When looking for the annual results of the Italian Activity Contest 2016 on 1296 MHz yesterday, I was really surprised, to be the winner. I haven´t expexted this, as Giorgio, IK3GHY, had a higher score in total all the time. But as he won in 2015, he was out of competition in 2016. I have to respect his success and congratulations for your extraordinary score, Giorgio!
But anyway, it was great fun to work the italian lads every 3rd Tuesday in month. Hopefully, there will be enough time to be QRV in the 2017 events. I am also looking forward to go to Italy in October, meeting friends in Venice and at the Alpe Adria meeting near Udine.
Steve, IU1EAF, will be the contest manager in 2017 and the rules have changed too (english version online now). Thank you to Alfredo, IK2FTB, for all the work in the past year.
Today PI9CAM´s QSL for the first Satellite Bounce QSO via an unmanned spacecraft done by radio amateurs arrived by mail. As we know, there have been previous commercial attempts for Satellite Bounce in the early 60s using ECHO 1 and ECHO 2 which were inflated balloons with diameters of 30 and 41 m. The initial orbits were at heights of 1500 km and 1200 km.
The theoretical radar cross section (RCS) of ECHO 1 was 700 m², but measurements by military radar stations resulted in 900 to 1000 m² in the beginning. Later, the satellite deformed and shrunk. OKEAN-O, the one we used, has a radar cross section of 18 to 20 m² but is in a much lower orbit at a height of 650 km. This leads to quite similar unit power budgets, regardless the difference in size,
Enjoy the movie “The Big Bounce” about our predecessors 55 years ago!
While yesterdays try for an ISS Bounce QSO failed by Ronny, SM7FWZ, missing my rogers, we tried again this morning. As this orbit culminated near the zenith for me, I decided to catch up the ISS on the descending part of the pass.
So I could avoid the singularity in the azimuth angle and we heard us right from the beginning with strong signals. As Ronny couldn´t copy any rogers yesterday, we had plenty of them today, as well as 73s!
Ground Track of the ISS versus the direct path between SM7FWZ and DJ5AR
It is remarkable, that Ronnys signal was audible on backscatter off the ISS, even when my elevation became less than 2 degrees. The slantranges to the ISS were about 2100 km for me and 1700 km for Ronny: A total distance of 3800 km!
This is the result of many tests and discussion before. Ronny transmitted and received on 1296.300 MHz during the whole pass and automatic Doppler compensation was done on my side for both of us.
It is funny, that we had a Moon Bounce QSO a couple of days ago, just to compensate some frustrating tests. EME is sooo easy!
Thank you, Ronny, for this fast and efficient QSO and enjoy your very special day!
A long time monitoring of the beacon F1ZMT in JN07CX via Aircraft Scatter on 1296.872 MHz shows asymmetrical reflections on most of the crossing planes.
As the distance to the beacon is 624 km and it´s ERP of just 10 W (a panel antenna to the south combined with an omnidirectional big wheel) is rather QRP, only weak reflections can be detected from time to time. This ensures, that received signals were reflected on single airplanes. In this example can be seen, that the reception starts shortly before the plane crosses the path between DJ5AR in Mainz and F1ZMT in LeMans. Unexpectetly the signal can be seen for quite a while after crossing. There is a continuous variation of the doppler shift and no spread of the signal, as is usual for a moving solid reflector.
On April 7th the PI9CAM team hosted some students, working on a film project. So there was some spare time to schedule more tests in our space debris project. The objects, selected to try on, were some rocket bodies. Many of the larger objects in low earth orbits are of this type. The operation style, as usual, was a center frequency of 1,296.300 MHz, 15 seconds periods with DJ5AR transmitting first. This time we wanted to try FSK441 mode, to compare it with the experiences, we had with ISCAT-B.
On two objects, NORAD #39679 (SL-4 R/B) and #39771 (H-2A R/B) we registered faint but continuous reflections. Only partial decodes were possible. It seems, that ISCAT-B is the better choice.
Reflections of DJ5AR in FSK441 recorded at PI9CAM
On SL-4, a russian rocket body, lauched on April 16th, 2014, a modulation of the reflections with a period of 2.8 seconds could be observed. It looks like, as the object is tumbling.
Since QSOs via ISS Bounce are quite easy to perform, Jan, PA3FXB, and I evaluated the possibilities, to use other objects in orbits around the Earth. The table below shows a selection of objects in earth orbits. There are some quite big ones in geostationary orbits, but the distance is the most limiting factor, not the size, as can be seen in the predicted maximum reception level provided by the radar equation. So I had an intense survey on the objects in low orbits and determined the maximum linkbudgets, to filter the most promising ones. My PC had to work a couple of hours to perform that. On the end it has been a little surprise, that COSMOS 1823, an old soviet geodetic satellite, wasn´t among them. We used it for previous tests and were able to detect faint reflections.
At our meeting on the Dorsten GHz Convention last Saturday, we discussed latest details. On Sunday, Jan and the crew of PI9CAM activated the Dwingeloo Telescope for the 23 cm EME SSB contest, but they had some spare time for other experiments. Just to warm up we had a nice SSB QSO via the moon first, right after their first QSO PA/JW: Congratulations!
Some of the top objects would pass on suitable elevations and we decided to start with NORAD 39771 which is the second stage of a japanese H2A202 rocket, launched on May, 24th 2014 with a radar cross section of 20.7 m². DJ5AR was to transmit CW continously, while PI9CAM checked for reflections. After some trouble with the tracking they caught it shortly before set.
The used power at DJ5AR was 150 W into a 3 m dish (28 dBi) and the PI9CAM team used their 25 m dish (48 dBi) for reception.
The predicted signal level was about -158 dBm, but, as can be heard, it´s clearly audible.
Titan 4B (26474)
Next one on the list was NORAD 26474, the 2nd stage of an american Titan 4B rocket, launched on August 17th, 2000. With a radar cross section of 15.4 m² it is a little smaller than H-2B. But the predicted reception level for Dwingeloo looked very promising anyway:
My signal could be picked up by PI9CAM when the rocket body rised up to 5 degrees over the horizon and they tracked it for about 4 minutes until I lost the object near the culmination point, when the angle velocity became too fast for my tracking system.
DJ5AR as received by PI9CAM. Picture is upside down for better matching to the table.
The signal has been detected at an predicted signal level of -160 dBm and became clearly audible soon for serveral minutes. So we can think of trying a CW QSO next time. The drift, which can be seen, has it´s cause in my transmitter, running for the duration of the whole pass without any pause. I will try to reduce the growing spread of the signal by using shorter intervals in the doppler correction.
Marten, PA3EKM, documented this (historical) moment on video:
Many thanks to the team of PI9CAM / CAMRAS: Cor, PE0SHF, Eene, PA3CEG, Marten, PA3EKM, Gert-Jan, PE1GJV, and Jan, PA3FXB
My presentation “Let´s Bounce” will be given on two more dates:
October 25th, 2014 on the 4th Hessian GHz Meeting in Fernwald
Short version of the lecture with focus on aircraft scatter and ISS bounce.
We meet at 15:00 MEST on the car park at the town hall. There will be a flee market for GHz stuff and the opportunity to test own equipment or to have QSOs with other participants.
After my complainments about using the ON4KST chat in March Contest and the response I received from Claus, OZ1FDH, and Kjeld, OZ1FF, recommending the KST2ME tool, I added my homebrew prototype of a selective ON4KST client extension to my station control software. It communicates via telnet with the server. While working satisfactorily under normal circumstances, it was a desaster under contest load. When the software didn´t crash, it at least slowed down, by computing hundreds of posts in shortest time. Between 300 and 400 users have been logged to the microwave chat during contest time. During the first contest hours I tried to solve the problems with certain bug fixes, resulting in a huge loss of contest time. So I had to return to the classic style in using the web client of the chat.
QSOs on 23 cm
In total I logged 73 QSOs on 23 cm to 12 DXCC countries, spread over 39 grid squares (results). ODX was HG7F over 817 km. The use of the AirScout software, written by Frank, DL2ALF, has been essential. Most of the QSOs have been completed by assistance of aircraft scatter.
A nice example is the one with DJ5BV in JO30KI. The distance isn´t really far enough to do it via aircraft sctatter, but it seems, both antennas were pointing west and that resulted in effects of aircraft backscatter with significant dopplershifted reflections.
Dopplershifted reflections of Gerd, DJ5BV, caused by backscatter of aircrafts.