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#13
July 21st 07, 03:28 AM
posted to rec.radio.shortwave
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Identify unknown signal or modulation mode commonly heard inthe 1960s
LORAN?
Northe wrote: Michael, msg wrote: Seeking opinions on an old, commonly heard signal (AM) on HF, of some considerable power, with a very memorable sound. The sound on the air was much like hearing several P51 fighters approaching at high airspeed and props not in phase; the spectral power is mostly in the range of about 200 Hz to 500 Hz with a varying heterodyne of several Hz. It had a bandwidth of at least 25 kHz (can't say more precisely due to the cheap receivers I had at the time). I know exactly what you are talking about. One of the first things I remember hearing on shortwave radio was that type of signal -- my first thought was that I was hearing airplanes. So far I can't find a reference, but as I recall it was a type of multiplexed teleprinter transmission (maybe also incorporating voice circuits) -- "something-plex?." Northe N6KO Green Valley AZ |
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