[ntp:questions] YEA! My Sure Electronics GPS just arrived.

unruh unruh at invalid.ca
Fri Mar 23 23:31:20 UTC 2012

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)


> Sincerely,
> Ron

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