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|fahnen/7.jpg Sounds from the First Satellites|
Sounds from the First Satellites
Roy Welch, W0SL, has provided these historical audio recordings of several "first" satellites as monitored at his station (then W5SLL).
Oscar 1 was launched on an Agena B rocket from Vandenberg AFB in California along with a Discoverer series satellite. KC4USA in Antarctica first reported signals as it passed over there after being launched. Oscar 1 was battery powered. Its signals lasted for about two weeks. The batteries were not rechargeable. The transmissions were on 145.00 MHz. The CW signal repeatedly sent HI in morse code. The number of HIs per minute, or the "HI Rate" was the only telemetry sent. The HI Rate gave the internal package temperature. Amateurs were asked to report the HI rate.
At W5SLL, there was no tracking antenna available. The antenna was cut for 108 MHz for listening to the new USA satellites. It was a six element colinear array constructed on a 13 by 13 foot wooden frame and suspended above a "chicken wire" reflector. The whole array was placed on the roof of the house looking up at about 75 degrees above the southern horizon. Satellites were captured as they flew through the main lobe of the antenna.
Listen to the normal speed recording (.WAV (113K) orRealAudio (14K)). Each HI is too fast to make out, and sounds more like a cricket chirping. Now listen to the half speed recording (.WAV (226K) orRealAudio (21K)), or if all that noise hurts your ears, listen to this filtered version (.WAV (226K) orRealAudio (21K)). You can distinctly read the HIs being sent. This recording was made in Dallas, Texas on December 14, 1961, at 0722Z using a Tecraft converter in front of a National NC-300 receiver.
See also thisnewspaper article (120K GIF) on OSCAR 1.
Sputnik 1 was the Soviet Union's and the world's first orbiting satellite. The signals heard in this recording are weak, over the horizon signals, recorded on a frequency of 20.007 MHz. Other recordings were made with signals strong enough to permit hearing the oscillator feeding through during key up periods. These were made with the satellite in line of sight. The weaker signal recording is presented to show a time when the keying of the signal was interrupted and a steady carrier was transmitted. There are two such instances in this excerpt. WWV which was nearby in frequency shut down their transmitters with each pass on this evening.
Roy and his three-year-old daughter would put the radio speaker in a window and then go outside and listen to the strong signals while they watched the third stage booster tumbling end over end like a bright pulsating star as it passed over in the evening sky. Listen with them to this recording of Sputnik 1 (.WAV (113K) orRealAudio (10K)). This recording was made in Dallas, Texas on October 7, 1957 at 0457Z using a military surplus AN/FRR3A HF RTTY receiver.
Here is anewspaper photograph (234K GIF) of Roy playing Sputnik signals at the State Fair of Texas on October 9, 1957.
Explorer 1 was America's first orbiting satellite, launched on an Army Redstone rocket after several failures to launch the Vanguard Satellite with the Navy's Vanguard rocket. The telemetry heard in this recording consists of a combination of three or more relatively stable audio tones and two alternating audio tones. The alternating tones were indications of cosmic particle collisions detected by an on board counter. The tones shift from one to the other when the detector has counted sixteen particles. It shifts back again with the detection of the next sixteen particles and so on.
The satellite had two RF frequencies, 108.0 MHz and 108.03 MHz. This recording is from the 108.0 MHz frequency. The 108.03 MHz frequency had a similar sounding telemetry, but without the alternating tones.
Listen to the recording of Explorer 1 (.WAV (110K) orRealAudio (10K)). This recording was made in Dallas, Texas on February 11, 1958 at 0100Z using a home-made VHF converter in front of a National NC-300 receiver. The antenna was as described above for Oscar 1.
Earth-Moon-EarthThese single sideband transmissions were from KP4BPZ in Arecibo, Puerto Rico via Moon Bounce. The KP4BPZ transmitter was running about 500 watts on 432 MHz and feeding the 1000 foot diameter radio telescope dish in Arecibo. Amateur radio operations were made on the two week ends of July 3, 1965 and July 24, 1965. Both SSB and CW operations were heard.
The receiving setup at W5SLL/0 was assembled quickly after the plans were announced. The antenna was a home made 32 element colinear array from the ARRL Antenna Handbook design. The individual small booms were completed, but they were not mounted on a metal frame. A 2X4 wooden frame was hastily built and holes drilled to accept the 16 individual element booms. The transmission feedline was 75 feet of plain old 300 ohm TV twinlead, terminating in a coax 4:1 balun.
The output of the balun fed the input of a homemade 432 MHz converter described in the July 1963 QST magazine article, "All Nuvistor Converter." The Nuvistor was a small vacuum tube, for those of you who don't remember the Nuvistors. The noise figure was not worth mentioning in view of today's technology. The output of the converter fed the input of a National NC-300 Amateur Band receiver.
The antenna was aimed by leaning the wooden frame against a kitchen chair in the back yard and eyeballing it toward the crescent moon in broad daylight. Not exactly an ideal Oscar 0 station. What a signal! Just imagine what it would sound like today with our low noise preamps in front of our high performance converters and radios with steerable circular polarized antennas.
Vanguard 1 was launched aboard the oft-troubled Vanguard rocket in March 1958. The transmitters were approximately 10 mW in power and transmitted on 108.0 MHz and 108.3 MHz. The only telemetry transmitted was the package temperature. This was indicated by the difference between the two transmitter frequencies which varied with temperature. The solar cells were manufactured by Bell Laboratories.
The signals were received on a homemade VHF converter in front of a National NC-300 Amateur Band receiver. The signals were continuous carrier with no apparent audio modulation. Therefore, the recordings were made with the receiver Beat Frequency Oscillator (BFO) turned on in order to produce an audible tone heard in the recordings.
Listen to these two recordings. In this recording made shortly after launch (.WAV (115K) orRealAudio (11K)) you can detect a rapid spin modulation on the signal and can determine that the satellite seemed to be spinning fairly rapidly. In this recording made approximately one year after launch (.WAV (115K) orRealAudio (11K)) you can tell the satellite is turning very slowly. By this time the batteries had failed and the satellite was powered only by the few solar cells on the surface of the satellite. The satellite was very small, not much larger than a large grapefruit, so there wasn't room for many solar cells. The transmitter frequency varies as the solar cells slowly turn into and out of the sunlight.
Sometimes the signal would disappear when no solar cells were exposed to the sun. It was easy to determine when Vanguard 1 went into the shadow of the earth, by the rapid change in frequency and abrupt loss of the signal altogether. This is not demonstrated in this recording.
Updated 15 December, 1996. Feedback toKB5MU. The RealAudio sounds on this page are encoded in the 14.4kbps mode, but you can listen to them over any speed link, since they are being sent to you as files and not as RealAudio streams. The RealAudio Player is available for free fromRealAudio.
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