Category Archives: WSJT

IC-9700: Drift on 23 cm

A question in a Facebook group about a GPDSO for an IC-9700 to be used on 23 cm for FT8 inspired me for a quick test. As I use my IC-9700 for 2 m and 70 cm only from home, I connected a dummy load to the 23 cm antenna socket. Next was to tune it to 1,296.174 MHz (of course) and to call in FT8.

The result in brief: No problem to decode, a moderate drift and the signal appeared about 100 Hz too low. Nothing to worry about.

But never the less, I prefer JT9f on 23 cm, as FT8 is useless on aircraft scatter.

Tropo to Belarus this Morning on 144 MHz

September 9th, 2020

A nice inversion could be seen out of the window of my shack this morning, promising good conditions. In fact I have been a little too far south for the duct, but at least I had two QSOs to Belarus in FT8.

Green: worked – Red: heard via tropo – Blue: heard via meteor scatter

The stations worked and heard via tropo have been in distances up to 1300 km. Occasionally signals appeared from more distant stations, 1500 and more km away. These could be decoded in one or two periods, then disappeared. Some reappeared later in the same manner, so it´s very likely it has been meteor scatter, as it happened in the early morning, when conditions are good for sporadic meteors.

Worked Hrd Tropo Hrd MS 
SP6URZJO71mdSP6EJO71kkUT4UEPKN49wv
SP1MVGJO74jaSQ6POMJO71vqUT2EMKN67qv
SP6CVBJO80veHF1JJO73fiUS4IEKKN87ux
SQ5ESMKO02hcSP1NENJO73fiUR7IMMKN88tr
EU3CZKO12JBSP1WSRJO73gjUS3ITUKN88wa
EU3AIKO22CESP6LTMJO80fuUT6LXKN89cj
SP3NJO81xkUS8ARKO60sr
SO3ZJO82kkR3LQKO64hk
SQ2SATJO83xg
SP1FJZJO84ee
SP9BCVJO90wb
SP7CKHJO92qf
SP2CHYJO94go
SP8NFOKN09ps
YL2IVKO06lm
EW3AAKO12TC
EU3ACKO12wd
SP4MPHKO14lc
UR4WWTKO20ec
LY1LRKO24ph

A digital evening on 23 cm

October 25th, 2017

There was nice activity in JT9F on 23 cm tonight. It seems this mode works fine with aircraft scatter. I first worked Conrad, PA5Y in JO21VO (255 km) and Sam, G4DDK in JO02VO (540 km) via Tropo. Then logged a QSO with Neil, G4BRK in IO91HP using mainly aircraft scatter. In another test I decoded Neil, G4DBN in IO93NR (756 km) by reflections on airplanes. PA0JME and ON5KTO were calling CQ, but not replying to my calls. Instead I worked John, G4BAO in JO02cg (619 km) in an (too) easy way.

Worked stations in green, the heard ones in blue.

Anyway, it was a promising and exiting evening!

Addendum October 27th, 2017

Yesterday I logged Rien, PA0JME, Wim, ON5KTO and John, G4ZTR, also in JT9F on 23 cm.

Chatting with John, G4BAO, last night, I learned, he recently initiated a “Digifest” on the microwave bands every Wednesday. This resulted in what happened two days ago. In my opinion it´s a very good idea to have such an activity evening beside the regular contests.

G8MBU – JT65c Beacon via Aircraft Scatter

July 5th, 2017

After installation of new transverters for 23 and 13 cm with stabilized LOs a couple of months ago. I gathered some experience in using JT65C mode on EME. So I undertook a new attempt to receive and decode G8MBU via aircraft scatter today. As antenna I use a 3 m dish with a dual band ringfeed.

Path DJ5AR to G8MBU

The beacon is located at Cowes on the Isle of Wight, IO91IR37, 683 km from Mainz, JN49CV. It runs 2 W power into an omnidirectional dual alford slot antenna. The mode used is JT65c. Nominal frequency is 1296.800 MHz. To successfully decode the signal, the SSB dial should be set to 1296.7986 MHz, to get a tuning tone of 1400 Hz in WSJT.

There is a small window between the Isle of Wight and Mainz, where high flying aircraft can be “seen” from either places. But only a few airplanes cross the path within and fewer fly along the path. Reflections of G8MBU could be seen from time to time, but mostly too weak and too short to provide decodes. It took nearly 3 hours until the first decode happened at -22 dB and just some minutes later a second one appeared on the display at -21 dB:

1158 -22  4.0 1282 #* G8MBU IO90IR
1206 -21  3.9 1268 #* G8MBU IO90IR

In total I monitored G8MBU for 5 hours. The propagation conditions were normal today, no tropo at all.

Moon Bounce on 13 cm

April 28th, 2017

Sometimes you hear words that hurt. Especially if they are true: Some years ago I tried 13 cm EME with Dan, HB9Q, and couldn´t copy anything of him. His comment after the test: “There is no way, not to hear me!” This is frustrating.

So I forgot Moon Bounce on this band and had fun with other activities, mainly on 23 cm. But the over 30 year old equipment caused more and more problems. So I started collecting parts and modules for a new transverter system covering 23 and 13 cm. It had been finished for the last VHF/UHF/SHF contest in March and was tested with good results. In the end of March I tried EME again after 2 years of absence. On 23 cm it worked fairly, but on 13 cm the drift was a serious problem. In a test with Alex, ZS6EME, I could decode his strong Signal, but not vice versa. So I added 10 MHz Double Oven Controlled Oscillators as references to stabilize the transverters.

PY2BS in WSJT-X Wide Graph

Today I tried with Bruce, PY2BS, and heard him strong in the speaker during his prior test with Toshio, JA6AHB:     1131  -6  2.5 2305 #* JA6AHB PY2BS GG66
At this time his elevation was -1.7° and the moon still under the horizon. After the moon set in Japan, we started:

1155  -8  2.9 1184 #* DJ5AR PY2BS GG66
1157 -13  3.6 1157 #* DJ5AR PY2BS GG66
1159 -10  2.7 1137 #* DJ5AR PY2BS GG66
1200  Tx      1500 #  PY2BS DJ5AR JN49 OOO
1201 -10  3.1 1114 #* DJ5AR PY2BS GG66
1202  Tx      1500 #  PY2BS DJ5AR JN49 OOO
1203  -9  3.3 1089 #* DJ5AR PY2BS GG66
1204  Tx      1500 #  PY2BS DJ5AR JN49 OOO
1205 -10  2.9 1066 #* DJ5AR PY2BS GG66
1206  Tx      1500 #  PY2BS DJ5AR JN49 OOO
1207  -9  3.1 1043 #* DJ5AR PY2BS GG66
1208  Tx      1500 #  PY2BS DJ5AR JN49 OOO
1209  -9  2.7 1019 #* DJ5AR PY2BS GG66
1210  Tx      1400 #  PY2BS DJ5AR JN49 OOO
1211 -10  3.0  994 #* DJ5AR PY2BS GG66
1212  Tx      1400 #  PY2BS DJ5AR JN49 OOO
1213 -11  2.2  969 #* DJ5AR PY2BS GG66
1214  Tx      1400 #  PY2BS DJ5AR JN49 OOO
1215 -22 -2.5  946 #  RO
1216  Tx      1400 #  RRR
1217 -10  3.1  919 #* RR -20 DB
1218  Tx      1400 #  73 BEST -8

As he switched his RX from 2304.070 MHz to my TX frequency 2320.070 MHz at about 12:14, we completed very fast. I am very pleased now with my first initial on 13 cm, a new grid square, a new ODX, a new DXCC and a new continent! After setting up a new Initials List for 2320 MHz and writing this blog entry, I enjoy my “Radio Operators High”!

QSL for first Satellite Bounce by Amateurs arrived today

December 23rd, 2015

PI9CAM QSL

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!

 

A new Chapter in the Book of Bounce

December 8th, 2015

2015-12-08 15_11_30-Radio Assistent for Space Communication by DJ5AR

Constellation at the end of the QSO

While ISS Bounce took Jan, PA3FXB, and me 2 months of testing and improving to succeed, Satellite Bounce was a much bigger challenge. Despite the fact, Jan and the team of PI9CAM are operating the 25 m dish of the Dwingeloo radio telescope, it took us nearly 2 years, enormous patience and scores of tests until we finally managed to receive “Rs” to complete a QSO today (December 8th, 2015). As far as we know, it is the first time ever, a two way amateur radio contact could be completed by using an unmanned spacecraft as a reflector.Above screenshot shows the position of the satellite at the end of the QSO. The Satellite rose in SSE and set in NNW. A calculative common window opened at the point, marked “O”. Local obstructions were not considered. Due to safety reasons transmissions in Dwingeloo are limited to elevations above 10°. So the AOS (acquisition of signal) happend shortly before the groundtrack of the Satellite crossed the 40th degree of latitude northwards, as soon as PI9CAM started transmissions. Sum of slant ranges (distance between ground station and satellite) was 3400 km at the beginning and 2000 km at the end of the contact.

Much of the reflections remained below the noise floor, but this one of PI9CAM, right at the beginning (14:10:10 UTC), is a nice example, of what can be received:

 

And vice versa DJ5AR as to be heard in Dwingeloo (14:11:00 UTC):

The used object OKEAN-O (NORAD #25860) is a joint Russian-Ukrainian Earth observation satellite, launched on July 17th, 1999 by an Ukrainian Zenit-2 carrier rocket. The satellite is in a polar orbit of about 650 km height with an inclination of 98°. The mass is 6.2 tons and the RCS (radar cross section) is figured between18 and 20 m². It has been used for research of natural resources, ecological monitoring and hazards prevention. Designed for a life time of 3 years, it is out of service now.

x2015-12-08 15_43_11-WSJT-X v1.6.1-devel by K1JT

QSO in WSJT-X

In use by the ground stations were the 25 m radio telescope in Dwingeloo by PI9CAM with 120 W and a 3 m dish with 150 W at the feed by DJ5AR in Mainz. The mode used was digital JT9H that comes with the new WSJT-X software by Joe Taylor, K1JT. The transmit/receive periods were set to 10 seconds, working around a center frequency of 1296.300 MHz. The automated Doppler tracking (+/- 60 kHz) has been performed for the complete path on DJ5AR´s side with a homebrew tracking software. The calculative power budget during the QSO was about -154 dBm. This value is very optimistic, as it presumes the optimum reflectivity of the satellite, which depends on its orientation.

Conclusion: The main difficulties in this game are:

  • Selection of suitable satellites, depending on radar cross sections and slant ranges.
  • Compensation of the Doppler shift with a maximum rate of 600 Hz/second.
  • Antenna tracking with dish of a mass of 120 tons.

 

To be continued…

ISS Bounce Tests with new WSJT-X

September 13th, 2015

Following Jan´s (PA3FXB) suggestion, we tried the new experimental WSJT-X software. The mode, we chose was JT9 H. Also we agreed in trying full doppler compensation to be used on my side. Everything worked fine, as can be seen in the screenshot below.

2015-09-13 08_15_51-WSJT-X v1.6.1-devel by K1JT

 

ISS Bounce in JTMS

September 5th, 2015

Back from our holidays Jan, PA3FXB, and I had another test via ISS Bounce on 23 cm today. As I located a bug in my Doppler correction software, causing unwanted steps, it could be fixed by finding a workaround for the malfunction in compilers NOW() routine, for returning the correct time in milliseconds. So the improved Doppler correction is working smoothly as can be seen and heard in the signals received.

2015-09-05 09-51-15 PA3FXB in JTMS

PA3FXB in JTMS received by DJ5AR via ISS Bounce. Center frequency was 1296.300 MHz.

094915  2.5 2270  3 36  248     DJ5AR PA3FXB
094915  6.5  520  2 26  276     PA3FXB DJ5AR
094915  9.7  360  1 26  310     PA3FXB DJ5AR
094945 12.8  180  1 26   64     PA3FXB R27 R27   DJ5AR
095115  3.1  300  2 26  268     DJ5AR PA3FXB R27 R27
095115  4.1  320  1 26  205     PA3FXB R27 R27   DJ5AR
095115  7.1  300  1 26  157     R27 R27   DJ5AR PA3FXB
095115  8.5  320  2 26  153     R27 R27   DJ5AR PA3FXB
095115 10.1 1560  8 36   65     PA3FXB R27 R27   DJ5AR
095115 11.7  300  5 26  138     R27 R27   DJ5AR PA3FXB
095115 12.3  820  7 26  111     R27   DJ5AR PA3FXB R27
095115 13.7  680  4 26   40     PA3FXB R27 R27   DJ5AR
095145  5.3  440  2 26  115     PA3FXB 73 73
095145  7.6  740  3 26  271     73 73 PA3FXB
095145  9.3 1440  3 36  283     73 PA3FXB 73
095145 12.0 1180  5 36  244     PA3FXB 73 73
095215 10.5 1120  3 36   56     WOW
095215 12.8 1520  3 36  190     WOW
095245  4.1  740  1 26 -116     SUPER
095315  2.1  420  1 26   -7     73
095445 16.0  140  2 26  252     DJ5AR PA3FXB
095615 14.7  140  4 26  231     73 73 PA3FXB          

We even had some kind of conversation at the end 😉

As further tests showed, the full doppler correction on my side is working very well now. This enables potential sked partners to work on a fixed frequency by just tracking the International Space Station with the antenna.

Sked requests are welcome:  dj5ar (at) darc.de

Modes, successfully being used so far: CW, SSB, ISCAT, JTMS

A day on Rocket Bodies

April 7th, 2015

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.

2015-04-07 12_02_30-SpecJTReflections 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.

 

TNX to Jan, PA3FXB and the CAMRAS team!