LR9548S GPS Module Technical Manual v1.52
© 2006 Leadtek Research Inc. All rights reserved. Page 19/20
Preliminar
Confidential - Information is sub
ect
o chan
e without
rior notice.
1PPS
Pulse which is generated once per second. GPS and some radio clocks and related timekeeping gear
have a pulse-per-second or PPS signal that is needed for high accuracy time synchronization. The PPS
signal can be connected in either of two ways, either through the data leads of a serial port or through
the modem control leads. Either way requires conversion of the PPS signal,
Most GPS devices emit an RS-232 serial stream with some kind of timestamp format. Many GPS
devices are small realtime systems with the satellite tracking done at high priority, positioning done at
medium priority, and time output done at low priority. The timestamps often have +- 200 ms of jitter
(variance in delay), and output a PPS signal on the exact second.
SMD (Surface Mount Device)
Electronic device components that are mounted directly onto the surface of printed circuit boards
(PCBs). In the industry it has largely replaced the previous construction method of fitting components
with wire leads into holes in the circuit board (also called through-hole technology).
TCXO (Temperature Controlled Crystal Oscillator)
An electronic device that uses the mechanical resonance of a physical crystal to create an electrical
signal with a very precise frequency and can be embedded in integrated circuits. TCXO reduces the
environmental changes of temperature, humidity, and vibration, to keep a stable output frequency.
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