Miscellaneous Projects

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h1. osmo-lea6t-gps

The swiss makes of GPS receiver chips and modules u-blox has (among others), a line of so-called _timing_ GPS modules.

The main difference of such modules compared to the standard modules is their ability to output arbitrary GPS-derived clock

signals anywhere between 0.25 Hz and 10 MHz.

This allows such modules to be used in a varity of high-precision timing applications where a simpler/traditional approach using

regular 1PPS outputs is not sufficient.

The Osmocom project has developed an evaluation / development board for the u-blox LEA-6T timing module.  Like all other

Osmocom projects, it is fully open source, i.e. schematics and layout files are freely available.

!{width:50%}osmo-lea6t_small.jpg!

h2. Electrical Design

h3. Schematics and Layout

The most up-to-date versions of the schematics and layout files can be found in the projects git repository which can be

browsed at http://cgit.osmocom.org/cgit/osmo-lea6t-gps/ or cloned like this:

<pre>

$ git clone git://git.osmocom.org/osmo-lea6t-gps

</pre>

For your convenience, PDF files are also attached as attachment:ublox-lea6-test.pdf and attachment:ublox-lea6-test_brd.pdf.

h3. Major components

* LEA-6T Module ("product page":http://www.u-blox.com/en/gps-modules/u-blox-6-timing-module/lea-6t.html, "data sheet":http://www.u-blox.com/images/downloads/Product_Docs/LEA-6_DataSheet_%28GPS.G6-HW-09004%29.pdf)

* FIXME: add more components here

h2. How to use

You can connect to it using one of the Osmocom-style serial cables (3.3V UART on 2.5mm audio jack) or using USB.  You will get

a serial port that can speak either NMEA or the proprietary UBX protocol.

The full protocol is specified in the "u-blox 6 protocol specifiation":http://www.u-blox.com/images/downloads/Product_Docs/u-blox6_ReceiverDescriptionProtocolSpec_%28GPS.G6-SW-10018%29.pdf.

h2. Where to buy

You can have the PCB etched anywhere you'd like, using the layout data we have provided.  Most of the components

are available via distributors like Digikey.  Only the LEA-6T module has to be obtained through an u-blox distributor.

"sysmocom":http://sysmocom.de/ *used to be selling* fully assembled boards "in their webshop":http://shop.sysmocom.de/ *but this service is discontinued!*

h2. Who

osmo-lea6t-gps was designed by Sylvain Munaut.  Prototype manufacturing and testing was performed by Harald Welte of sysmocom.