Category Archives: Satellites

Playing with the bird

April 1st, 2019

As soon, as the narrow band transponder was opened in February, I had my first QSOs via QO-100. Using an MKU LNC 10 in a 80 cm offset dish and my 3 m mesh dish for transmitting, made the first steps very (too) easy.

In the meantime I mentioned, some hams from the Netherlands, experimenting with ADALM-Pluto SDRs had very good results. So I got one too and was amazed of variety of possibilities it offers. So I heard my first beacon on 9 cm and it was easy to produce a signal on 13 cm. Recently I got two broadband LNAs (I will call them “A” and “B”) from China and was curious to see how these can be used as power amplifiers too.

Power SourcePower in mW
Pluto 3
Pluto + LNA "A" 22
Pluto + LNA "B" 30
Pluto +LNA "A" + LNA "B"120

After some power measuring I connected the stuff to a W2IMU feedhorn, mounted on a tripod. No problem at all to find my signal on the NB transponder of QO-100. The estimated EIRP is about 2.4 W and results in a signalstrength of 12 dB.

Addendum: April 10th, 2019

3 mW are enough!

At least I mounted a DJ7GP patch feed with the bare naked Pluto in the focus of my 3 m mesh dish. the 3 mW were enough to produce a solid signal on the NB transponder. In this case I have 6 W EIRP to get 16 dB signal.

Longjiang-2 S-Band Beacon received over 400000 km

January 10th, 2019

As I digged a little deeper, I learned, the source of the signal on 2275,225 is not Queqiao, but it is it´s companion Longjiang-2 or DSLWP-B in an orbit around the moon.

August 23rd, 2018

Designed as a relay for the planned chinese Chang’e 4 misson to explore the far side of the Moon with a lander and a rover, the Queqiao probe has reached it´s final destination 60000 km behind the Moon. There it is in a halo orbit with a radius of 15000 km around  the Langrangian L2 point of the Earth-Moon-system. So it won´t be covered by the Moon, seen from Earth.

Queqiao also carries a radio astronomy experiment for low frequency exploration in collaboration with dutch ASTRON. After the lainch in May 2018 two microsatellites Longjiang-1 (DSLWP-A) and Longjiang-2 (DSLWP-B) were released, to enter orbits around the moon. These satellites carry a radio astronomy experiment as well as amateur radio payloads. While Longjiang-1 went lost, Longjiang-2 is operating and can be monitored in the 70 cm band as well as in the S-Band.

The signal of the S-band beacon is audible at about 2275.225 MHz. The used equipment is HDSDR software with a RTL-SDR-Stick connected to a 13 cm ATV Converter (LO=916 MHz) and a 13 cm LNA (Kuhne) at a 23/13cm dualband ringfeed in my 3 m dish.

Reception of ISEE-3

July 30th, 2014

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!

2014-07-30 11_30_21-HDSDRThe 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.