GPS receiver
A GPS receiver with a precision 1 pulse per second (PPS) ouput is required. The 1 PPS signal is connected to an input channel of the sound card.
The width of the 1 PPS pulse must be either less than or equal to 10 microseconds or else wider than 1 millisecond.
For accurate signal timing, the PC clock must be set to within +/- 500 milliseconds of UTC. This can be achieved using the Network Time Protocol.
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23 May 2006