[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[gpsd-users] Trouble Receiving Time from Delorme EarthMate USB (LT-20)
From: |
Jeff Morris |
Subject: |
[gpsd-users] Trouble Receiving Time from Delorme EarthMate USB (LT-20) |
Date: |
Wed, 13 Mar 2019 08:47:20 -0700 |
User-agent: |
Mozilla/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 |
Hi all,
I recently came across a Delorme EarthMate USB (LT-20) at a thrift shop
for a couple of bucks, and picked it up with the hope of being able to
use it as an NTP stratum-0 time source for an NTP server on my home network.
I've managed to get gpsd installed and running, and it sees the
EarthMate. The EarthMate acquires satellites and gets a fix and shows my
correct position, so it seems to be working properly. However gpsd is
reporting a date from the EarthMate far in the future. For example for
today, 2019-03-13, it's reporting the date as 2099-07-28. The time is
correct, but the date is way off. If I look at the raw time in
seconds-since-the-epoch format, I see numbers like 134439.000. (These
numbers are both from the output of gpsmon.)
I'm also having no luck getting ntpd to receive messages from gpsd. I've
added the following lines to /etc/ntp.conf (and removed all other servers):
server 127.127.28.0 minpoll 4 maxpoll 4 prefer
fudge 127.127.28.0 time1 0.0 refid GPS
However, ntpq -p reports that it has never successfully polled this source:
remote refid st t when poll reach delay offset
jitter
==============================================================================
SHM(0) .GPS. 0 l - 16 0 0.000 0.000 0.000
I'm aware of the GPS week rollover issue, and given that this is an old
receiver that I picked up at a thrift shop it may very well be
susceptible to that. However, the numbers I'm seeing don't make any
sense to me. The 10-bit week rollover issue should result in a rollover
every 20 years? The date I'm seeing is 80 years in the future however,
and the seconds since epoch number works out to only a day and a half
(134439.000/60/60 = 37.34 hours), even though the next rollover isn't
due for a few more weeks.
Can someone explain these numbers I'm seeing, and does anyone have any
suggestions as to why ntpd isn't able to poll the gpsd time source?
Thanks in advance.
- [gpsd-users] Trouble Receiving Time from Delorme EarthMate USB (LT-20),
Jeff Morris <=