October 27th, 2013
Last night we returned from Italy, where we spent some days after the Alpe Adria Meeting. It was nice to receive the award for the 2nd place in the Alpe Adria Contest 2013 on 23 cm, to meet the Hams there and to have interesting talks with them.
Dino, IV3FDO was very hospitable and took some time to show us certain interesting places. So we learned, that the most delicious prosciutto of the world is produced in San Daniele and not in Parma.
See you on Sunday …
Tonight I created a new list of all beacons, I have been able to receive here in Mainz (JN49CV) on 23 cm and 13 cm since becoming QRV again in 2011.
It can be found here.
While performing a last beacon check before going to bed and all local beacons were quite normal, I took notice of a weak carrier 1 kHz up of F1ZBK on 1296.855 MHz. After optimizing the antenna and using a narrow filter I heard EA2TZ in IN93BF over 1073 km for the first time ever.
Left signal: F1ZBK/B, right signal: EA2TZ/B
EA2TZ/B as received by DJ5AR over 1073 km on 23 cm
After posting this information in the ON4KST chat, Matej, OK1TEH sent the phone number of EA2TO and told me that Javier is currently QRV on 23 cm from IN83. After exchange of a few SMS he came back on my CQs and we could complete a QSO: A new DXCC, a new square and a new tropo ODX of 1173 km on 23 cm!
When closing down the station I had a quick look on 70 cm. There he was again: EA2TO in SSB. We had a nice chat and for me: A new DXCC, a new square and a new ODX of 1173 km on 70 cm!
Only 2 QSOs tonight, but I am very happy with it.
While performing my daily beacon check, a strange constellation around 1296.850 MHz appeared on the display of my SDR. The dish was turned to 254° at that time, to look for F5XBK.
From left to right: F5XBK, F1ZBK, ON0NR, HB9EME
Combined with strong QRN and radar noise I could copy F5XBK in JN18JS quite normal via tropo but also F1ZBK in JN38BP, ON0NR in JO20KJ and HB9EME in JN37KB via a rain scatter point in JN39LP. Later DB0GP in JN48WQ and DB0AJA in JN59AS could be heard too.
Then I continued to have a look on 2320 MHz where DB0UX in JN48FX, DB0FGB in JO50WB and DB0MJ in JO31UB could be copied via a scatter point in JN39JR.
Beacons heard via rain scatter on 23 and 13 cm
The map shows the location of DJ5AR in Mainz (green marker) in relation to the scatterpoints (blue markers). The paths to the beacons on 1296 MHz are in light blue and on 2320 MHz in dark blue. For that time heavy thunderstorms with flooded roads and cellars were reported for the area of Hermeskeil in JN39.
….. I worked in the Alpe Adria Contest last Sunday on 23 cm. In parallel there was an activity contest in Czechia. So a lot of stations from east, southeast and south filled the log.
Alpe Adria Contest 2013 on 23 cm
Remarkable was a nice SSB-QSO with Mirek, OK2UYZ in JN99FS over more than 700 km via tropo. Lane, S54AA in JN76EG could be worked, who was beaming into a large valley towards the Alps with mountains of 2.500 m. Another aircraft scatter QSO I had with Walter, IW3SPI in JN66OD, who is very, very close to the Alps.
Path information by AirScout
The reflections were rare and short but enough to complete.
Once the news about our QSO were spread out over the internet, Jan and I had an overwhelming feedback from all over the world. Many sent just congratulations, but a number of hams supported us with additional information. Domenico, I8CVS did calculations using the radar equation. His results concerning the expected signal levels correlate very well with our recordings.
A lot of details about earlier attempts were reported by GW4DGU (ex G4DGU), VK3UM and VA7MM. Here a summary in brief:
Chris, G4DGU and John, G4ANB performed tests with Ben, SM6CKU in 1980 on 70 cm. Ben was able to copy a SSB burst of Chris reflected on a COSMOS 3 stage launcher.
Dough, VK3UM had several QSOs with Graham, ZL3AAD on 432 MHz in the 1990s by bouncing signals off the Russian space station MIR. It seems, they were the first to complete a QSO using a space craft as reflector!
In an AMSAT forum Miles, WF1F, reports about reflections of Joe´s, W2KQ, signal bounced off the MIR on 2 m while arranging school schedules with one of the cosmonauts in 1994.
We knew that Mark, VA7MM and Cor, VE7BBG (sk) had their first tests on 23 cm on May 16th, 2004, as Mark published on his website. He now told in an email about four(!) QSOs they had on May 23rd, May 25th, May 31st and June 5th, 2004. As far as we know now, this team was the first to complete a QSO via ISS bounce at all.
In end of 2007 a lot of activities happened on 144 MHz. Rob, PE1ITR tried with Mike, DK3WN, who received reflections. Peter SM2CEW nearly completed a QSO with Håkan, SM7WSJ and tried also with Petros, SV3AAF (more). Frank, PE1NFE and Rune, SM5CUI were able to copy the signals from Sweden as well. Bernd, DF2ZC completed on 2 m with Frank, DH7FB on December 9, 2007. They had three more QSOs in 2008.
Addendum May 2016:
I found a link to the website of Philippe, F6ETI, where he described the successful experiments with F6AGR to bounce reflections off the Russian MIR space station on 144 MHz in February 2001. As he told me, they performed just a one way test and had no QSO.
To be continued ……
May 23rd, 2013
(Copyright by NASA [Public domain], via Wikimedia Commons)
After a lot of tests and improvements have been done in tracking the doppler shifted signals, Jan, PA3FXB any I had another try around 1296.300 MHz this morning. Both of us performed compensation of the own doppler component as well in receiving as in transmitting. We agreed in using the EME QSO protocol and periods of 30 seconds.
PA3FXB as received by DJ5AR
Jan appeared within my filter bandwidth as soon as the ISS became visible to both of us. His signal strength was peaking up to nearly 20 dB above noise and was easy to copy. The tracked frequency seemed to be stable until the ISS culminated. Then the variation of the doppler shift became so rapid that the compensation mechanism was not fast enough anymore. But that happened to the very last part of our QSO while we were transmitting our final 73s. So I can state that the best signal quality can be expected during the ascending and the descending parts of the pass.
In the meantime I received Jan´s recording. Listen how DJ5AR sounds on his side:
DJ5AR as received by PA3FXB
Many thanks to Jan for his cooperation and his patience in numerous tests before.
This success is dedicated to our fathers, who suffer from the same disease!
If you are interested in a try, do not hesitate to contact Jan or me. You can find us in the HB9Q 1296 MHz EME logger or in the ON4KST microwave chat, when QRV.
Today Jan, PA3FXB and I used ISS passes to improve doppler compensation.
The first pass of three was disappointing because no reflections could be detected. In the second one I found Jan shortly after his window opened. But it sounded more like a strange kind of music than CW, Jan stated after listening to the audio file, I recorded of his signal. The reason were too long steps in timing for the frequency correction. I reduced it for the last try from 100 ms to 10 ms. After some recalibration of frequency and rotor control I started the system again when the ISS rose.
I could hear Jan without any manual corrections immediately after he started transmissions. The frequency tracking worked quite smoothly and reading his CW was possible without any problems.
PA3FXB as received by DJ5AR with QRG tracking every 10 ms
The audio file contains Jan´s signal in three periods. From 0:00 to 1:00 the signal raises while being on the upper flat part of the doppler curve shown above. During the second period from 1:00 to 2:00 the signal passes the steep part and even an adjustment every 10 ms leads to a kind of jumping signal. When receiving the third period, the signal was quite stable again and faded out, while the ISS moved to the eastern horizon.
In between his TX periods Jan tried to catch my signal without doppler compensation, just playing with the RIT. He successfully got a short part of my transmission:
DJ5AR as received by PA3FXB without QRG tracking
Doppler compensation on my TX part did not work. It seems that the SDR does not accept CAT commands for frequency change while transmitting. So we will work on another strategy, where TX frequencies remain fixed and both stations will do full doppler compensation only while receiving.
The doppler shift was the problem to be solved for performing further steps in ISS bounce. There are two practical strategies: If every station will compensate its own doppler component, so even random QSOs would be possible. The other solution is, when the whole compensation will be done by one of the stations. That would open ISS bounce to stations that are able to do antenna tracking on the ISS, but not to compensate the doppler. In this case it is required to arrange skeds, because the compensating station is required to know the coordinates of the other one.
Basing on DC9ZPs E-Book I extended the software, I use for station control, by satellite tracking. That opens the possibility to calculate the relative speed and the resulting doppler shift of the ISS pertaining to given locations and given frequencies.
Above diagrams show the elevation with the according doppler components on 1296 MHz for a window between DJ5AR, JN49CV in Mainz (green) and EI8HH, IO53HN near Galway (blue). If the full doppler compensation will be done by one of the stations, the red line with a total span of 120 kHz will be relevant. The window in this example would open for about five to six minutes.