[time-nuts] GPS for ntp

Brian Inglis Brian.Inglis at SystematicSw.ab.ca
Wed Oct 22 09:15:36 EDT 2014


On 2014-10-20 19:39, Joseph Gray wrote:
> What does everyone think of this GPS module for ntp use? According to the
> specsheet, it uses a Ublox Neo-7N.
>
> http://www.ebay.com/itm/RY725AI-10Hz-UART-USB-interface-GPS-Glonass-QZSS-antenna-module-flash-memory-/181562403752

> Does anyone want to take a wild guess as to the best/worst case UTC offset
> I might get with such a setup? I realize that I'd have to try it to really
> find out, but guesses and advice from those more knowledgeable is always
> appreciated.

RYN25AI and RYN25DI actually use a MAX-7C (Crystal), with no RTC, designed for
low cost, low power, a passive antenna, and for the AI, a USB interface.
The USB interface will give you unpredictable timing and you still have to hook
up the PPS output somehow, so can only really be recommended for navigation uses.
http://www.ebay.com/itm/RYN25DI-10Hz-RS232-interface-high-performance-GPS-Glonass-antenna-module-battery-/181553452840?pt=LH_DefaultDomain_0&hash=item2a456dd728
The DI has an RS-232 interface so you can at least hook that up with the PPS on
DCD to the BB UART and get less jittery results, which will vary with temperature,
as it uses only a regular crystal oscillator.
-- 
Take care. Thanks, Brian Inglis



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