2017-03-26 Going full duplex with amateur satellites, part 2 : Installing Gqrx SDR software and the first tests 3 days ago
With the hardware available it's now time to test the first part of the software setup: whether I can have running software defined radio. To (re)install Gqrx I followed the instructions at Install Gqrx SDR on Ubuntu Linux. The first 'sudo apt-get purge --auto-remove' steps removed a lot of software and the latter 'sudo apt-get install' steps added newer (or maybe the same) versions. But I was glad to do a full reinstall, I have had weird problems with gqrx versions before. The laptop on which I am doing this has had an install of gqrx before, but was upgraded from Ubuntu 14.04 LTS to Ubuntu 16.04 LTS in the mean time, so a clean reinstall seemed a good idea. I plugged in the RTL-SDR stick and checked whether no drivers were installed, which was indeed still correct. The kernel messages:[156490.915435] usb 2-2: new high-speed USB device number 7 using xhci_hcd [156491.111136] usb 2-2: New USB device found, idVendor=0bda, idProduct=2838 [156491.111141] usb 2-2: New USB device strings: Mfr=1, Product=2, SerialNumber=3 [156491.111143] usb 2-2: Product: RTL2838UHIDIR [156491.111145] usb 2-2: Manufacturer: Realtek [156491.111147] usb 2-2: SerialNumber: 00000001To make sure the drivers aren't loaded, I have a /etc/modprobe.d/local-blacklist.conf with:blacklist dvb_usb_rtl28xxu blacklist rtl2830 blacklist rtl2832 blacklist lirc_devTo test it with the 'minimal' setup I started with just the RTL-SDR and a simple antenna, and Gqrx. Enabled remote control in Gqrx and added a radio 'gqrx-sdr' in Gpredict with host 'localhost' and port '7356' (default for gqrx remote control) and Radio type 'RX only', PTT status 'none'.
2017-03-26 Going full-duplex with amateur satellites, part 1: introduction and I bought the hardware 3 days ago
I still want to get active on amateur satellites again, but the main reason is that the amount of work per contact is a lot more than for example in a digimode contest. But I still want to make those 'special' contacts, especially when the amount of local radio noise on HF is bothering me. One of the most important improvements in making contacts on amateur satellites is working 'full duplex', meaning receiving signals while transmitting. The expensive way to reach that goal is buying a second amateur radio capable of receiving in FM and SSB modes in the 2 meter and 70 centimeter amateur bands and having computer aided tuning so gpredict can control the receiving frequency. The less expensive way to reach that goal is using software defined radio. The good news is that Gqrx SDR can be controlled by other software which as the page shows is intended for remote control by Gpredict. All I needed now was reception hardware. Since the first RTL-SDR device I bought is always in use for receiving ADS-B signals from airplanes I decided to buy another cheap one to get me started. So it was on the shopping list for a recent visit to a hamfest. At the hamfest I found a RTL-SDR stick with mcx connector and an mcx to bnc cable. But the same guy also sold cheap low(ish) noise amplifiers with SMA connectors and a 9V battery connector for power. So at one of the booths selling cable assemblies I found an mcx to male sma cable and a female sma to bnc cable, and a male to male sma cable. The plan is to put this all together in some metal case to shield the lna from the outside world. Maybe also shield the amplifier from the RTL-SDR stick so it won't pick up any extra noise. Should this work it would be possible to think of an upgrade with better SDR hardware and/or a pre-amplifier at the antenna side.
2016-06-10 ISS SSTV MAI-75 image received 9 months ago
I had no advance warning but suddenly mailing lists and other places I find my amateur radio satellite news lit up with news of another round of slow scan TV (SSTV) images. I thought at first things would be over Friday evening but then the reports started again and I put the radio, antenna and laptop outside to record another pass and decode it. Reasonable decode, especially for the pass starting in the noise.
ISS SSTV June 2016 MAI-75 image recieved by PE4KH at JO22NC 20160610 at 1900 UTC
2016-04-23 Recorded a Tim Peake ARISS contact 11 months ago
This afternoon was a contact between Wellesley House School in Britain and Tim Peake on the International Space Station. So I decided to put the finished antenna rotor to good use since one of the triggers for building a rotor was getting my arms real tired on earlier ISS passes. And indeed, I had no problem with holding the antenna. But it still took a while before I heard anything and the signal was not very good.
Listen to audio attachment:
2016-04-15 ISS SSTV MAI-75 image received 11 months ago
And a chance to receive an image from the Russian 'MAI-75' project. Originally I had a lot of trouble decoding the image with qsstv and the author of qsstv helped me find the ideal workflow. Upgrading qsstv and using a 48000 samples/second .wav file helped. Earlier I played the audio in audacity and decoded in qsstv with pavucontrol setting the 'Monitor of builtin audio' as input for qsstv.
ISS SSTV April 2016 MAI-75 image received by PE4KH at JO22NC 20160415 1627Z
2016-04-14 Tried an SO-50 pass this evening 11 months ago
And while I had the amateur satellite gear out I checked for upcoming interesting passes and saw that SO-50 would pass right after the ISS pass between SSTV experiments. I tracked the pass and heard activity, mostly from IZ5TEP with F0DTV. I tried answering a few times, to IZ5TEP and in general but no contacts. The amount of interference was not as bad as I heard a few times last year but it was not perfect amateur satellite behaviour either.
Listen to audio attachment:
2016-04-14 ISS pass between SSTV experiments, nothing heard 11 months ago
I saw people post more images which seemed to be from the MAI-75 SSTV program. I tried a pass at 18:27 UTC but heard nothing. Checking the article ISS Slow Scan TV in April - Amsat-UK shows that the ARISS commemorative SSTV event ended at 14 April 11:35 UTC and the first MAI-75 activity was 14:45 until 18:00 UTC. The next MAI-75 activity is Friday 15 April 14:10 until 19:00 UTC.
2016-04-13 Two partial ISS SSTV April 2016 images received 11 months ago
In a later pass I received two partial images.
ISS SSTV April 2016 image 06/12 received by PE4KH at JO22NC 20160412 1920ZThe good news is that standing outside holding my Arrow antenna I did some serious thinking how the Arrow is going to fit on the antenna rotor. And I tested how reception is when I fix the elevation at around 20-25 degrees: fine.
ISS SSTV April 2016 imagereceived by PE4KH at JO22NC 20160412 1920Z
2016-04-13 ISS SSTV April 2016 image received 11 months ago
Read the rest of ISS SSTV April 2016 image receivedToday a nice pass which fit between two stages of cooking our dinner so I recorded the audio. Again I heard no signal but then I heard the starting tones of a slowscan TV image and saw the signal meter pegged to S9++ (the maximum). One image was received in full.
ISS SSTV April 2016 image 12/12 received by PE4KH at JO22NC 20160412 1606Z
2016-04-11 First ISS pass with chance of SSTV, nothing heard 11 months ago
In one of the articles about the current ISS SSTV event was a starting time of
19:2518:25 UTC, and the pass over my QTH JO22NC started at 19:28 UTC. So I was out with the whole setup and a strong arm to aim the antenna at the ISS in the hope of receiving something. But nothing was received. The fun part is that an ISS pass shortly after sundown gives a visual aid to aim the antenna at, but no signal received. Also noticed by Mike Rupprecht DK3WN: ISS – no SSTV active - DK3WN Satblog with a very nice image. Update: Corrected starting time after rereading ARISS commemorative event (April 11-14) - ARISS SSTV Images which has been updated with:*** Update (April 11, 2016)Update 2016-04-12: First images received now in Asia and available from the ARISS SSTV Gallery
Looks like the start will be delayed. Seems the hardware is having issues and not transmitting. Troubleshooting is in work.
2016-04-10 First turns on antenna rotor 11 months ago
The antenna rotor made its first turns. I mounted it to a very old stepladder which has an almost vertical part at the top. The fun part is that with the upcoming ARISS SSTV event from ISS I could use a good rotor in the upcoming week.
2016-03-05 Listened to the ARISS contact with Tim Peake this morning 1 year ago
I listened to the ARISS contact with England (Wales, to be precise) this morning. I followed the preparations via the principia live stream but I went outside with my arrow antenna for the contact itself. Elevation at my location was not too high (maximum of 46 degrees) which was a bit of a problem between the houses. I held up my arrow above my head for maximum reception but that got tiring real quick. So I heard the answers to about 3 or 4 questions. But it is still quite special to hear an astronaut talk live. On the principia live stream I followed the rest of the event. It's good to see the contact is much, much more than just 10 minutes of Q and A. There was a lot of explanation about the ISS, the work Tim Peake does, the influence of space on the human body. Including bits where the scientists say "we don't know why this happens, we're still researching it". The ARISS program and the Tim Peake mission must be a boost for STEM (Science, technology, engineering, mathematics) education and amateur radio.
2016-02-10 First QSL card for a satellite contact 1 year ago
I picked up new QSL cards at my radio club Veron A08 Centrum and it had a very special one: the confirmation of my first radio contact via amateur satellite with GS3PYE/P.
2016-01-08 ARISS contact with Tim Peake heard 1 year ago
I brought the handheld radio this morning to listen to the school contact with Tim Peake GB1SS - amsat UK I had good reception of the school contact. It did sound to me like there were a few starting problems: I heard the astronaut trying to call the school when the ISS was already rising in my location and I only heard answers to about 4 or 5 questions. On a west-to-east pass that went over the UK first this means the contact started a bit late. Comparing the list of prepared questions in ARISS contact planned for school in St. Albans - amsat UK with the report in Pupils make radio call to Tim Peake - BBC News shows indeed the fifth question was the last question answered.
2015-11-18 I received some signals from the FOX-1A (AO-85) amateur satellite 1 year ago
Earlier today I had an opportunity to listen to the FOX-1A amateur satellite. Due to the pass not being very high (a maximum of 61 degrees elevation) and not much time to 'play' I took the Wouxun radio and the arrow antenna out so I would not be busy with unmounting and mounting the FT-857 radio in the 'home shack'. The upside of the downlink signals (from the satellite to the earth) being in the 2 meter amateur band is that the absolute dopplershift isn't as high, so my radio tuned to 145.975 MHz was able to receive some signals. I mainly heard OM3WAN active, calling CQ for new contacts and making a few. Reception was spotty, so to try anything I will concentrate on higher passes (which have to match my schedule) and use the FT-857 radio.
2015-11-07 Recording of a (failed) satellite QSO 1 year ago
Searching for my own callsign I found this video:
At 4:42 you will hear me attempt answering someone. Since it's not clear who I am answering it failed as a radio contact (QSO). But it's nice to find a recording of my satellite QSO attempt!
2015-10-15 More choice in amateur satellites, Fox-1A available 1 year ago
Another long expected amateur satellite has been launched and is available to amateurs, the Amsat-NA Fox-1A satellite, which gained amsat identifier AO-85. Since it was launched as part of a militairy mission it's a bit harder to find the right keplerian elements (the numbers describing the orbit). The official Norad catalog number is 40967, but the standard sources for keplerian elements won't have this listed. Other sources have keplerian elements, but use different temporary object numbers. Since gpredict links everything together using the object number, this can get a bit confusing. I found usable keplerian elements at http://mstl.atl.calpoly.edu/~ops/grace_tle/grace_jspoc.txt which has Fox-1A as object 90747 named GRACE_47. So I created a preliminary transponder file ~/.config/Gpredict/trsp/90747.trsp with:[Fox-1A FM trsp 67 Hz PL] UP_LOW=435170000 DOWN_LOW=145978000Frequencies adjusted based on research by Jan PE0SAT and Tom Worthington NH6Y Now to find time to actually hear this satellite and attempt to work it.
2015-10-05 A new FM amateur satellite in the sky 1 year ago
Recently nine (!!) small satellites were launched from China with one rocket. Six of these have each digital telemetry, CW beacon and a lineair transponder in the amateur bands (I really should make some time to practise making contacts on SSB), two only have telemetry downlinks and one has a beacon, APRS transponder and an FM transponder, which should be easy to work. The one with the FM transponder is LilacSat-2 (or CAS-3H, 2015-049K). I created a preliminary transponder file 40908.trsp for gpredict with:[FM V/U] UP_LOW=145350000 DOWN_LOW=437225000 MODE=FMAt this time untested. The satellite has a schedule for operating the FM transponder (which probably has to do with power budget and other experiments on board):LilacSat-2 is scheduled to switch on the FM transponder for 24 hours at about 2200 UT each Monday, Wednesday and Friday.Now to find time to try this satellite transponder at the available times. Links for more information:
2015-07-26 Mapping amateur radio contacts 1 year ago
In a lot of the amateur radio contacts I have location information is exchanged. This is done in the Maidenhead Locator System which uses letters and digits to pinpoint locations with an increasing precision. I give out my home location as JO22NC. In the contacts I make I also log all those locators and using the Linux version of gcmwin I plot these on great circle maps. The results:
2015-07-22 A nice high pass of the SO-50 amateur satellite but no luck this time 1 year agoOlder news items for tag amateursatellites ⇒
I had a nice high pass of the SO-50 amateur satellite but no luck on making a contact. I heard several other active amateurs and noted their callsigns and locators: HB9OAB in JN46ME, MW0URC in IO82JB, DL3XAC in JO53GN and 9A5YY in JN75DH. Silence in the recording is when I transmit. I still trip over new (to me) callsigns when trying to reproduce them, so I need the recording to get all the details right.Read the rest of A nice high pass of the SO-50 amateur satellite but no luck this time
Listen to audio attachment: