[ntp:questions] ESR looking for good GPS clocks

Michael Deutschmann michael at talamasca.ocis.net
Sat Mar 3 23:39:25 UTC 2012

On Sat, 3 Mar 2012, Terje Mathisen wrote:
> ESR was asking for a purpose-built USB GPS unit, it would obviously have
> some kind of embedded cpu to handle the USB stack and the differential
> timing between the gps chipset sending a PPS and host cpu sending a USB
> poll.

Actually, no.  ESR wants someone to modify the design of the $40 GPS fobs,
which consist of off-the-shelf GPS chips paired with off-the-shelf
RS-232-to-USB chips, so that the PPS pin of the one chip is coupled to the
DCD pin of the other.

That trace is not harmful to the function of the device as a location
sensor, and its omission probably saves only a fraction of a cent per
device.  Yet ESR faces a more than $100 markup to have it put back.

---- Michael Deutschmann <michael at talamasca.ocis.net>

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