[SLUG] Purchasing GPS receivers suitable for LinuxPPS and NTP.

[M Willis]

Hello Sluggers Online (and Offline),

Those at the previous talk on GPS and time transfer will be aware of
the important role that GPS plays in accurate time synchronisation.

Only a small number of GPS receivers are suitable for precise time
synchronisation. These receivers provide the Pulse-Per-Second (PPS)
essential for time synchronisation.

At recent SLUG meetings I have been selling a few of the
inexpensive GPS receivers suitable for use with NTP and LinuxPPS.

However SLUG is both a online and offline community -- many
usually don't attend the monthly meetings. So I thought it might
be fair to offer the other half access to these receivers.

1. U-Blox and USB serial kit: ($20)
- U-Blox RCB-LJ-0-000 GPS receiver board
- PL-2303 serial to USB adapter
!! "Red-Wire" modified to connect the DCD pin to PPS line !!
- Serial adapter and GPS connected with copper wire-wrap.
- MCX to SMA adapter
- GPS Patch antenna with 3M cable and SMA plug.

http://i.imgur.com/hcaAE.jpg

Currently there are *NO* other GPS adapters on the market
that include a connection between the USB DCD and PPS line.

USB serial with in-band DCD/PPS serial can achieve:
0.5-1 milliseconds jitter.

SEE: Eric S. Raymond (ESR) and http://bufferbloat.net
----

2. Garmin 16HVS and adapter ($25 RRP $140)
- Gamin 16HVS
(nominally 12 VDC, accepts 8 - 40 Volts)
- RJ-45 to D-9 connector with Molex drive power connector.
* PPS connected to DCD pin 9 *

http://i.imgur.com/VwSIn.jpg

RS-232 serial and PPS with LinuxPPS can achieve:
0.1 - 5 microseconds jitter.

SEE: http://blizzard.rwic.und.edu/~nordlie/ntp-gps.html
http://www.worldtimesolutions.com/support/ntp/Debian_Lenny_Linux_PPS_support_for_ntpd.html
http://www.lammertbies.nl/comm/info/GPS-time.html
http://time.qnan.org/
----

3. U-Blox bare board ($10)
- U-Blox RCB-LJ-0-000 GPS receiver board
* TTL serial board, 3V3 power supply
* MCX antenna connector.
----
Prices do NOT include shipping, pickup at SLUG is fine.


For those that missed my talk:

Slide-set:
http://archive.org/download/SLUG_2011Nov_GPS_timesync/SLUG_2011Nov_GPS_timesync_slides.pdf
Size: 1292262
MD5: c26ee475b3ce5db15341ef24cc56c0d9
SHA1: ce9d70cf1e56904a422363cb0eb3e1d4c3caf321

Notes:
http://archive.org/download/SLUG_2011Nov_GPS_timesync/SLUG_2011Nov_GPS_timesync_notes.txt
Size: 67478
MD5: 82c62ee95ff96c3c210117fe6be3f2b8
SHA1: 0c484831aecdfcd1f0a1f830d5ce32e6e2ec4249

Regards

Mark.
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