The destructive thunderstorm in the Köln/Düsseldorf area last night was intense enough to provide rainscatter even on 1.3 GHz. DB0AJA near Würzburg in JN59AS could be heard with the typical rainscatter sound when the dish was heading 325°. An awful lot of water must have been in the air. The total distance of the signal path was about 400 km (150 + 250).
The waterfall shows the spread of the signal. DB0AJA runs 20 W output into a 16 element Flexa yagi beaming northwest.
The italian-dutch artist Daniela de Paulis is the inventor of visual moonbouce. Slow scan television is used to send pictures towards the moon. When the bounced signals will be received and visualized, the pictues are a kind of distorted and win a very special charm.
The pictures shown below are screenshots, I took during a performance on April 13th, 2014.
I am very proud, that Daniela has choosen one of my pictures for her performance. It shows the moon resting on clouds and has been bounced at the moon.
Nando, I1NDP, transmitted a selection of pictures in SSTV, to be received by PI9CAM with the radiotelescope at Dwingeloo. Using a “GOOGLE Hangout”, an audience from all over the world watched live, how Daniela and her team (Nando, I1NDP, Jan, PA3FXB, and many more) were bouncing all the pictures at the moon.
A video recording of the session can be found here.
One of my favourite beacons to be watched via aircraft scatter is PI7ALK in JO22IP. The beacon is running 4 W to a 4 times stacked omnidirectional antenna as described in DJ9HOs “UHF Unterlage V” on page 1001. The design of the antenna is by DC0BV. More details and the history of the beacon can be found here.
After about a minute first reflexions can be seen. The signal is increasing in strength, until the plane reaches the midpoint of the path. While other planes join, the signal will be spread by the doppler effect.
Many thanks to all enthusiasts on 23 and 13 cm, who spent up to 20 minutes to complete a QSO with me. Tropo conditions were not too good this time and especially 2320 MHz it seemed to have an additional attenuation on all signals. But never the less, quite a lot of QSOs filled the log. More stations than I could handle, requested skeds via the ON4KST chat. I have to apologize for all my replies like “pse qrx, meep u when free”, I forgot about. So, all I can say is:
Please excuse me for forgetting to meep you!
Indeed, this chat is a great tool, I don´t want to miss it. But in times of contest it can be a challenge, like the contest itself. I will not apply for to do without, it is rather a question, how to use it. The amount of information, flowing over the screen, is immense. On saturday afternoon or on sunday morning, relevant entries might disappear within less than a minute. So I have to think about optimizing my software tools.
QSOs on 1296 MHz
Skilled VHF Operators may smile, when I tell them, 58 QSOs on 23 cm and 19 QSOs on 13 cm are hard work. The sum of that is the number they work within the first hour of their contest section. But in fact, the world above 1 GHz is a different one. The beams of the antennas are much narrower compared to VHF and UHF. The dense of stations is much less, since it is not like plug and play to become QRV up there. The attenuation increases GHz by GHz and all that results in real work for most of the QSOs. There are only a few big guns on 23 cm to be heard from any antenna direction. So the band seems to be empty, even at contest time. But the chat is an oppotunity for all kind of stations to arrange skeds and to have QSOs over distances of several hundred kilometers. And, especially when using aircraft scatter, patience could be needed to complete.
QSOs on 2320 MHz
After getting familiar in working us in CW via ISS Bounce, Jan, PA3FXB and I were looking for a new challenge. So we decided to try it in SSB. After some tests in the last days and finding a workaround for a bug in my PowerSDR, we completed a two way contact in SSB on a center frequency of 1296.300 MHz tonight. The doppler compensation worked well on both sides. Just minor corrections with the RIT were neccessary. The signals weren´t as strong as they were in the days before, but strong enough to copy even some 73s at the end. It seems to be the first SSB QSO via reflections on a spacecraft at all.
The audio recording starts with my recording of PA3FXB on one channel synchronized with Jans recording of my signal on the other channel.
Tonight I had a sked with Jan to try ISS Bounce once again. We agreed in trying SSB after getting in contact in CW. Jan appeared shortly after rise of the ISS and it was no problem to exchange reports and confirmation with strong signals. Then we switched to SSB and I could hear Jan clearly, but my tracking software refused to stay in SSB mode. So I have to fix this bug for our next test.
Later we tried to detect reflections from Iridium 4. We expected to see something about -19 dB, but nothing was to be seen in the waterfall diagram. Maybe that the choosen pass wasn´t too high in elevation and we will try again. When Jan was operating PI9CAM on February 2nd, faint traces of reflections on COSMOS 1823 could be detected by Hannes, OE5JFL, Dan, HB9Q and myself. As it is quite time-consuming, to find reasonable passes of satellites, I wrote a small Excel tool get an overview over satellites, passes and elevations. It can be found for free download here: Visibility
Macros have to be enabled in your Excel. Just enter the date, time, period and the locators of the two stations in the approriate cells, click “Calculate” in the “ADDINS/Satellite Overview” menu and the worksheet will be updated. Don´t forget to fill the TLE worksheet with the latest data of your choice.
While performing my beacon check on December 16th, 2013 at 8:30 UTC, I stated that all beacons seemed to be at a normal level. Except, when looking for DB0FGB (JO50WB) with the dish heading 85°. There was a constant carrier of about 20 dB 15 kHz up, keying F1ZBK (JN38BP). Expecting a big signal, I turned the dish to France. But the beacon was only 15 dB with QSB, when beaming directly to it at 228°. Then I turned the dish back to 85° and noticed, that HB9EME (JN37KB) joined the party.
DB0FGB, F1ZBK and HB9EME with dish heading 85°
The rain radar didn´t show anything unusual and the F5LEN Refractive index forecast for Europe promised only marginal tropo conditions for this area. Only DL7QYs Condition Index for south Germany has been on a level of 7 (1 = poor; 10 = extreme).
F5LEN Refractive Index
DB0FGB was a bit above normal at about 15 db with little QSB up and down. F1ZBK was constantly at 20 dB, when beaming 85° and around 15 dB with QSB heading 228° (direct). HB9EME was up to 20 dB in 85° and peaking 15 dB in fast QSB when beaming 198° (direct).
Green: Paths from Mainz to the beacons
Orange: Paths of the beacons to the area of the supposed reflection point
I checked HB9BBD, F5ZBS, F1ZBI and others, but couldn´t see any similar effects. The angle was very small. When turning the 3 m dish 5° left or right, the signals disappeared. These conditions lasted for about one hour.
Topographic profile between DJ5AR and DB0FGB
The horizon in 85° is about 80 to 90 km off. A plausible explanation could be a strong troposheric duct between the beacons and a reflecting topographic formation.
Update:
In issue 2/14 the german magazine “Funkamateur” published an article by Matthias Hornsteiner, DG4MHM “Prognosekarten für troposphärische Überreichweiten” (Prediction maps for troposheric ducting). Matthias explains the basics of ducting and analyses the models, the well known refractive index maps of F5LEN and W. Hepburn are basing on.
So I had the intention, to ask him about a possibility for a reconstruction of the wheater constellation of that day. I have to thank him very much for his comprehensive answer.
As Matthias explained, the situation, shown on the map, was quite common for this, as he describes it, “anti-winter”. But it holds the possibility, that warm air might glide onto cold air at ground level. And indeed, when he reviewed the data of weather balloons launched at Stuttgart on that day, he found indications for a strong inversion in an estimated level of 400 to 600 m over south Germany. That matches!
In a distance of 200 km from here, the the topographic profile shows a formation, high enough to reach the level of this duct, as well as the mountains of the Fichtelgebirge do, where DB0FGB is located. The distances from Mainz to the area of the supposed reflection point is between 200 and 250 km. From F1ZBK and HB9EME it varies between 400 and 500 km. So the total path should have been between 600 and 750 km.
The battle is over. I had my last QSO with Patrick, DH2PA on 70 cm just before the contest closed after seven days. There was a big regional activity on VHF, UHF and SHF, much more than last year. Finally I logged 414 QSOs on the four bands I have been active, compared to 266 in 2013. It is remarkable that there were many locals with improvised equipment on 23 cm. Just one new square on 2320 MHz could be worked during the activityweek: IK3GHY in JN65DM via aircraft scatter. But collecting new squares is getting harder and harder, the more are already worked. The tropo conditions remained normal during the seven days, so there was less DX than last year. This time I found four partners for 4-band-QSOs: DL7QY, DL8YG, DF5AY and DB6NT.
The top five of the most worked stations in this contest: 1. DL7QY 24 QSOs on 4 bands (2 m, 70 cm, 23 cm, 13 cm) 2. DC8WPA 18 QSOs on 3 bands (2 m, 70 cm, 23 cm) DJ1FZ 18 QSOs on 3 bands (2 m, 70 cm, 23 cm) DK0RLP 18 QSOs on 3 bands (2 m, 70 cm, 23 cm) DK7UP 18 QSOs on 3 bands (2 m, 70 cm, 23 cm) Thank you all for your support and your patience!
Statistics: total District K DL ex K F,I,OK,OZ,SM Squares BAND QSO Stn QSO Stn DOK QSO Stn QSO Stn total new 144 183 94 99 43 26 82 48 3 3 15 432 134 66 69 31 20 65 35 0 0 10 1296 79 37 36 14 12 34 16 9 7 16 2320 19 11 1 1 1 15 7 3 3 10 1
Thursday night I tried a QSO on 23 cm with DG2PU in JO30PH, what´s a distance of only 80 km. Unfortunately Thomas is located down in a valley with Taunus and Hunsrueck mountains between us. His neighbor Marcel, DK7UP is closed by, but up on a hill. While it´s no problem to contact Marcel on 23 cm, Thomas signal was only 41, peaking 51 from time to time. Since beacons in similar distances often produce nice signals via aircraft scatter here, I suggested to try a QSO using airplanes to get reflections, but Frankfurt airport was already closed at that time that there was only very little air traffic. So we tried this evening. Our antennas were elevated by about than 10°, because the hot spot was in a distance of only 40 km (and a heigt of 10.000m). The second plane passed by in perfect manner and I could copy Thomas for about 10 to 15 seconds with 57, enough to complete a QSO. Due to the short distance the hot area around the center of the path is relatively small and reflections will not last too long.
Path between DG2PU and DJ5AR in AirScout
It is funny to check the beacons tonight. Most remarkable are two constellations, shown below:
While looking for DB0AAT in JN67HU, DB0VC in JO54IF could be received too. When beaming to Kiel, DB0VC can be heard even on 2320 MHz. It is beacon #9 on 13 cm.
DB0NCO beats Frankenstein
From my QTH DB0NCO has the same bearing as DB0FKS. The location of DB0FKS, the Frankenstein Castle, can be seen visually from here in a distance of 34 km. DB0NCO is 203 km away but tonight it is stronger than DB0FKS, when coming up in QSB.