[time-nuts] Advice on Synergy M12+ adapter and SYMTRIK SYM-RFT-XX.

[Hal Murray]

andrew at carrierdetect.com said:
> So, I have a Motorola M12+ GPS receiver in a Synergy Systems adapter board,
> and one of those little Symtrik MSF receiver boards. I'd like to try and get
> both working under Linux with ntpd (not at the same time!), and was hoping
> that someone might be able to provide some pointers. Namely: 

You can plug 2 refclocks into NTP.  (It may need 2 serial ports.)

You can either let the system figure out which clock is best, or mark one of 
them as "noselect".  In the noselect case, ntpd does all the normal data 
collection and logging but doesn't use that clock for figuring out the time.  
You can see how well it works compared to the first clock and/or ntpd's 
general timekeeping.


> As to the host, I'm looking to use a Raspberry Pi board running Linux: 

I suggest two steps.  Assuming you have Linux running on a normal PC, start 
there.  When you get that working you can move to the Raspberry Pi.

> This does have a UART, but I think I'll only have TXD and RXD with the USB<->
> 3.3v serial adapter that I'm using. Though the board does also have GPIO
> pins, which I'm hoping I could somehow use for the PPS with GPS, or with the
> Symtrik. 

You will get much better results if you can get a timestamp from the PPS 
signal.

I think Linux has code to get the PPS from a printer port.  You might be able 
to use that as a starting point for code that works from a GPIO pin.


-- 
These are my opinions, not necessarily my employer's.  I hate spam.