Amateur Radia COMSATS
AMATEUR RADIO
As noted in chapter 1, amateur radio satellites have been used to link stations in Antarctica with the Soviet Union. RS5 was used to relay a digitally encoded electrocardiogram to specialists in Moscow from the Soviet Druzhnaya base on the coast of the Wed- dell Sea. The cardiogram was stored in the satellite's memory and downloaded over Moscow 48 minutes later. It was telephoned to the Institute of Biophysics of the Soviet Ministry of Health and imme diately decoded. The diagnosis was returned to Antarctica using the same technique. 31
No Soviet satellite dedicated to amateur radio support was launched from 1984-1987. However, two amateur radio transpon ders, RS10 and RS11, were incorporated in Cosmos 1861, a naviga tion satellite. The launch of Soviet amateur radio satellites RS9 and RS10 had been confidently predicted by the amateur radio community for more than two years and some details had been published, including provisional orbital parameters of 83°, 105 min utes, 1000 km, but it would appear that RS9 did not meet the nec essary pre-launch checkout criteria and was by-passed. A newspa per report announcing the launch included the ambiguously worded statement, "two artificial satellites began work simulta neously . . . RS10 and RS11, launched together with Cosmos 1861." 32 Although this was taken in some quarters to imply that three separate satellites had been launched, Kettering Group reception of the radio transmissions from all three payloads indicated that all three were integrated into Cosmos 1861. 33 This was supported by the NORAD catalog which listed only two objects, 1987- 54A and 54B, Cosmos 1861 and the final stage of the rocket which launched it.
Cosmos 1861 is a civilian navigation satellite in the Tsikada system, launched from Plesetsk on June 23. Transmissions on 150.00 MHz at 0945 GMT on June 24 were identified as emanating from Cosmos 1861 but, instead of transmitting its own parameter block, it was transmitting that for Cosmos 1727 with identity number 12. In the normal course of events, Cosmos 1861 could have been expected to replace Cosmos 1727 as number 12 in the oper ational constellation. However, on June 26, the standard naviga tion message transmission was switched on at 1950 GMT, and could immediately be identified on 29.350, 29.370 and 29.280 MHz in addi tion to breaking-in on the RS10 telemetry on 29.358 MHz. That was the first occasion on which the navigation message and amateur radio transponders had been observed to operate simultaneously. 34
Presumably this unintentional cross-modulation posed problems and navigation message transmissions were discontinued, leaving the satellite to function as a dedicated amateur radio satellite through the end of 1987. It will be interesting to see if a new satel lite is launched to replace Cosmos 1727 as number 12 when it even tually comes to the end of its serviceable life or whether Cosmos 1861 will be re-activated at the expense of its amateur radio role.
RS10 and RS11 were constructed at the Tsiolkovskiy Museum for the History of Cosmonautics at Kaluga, 180 km southwest of Moscow. Each uses the 15 meter band as an uplink only, the 10 meter band for downlinks only, and the 2 meter band for both uplinks and downlinks. Transponder power outputs are up to 5 watts and so the signals are very loud and easy to receive. Various combinations of uplink and downlink yield up to five distinct modes of operation. 35 Each mode employs five frequencies spaced at 10 kHz intervals above the basic frequencies quoted below. RS11 frequencies are 50 kHz above the corresponding RS10 frequencies. Uplink and downlink frequencies are 145.860 and 29.360 MHz, 21.160 and 29.360 MHz, and 21.160 and 145.860 MHz, for Modes A, K and T respectively. Modes KA and KT are combinations of modes K and A and modes K and T respectively. RS10 has beacons on frequencies of 29.357, 29.403, 145.857 and 145.903 MHz and RS11 beacons are 50 kHz higher than these. Robot uplink frequencies are 21.120 and 145.857 MHz for RS10 and 21.130 and 145.830 MHz for RS11. Both robot downlinks are on a frequency of 29.403 MHz. 36 (The "robot" device is described below.)
The telemetry represents various status indicators and measure ments made on the transponders and is sent in a frame of 16 words. Each word consists of a four-character Morse code group. The first two characters are letters and the last two characters give a number in the range from 0 through 99. Each frame is pre ceded by an identifier, also in Morse code. A typical frame from an early pass is
RS10
GS81 GROO RD11 RG45 SU45 SWOO SKOO SOOO
US37 UR26 UD39 UG36 WUOO UW46 UK46 UOOO
The first letter of each group determines in which half of the frame the particular word lies, whether or not the command sta tion is accessing the satellite and, if so, in which waveband, accord ing to the matrix below.
|
Option |
No command uplink |
15 m command uplink |
2 m command uplink |
|
First |
I .. |
s... |
D-.. |
Words 1-8 |
|
|
|
|
|
Second |
N -. |
R.-. |
G-. |
|
First |
A.- |
u… |
K-.- |
Words 9-16 |
|
|
|
|
|
Second |
M- |
W…. |
0- |
It will be noted that a dot is added in front of the character when the 15 m command uplink is employed and that a dash is added when the 2 m uplink is in use. There are two options for the meaning of the first character in each word. For example, if the first character of the first word is I then the telemetry data sampling period is 90 minutes, whereas if it is N then the sampling period is 10 minutes.
The sequence of the second letter in each group (S, R, D, G, U, W, K and O) is repeated in the second half of the frame. A logical explanation of the sequence can be derived by expressing these characters in Morse code dots and dashes, transposing the last of these to the front and assigning values 0 to dots and 1 to dashes. This yields the ascending series of integers from 0 through 7 and thus the second character in each word determines its position in the particular half-frame.
The two-digit numeral specifies a particular parameter value which may be derived by substitution in a transfer function. For instance, in the example provided above, the twelfth group is UG36. The U shows that the word is in the second half-frame, that the command station is accessing the satellite on the 15 m uplink and that the first option should be considered. The G signifies the fourth word of the second half-frame, which has the options of the codestore memory being "open" or "closed"—in this case "open"— and provides the temperature of the 9 V power supply. Substitu tion in the formula
T = N - 10°C
reveals that the temperature of the power supply was 26°C.
For full details of the telemetry coding the reader is referred to papers in the amateur radio literature. 37
Normal radio contacts between licensed amateurs world-wide can be established through the RS10 and RS11 transponders. In Mode A, a transmission to RS11 on a frequency of 145.930 MHz is re- broadcast by RS11 on 29.430 MHz and can be received by any shortwave listener within the satellite's footprint. The listener can then reply on, for example, 145.950 MHz and the original caller will receive that reply, rebroadcast from RS11 on 29.450 MHz. Theoretically it would be possible for two stations separated by as much as 7,400 km to communicate, whereas the normal range of a 2 meter transmission is limited to line-of-sight or some tens of kilo meters only. Under certain ionospheric conditions even greater ranges have been reported due to anomalous propagation condi tions.
The first radio contact through the new satellite was made by Master of Sports Valeriy Petrov in Alma-Ata. The report of this went on to say that some 800 individual and 250 collective radio stations in the Soviet Union are operating via artificial Earth satellites and that more than 3,500 foreign radio stations from 75 coun tries make use of Soviet RS satellites for the retransmissions of their signals. 38 Another report on the following day, June 26, 1987 stated that RS10 and RS11 would be switched on for work with shortwave enthusiasts world-wide at 0928 Moscow Time today (em phasis added). 39
The "Robot" is a useful device with which a radio amateur can have a contact as opposed to communicating with a fellow amateur via the satellite. The Robot transmits a "call" and expects to be an swered on its declared uplink frequency with its own callsign and the amateur radio operators call sign. If the correct procedure is followed it then responds with a serial number. The Morse code character-pair "AR" must be sent without a break as di-dah-di-dah- dit.
A typical example to illustrate the full procedure is given below. The satellite transmits the sequence
CQ CQ DE RS10 QSU 21120 KHZ AR
which may be interpreted as "General call, general call from RS11. Send your reply on 21.120 MHz." A typical reply might take the form
RS10 DE G3FOZ AR
which is "RS10 from G3FOZ, please acknowledge." If the operator's message is correctly received the satellite will reply
G3FOZ DE RS10 QSL NR 10 OP ROBOT TU QSO
NR 10 73 SK
acknowledging the contact and allocating the contact number 10. All the call signs worked are stored in memory and downloaded by ground command.
References:
A . SOVIET SPACE PROGRAMS: 1981-87, SPACE SCIENCE, SPACE APPLICATIONS, MILITARY SPACE PROGRAMS, ADMINISTRATION, RESOURCE BURDEN, AND MASTER LOG OF SPACEFLIGHTS, Part 2, April 1989, Printed for the use of the Committee on Commerce, Science, and Transportation, U.S. GOVERNMENT PRINTING OFFICE, WASHINGTON, D.C. 1989, Committee print 1981-87- part-2
27. Aviation Week and Space Technology, Mar. 25, 1985, p. 26.
28. Ibid.
29. Ibid.
30. Aviation Week and Space Technology, Sept. 9, 1985, p. 15.
31. TABS, 1651 GMT, Feb. 16, 1984.
32. Sovetskaya Rossiya, June 26, 1987.
33. . Perry, G. E. and D. G. Hawkins, Kettering Group Technical Memorandum GP/DH8701, re produced in SPACE, E.S.R.U. University of Aston in Birmingham, no. 26, July 3, 1987; and Oscar News, AMSAT-UK, London, Sept. 1987. p. 24-25.
34. Ibid.
35. Limebear, R. W. L. RS10-11 Tech Data Manual, AMSAT-UK, London, 1988.
36. Ibid.
37. Ibid.
38. TASS, 1420 GMT, June 25, 1987.
39. Sovetskaya Rossiya, June 26, 1987.
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