'UVB76 The Buzzer is DOWN !!'
The WebSDR at the University at Twente is often used
for listening to the UVB76 signal , often called , The
Buzzer on 4625kHz.
At least 1 or 2 times each hour a visitor in the chat
box will ask - '' uvb 76 - it's down ? ''
The answer is The BUZZER is NOT DOWN !
Due to the signal not being heardon the WebSDR
some come to the conclusion that the Transmitter is
Some have said it was turned off for maintenance.
Some claim that it only is turned on at night time.
Even some say that that it is now transmitting at
And on and on the stories go.
The facts is that the UVB76 Buzzer is
turned on and is running 24 hours a day.
So why then can't it at times
be heard ?
The reason is because of the low frequency of 4625kHz
that it is on.
In the HF bands
, low frequencies are more affected by atmospheric
absorption than higher frequencies are.
The Buzzers low 4625kHz frequency is In
a part of the shortwave spectrum where transmitted
signals suffers very greatly from atmospheric
absorption during daylight hours.
During the day the signal will be able to be heard up
to a few hundred or so kilometers away by Ground Wave
propagation , but due to absorption of the ionospheres
D layer at that time , not very long distances will be
This diagram shows the transmitted signal arriving at
the D layer , but there it gets effectively absorbed
and its trip ends there.
At night time things change as the D layer dissipates.
The absorption effect reduces , and this allows the
signal to reach the upper F layers of the ionosphere ,
and when this happens , the signal can be reflected /
refracted down to to Earth at much further distances
away via Sky
The WebSDR's location in the Netherlands is too far
away for the Ground Wave to reach , so it relies on
the signals arriving to it through Sky Wave
At nigh time the Buzzer signal from Russia arrives through Sky Wave
propagation and can then be heard on the WebSDR in the
So the Buzzer is NOT down , it is just that it
cannot be heard in the
daylight hours in Europe.
Fortunately for Buzzer fans there is an
alternative to the ineffective WebSDR in the
You can listen to a live stream of the
Buzzer from a receiver located in Helsinki
This location can hear the Buzzer 99% of the