During the morning I was able to monitor GB3FM in IO91OF on 1297.050 MHz and G8MBU in IO90IR on 1296.800 MHz. Now in the afternoon F5ZCS in IN87PT on 1296.959 MHz came out of the noise with a strong signal of 549 with fast QSB. It is my 53rd beacon on 23 cm. The weather here in Mainz doesn´t look like tropo: 8/8 cloudy and wind at 40 km/h.
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.
The monitoring of distant beacons can be a boring job, even when using the waterfall diagram of a SDR. I prefer SpecJT of the WSJT package in JT65c mode. It is much more sensitive and even at slow speed faint refections can be seen clearly.
The example shows F1ZMT in JN07CX, 624 km from Mainz. The beacon operates 10 W into an omnidirectional antenna on 1296.872 MHz. The reflections in the screenshot were caused by 3 airplanes crossing the path one after the other.
There are good tropo conditions to the east from here for quite a while. I worked OK1MAC on November, 26th with an outstanding signal. OK0EA, SR6LHZ can be monitored constantly. I missed OK0EL on 1296.940, but solved the miracle today. The frequency shifted to .942 and the signal has been covered by DB0AJA. It´s nice to listen, how OK0EL in 526 km distance is battling against nearby DB0AJA,131 km away. As can be seen, DB0AJAs signal is accompanied by several dopplershifted reflections on airplanes.
It is interesting to see, that F5LENs refractive index as well as Hepburns tropo index don´t really illustrate the real conditions today. The conclusions is: Always perform a beacon check before switching off! The result may be surprising.
Josemi, EA2TZ, informed me about the new setup of his beacon EA2TZ/B on 1,296.855 MHz.
The antenna is a stacked 2 x big wheel now, omnidirectional and the power is 10 W. The location is in about 630 m asl in IN93BF88CP, east of Bilbao.
Reports are welcome!
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.
Jürgen, DK2AN phoned me tonight, to tell me, the new beacon DB0XY will be transmitting on 1296.910 MHz. It is located on the Bocksberg in the Harz mountains in JO51EU, about 750 m asl. The power is 10 W into a 4 times double quad, omnidirectional. The keying is in A1: callsign, locator, carrier, dashes, carrier….
In a first quick try it could be received here with 519 to 539 via tropo. When Planes crossed the path, the signal increased up to 559.
Another beacon will be installed on 13 cm soon. The intention is to provide beacons for monitoring via aircraft scatter.
For quite a while now I try to catch a signal of ISEE-3. Because of severe thunderstorms, there was no opportunity to check out yesterday. But today (July 30th, 2014) is the day to listen to this 36 year old bird.
The signal of the beacon on 2,270.414 MHz isn´t too strong, but clearly audible in the speaker. The actual distance is about 1.6 million km, the furthermost man made signal I ever received!
The downlink transponder A on 2.270.4 MHz uses an antenna array with a gain of 7 dBi, a beamwidth of 12° and circular polarisation. The nominal TX power is 5 W.
The equipment I am using, is just a FUNcube Dongle Pro with a 13 cm ATV converter (LO 916 MHz, IF 1,354 MHz) and a 13 cm LNA near the 23/13 cm dual band ringfeed at my 3 m dish.
Frequency calibration is performed on ordinary 13 cm beacons like DB0UX. The dish calibration is done by optimizing sun noise on 23 cm or the levels of SIRIUS satellites on 13 cm.
The rhythmical fading of the signal seems to be caused by the space probe´s spin of 19.76 revolutions per minute.