[time-nuts] NMEA time off
jgray at zianet.com
Thu Mar 3 19:02:05 UTC 2011
Using a real PC serial port which sets DTR, you just need to send the
string ASTRAL to the Tripmate. Then it will start sending NMEA data to
For a mod which takes care of DTR and feeds ASTRAL back to selfstart
the Tripmate, look here:
http://www.nwaprs.info/delormetinytrackproject.htm. This method causes
the Tripmate to stay powered up all the time, so you should not use
the battery pack.
On Thu, Mar 3, 2011 at 11:33 AM, Tom Holmes <tholmes at woh.rr.com> wrote:
> Any tips on how you set it up to get those messages?
> Tom Holmes, N8ZM
> Tipp City, OH
>> -----Original Message-----
>> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
>> Behalf Of Joseph Gray
>> Sent: Thursday, March 03, 2011 4:07 AM
>> To: time-nuts at febo.com
>> Subject: [time-nuts] NMEA time off
>> Months ago a bought an old Delorme Tripmate for $5 (for that price,
>> why not?). Tonight I finally got around to fooling with it. After
>> finding out that it was designed to talk only to Delorme software
>> without some finagling, I got it to spit out NMEA data to Teraterm and
>> other programs.
>> I discovered two things about the Tripmate. First, the sensitivity
>> sucks indoors. It is currently showing 13 satellites visible, but only
>> tracking three. Second, the time data from the GPRMC sentence is about
>> two seconds behind UTC (using my calibrated eyeball for measuring).
>> Is the time delay simply due to a firmware error, a low priority
>> processing and outputting the NMEA data, or something else?
>> I was going to attach the Tripmate to a modified Linksys WRT54G WiFi
>> router and make it an el-cheapo NTP server. No reason, other than just
>> for fun. Even without the two second delay, I know that the WRT54G
>> will not be a very accurate NTP server. I was assuming that I'd be
>> able to at least get better than one second accuracy, though. I guess
>> I can just put in a large fudge factor for ntpd to compensate.
>> Unrelated to the above, I also have a Timex Ironman runner's watch
>> with mating GPS unit (another $5 purchase). The GPS is worn on the arm
>> and transmits data to the watch for displaying distance, speed, etc. I
>> need to get a battery for the watch, but I believe everything works.
>> Taking the GPS unit apart, I find that it is a Garmin. I see some
>> interesting test points on the circuit board, so I'm going to see if I
>> can get some serial data directly from the GPS, without using the
>> Joe Gray
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