Garmin 18 Configuration Issue
A couple of people in 2007 reported that their GPS 18 was not working correctly. The symptoms were that KIWI OSD would continually display "RS232 OR 1PPS ABSENT" and the LED in the OSD box would not flash once per second.
The users were able to restore their time inserter operation by reloading the required GPS18 configuration using the SNSRCFG software. I was puzzled as to what may have happened - was it static electricity or a power glitch of some sort that had changed the GPS configuration?
On making a casual check on the Garmin web-site in January 2008, I noted that Garmin (in October 2007) brought out a new version of the software for the GPS 18 (version 3.20) that allows:
"Improved reliability of non-volatile memory management."
The non volatile memory is where the "configuration" is stored, perhaps this explains the problem mentioned above (where the config was lost, and so the 1PPS was not enabled).
Because the Garmin GPS software can be upgraded by the user - this page contains some brief notes on how to upgrade the software on the GPS 18 module.
Please NOTE:
Only do this upgrade if you are "confident" about connecting the serial cable from the KIWI OSD box to a computer (that has a serial port) and running the Garmin software to perform the upgrade.
It would appear that this (loss of GPS configuration) issue is not common, so for someone not too keen to change the software in their GPS18, it may be best NOT to attempt the following. If instructions are not followed "exactly", one could end up with an inoperative GPS.
Some may wish to update using the WebUpdater software.
Because I prefer to test what I'm doing - I updated using the older manual method:
NOTES:
After updating both of my Garmin 18's ( to version 3.20 ) I found that KIWI OSD worked as per normal, there was no need to reload the configuration to the GPS module.
The version displayed by KIWI OSD on the TV monitor (V3) - applies to the software code in the KIWI OSD computer - NOT the GPS software version.
If you purchased your Garmin 18 prior to 2008 (mine are 3 years old) then the GPS will probably have a software version number lower (older) than 3.20
Handy Hint for technical folk: While you have SNSRCFG running and connected to KIWI OSD, you may want to "enable" the sentence PGRMT, this sentence is transmitted once per MINUTE (not once per second like other sentences) from the GPS. Mine currently shows (using the VIEW command and "NMEA Transmitted Sentences" command in SNSRCFG):
$PGRMT,GPS 18LVC - software ver. 3.20,P,P,R,R,P,,29,R*3F
We can see that my GPS is now running version 3.20. The other interesting data is near the end of the sentence, which gives the temperature of the "core" of the GPS, where we can see the temperature is 29 Degrees C. This is 9 degrees above the current ambient room temperature, which (using a normal thermometer) is currently 20.3 degrees C.
To find the full definition of the PGRMT sentence, please refer to the GPS 18 Technical Specification.
Only the sentences GPGGA, GPRMC ( and optionally PGRMT ) should be enabled for reliable KIWI OSD video time insertion.
I have been running tests for 3 years now on the GPS 18 and found it to be a very reliable sensor for generating accurate time. I have not had any problems myself with configuration being lost, however it is nice to have a "software fix" to make a nice GPS even better!
Enjoy ;-)
Regards, Kiwi Geoff (New Zealand, January 2008)