[ntp:questions] YEA! My Sure Electronics GPS just arrived.
unruh at invalid.ca
Fri Mar 23 23:39:02 UTC 2012
Sorry, just realised what you meant by "programming"-- change in baud
rate, sentence delivery, etc. I use the default ( and use the PPS from
the Sure for the actual timing via either the serial port (with
pps_ldisc on linux) or with the parallel port and a special program I
wrote to handle the parallel interrupt (mostly stolen from Linux Device
Drivers by Rubini and Corbet)
So I have no idea whether it retains the new baud rate, etc or for how
On 2012-03-23, unruh <unruh at invalid.ca> wrote:
> On 2012-03-23, Ron Frazier (NTP) <timekeepingntplist at c3energy.com> wrote:
>> Hi all,
>> YEA! My Sure Electronics GPS just arrived. I ordered on 03/05/12 and
>> it arrived on 03/23/12, so it took 18 days.
> Yes, you pay for the cheapness by slowness. Note that you want to keep
> eyes on the antenna. If you find your sure blue light stop flashing you
> probably have a defective antenna.
>> My configuration is:
>> GPS USB port --> PC 2nd USB port - for power only
>> GPS serial port --> Trendnet TU-S9 (Prolific based) serial - USB adapter
>> --> PC 1st USB port (same as I had the BU-353 on)
>> GPS antenna port --> included antenna
>> Using Terje's NMEA-MTK program, I sent the commands to the unit to
>> engage WAAS, send only GPGGA, and change the baud rate to 57600 as follows.
>> You can get help from the program as follows:
>> nmea-mtk /?
>> The board was already at 9600 baud transmitting several sentences.
>> I sent this command to enable WAAS and set for GPGGA sentences only (the
>> default action):
>> nmea-mtk -p \\.\COM5
>> I verified that it's working with SirfDemo. This is OK as long as I
>> don't send any commands from SirfDemo and use it for display only. I
>> set the SirfDemo data source for COM5 at 9600 baud, connected to the
>> GPS, and observed the NMEA data sentences. Then I disconnected SirfDemo.
>> I sent this to change baud rate to 57600:
>> nmea-mtk -p \\.\COM5 -c PMTK251,57600
>> I verified that it's working with this command. Now I have to send the
>> new baud rate in the command so nmea-mtk will read the port and match
>> the baud rate of the GPS. This reads out NMEA data for 10 seconds.
>> nmea-mtk -p \\.\COM5 -b 57600 -t 10
>> I also verified that it's working with SirfDemo after settings its baud
>> rate for the data source to 57600.
>> At the moment, I'm using NMEA only through the serial port of the GPS.
>> I haven't tried NMEA through the GPS's USB port, but I assume it would
>> be similar, since, either way, I'm going though a serial - USB
> Why would you do that when the Sure board already sends USB nmea data on
> the usb port.
>> converter. The Sure board uses a CP2102 usb to uart chipset, whatever
>> that is, but I never loaded the driver for it. Since my external TU-s9
>> adapter uses the same Prolific driver that the BU-353 GPS did, I'm just
>> using that. I am currently testing in Windows.
>> Preliminary graphs indicate I'm getting a variance of + / - 25 ms from
>> my PC's clock to the GPS polling it every 8 sec. That's a bit
>> disappointing, since I was getting + / - 10 ms from the BU-353 going
>> through it's internal serial - USB converter. I'm going to monitor it
>> for about a week and see how stable it is relative to the internet
>> servers. Also, I'm hoping it doesn't have periodic heart attacks like
>> the BU-353 did. I am testing indoors, as before.
>> I have a question for someone with experience with the board. If I
>> unplug the board, will it retain it's programming, or will it lose it?
>> If it retains it, how long will it keep the data? If it loses it, how
>> can I prevent that?
> It keeps its programming forever. It keeps its current solution for I
> think about an hour using the onboard capacitor. But it does not take
> very long to aquire a new solution and start delivering the time to far
> higher accuracy than you need (something like a couple of minutes)
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