[time-nuts] USB Low Cost GPS Timing Receiver
Hal Murray
hmurray at megapathdsl.net
Sun Nov 28 07:13:59 UTC 2010
jfor at quik.com said:
> Some of the older GPSs had the 9 pin COM port connectors to interface with
> the mapping SW running on a PC laptop (Magellen or Garmin ?). Might that
> data stream contain good enough timing info? I don't knoe what protrocol
> they used.
Most of the low cost GPS receivers will talk NMEA over RS-232. Most of them
also talk a vendor proprietary protocol.
The ones I'm familiar with don't come with a connector. You have to wire it
up yourself. You also have to provide power, either from a wall-wart, or
steal it from USB. Neither is much of a problem if you know how to use a
soldering iron.
The timing on the NMEA stream is poor in the time-nut context but probably
good enough if all you need is the nearest second. Some of them come with
PPS signals. ntpd and gpsd expect the PPS on pin 1, DCD.
Here are a few samples:
Garmin GPS 18x LVC:
https://buy.garmin.com/shop/shop.do?pID=27594
Garmin used to make many others. They are older technology, not as sensitive.
GlobalSat MR-350:
http://www.usglobalsat.com/p-58-mr-350p-bulkhead.aspx
If anybody notices any other modern ones please let me know.
There are probably several units designed for marine navigation.
--
These are my opinions, not necessarily my employer's. I hate spam.
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