Re: [chrony-users] chrony with only 2 sources

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William G. Unruh   |  Canadian Institute for|     Tel: +1(604)822-3273
Physics&Astronomy  |     Advanced Research  |     Fax: +1(604)822-5324
UBC, Vancouver,BC  |   Program in Cosmology |     unruh@xxxxxxxxxxxxxx
Canada V6T 1Z1     |      and Gravity       |  www.theory.physics.ubc.ca/

On Wed, 12 Mar 2014, Yan Seiner wrote:


On 03/12/2014 02:47 AM, Ed W wrote:

Probably a bit late, but the GR-601W (code name MACX-1) from navisys.com.tw can work adequately (it's not a standard part, email them, cost $49 ish in small quantity plus shipping)

I have a couple of these. They have a built in USB to serial adaptor, but with the PPS attached to the correct lines. Obviously because you are using USB you now have a max accuracy limited by the USB polling speed which is about 1ms. However, for a simple plug-in and works out of the box device it's pretty nice. I have a couple here, I could probably arrange to setup a Chrony feed if someone wants to examine the stability externally?

Another idea I had (but never completed) is that I have a few Garmin 18 devices. I was going to splice a serial port and USB cable together to give power to the Garmin 18... (if you don't need the accuracy better than 1ms you could attach it to a butchered serial to usb adaptor)

I got a "Globalsat Timing 1pps GPS Module MTK MT3301 MT3179 Chip" from ebay. Not a bad price, and seems pretty solid. It's ttl level, so you need a max232 or similar chip to match TX, RX, and DCD.

No. Most serial ports respond to ttl level inputs. While the standard is
different, the actuallity is that serial port chip manufacturers know that
they are often (almost always) driven by sources that do not obey the
standard.
Ie, try it without a serial adapter ( which introduces a time delay as well
although probably at the usec level ).



Don't have it hooked up completely yet - turns out I'm missing the correct gender serial null modem cable parts - so as soon as that gets here I will hook it up.

PPS does work; at least gpsd sees it.


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