RS-15 A Real Challenge

Among the analog satellites this member of the Radio Sputnik fleet is a real hard one to catch. But it is the only one left, so here we go.

It is a Mode A type, that means 2m uplink and 10m downlink. Due to its age the signals from satellite are suffering of power budget problems.

Latest News

Mike, KF4FDJ reports succesfull QSOs with 4 other stationend of february 2004

Tony, AA2AE reports:
I worked RS-15 on 1/27/04 during the 10:30z pass. The bird was in sunlight and the beacon seemed exceptionally strong. I didn't detect any FM'ing on my CW downlink, but I know RS-15 can be unpredictable at times. Appartenly, supply voltage was low during the 00:10z pass despite solar illumination.
If you monitor RS-15 for a while you'll notice that, more often than not, the 10 meter downlink signals are pretty weak. I have a 4 element 10m Yagi on the tower and this mornings pass showed the beacon signal peaking S-7, but my downlink was just above the noise ( 50w 7el 2m uplink ).
I use a 4 element Force12 Yagi on the 10m downlink and the beacon signals can be exceptional at lower elevation.

Robert, G8ATE, has a report from 12.Dec '03. He succeded in hearing the cw telemetry when the satellite was fully illuminated and with 300 W ERP uplink power he was able to produce only a very weak downlink signal.

RS-15 is basically not in a good shape. What Mark, KB3CWS, reports you can find out the actual mode of the satellite by listening the beacon on 29.352 MHz (+/- doppler shift of up to 400 Hz).

Take also a look at Mark's Satellite page for information about other analog satellites.

Receiving RS-15

The first rule for satellite operation is making you capable to hear the downlink. Here on the RS series this is a 10m signal (RS-15 and RS 12/13) or a 2m signal (RS-12/13, sometimes if activated).

Uplink: 145.858 MHz - 145.898 MHz SSB/CW
Downlink: 29.354 - 29.394MHz SSB/CW
Beacon: 29.352 MHz in CW

If you can hear the beacon given constantly telemetry in CW the transponder is activated and you can try to use it, also if no signal at all can be heard.

A difficult time is when the beacon provides a solid carrier for several seconds and then switching off for serveral seconds. The downlink is only active when the beacon is on ! So in this case you have to deal not only with QSB and weak signal you also have to consider the activity of the beacon/transponder.

The Antenna

If possible try to errect your receiving antenna in a quiet area where noise is as low as possible. I couldn't achieve any satisfying results with my simple wire dipole I am using for HF-operation. So I decided to install a new antenna that provide a good signal at high and middle angles. An omidirectional pattern is also a need if you won't turn the whole antenna.

Chosen was a horizonztal monoband quadloop (also useful for shortskip 10 m FM), due to the omnidirectional pattern, the 'low noise' qualities of loops and the elevation pattern installed at that low height (also good for service work)

Other antennas you can use to receive 10m downlinks is the classic Turnstile (two crossed phased dipoles). If you wish to increase the performance on high elevation passes you can add radials lying on the ground. Another option is to have polarization choice (add a relay for switching).

Another simple but effective antenna providing good signal is classic 10-m-dipole bent 90° with a vertical section and a horizontal section, compensating the different polarization a satellite signal can have.

The Signal Strength

With the quadloop I managed to receive RS-15 the first time. Signals are mostly low. This antenna gives a good reception above 25° of elevation. Especially very high passes can give you a signal up to S 5, but mostly it is around the noise floor (no S-meter reading). I found it very useful to use the DSP noise reduction feature on my IC-706MkII. Although this is not the most effective DSP unit it helps often to bring the CW signal out of the noise floor (no CW filter installed).

Working The Bird

This is the next step to go. At the moment I am building a 2m broadband yagi (144 - 146 MHz) which I plan to give it a try for satellite operation on RS-15 or even AO-10. Having different polarization will improve your signal but for the moment I use this single plane yagi for simplicity reasons. The amount of RF power is quite high. Jerry, K5OE did a calculation of different link budgets and the results are a bit sobering for RS-15.

Mike, KF4FDJ suggest 110 W into a 2x11ele cross yagi with a heavily used polarisation switch to overcome the deep fades.

Since months I didn't hear the beacon until end of may 2001. The beacon gives a constant carrier for about 4 seconds, followed by a gap of 4-5 seconds. At 45° elevation the S-meter on my IC-706MKII gives about a S5 reading with my low horizontal loop. This ant certainly prefers signal angles > 30°. The next high angle passes I'll give it a try, motivated by the report of Andras, HA2RD who reports a transponder activity back in February 2001. Although he couldn't here the beacon he was able to make some QSOs. I hope at least I can hear my CW signals, SSB seems to be very diffcult , requiring high ERP. Another problem is the low (no ?) activity due to the difficult situation of the bird.

Comments On That Bird:

Mike, N1JEZ says: " Keeping the receive noise floor as low as possible has made all the difference on RS-15."
A statement I can only agree with.

Mike, KF4FDJ says:" First, you need to have a good 10 meter receive antenna. I built 2 different ones which seemed to work OK. The first was a 10 meter turnstile. I mounted it about 10 feet off the ground, and seemed to work through some of the deep fades. The second antenna I tried, was a pair of hustler 10 meter elements mounted dipole fashion.
The most critical thing in working RS-15, is the ability to switch polarity on your uplink. "