Pitch of the Greenwich time signal
bill at h...
Wed Mar 6 15:59:51 GMT 2002
Dave Kelly suggested that the 'pips' on the radio were 1 kHz tones
and could be used for a frequency check. In an idle moment at work I
downloaded a wav file of the pips and analysed it with Wavanal, as
The start times of the pips were 0s, 0.99873s, 1.99800s, 2.99673s,
3.99619s and 4.99492s. The end of the last pip was at 5.49678s.
Therefore, the timebase of the recording was accurate to within about
0.1%. However, Wavanal gives the frequency of the pips in this sample
as only 985.4 Hz.
I read the following on another website:
As it happens, the pitch of the pips is only approximate - the tone
is derived from a very simple oscillator circuit, which is prone to
drifting a little in frequency as it ages.
Therefore, the time signal is not to be relied on as a frequency
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