In these 3 frames you can see:
MENU_HP: Time signal
processing: HBG Time-Code (CH)
A) one 10 s window of a generic HBG
Time-Code, from Newchatel (CH), recorded during this seismic recording
(Apulia, South Italy, 1972), sampled at 100 Hz; if you 'read' it carefully,
you could see the 3-spikes hour mark, pointed out by the arrow;
B) the results of the two stacking algorithm, regarding
the first and last 30 s of the Time-Code signal; in this case the routine
TSTAC was set in 'AUTO' mode (and it worked properly: see the correct 'X'
positions on the beginning of the big slope);
C) a 13 s length signal window (from sec 7 to 20)
of the VR channel; note the offset and the amplitude levels.
The Time-Code, here, was the HBG; but many others
do exist in Europe, and more complete, for example the DCF
(from Mainflingen, Germany)