Odd GPS problem

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Barberp

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We have a Raymarine RL80C which used a Raymarine Seatalk GPS for the last few years with no issues. During the pandemic the date from the GPS became fixed at 2002 although the fix was still correct and stable. This date issue was confirmed by viewing the data received on the hidden diagnostic menu (chart menu hold down ENTER key) - the date was incorrect from the GPS. I recently installed a brand new NMEA GPS in place of the old, but connected to the NMEA 1 input of the plotter. This provides the correct date and location, again the data can be viewed from the diagnostic menu and is correct and stable, refreshed every few seconds. However, every now and then ( around a minute or so but not consistent) the plotter displays LOST FIX and beeps, this is only for a few seconds then the message disappears and all is well. If I could turn off the alarm it would help as the fix displayed is always correct but I cant (although I would prefer to sort the issue). Any ideas ?
 
I’ve also got an RL80C and have suffered from intermittent LOST FIX issues (I never found a way to stop the alarm beeping)
I’m still using the Seatalk GPS and I found that it’s internal battery needed to be replaced - when I did that the LOST FIX issues went away (I wonder if your date issue may have been a depleted battery ?)
I presume the RL80C has a timer that looks for a fresh GPS update and goes into an alarm condition if it senses that it has not been received after X number of seconds.
I do have a suggestion - Is it possible to increase the baud rate of the transmission from the NMEA GPS to the RL80C ? (Obviously need to do that at both the transmitting and receiving end). I not at all sure this is the solution, but it might just be enough to avoid the RL80C going into an alarm state.
Hope this helps.
 
I would try changing the baud rate but it appears the rl80c only accepts 4800, unless I have missed a menu option. I believe the date and time should be acquired from the gps signal rather than an internal clock but have changed the battery previously when it took too long to acquire a fix. For many years its heen totally reliable, thanks for reply though, running out of ideas now....
 
Hello and welcome.

When did you last update the firmware of the RL80C?

I had the same date issue with my Garmin GPSMap 750 this summer all fixed once I installed the firmware update.
 
Unfortunately these units are so old that updates are no longer even listed let alone available. Annoying since it all worked with the old gps other than the date.
 
Are you sure that you have disabled the original GPS? I used to get lost fix from time to time on my Raymarine A95 plotter when it also had an input from another GPS. The lost fix alert is triggered by several seconds of no fix, so baud rate shouldn't be relevant (message taking around 30 milliseconds to transmit rather than 15 doesn't seem critical to me). But time offsets between two GPS sources could very well trigger it.
 
Yes original definitely disabled (in bin). As an update I think we have cracked it. The old Raymarine choc block had seatalk connections that were disturbed during removal of the old, I have remade all the connections and no alarm for several hours. Fingers crossed....
Thanks for all replies, always useful.
 
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