The first, 244.512 MHz is relatively easy to track as the satellites generate a 0.5s long 'trigger pulse' every 60 seconds. Its purpose is to activate ground based transmitters waiting to send a message. Satellites can be identified relatively easily by measuring the time of closest approach from Doppler curve.

Received messages are then re-transmitted on the second frequency at 261.035 MHz.

From western Europe, it is unusual to hear more than a single 10-40s burst of data at 261.035 MHz on any particular pass. Transmission is usually heard near the start of a path that takes the satellite across Russia. Transmissions on passes to the west of the UK, for example, seem to be non-existent. Occasionally there are multiple bursts as a satellite triggers and retransmits two or more bursts of data from the ground but this is relatively rare.

The way to identify an individual satellite on this channel is to measure the received frequency of the data burst and compare it to the expected Doppler shifted value at that moment. Not every active satellite dumps messages on every pass and often there are several satellites above the horizon simultaneously. Simple logging of event times is not sufficient to identify the transmitter. One point to note is that NORAD has misidentified the payloads on one of the multiple-satellite launches involving both Gonets-D1 and Strela-3 payloads. It has interchanged Cosmos 2386 (a Strela-3) and Gonets D1-8 - to the significant confusion of some observers.

Thanks are due to Ary Boender and Hans Oeben for their assistance in this piece of work on both the Strela-3 and Gonets-D1 satellites during a period of concentrated observations early 2009, and particularly to Ary for detecting use of the 261 MHz frequency.

Three military satellites were launched from Plesetsk 2009 July 6 at 01:26 UTC using a Rokot vehicle. Two of them (Cosmos 2451 & Cosmos 2453) have been detected transmitting Strela-3 type trigger pulses at 244.512 MHz and dumping messages at 261.035 MHz. No transmissions have been detected that can be determined as coming from Cosmos 2452. This leads to the conclusion that two of the satellites are Strela-3 and the other is possibly a Rodnik store/dump comsat used by a different branch of the Russian military/government. If true, this will be the second Rodnik but, as yet, transmissions have not been detected from either satellite.

Following launch of the Rokot, a check from the Zarya location showed transmissions at all the frequencies listed below. Notably, the wrongly named (by NORAD) Gonets D1-8 produced several passes with a very high power tranmission.

A check by Hans Olben early in the month revealed all the listed satellites to be alive and apparently well at both frequencies.