Recovery Beacon Signals from Kosmos
Satellites
Contents
First
Reception
In early 1966 I was a
novice
at tracking satellites and listened intently to every signal that I
heard.
That is why I stumbled upon the recovery beacon signals from the Zenit
reconnaissance satellites. On 14 April 1966 I and Geoff Perry both
picked
up the normal FSK-PDM signals on
19.995
MHz from Kosmos 114 during its last revolution around the earth at
0702.30-0710.08 UT. At Kettering the listeners went 'off watch' after
having
lost the normal signals. I, on the other hand, not knowing what to
expect,
kept my radio switched on. This is what I wrote to Geoff Perry six days
later:
".... It was not
possible
to hear any more beacon signals of the usual kind. However, at 0725 a
signal
of this type started to be
transmitted:
-
-.- The signal continued until at least 1100. ..."
Identification
On 6 August 1966 Kosmos
126
was due to be recovered. At Kettering normal FSK-PDM signals on 19.995
MHz were picked up at 0908-0918.20 UT followed by 15 minutes of -
-.- - -.- - -.- .... signals
starting
at 0920 UT. The Morse code interpretation of these signals is TK, and
that
is what we started to call them - "tee-kays"! They became a normal
feature
of recoveries of reconnaissance satellites. later, we found variations
in that TG's and TF's were transmitted by other versions of the basic
Zenit
satellite design. (Listen
to TG signals here)
The image below shows a
short
piece of a TK transmission. the ordinate is frequency in Hertz and the
abscissa is time in seconds. As can be seen the interval between each
TK
burst was 2.8 seconds. One can also see that the dash in the "T" is
much
longer than the dashes in the "K". (Click on the picture to hear the
signals)
Basing ourselves on 11
receptions
of such recovery beacon signals Geoff Perry and myself published a
paper
in the BIS Spaceflight magazine (April 1968) where we had calculated
that
the average delay between the cessation of FSK-PDM signals and the
onset
of TK's to be 6.75 +/- 0.5 minutes. We speculated in that article that
the TK's started when the main parachute of the recovery capsule
opened.
Sometimes the TK's continued for hours and at other times they ceased
in
as little as 6.5 minutes. we took this time to indicate the time it
took
for the recovery forces to reach the landing spot. (Robert
Christy has vividly described how he picked up TK's back in
1968).
Location
of transmitters
Were the two transmitters
for
FSK-PDM and TK's in the same part of the satellite? At the time we
thought
so, because the Vostok re-entry vehicle carried short-wave antennas,
but
now that design sketches of Zenit satellites have been published, we
know
that the short-wave antennas were mounted on the instrument module.
therefore
the cessation of FSK-PDM signals could either represent the detachment
of the re-entry vehicle or the destruction of the instrument module.
Probably
the former explanation is the most probable, since we noted no changes
in the telemetry during the last minutes, which one could expect if the
re-entry vehicle had been detached.
An
even
earlier observation!
Was Kosmos 114 the first
time
that TK's were transmitted? No, I do not think so. On September 9-10,
1978,
when I visited space listener Dieter Oslender in Bonn, I ran across a
note
in Dieter's log for 25 April 1965 that said "Molniya 0632.45-0755.00 UT
19.996 MHz". I asked Dieter to let me listen to the corresponding tape
recording and you can understand my astonishment when I heard a steady
stream of TK signals coming from the loudspeaker. Dieter had
tentatively
assigned the signals to Molniya because nothing else fitted the long
observation
time. I explained about the TK's as recovery beacon signals and the
fact
that Kosmos-65 was recovered that morning. So, it seems that the
recovery beacon on 19.995 MHz was a regular feature of the Zenit
reconnaissance
satellites and probably this system was used from the very beginning
with
Kosmos-4 in 1962.
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