Tag Archives: DJ5AR

ISS bounce III

April 30th, 2013

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.

DJ5AR-EI8HH Elevation DJ5AR-EI8HH DopplerAbove 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.

ISS bounce II

April 8th, 2013

Another test tonight with the experience of the one two days ago, was more efficient in finding the reflections. The ISS passed south of our QTHs. So I could track the whole pass from rise to set. Jan´s signal could be detected most of the time during his window. The picture shows his signal shortly after the rise of the ISS. Caused by the doppler effect it moves from right to left. The shift in this detail varied between 47 kHz and 38 kHz, while PA3FXB was transmitting on 1296.300 MHz in CW.  By a length of about 25 seconds there was a variation of 400 to 500 Hz per second.

PA3FXB shortly after rise without QRG tracking

PA3FXB 2013-04-08 shortly after rise Audio

PA3FXB shortly after rise

PA3FXB shortly after rise with manual QRG tracking

Jan was transmitting his callsign “PA3FXB” followed by “T”s. The variation of the pitch in the first audio file is caused by manually tracking the signal. The second audio file gives an impression of the speed of the doppler variation. An effective  compensation of the doppler effect seems to be most important.

There have been earlier attempts to realize QSOs by reflections on the ISS. SM2CEW reports about nearly completing QSOs on 144 MHz with SM7WSJ in 2007 and he tried also with SV3AAF (more). DF2ZC claims the first ever QSO via ISS scatter on 2 m with DH7FB on December 9, 2007. They completed three more QSOs in 2008. It seems that these were the only four QSOs via ISS bounce since then. VA7MM reports about tests on ISS bounce with VE7BBG on 23 cm in 2004. PE1ITR tried with DK3WN in 2007.

ISS bounce

April 7th, 2013

Tonight Jan, PA3FXB and I tried, what we were discussing about for quite a while. There was a prediction of an ISS pass shortly after local midnight and both of us had no other appointments. So we agreed that Jan should make a transmission on 1296.300 MHz as soon the ISS became visible to him and tracking it as long as possible. My part was to monitor the pass of the International Space Station on my SDR. We used 3 m dishes on both ends and Jan had approximately 375 W in CW.

PA3FXB via ISS Beginning

PA3FXBs signal at the very right

Here is the result. Jan appeared with a relatively strong signal (on the very right), faded out and came back with weaker signal strength. I interpret it, that the first appearance was backscatter and the second was forward scatter, what has to be discussed. Doppler was extremely strong and more than 40 kHZ at the beginning.

Aircraft Scatter, AirScout and the ISS

February 23rd, 2013

Frank, DL2ALF has written an amazing tool for aircraft scatter prediction, called AirScout. Positions of planes are shown in a map like at http://planefinder.net or http://www.flightradar24.com, but in addition the path and the part of it, where planes could be seen from both stations will be marked. Frank is using open street map for the maps and an elevation model of NOAA to respect the topography of the path. I made use of a beta version last Tuesday in the NAC on 23 cm and found it extremly helpful.

The latest version can be found here.

Thank you Frank!

1.2G_DJ5AR_IK3HHG_20130219

Path DJ5AR – IK3HHG with planes and topography

As can be seen in the screenshot, the effective area is excentric to the center of the path. It is displaced southwards because IK3HHGs horizon is limited by the alps.

Ik3hhg

Eight times IK3HHG shifted by doppler, corresponding to the screenshot above

Last saturday at the GHz meeting in Dorsten Frank told me, that he integrated the groundtrack of the International Space Station to be drawn in the map too. So we have been discussing about the possibility of performing QSOs via reflections at the ISS.

ISS

AirScout with groundtrack of ISS

Back home I was very optimistic and used overflights, where the ISS  passed by nort of my location to look out for reflections of GB3MHL on 23 cm, but had no success. There was no trace at all in the waterfall diagram of my SDR. The duration of a pass is only up to 9 minutes and the expected doppler shift is +/- 84 kHz due to the high speed of 28000 km/h. So even if something could be heared or seen, tracking and decoding the signal will be another problem to be resolved.

But anyway: I am looking for somebody to perform tests with me, just to detect reflections at the ISS. Skeds are welcome via chat (ON4KST and HB9Q) or email dj5ar (at) darc.de

Review: Activity week Rhineland-Palatine 2013

January 14th, 2013

It was big fun working in contest for a whole week. I felt a bit like Phil Connors in the movie “Groundhog Day” (german: “Und täglich grüßt das Murmeltier”), in meeting most of the stations again day by day. My main activity was in the evenings on 23 and 13 cm, using 2 m, 70 cm and the ON4KST chat to arrange skeds. The conditions were slightly over normal but increasing on monday with a small opening to France. During the seven days I could work one new square on 2 m (JN15), two on 23 cm (JN09, JN15) and three on 13 cm (JN09, JO42, JO44). There were only two 4-band QSOs with DL7QY and DC1UR.

My top 5 of the most worked stations in this contest are:
DF8PR    16 QSOs on 3 bands (2 m, 70 cm, 23 cm)
DC8WPA   15 QSOs on 3 bands (2 m, 70 cm, 23 cm)
DK7UP    13 QSOs on 3 bands (2 m, 70 cm, 23 cm)
DL7QY    12 QSOs on 4 bands (2 m, 70 cm, 23 cm, 13 cm)
G3XDY     8 QSOs on 2 bands (23 cm, 13 cm)

Thank you all for your support and your patience!

Statistics:
        total      District K     DL ex K    France     I,OE,G,LX    Squares
Band    QSO Stn    QSO Stn DOK    QSO Stn    QSO Stn    QSO Stn      total new
 144    100  58     72  31  18     25  24      3   3      0   0        11   1
 432     65  31     54  22  15     11   9      0   0      0   0         6   0
1296     73  34     27   9   8     21  11     14  10     11   4        21   2
2320     28  15      2   2   2     14   8      5   3      7   2        12   3

Opening October 19th – 23rd

October 24th, 2012

The beacon check in the morning of October 19th gave me the impression of a strong inversion over southeast Germany. When looking for Stations on 23 cm on the SDR I noticed a big signal in CW: OE5VRL/5 calling to Hungary. I gave him a meep in the chat to tell him how strong his signal was here in Mainz, despite the fact that I was in the back of his 3 m dish. After turning the antenna to me he was stronger than many locals.

In the following days a lot of DX stations from OK, SP, HA, S5, OE, HB9, F, LX, G, PA, I and OZ filled the log while the inversion moved from east to west. All of the four OK beacons could be heard on 23 cm. Sometimes it was a little bit confusing when I was looking for new DX beacons and DB0AAT, DB0AJA, DB0GP, DB0LB, DB0FGB, DF0ANN, HB9EME and others could be heard in nearly any direction the dish was pointing to.

QSOs on 23 cm > 400 km

QSOs on 13 cm > 400 km

QSOs on 13 cm > 400 kmI am happy with a couple of new squares on 23 and 13 cm. Two new countries on 13 cm made it perfect: S51ZO in Slovenia and I1KFH in Italy. But I fear that it was more aircraft scatter than tropo.

Beacons heard on 23 cm

DB0AAT JN67HU
DB0AJA JN59AS
DB0FGB JO50WB
DB0GP JN48WQ
DB0LB JN48OV
DB0LTG JO31TB
DB0VC JO54IF
DB0WTT JO40LG
DB0YI JO42XC
DF0ANN JN59PL
DF5AY JN49DX
F1XBC JN06JG
F1ZBK JN38BP
F5XBK JN18JS
HB9BBD JN47GA
HB9EME JN37KB
OK0EA JO70UP
OK0EJ JN99FN
OK0EL JO70SQ
OK0EQ JN89BE
PI6ASD JO22KJ
PI7ALK JO22IP
SR6LHZ JO70SS

Contest results on 23 cm: 1990 vs 2012

October 11th, 2012

My operating conditions have changed quite a lot compared to October 1990. But my QTH is still the same in the south of Mainz, JN49CV. The most serious circumstance is, that we have internet and software defined radios nowadays. The possibility to arrange skeds and to gather information is revolutionary. It´s easy to find stations in the waterfall diagram, that are not on your frequency. No more CQs for hours and hours. Instead the chat must be watched and skeds will be arranged.

QSOs in October contest 1990

Rig: 1.2 m dish / 10 m RG213 / 120 W

Claimed result: 78 QSOs, 12000 km, ODX 404 km

 

QSOs in October contest 2012

Rig: 3 m dish / 3.5 m ecoflex 15 / 0.4 dB preamp / 10 m ecoflex 15 / 200 W

Claimed result: 53 QSOs, 18000 km, ODX 725 km

 

IARU-Region-1 UHF/Microwaves October Contest

October 8th, 2012

“Bad weather and bad conditions” that is, what most comments say about this contest. The weather here in Mainz was bad too, but I cannot compare the conditions with the contests in the last years, because my last participation in this contest was in 1990. This year it ended up in 50 QSOs on 23 cm and 19 on 13 cm. I am quite satisfied with these results.

QSOs on 23 cm

 

QSOs on 13 cm

My new ODX on 13 cm is OL9W in JN99CL over 720 km. A lot of new squares could be worked too. Many DX stations were nearly as strong as they were on 23 cm.