QRP Labs QCX-mini CW, Assembly Instructions Manual, Page: 81 / 121

3.48 QCX-mini GPS interface and PTT output
The picture below shows the connectors on the main QCX-mini PCB.
GPS interface
The QCX-mini has a GPS interface which can be used to:
•
Calibrate the reference oscillator (27MHz crystal or 25MHz TCXO module option)
and the 20MHz system oscillator
•
Keep the oscillators disciplined and drift-free (frequency and time) during WSPR
beacon operation
•
Set the internal Real Time Clock, which is critical for WSPR options and may be
displayed on-screen if you have configured it.
The GPS produces two output signals, PPS (Pulse-per-second) and RxD (Serial data), in
addition to ground. Opti5V may also be connected, in order to power the GPS
module. A GPS such as the QRP Labs QLG1 is perfect for this see
http://qrp-labs.com/qlg1
The GPS signals (PPS and RxD) use the same microcontroller pins as the paddle Dah and
Dit respectively. Therefore you cannot use the Paddle and GPS at the same time. In fact,
you should only connect the GPS during the calibration of the synthesizer reference
frequency, system clock, and while operating the QCX-mini as a beacon (CW, FSKCW or
WSPR).
QCX-mini assembly Rev 1.05
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