NAVIOR-24S
™
CHAPTER II
Hardware Integration
39
NAVIOR-24S ™
Revision
V1.00 20.05.2008
Pulse-Per-Second (PPS)
The NAVIOR-24S GPS/GLONASS receiver provides one microsecond wide, CMOS compatible
TTL level Pulse-Per-Second (PPS). The PPS is a positive pulse available on pin 5 of the power and
I/O connector. The rising edge of the PPS pulse is synchronized with respect to GPS. The timing
accuracy is ±50 nanoseconds when valid position fixes are being reported.
The rising edge of the pulse is typically less than 25 nanoseconds. The distributed impedance of the
attached signal line and input circuit can affect the pulse shape and rise time. In early PPS mode, the
PPS can drive a load up to 5mA without damaging the module. The falling edge of the pulse should
not be used. In its default mode PPS is always on (early PPS) and is driven by the Real Time Clock
(RTC) until the receiver acquires GPS time from the satellite and is getting fixed. In early PPS
mode the PPS is output immediately after main power is applied, and continues even if the receiver
loses GPS clock. The drift of the PPS, when the NAVIOR-24S GPS/GLONASS receiver is not
tracking satellites, is unspecified and should not be used for synchronization.
The PPS output modes can be controlled with BINR packet 72h. The modes are always on (default),
Fix Based, or Always Off. Cable delay compensation is available through the use of BINR packet
72h.
Note
– NAVIS has measured less than 50 nanoseconds accuracy on the NAVIOR-24S
GPS/GLONASS receiver PPS signal in static mode. For more information on the use of the
NAVIOR-24S GPS/GLONASS module in timing applications, contact your NAVIS sales
representative.
