The radio monitoring community was agog over the weekend after a report was published at http://www.slashdot.org that the “Buzzer” (station UVB-76 in Russia on 4.625 MHz. AM) had gone off the air. If there was an outage it must have been short-lived as the station has been heard several times since.

The purpose of UVB-76 is a mystery and there is an excellent wikipedia article about it at http://en.wikipedia.org/wiki/UVB-76

A lot of listeners are not familiar with the propagation characteristics of frequencies at the low end of the shortwave spectrum (such as UVB-76). They are highly absorbed by the D-layer of the ionosphere during daylight hours. Their range during the day is probably only a few hundred miles, which is probably not a problem for the Russians’ intended use for this station.

At night, the D-layer disappears and the propagation at that frequency is theoretically unlimited, as long as the path of interest is mostly in darkness.

Since the summer solstice is only a few days away, the days are long in the northern hemisphere meaning there are only a few hours during which UVB-76 can be heard each day.

Propagation can also be degraded by solar disturbances.

Receivers in Europe (such as the ones on the GlobalTuners network) are close enough to UVB-76 for generally good copy. Today, as early as 1530Z, I heard the Buzzer on the Hannover, Germany and Vienna, Austria HF/MF GlobalTuners.


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