      These satellites use several frequecies accross several band

    • Thanks to everyone who responded! I've been using heavens-above to forecast Iridium flares for some time now, so I'm aware of their ISS tracking. What I didn't know is how close satellites such as ISS had to be in order to pick up their transmissions.

      I presume that since the shuttle is currently docked to the ISS, its passes overhead are concurrent with ISS. There is no pass listed over my area until 8 August, so I imagine that I should keep my scanner tuned to the local po-po trunk until then... ;)

      Thanks a
  • Shouldn't that "Yet Another Amateur Radio Satellite"?
    Did someone miss a chance to add "Yet" to derive a "Yet Another Names Starting With Yet"
  • Yes the satellite is still operational, too bad the website isn't :)

  • In case of slashdot... (Score:5, Funny)

    by anthony_dipierro ( 543308 ) on Wednesday August 03, 2005 @11:11PM (#13237487) Journal
    In case the site gets slashdotted, here's a copy of the recent activity:
    00:08:54:51 : PC2XXB]APRS,RS0ISS-3*,qAO,KB8ZGL-5:!3900.00N/07630 .00W0Testing

    00:08:56:20 : PC2XXB]APRS,RS0ISS-3*,qAO,KB8ZGL-5:]testing
    02:03:26:43 : PCSAT2]APRLTM,SGATE,qAO,KC9XG:{T# IGNORE ALogger A side test packet
    02:03:26:43 : KC9XG]APRS,PCSAT2*,qAC,KC9XG:] IGNORE ALogger A side test digi packet
    02:03:26:44 : PCSAT2]APRLTM,SGATE,qAO,KC9XG:T# IGNORE ALogger A side test packet
    • 02:03:26:43 : KC9XG]APRS,PCSAT2*,qAC,KC9XG:] IGNORE ALogger A side test digi packet
      02:03:26:44 : PCSAT2]APRLTM,SGATE,qAO,KC9XG:T# IGNORE ALogger A side test packet
      ???
      Profit!
    • Have you ever looked at the wire protocol of IRC?
      It's actually fairly similar to this.
      • In case that wasn't a rhetorical question, yes, I have.
        • Great, so what you were seeing is the raw protocol data.
          For examples of what gets done with it see
          aprsworld [aprsworld.net], an open source site and database of APRS location-based service data generated by and for hams.
          You can see google map overlays, ACME.com topo map overlays, tracking data, historical events, and also other services such as weather reports from individual weather stations.
          • Yeah, it's a bunch of low-tech do-it-yourself stuff that I'm not even allowed to play with because of stupid government rules.
            • Well, it's an international limited resource with a minimal competence and rules examination you have to pass first. The tests are online at QRZ.com [qrz.com] (click on practice exam) and you can have your license in a few weeks. It's actually fairly similar to certification exams for IT professionals, for MS developers, or DBAs.

              As for low tech, far from it. I just finished building a PIC-based microprocessor controled module for my radio; it's actually quite similar to the kind of experimentation that people do n

              • Well, it's an international limited resource

                So are sidewalks, but I don't need a license to walk down the street. So is the internet, and where do you think the internet would be today if you had to take a test and get a license to use it?

                It's actually fairly similar to certification exams for IT professionals, for MS developers, or DBAs.

                Except that you aren't required by law to take those exams in order to be an IT professional, MS developer, or DBA.

                As for low tech, far from it. I just finished

              • So, go check out QRZ.com for the Technician (no morse code required) test

                Alright, how high do I have to score? I got a 60% on the practice test, and that apparently wasn't high enough.

                Then, assuming I read up on a few things, and can get a passing score, all I have to do is go to one of the places listed at http://www.arrl.org/arrlvec/examsearch.phtml?State =FL [arrl.org] , give them $14, and take the test? I guess that isn't too bad. Not sure how useful it'll be, though, especially since I live in an apartment

                • Hey, that's great news!
                  You can try hamtestonline.com as well, which has a study guide (free for the first 15% of the questions or so) and see if that fills in the gaps.

                  You don't need roof access to get to a satellite, you can do it from outside.
                  Send me mail please if you want to go further and I can hook you up with people to help.

                  (That goes for anyone.)

  • Antenna Picture (Score:4, Informative)

    by anagama ( 611277 ) <obamaisaneocon@nothingchanged.org> on Wednesday August 03, 2005 @11:21PM (#13237517) Homepage
    I didn't see any pictures of this infamous antenna, but some googling brought me to this picture [uiuc.edu]. Seems as though this idea has been in circulation for quite some time! Funniest line:

    We were allowed ten pounds total-payload weight, including antenna and batteries and enclosure. We wanted to transmit on 20 MHz, the same frequency as the Sputniks, so we needed a long antenna, on the order of 3.75 meters, to get the best possible efficiency. It had to be confined to the Lockheed-supplied box during launch, and to erect itself upon signal after orbital injection. The Air Force suggested a design for a pin-puller, an explosively activated latch which could release a spool, upon which the antenna could be rolled during the launch phase. The antenna itself was a steel tape, with a lengthwise crimp to give it some stiffness. We just walked down to the neighborhood hardware store and bought a carpenter's tape measure. (When an Air Force engineer asked why our antenna had inch marks, I told him it was to measure the mean-free path in the ionosphere.)
    • It is actually a very good idea!
      Why? Because it is so simple. It can hardly fail.
      Try it yourself with a 50cm (20 inch) piece, you will see it always rightens itself no matter how you hit it.
      Under wightless conditions, any length reasonable for an antenna will behave the same, and still can be packed in a small space.

      Compare that to an automatically extending car antenna. It is complicated, uses a lot of current, and can get stuck anytime.

  • ATV (Score:3, Informative)

    by leighklotz ( 192300 ) on Thursday August 04, 2005 @12:40AM (#13237783) Homepage
    I've been watching the shuttle mission on the K6BEN [qrz.com] 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 [wa5znu.org] from a magazine article. The NASA Ames Amateur Radio Club is providing the feed [nasa.gov] with a 1.2GHz uplink to the repeater. They also have shuttle audio [nasa.gov] on two meters, and I can receive that with my VX-2R HT [universal-radio.com].

  • There's supposedly no SPAM.

  • Here's an actual link (with images) (Score:3, Informative)

    by eples ( 239989 ) * on Thursday August 04, 2005 @03:35AM (#13238209)
    PCSat2 .Info page (with images) [pcsat2.info]

    You can kind of see it mounted on the ISS.
  • Is it Imperial or Metric?

    Because I'm in Europe, and need to know if I'll be able to listen in.

    Jolyon
  • Not to pan amateur radio (I wish I had my license) but why the excitement about hearing a signal from a couple hundred miles away? If that guy in Key West had a chat with another amateur in, say, Pensacola, that would be routine.
    • Not to pan amateur radio (I wish I had my license) but why the excitement about hearing a signal from a couple hundred miles away? If that guy in Key West had a chat with another amateur in, say, Pensacola, that would be routine.

      It's not all about distance in Amateur Radio. In this instance you're talking with a box in space and that's exciting for many. I have a commercial $2K HF radio, but I get more kicks out of operating a $300 kit radio and little flea-powered circuits I design and build.
    • Get your license, it requires very little effort or cost and the toys it lets you use can be pretty cool. There's lots of variety to amateur radio so I guess you go with whatever floats your boat. There are people doing EME (reflecting signals off the moon). Hearing a signal that has travelled almost half million miles may sound more impressive than a hundred miles. There are others that bounce signals off the ionisation trails of meteors. I was at a local amateur radio emergency services meeting earlier th
      • I'm in an apartment and really don't want to hassle with jury-rigged antennas and going to QRP to cut back on annoying the neighbors. If I had room for a decent antenna, I'd have my license.

        (I've looked at some of those so-called "invisible" and other antennas marketed at apartment and condo dwellers, but I'm pretty skeptical. There's never any discussion of their abilities on the receive side of an exchange. Just how good at reception can a few feet of wire hidden on a balcony really be?)
        • So, do you want to do HF or VHF?

          HF, yup, you're kinda stuck with larger antennas. I have seen some pretty nifty setups where the antenna is dangled out of a high window, and it's rolled up after the transmission is done. If conditions are right, you can talk pretty far with a pretty minimal setup.

          If you want to do VHF (or UHF) the antennas are a little smaller AND there's a pretty good chance that there's a repeater near by.

          That's one of the neat things of radio - getting by with what you have. Any twit
          • Thanks. It'd be HF for me. VHF has never gotten me excited.

            When my father was a kid, in the American midwest, he was into SWL'ing. He used a Hallicrafters that was about as big as two microwaves; a big, heavy, solid metal box. His antenna was a longwire that ran down the street on the top of telephone poles for three blocks -- about 1000 feet. His interest was MW, and he had QSL's from 10-watt MW stations in the middle-of-nowhere Australia and others in that ballpark. Kinda difficult to repeat now, I su
        • In prioncipal, a bigger wire isn't necessarilly a better antenna. A tuned wire is the best antenna. A 2m radio probably doesn't work as well with a 50 foot antenna as it would with a 3 foot antenna. I have a little 2m/70cm handheld radio with a truly pathetic rubber-duckie antenna. I can sit in my basement and get out with only 5W (QRP anyway) to the entire valley I live in (maybe 80x40 miles) because I can reach a repeater, even from the basement. From the ground floor I get out with a perfect signal to ev
    • Because it's a VHF satellite, and on the Earth, VHF communications are limited to line of sight, and a couple of hundred miles is considered DX (a long-distance communication) for VHF, usually only possible with a) tropospheric ducting (weird form of radio propagation where temperature inversions bend radio waves) 2) bouncing the signal off a meteor trail (woo, ionization!) or 3) using a satellite... or a really tall directional antenna which can peek over the curvature of the Earth. What you're thinking
    • The fact that it's a couple hundred miles up is what makes it different. Sure, getting a signal from Pensacola to Key West wouldn't be a big deal today, because you can retransmit the signal via repeaters located up and down the peninsula. (Or use HF, which is a completely different technical challenge, but is pretty well understood.)

      Imagine trying to get a signal from Key West to a point equally far away, but without any repeaters or being able to use longer frequencies for the HF advantage -- that's more

  • tape antennas (Score:3, Interesting)

    by scharkalvin ( 72228 ) on Thursday August 04, 2005 @06:55AM (#13238588) Homepage
    The very first amateur radio satelite, OSCAR-I used tape antennas back in 1961. The antennas were made out of steel measuring tapes because they could be folded back against the satelite during launch and would spring into position as the satelite separated from the rocket. The tapes are 1/4 wavelength long, which at 2 meters (145 mhz) is about 19" long. Most satelites operate at higher frequencies, though the amateur 10 meter band at 28mhz is also available for satelite use. You do the math to see how long those antennas would be....(75/frequency in mhz = length in meters for a 1/4 wave antenna)
  • When we designed the SPARTAN Packet Radio Experiment [umd.edu], we designed and used a microstrip antenna (aka patch antenna) for VHF communications. It makes a lot more sense for a space payload to use patch antennas rather than anything that sticks out of the side of the spacecraft.

    Here [mit.edu] is a good wideband VHF/UHF microstrip antenna example.

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