While I am on the antenna kick, Howard, G6LVB mentioned his page on putting two cheap yagis on the same boom. Very, very nice. 10db of gain for a reasonably small antenna, and RHCP to boot.
Category Archives: Amateur Satellite
K1EL remounted in a better box…
This morning, I decided to take the new box that I had acquired and remount my K1EL keyer into it. The new box is somewhat larger, so it actually has space for all five of the possible dedicated buttons that the K1EL supports, instead of the mere three that I had haphazardly bored into the previous incarnation. I was a bit more careful to make sure that there was sufficient internal clearance. As it was, I still had a single minor issue: the input jack can actually make glancing contact with the button cell. A quick fix was found however, I simply stick a piece of post-it note to the jack, and that was enough to break the contact.
I didn’t have time to wire up all the additional switches, but they are at least all mounted, and maybe next week I’ll get them all wired in. I’m quite pleased with the overall result this time: I don’t think I’ll need a third try. 🙂
Addendum: I realized yesterday that I didn’t have a complete drill set anymore. I was in the neighborhood of Harbor Freight, and picked up one of their cheap 29 piece sets. I was going to drill a 1/4″ hole, so fetched out the 1/4″ from my new set, chucked it in the drill press, and…
It was bent.
I have gotten smaller diameter drill bits that were bent before, but not 1/4″. Annoying.
Low NOAA 17 Pass
I woke up this morning, and wanted to relax a bit before the day’s exciting activities (more on this later), so I noted that NOAA17 was coming up. I got out after the pass (which had a maximum elevation of under 15 degrees) was under way, but the audio sounded pretty clear, so I recorded the audio and got the following picture:
Because it was so short, I wasn’t 100% sure what I was staring at. The water at the lower right was (I suspected) the Gulf of Mexico, but I wasn’t 100% sure. So I got out my mapping software and plotted the path of NOAA17 along the ground. Sure enough, that seems plausible.
I should figure out how to plot the visible region for NOAA passes, so I can do this more routinely. In fact, I could probably merge this with my satellite prediction code to give the ground tracks of satellites more routinely. More stuff for the future!
Pico-Satellite Solar Cell Experiment (PSSC)
I just head that Endeavor will eject a small picosatellite (5x5x10 inches) that will test two different types of solar cells in the environment of space before it begins its deorbit maneuvers. I was interested in seeing if I could find any downlink frequencies for it, but haven’t managed to do so. I did find the following NASA page:
Happy Thanksgiving!
In my house, we celebrated the holiday yesterday, to give my son a chance to go and have Thanksgiving dinner with his in-laws. So I made a turkey, a ham, two pumpkin cheesecakes, potatoes, stuffing, a ratatouille, some gravy and a bunch of veggie appetizers. My future daughter-in-law made some green bean casserole. My wife made her famous yams. We ended up having fifteen or so people: more than any other time since we got married. A good time was had by all.
Here’s hoping that wherever your Thanksgiving is, you and your love ones are healthy, and happy, and able to focus on the things which are good in your life. Best wishes!
Addendum: Here’s the NOAA-17 pass that just happpened out over the Pacicific. Max elevation was around 32 degrees, so it’s fairly short and noisy. Someday, I’ll have to get a proper WXSAT antenna and receiver.
My tussle on amsat-bb
Today’s example comes from the amsat-bb mailing list. I am a member of AMSAT and a subscriber to the amsat-bb mailing list because it’s an interesting subject that I desire to learn more about and that I enjoy sharing with my fellow hams. But AMSAT is seemingly in a struggle to save itself from extinction, and it seems to be gnawing off its own limbs while doing so. An all-too-typical example came in today. Mike Rupprecht, DK3WN and member of the COMPASS-1 cubesat program wrote a simple, concise message:
Dear all, we are looking for someone to assist us in commanding of our cubesat COMPASS-1 at the West Coast. If someone (or more) is interested in, please contact me. Thanks! 73, on behalf of the COMPASS team, Mike DK3WN
This was a simple, concise plea from help from the amateur committee. You’d think that we as amateurs would be eager to jump at the chance to help. After all, how many of us volunteer to help put up antennas, or fix equipment, or help one another to prepare for license exams, or even help with genuine emergencies, all without any kind of reward beyond our own feeling that we are doing something good.
Here’s one of the first responses that Mike’s plea received:
Hi Mike, DK3WN COMPASS-1 is not an amateur satellite http://www.raumfahrt.fh-aachen.de/ If the COMPASS team is looking for someone (or more) radioamateurs all around the world in assisting with command and telemetry using our amateur ground stations built using our amateur money in my opinion the COMPASS-1 scientific organization should donate contributions to AMSAT in order to buid our communication satellites. Is the COMPASS-1 scientific organization in Germany donating contributions to AMSAT-DL to build P3-E or not ? Tank you for you answere 73" de i8CVS Domenico
First of all, as a matter of practicality, University cubesat programs such as COMPASS-1 are typically funded by grants. The grant money is typically given to perform a given piece of research, and in the case of cubesats, to build, launch and deploy a specific payload. The teams cannot simply give such money away to other programs, no matter how worthwhile or deserving, simply because you or I would like them to. It would be an improper use of their grant money. They simply don’t have that kind of discretion. Even if 100% of their team wanted to split their grant money with P3-E, they couldn’t.
Second of all, cubesat programs are by definition low budget projects. They are low mass, low power objects launched into low earth orbit by begging space on other platforms. A typical cubesat is a 4 inch cube that weighs a kilogram, and is launched into an orbit with an apogee of around 650km. By comparison, P3-E will have an orbital mass of 90kg in a HEO with an apogee of 44,000km. Domenico’s comments make it seem as if they have cash to spare: the reverse is actually the true. A typical cubesat program grant might pay for the satellite, but control stations are typically underfunded if they are funded at all. These cubesat programs are running on very tight budgets, which is one of the reasons why they sometimes seek the cooperation of radio amateurs to gather telemetry, or, in the case of COMPASS-1 to assist with ground control operations. Even if they did have cash to spare, and the discretion to donate it to P3-E, the cost of launching P3-E compared to launching a cubesat is so great that no meaningful fraction of the P3-E’s launch costs could ever be gained by extracting pennies from cubesat launches. We might as well just try funding the launch with bake sales.
Third, one might reasonably ask: why don’t university programs try to work with us to get our satellites launched? Why can’t we compete successfully for the kind of grant money that these cubesat programs tap into? The answer is similar to the answer above: because we don’t offer them anything of any real interest relative to the cost that we would incur to launch P3-E. The cost of launching every cube sat for the last 5 years will not come close to the cost of launching P3-E, and P3-E isn’t carrying any payload that granting agencies are interested in flying anyway.
So, at best Domenico’s criticism is pointless. They can’t do what they ask. Even if they could, it would be a pittance compared to the real costs of launching the satellite that he (and frankly I) would like to see launched.
But it goes well beyond just saying something that is pointless. Domenico is essentially asking for a quid-pro-quo of money in exchange for services. In the United States, all radio amateurs are governed by Part 97, and one of the fundamental principles of this set of regulations is that we are amateurs, and we are prohibited from providing communications for a pecuniary interest. Domenico’s suggestion is that we do precisely that: that we aren’t interested in helping unless they provide us with a financial incentive to do so. It’s a violation of regulations for us to behave this way.
But even more than that: it’s beneath our character as radio amateurs. We have the motto: “When all else fails, amateur radio works.” This isn’t just a statement of technology, it’s a commitment on our part as volunteers to help each other. It’s what we do, and not just when there are lives to be saved. Amateur radio works because generous, thoughtful people give of themselves to make the world a better place. Mike reached out to the ham community for help. Domenico asked for a five spot. That’s not what we are supposed to be about.
I must admit that I lost it when I read Domenico’s letter. I called him a jackass, and while I must admit that might be a bit too harsh, he certainly is acting like a jackass. Nothing he said will help the amateur radio service. It was a pointless, useless attempt to get money from a stone that has no money to give. I also think it was petty and not in the spirit of our service.
Some people disagree or claim that my criticism was uncalled for. They also seemed to use the excuse that Domenico is entitled to his opinion, and that means I should apologize. I wonder why none of them seemed to defend my own entitlement to my own opinion. It’s always easy to defend opinions that you agree with I suppose. But in any case, no apology will be forthcoming.
Mike offered some lucky radio amateurs the opportunity to serve science, to work with a team dedicated to building relationships radio amateurs, and to operate as the control station for an satellite on amateur frequencies. My own resources are too meager to be of any practical use to him, but I suspect he’ll find some with both the equipment and the desire to help.
Addendum: Here is a link to the IARU webpage which outlines the requirements that a satellite needs to go through in order to use amateur radio frequencies. The COMPASS-1 cubesat was coordinated and its use of amateur frequencies was authorized by the International Amateur Radio Union.
Addendum2: While scanning the list of downlink frequencies for cubesats to determine their potential for interference to birds with linear transponders, I came up with this list:
Satellite No. Uplink Downlink Beacon Mode Callsign CO-66 (SEEDS-II) 32791 . 437.485 437.485 FM,CW,Talker JQ1YGU COMPASS-1 32787 . 437.405 . 1200bps AFSK DP0COM COMPASS-1 32787 . . 437.275 CW DP0COM CUTE1.7+APDII 32785 1267.600 437.475 . 9600bps GMSK JQ1YTC CO-65 (APDII) 32785 . 437.475 . 1200bps AFSK JQ1YTC CO-65 (APDII) 32785 . . 437.275 CW JQ1YTC PolySat CP4 31132 . 437.325 437.323 1200bps SSB N6CP CO-58 (XI-V) 28895 . . 437.345 1200bps AFSK JQ1YGW CO-58 (XI-V) 28895 . . 437.345 1200bps AFSK JQ1YGW CO-57 (XI-IV) 27848 . 437.490 . 1200bps AFSK JQ1YCW CO-57 (XI-IV) 27848 . . 436.8475 CW CO-56 (CUTE1.7) 28941 . 437.505 437.382 1200bps AFSK JQ1YPC CO-56 (CUTE1.7) 28941 1268.500 437.505 437.382 9600bps GMSK CO-55 (CUTE-I) 27844 . 437.470 . 1200bps AFSK JQ1YCY CO-55 (CUTE-I) 27844 . . 436.8375 CW
Frequencies cribbed from this link..
An astute observer will note that in virtually every case, these cubesats are using the top 1Mhz of the 435-438Mhz allocation that is internationally recognized as the satellite subband on 70cm. Currently no transponders operate in this section of the band. VO-52 has uplinks on 435.230-435.200. DO-64 has uplinks on 435.570-530. FO-29 has the downlink on 435.900-800. And AO-7? It’s not even in the subband, with an uplink on 432.125-175. The simple fact is that the chance for interference between cubesats and any existing or even forseeable launch is exceedingly low. I was going to run a calculation to demonstrate that even if their frequencies did overlap, the chances of them actually being in the passband of a linear bird was essentially zero, but given that they don’t overlap in frequency at all, the odds aren’t just essentially zero, but are in fact precisely zero.
First SSTV image from ISS
It’s not too exciting, but it’s a start. During a 30 degree pass, I managed to get MacRobot SSTV to decode this partial image. It’s not the greatest SSTV decoder: it seems to miss the VIS preamble almost all the time, and loses sync fairly often when noise interrupts, which when you think of it, is pretty inexcusable. I’m told the various Windows programs are better. But it’s a start, and until I write something better, it’s all I got. I’ll be trying for some more passes later today.
Addendum: During my second pass of the day, the SSTV was off, but we heard the voice of Richard Garriot answering questions (which we can’t hear) but which were very legible in response. It starts out a little scratchy, and there are relatively long bursts of static where we don’t hear the questions, but his answers are interesting. Enjoy!
Richard Garriot Speaks from the ISS (MP3)
Addendum2: Here is a link to a master repository of received SSTV images from the ISS. Check back frequently.
YouTube – Cute-1.7 + APD II Earth Movie
YouTube – Cute-1.7 + APD II Earth Movie
From the amsat-bb:
We release the movie taken by Cute-1.7 +APD II.
It was taken above Japan.The movie is very short. But, it is the 1st movie taken by 3 kg
satellite in the world. From this movie, we could confirm that
the satellite rotates at about 0.2 rad/s.We are planning to take pictures and movies continuously.
So we’re very happy if you cooperate in our operation.This movie was taken at 2008/07/17 0:02:14(UTC)
Space Tracking Notes
Sven Grahn’s Space Tracking Notes talks about his efforts in using radio to track satellites. There is all sorts of really good stuff in here, a lot of it having to do with tracking the secret launches of Russian satellites during the Cold War. Very, very neat stuff.
CubeSat Community Website – Developers Workshop 2008
Just a link to the papers from the CubeSat Developer’s Workshop 2008. I’ve gotten more interested in satellite design and what’s possible over the last few months, particularly in power management.
Threefer of Satellites…
I’ve been trying to catch the SEEDS cubesat in SSTV/digitalker mode for a while. No dice. But I did record three of the cubesats as they marched across. Below is a 15 minute mp3 file. First up is COMPASS-1, which has a very squirrelly sounding morse signal. Next up is CUTE-1.7 APD II (honestly folks, next time pick a shorter name!) and finally is good old SEEDS II, beeping away.
COMPASS-1, CUTE-1.7 APD II, and SEEDS on June 13, 2008
Here’s my spectrogram of the audio. You can see that COMPASS-1 ramps up in frequency, making little hooks in the spectrogram. It’s followed by the CUTE telemetry, which is being Doppler corrected. When I quit tracking this, the frequency drops off the bottom. I then have a bit of an audio drop out as i accidently shifted to FM, and then began to track SEEDS II as it came from the north. I tracked it down to about 4 degrees elevation, where I could no longer hear the signal.
Picture from CUTE-1.7
Click below for a color picture relayed back to earth from the CUTE-1.7 satellite. It is my understanding that CUTE is only capable of sending this kind of data back under command from its ground station in Japan, so I won’t be receiving these myself, but I’m fairly impressed. The camera on board is essentially a CMOS cell-phone camera, so this is basically a snapshot from an orbiting cell phone.
Website with Amateur Satellite Frequencies
All the fun I’ve been having with tracking satellites has made me want to create a nice little database of all the frequencies they use. This page seems like it had everything you need:
SEEDS spectrogram
Last night I was redoing my Python script that did Doppler tracking. There was a very low (max elevation under fifteen degrees) pass of SEEDS II that came up while I was making changes, so I went ahead and used it to record some of its Morse telemetry. The signal was pretty weak and intermittent, but I was able to hear it pretty well. I keep hoping that I’ll catch it in SSTV/Digitalker mode, but so far, no dice. I did make a spectrogram of the pass, just to see that morse telemetry. Click the link below to get the (very wide) picture of the telemetry.
The signal was pretty weak and hard to hear, since I was recording it on a low pass, and from within my house to boot. Here’s the audio:
Another look at Yubileiny
In an earlier posting, I presented a recording that I did of the new Russian satellite Yubileiny, also designated RS-30. I finally found my spectrogram code, and made a picture of the resulting recording. It’s kind of big, but click the thumbnail below if you want to have a peek:
The image consists of 27 spans, each of about 30 seconds. You can see that every five seconds, my program corrects for the doppler shift, perhaps causing a break in the morse line. It’s relatively easy to read the morse code off the resulting image.