GPS Time Signal Error

Good explanation continuouswave. Maybe I could have saved myself a lot of time, trouble and worry by simply waiting till next April. So far, I have tried every re-set and adjustment possible and have now updated the software on my HDS unit, which now has somehow resulted in the failure of my Navionics Platinum plus SC card!
 
I have two Lowrance combos in the cockpit; either can send data to a depth/position logger by NMEA 0183. One is an ELITE 4 DSI about 7 years old and the other a Hook 5 Chirp about 2 years old. They both transmit nonsensical dates and times. Today the date is sent as 21-02-2056 on both the Hook 5 and the Elite 4 so the software bug is common to both. The date on my very old portable Garmin GPS is perfect.
 
bcoulter said:
I have two Lowrance combos... the software bug is common to both.
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You'd be better off if you would apply the firmware patch made available by LOWRANCE instead of posting comparisons to other brands.

You should be able to locate the specific firmware update patch from the Lowrance website at

https://downloads.lowrance.com

The patch will remedy the problem you are experiencing.

The problem is in the actual GPS receiver chip, not in the Lowrance chart plotter. The patch is skillfully designed to communicate with the embedded GPS chip and alter its behavior. This problem affects many devices which happen to use the OEM chip and that series of GPS chip. It is not particularly specific to Lowrance.

By examining the shell script that is contained in the updater patch, it looks like the target GPS chips are the STM Teseo chips and possibly certain SiRF chips. These chip makers did not properly handle the GPS Week Epoch numbering.

I think NAVICO (Lowrance parent company) has done a good job in fixing the chip maker's problem. The STM Teseo chips are probably in thousands of products using GPS.
 
Thank you continuouswave, your reply was very informative. I have now installed an update in the Hook 5 and it works fine. I will try the latest update with the Elite but I believe it does not contain the required fix.

However, you did not need to chide me for saying that my Garmin portable GPS gave the correct time; that was merely evidence that there was a problem and that it appeared to be within the Lowrance units. It was not intended to be a comparison of manufacturers.
 
sarabande said:
Ha ! exactly the same problem that gave beneficial employment to thousands of Y2K contractors and consultants in the late 1990s :)
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Yeah, I got the best part of three years well paid contract work doing Y2K work, as did thousands of others. I do get annoyed though, by people who should know better writing newspaper articles saying that "the millennium bug" was a false alarm. No, it was real. We sorted it though.
 
continuouswave said:
I think NAVICO (Lowrance parent company) has done a good job in fixing the chip maker's problem. The STM Teseo chips are probably in thousands of products using GPS.
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Hmm. I agree that its good that they have release patches, however the patch for my HDS Gen 2 Touch is 134MB !! I'm glad I'm not trying to do this over a satellite link! And the patch actually fails to work as well. My unit didn't upgrade at all - not sure what I'm doing wrong. SD card, formatted exfat, with the 'Legacy GPS patch' image on it....

Edit: I did manage to get it to accept the update by reformatting the SD Card as vfat (rather than exfat). Date is now correct.
 
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rickp said:
...the patch for my HDS Gen 2 Touch is 134MB...
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That does seem very large. Perhaps NAVICO rolled up several changes into one big patch. I can't imagine it took that much code to change the GPS chip handling of the GPS week number.

Also, the real "Y2K" date will be in April 2019, when the GPS week number rolls over to zero. That may break more devices. The week rollover occurs about every 20-years, so for many devices this will be the first time they've experienced this event.
 
continuouswave said:
That does seem very large. Perhaps NAVICO rolled up several changes into one big patch.
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Or more likely just replaced one whole module with a new version. Like issuing a new chart instead of publishing a correction. When data is cheap, it's easier and more reliable that way.

Pete
 
For those Lowrance HDS Gen2 users who applied the Feb 2019 patch against the 21/12/18 GPS week 999-1000 rollover bug,
your unit may well have died again from the April 6th 2019 week 1023-0000 rollover bug - no GPS position. Mine died.

No fix from Lowrance yet, and the Feb2019 patch has been removed from their website.
You can sign up for a notification when a fix is available.

The firmware currently available on downloads.lowrance.com 4.0-45.2.200-Standard-1 will give you back your GPS position, but you will still have no date/time (so your tide information s and NMEA0183-connected DSC equipment will not work)

Better than no position though!

A workaround is to install NMEA2k external GPS antenna, or ditch your Lowrance gear - take this opportunity to see which manufacturers either fix the bug in a more timely manner than Lowrance, or have the hindsight/good fortune to pick a GPS chipset that is not prone to such errors.
 
a7southwest said:
For those Lowrance HDS Gen2 users who applied the Feb 2019 patch against the 21/12/18 GPS week 999-1000 rollover bug,
your unit may well have died again from the April 6th 2019 week 1023-0000 rollover bug - no GPS position. Mine died.
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Interesting, as I did apply the Feb 2019 patch to my HDS Touch Gen 2, and mine is still working. Attached are a screenshots showing version info and satellite reception.

shot017.pngshot016.png
 
My gen2 not working after the February patch. There is a new patch released yesterday hopefully that will fix things. They did say before the rollover date that the gen 2 had been tested and would work so I'm not impressed.

Martin
 
continuouswave said:
...it looks like the target GPS chips are the STM Teseo chips and possibly certain SiRF chips. These chip makers did not properly handle the GPS Week Epoch numbering.
Click to expand...

I can't speak for STM, but why do you believe that SiRF chips don't handle the epoch numbering? I assume you must mean SiRFStar 2, ie prior to 2004.

My pre 2004 RayNav300 uses SiRF chips and there have been no problems with it due to GPS roll-overs. The internal CPU is an ARM7-TDMI, a 32 bit machine, so it would be a strange piece of coding to limit anything to only 3 decimal digits as it wouldn't save any memory. Not that the internal calculations are done in base 10 anyway. The standard ARM floating point library representation is compliant with IEEE 754 in which case it can represent values up to about 3.4 × 1038 although the SiRF chips prior to 2004 used a hand-crafted version. But even here, week number would be represented as an unsigned integer of at least 16 bits (and so not roll over at 999).
 
My HDS 5 Gen 2 also lost the date. I had installed the 'gps fix' software update about 3 weeks ago and subsequently, the unit was ultra slow to locate satellites and then would not lock on. I reverted to the previous software which resolved the satellite lock but date is now wrong. Lowrance have updated software pending for this and a few other models. Looks like they are working through various models.
https://www.lowrance.com/news-videos/gps-week-rollover/

Jeff
 
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