Mentor XL
12.7
A
CQUISITION
P
ROCESS
With satisfactory reception, the acquisition process commences automatically and takes around 15
minutes. The front panel display provides information on used satellites. An indication of suitable
values is given below for guidance. The figure can vary during the day so we would advise taking
readings at various times to get an idea of the trend. For example, a single “snap” reading of 8 may
well be the peak: the value could slip as low as 5 later, which may well lead to loss of 1 PPS.
Satellites
Minimum
Optimum
Notes
Used
5
8-10
12.8
1
P
ULSE PER SECOND
(1
PPS)
S
IGNAL
W
AVEFORM
The leading edge of the positive going pulse provides the timing reference plane for locking external
equipment. There is no agreed standard for the pulse width.
With “Lock to 1 PPS” turned on, this signal locks the internal 27 MHz PLL oscillator such that PAL
output signals are both frequency locked and phase locked. Any NTSC output signals are frequency
locked but cannot be phase locked. In addition, the real-time clock (RTC) is locked to GPS time.
1 second
Page 67 of 84
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