[time-nuts] NEO-M8N vs. NEO-M8T

Peter Vince petervince1952 at gmail.com
Mon May 21 17:08:14 EDT 2018


On 21 May 2018 at 21:24, Mark Sims wrote:
>
> One thing to look out for when messing with sawtooth messages is the
question of does the message come
> out before or after the PPS pulse...  good look finding the answer in the
receiver documentation...
>
> "After" seems to be the most common answer.  That makes hardware/delay
line compensation rather tricky.
> Sometimes you can use the antenna cable delay / pps offset commands to
shift the pulse before the true
> position (assuming that they support negative offsets) and use a longer
delay line to add the tweak back in.


In the protocol specification for the Furuno GT-87
( from, for example:
https://www.marutsu.co.jp/contents/shop/marutsu/ds/GT-87ProtocolSpecifications.pdf
)
the sawtooth correction figure is given in the CRX message, at the top of
page 30 of that document says the figure given refers to the second before
last (t-1) !

     Peter



More information about the time-nuts mailing list