satellite – Dhakajack

5B4APL

It occurs to me that I got ahead of myself with my last post about operating on six meters from Cyprus — I forgot to mention that about six weeks ago, I acquired a Cypriot callsign: 5B4APL. Up to this point, I had been operating as 5B/AI4SV, but in February I sat the licensing exam. The new callsign is not that much shorter, but it is much more appropriate since I will be based in Cyprus for at least the next two years. Many thanks to CARS (Cyprus Amateur Radio Society) for guidance on how to prepare for and take the exam. I think there were twelve of us who took the exam that day, and I’ve already met a couple of them on the air.

Ham Meteor & Satellite Event

ADDENDUM APRIL 19: This event was canceled due to inclement weather; we will reschedule at a later date.

The Vienna Wireless Society will be conducting on the evening of April 20 and morning of April 21. Those dates coincide with the onset of the Lyrid meteor shower. I am soliciting SKEDs up to the day of the event and would also welcome replies to CQs during the event. Full details, below.

Postcard from the ISS

This weekend, Russian-ARISS transmitted SSTV images of satellites hand-launched from the ISS. They used a high-resolution mode, PD-120 transmitted FM on 145.800.

I was set up for FT8, but switched over for one pass and captured this image. My process for decoding was suboptimal — I recorded using audacity on my Mac and then later played the audio back to a PC set up with MMSSTV. I didn’t have an attenuator on hand, so of course the sound level was high for the PC input, but was able to drop the gain a bit in audacity. Maybe I traded off a little image quality, but it worked.

This was a low pass (max elevation of about 12.5 degrees) on a side where I have some obstructions — those horizontal lines are probably tall trees — so probably not the best image I could have captured, but I was just curious if it would work at all.

I’ll be squeezing out what QSOs I can on 17m FT8 through the end of July 4th and will then swap in a 30m element on the antenna for the next couple weeks.

Cheap Radio Email

“Station 2” set up for digital modes including pactor.

Being in a remote location with limited infrastructure and occasional disasters of various flavors, I thought it would be a good idea to have some options to get email on and off the island without relying on local communication providers. There are some satellite phones around, but a limited number, and bandwidth is still costly. I have found two ways to get email off the island using amateur radio: APRS via satellite and via HF. I managed both with equipment already on hand and no additional expense.

Both systems rely on some sort of gateway receiving station to route the email to the internet. I’ll focus on HF because it is more robust and more likely to be available at any given time of day.

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Satellite Interlude: ISS and Fox1A

Last weekend was Memorial Day in the US, and I spent it with friends camping at Chain Of Lake State Park in Indiana. I lugged along my FT817 and VX8R and Ben (NN9S) also brought some ham equipment including his Arrow-II antenna. The camp site was a short walk from a large field, which afforded a good view of the sky, with a tree lines down around 10 degrees elevation from the far side of the field. We had some help from a couple hams-in-training interested in pinging the ISS with an APRS beacon and in having a voice QSO via Fox1A.

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VHF Update: Repeaters, Earth and Sky

I got an email from Albert, 5R8GV, last week alerting me and other hams in the area that Serge, 5R8GX/FR5GX, had put a repeater into operation: 5R8ZZ. The repeater is based at his house and puts out 16 watts (after filters) through a quarter-wave ground plane antenna on his roof. The repeater’s input frequency is 145.150 Mhz and the output frequency is 145.750 Mhz (i.e., set your radio to 145.750, with 600 khz negative offset). No PL tones are used; instead send a brief 1750 Hz tone to open the repeater.

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Arissat1 – First Attempt

I got up a bit early this morning and parked the car on top of the 6-story NIH garage in Bethesda to catch the 10:45 UTC (06:45 local) pass of Arissat-1. From there, the view North is unobstructed. The max elevation on this pass was 20 degrees, with AOS at azimuth 304 and LOS at 94, almost ten minutes in duration.

I tuned to 145.920 on USB and twirled the RIT back and forth above that frequency because I wasn’t sure how much doppler shift would matter. About a minute and half in, I picked up the CW beacon. I did not hear the bpsk signal as clearly as in this audio file. Here is what I heard this morning: Audio from Arissat-1 attempt #1 from FM19km.

In principal, to decode the BPSK1000 signal, the lower cw beacon should be kept near 500 hz. I tried my best, but after today’s experience, I realized I need something to look at — either some sort of spectrum display or the windows version of the TLM software. I had not played with the software earlier, but hoped that if I kept the signal within the receiver’s bandwidth, the decoding software would be pretty tolerant to centering, and might even track the signal pitch. Well, that is not the case. Maybe I can somehow pitch shift what I’ve captured, but I think the more practical solution is to try again, adjusting pitch live.

I did switch briefly to FM and heard just a couple syllables of speech before it went into SSTV mode and faded to static. In the above audio clip, the first part is USB, and you can easily pick out the CW signal. About halfway through, I switch to FM and you can definitely hear the SSTV, although the signal goes up and down rapidly (changing orientation of the satellite?).

I have to admit, this was something of a last minute effort, but I did remember to throw an audio splitter cable and the computer into the car before taking off to work today. I am not using a special antenna — just my trunk-mounted antenna (1/2 wave on 2m, 3 dBi). Considering that this was all before coffee, I guess I should consider myself lucky to have heard anything at all.

Later in the day, I fired up the Mac version of the TLM software, which seems less developed than the windows version. I tried to import a wave file, and it seemed to hang for quite a while, but them became responsive again. I assume it was trying to decode the bpsk, and having a hard time because the signal is very low in my recording and the frequency is all over the place. Unfortunately, for purposes of troubleshooting, no sample file is available on line, although the Arissat website says one will be posted shortly.

There’s another higher-elevation pass tomorrow at 11:23 Z / 07:23 local, and I’m planning to be set up for it. This time, I would use the PC-based version of the TLM software, which provides a real-time frequency analysis to keep the cw beacon in a narrow-enough window to center the bpsk1000 within the expected bandpass for decoding.

It would be helpful if I could figure out when the satellite is in eclipse, to know when it will be operating in lower power mode. I assume that it’s keps are not very stable, so I’ve just been going to the orbit prediction page.

Addendum: Not sure why the Amsat page just went down this evening (Aug 4th), but there’s another tracker that does a nice job — it shows whether the satellite is in eclipse or not, and if it is likely to be visible. It also provides real time tracking: