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

Ron Frazier (NTP) timekeepingntplist at c3energy.com
Fri Mar 23 21:08:34 UTC 2012

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.

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 
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?




(PS - If you email me and don't get a quick response, don't be concerned.
I get about 300 emails per day from alternate energy mailing lists and
such.  I don't always see new messages very quickly.  If you need a
reply and have not heard from me in 1 - 2 weeks, send your message again.)

Ron Frazier
timekeepingdude AT c3energy.com

More information about the questions mailing list