Two GPS systems fail - both at the same time

TwoHooter

TwoHooter

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We have 2 GPS systems - a Raymarine C80 Plotter and a Furuno GP33, each with its own aerial "mushroom". There is a Seatalk bus but I think it is restricted to connecting the Raymarine plotter and VHF. I think the Furuno is independent of everything else. Everything has been working well for weeks. It was all working when we left the boat 8 days ago.

Today when I switched the two GPSs on neither would get a fix and the VHF told me it didn't know where it is for the MOB/Distress button. The Raymarine and Furuno screens were live and the plotter's radar scannar worked, but no GPS fix on either of them. The Raymarine screen which should show the satellites had none showing and requests for a reboot got either no response or "Request Failed".

Suddenly, at the end of today's short passage, the Furuno got a fix and is now working. The Raymarine GPS diagnostic screen continues to either show no satellites or, when it does produce a list there is no status bar for any of them, and there is a blinking orange light on the Raymarine aerial mushroom head.

The Furuno has always worked perfectly since we got the boat; the Raymarine used to struggle to get a fix but this was solved by a Raymarine engineer soldering a new battery into the aerial.

If the Raymarine had failed on its own I would have deduced that the aerial has failed again. But why would two independent systems exhibit the same failure mode at exactly the same time? And why would one of them come back by itself?

I have done the obvious things: checking for physical damage to the aerials (none); checking voltage (was 13v+, as I write it is 12.6); recycling power; withdrawing checking and replacing leads; and I have even read the manuals (no help there).

I have searched the forum to see if this has been dealt with before without success so here's hoping someone has some bright ideas.
 
T
TwoHooter said:
We have 2 GPS systems - a Raymarine C80 Plotter and a Furuno GP33, each with its own aerial "mushroom". There is a Seatalk bus but I think it is restricted to connecting the Raymarine plotter and VHF. I think the Furuno is independent of everything else. Everything has been working well for weeks. It was all working when we left the boat 8 days ago.
I
Today when I switched the two GPSs on neither would get a fix and the VHF told me it didn't know where it is for the MOB/Distress button. The Raymarine and Furuno screens were live and the plotter's radar scannar worked, but no GPS fix on either of them. The Raymarine screen which should show the satellites had none showing and requests for a reboot got either no response or "Request Failed".

Suddenly, at the end of today's short passage, the Furuno got a fix and is now working. The Raymarine GPS diagnostic screen continues to either show no satellites or, when it does produce a list there is no status bar for any of them, and there is a blinking orange light on the Raymarine aerial mushroom head.

The Furuno has always worked perfectly since we got the boat; the Raymarine used to struggle to get a fix but this was solved by a Raymarine engineer soldering a new battery into the aerial.

If the Raymarine had failed on its own I would have deduced that the aerial has failed again. But why would two independent systems exhibit the same failure mode at exactly the same time? And why would one of them come back by itself?

I have done the obvious things: checking for physical damage to the aerials (none); checking voltage (was 13v+, as I write it is 12.6); recycling power; withdrawing checking and replacing leads; and I have even read the manuals (no help there).

I have searched the forum to see if this has been dealt with before without success so here's hoping someone has some bright ideas.
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I don't suppose you were in th western Solent near or approaching Yarmouth or Lymington? My raymarine always looses its fix in that area every time. I've thought it's a time thing fault say 1 hour after switching on but it's not it's an area problem
 
my thoughts turn to a transient power surge perhaps when turning the engine on, or a EMF pulse from perhaps a nearby lightning strike or radiation source (radar >?). Are both aerials to a common earth point ?
 
Are the two mushrooms antennae or GPS engines? I mean are they computing GPS position within the mushroom, then sending it as nmea0183 signal to their respective "listener", being the raymarine and furuno boxes? Or are they antennae joined by coax with all the GPS position calculations done inside the Raymarine/Furuno box?

Actually I'd be 99.99% sure the Raymarine mushroom is an engine talking 0183, but I don't know about the furuno
 
Sorry to hear about your problems, have you considered the third set up, a hand held unit and plug it into the 12v socket
 
Were you close to a military area? Another forumite might also remember this but last year I bought a new (to us) boat and parked it in a marina in La Spezia in Italy. One day we went to our boat and I switched on the plotter to do some passage planning. The plotter is driven by either of 2 independent GPS aerials (I believe GPS 'engine' is the right terminology). On this occasion, neither GPS provided a fix and like you I checked all the wiring and connections and rebooted everything several times but still neither GPS got a fix. I was completely flummoxed and phoned the dealer who had supplied the boat for advice. He told me that there were rumours that GPS signals were being affected by the activities of the nearby naval base and advised me to take the boat out to sea to check. So the following day, we took the boat out of the harbour, motored about a mile out to sea and both GPS aerials suddenly started to get a fix. I don't know for sure whether the activities of the naval base were jamming GPS signals to my boat and nor how it was being done. All I know is that it happened to me once and then again a few weeks later. We have since left La Spezia so I can't confirm whether it is a regular event there
 
volvopaul said:
I don't suppose you were in the western Solent .... it's an area problem
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We were in the River Orwell today

sarabande said:
my thoughts turn to a transient power surge perhaps when turning the engine on, or a EMF pulse from perhaps a nearby lightning strike or radiation source (radar >?). Are both aerials to a common earth point ?
Click to expand...
Coming from an aviation background I am usually careful about turning navigation kit off before starting engines but today I didn't so perhaps that was it - a transient power surge. No lightning here today but we have been away 8 days. Earth: don't know; will have to look at that.

jfm said:
Are the two mushrooms antennae or GPS engines? I mean are they computing GPS position within the mushroom, then sending it as nmea0183 signal to their respective "listener", being the raymarine and furuno boxes? Or are they antennae joined by coax with all the GPS position calculations done inside the Raymarine/Furuno box? Actually I'd be 99.99% sure the Raymarine mushroom is an engine talking 0183, but I don't know about the furuno
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Sorry, I don't know and I don't think that's in the manuals

Red said:
Sorry to hear about your problems, have you considered the third set up, a hand held unit and plug it into the 12v socket
Click to expand...
Yes, soon as I can I'm going to get a Tablet. All I have at the moment is my mobile phone, not very reliable.

Deleted User said:
Were you close to a military area? Another forumite might also remember this but last year I bought a new (to us) boat and parked it in a marina in La Spezia in Italy. One day we went to our boat and I switched on the plotter to do some passage planning. The plotter is driven by either of 2 independent GPS aerials (I believe GPS 'engine' is the right terminology). On this occasion, neither GPS provided a fix and like you I checked all the wiring and connections and rebooted everything several times but still neither GPS got a fix. I was completely flummoxed and phoned the dealer who had supplied the boat for advice. He told me that there were rumours that GPS signals were being affected by the activities of the nearby naval base and advised me to take the boat out to sea to check. So the following day, we took the boat out of the harbour, motored about a mile out to sea and both GPS aerials suddenly started to get a fix. I don't know for sure whether the activities of the naval base were jamming GPS signals to my boat and nor how it was being done. All I know is that it happened to me once and then again a few weeks later. We have since left La Spezia so I can't confirm whether it is a regular event there
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As mentioned we have been in the River Orwell today, from Ipswich to Shotley. Don't know of any military activity.

And, as I write, my wife remarks, "Oh look, it's shifted". What she means is the Plotter has got a fix and is working again.

Don't you absolutely hate transient faults?

I am tremendously grateful for all the advice. Somehow it just feels better knowing there are people willing to help with things like this.
 
I think it is critical to find out whether the signal generally isn't there or you have a fault. When they lose fix can you try every other gps device you possses like phones and ipads and see what they do?

Are you at the Neptune marina end? Tap on the door of Fairline and ask Martyn (the boss) or Dean or Ben whether they have had any GPS drop outs. They drive up/down Orwell most days of the week, testing new Fairlines. They're nice/helpful guys

I don't know where you're berthed but remember GPS jammers are cheap - £50 ish. http://www.theguardian.com/technology/2013/feb/13/gps-jammers-uk-roads-risks You haven't got an annoying prankster nearby have you? Or taxi driver/other who parks close by and uses it for questionable reasons. (Cell phone jammers are similarly cheap and I've lost count of the times I wish I had on trains with a loud person in the carriage!). If you're in Neptune there will be plenty of people/cars close to you, in range of one of these things. I mean, have you found the problem ends if you move your boat a mile away? Ignore this para of course if the no fix held all the way from Ipswich town to Shotley

Just on wiring, I think you'll find the Ray mushroom is on the same seatalk bus as the VHF and any other Seatalk devices. Seatalk is NMEA0183 as annoyingly tweaked by Ramarine
 
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jfm said:
I think it is critical to find out whether the signal generally isn't there or you have a fault. When they lose fix can you try every other gps device you possses like phones and ipads and see what they do? Are you at the Neptune marina end? Tap on the door of Fairline and ask Martyn (the boss) or Dean or Ben whether they have had any GPS drop outs. They drive up/down Orwell most days of the week, testing new Fairlines. They're nice/helpful guys I don't know where you're berthed but remember GPS jammers are cheap - £50 ish. http://www.theguardian.com/technology/2013/feb/13/gps-jammers-uk-roads-risks You haven't got an annoying prankster nearby have you? Or taxi driver/other who parks close by and uses it for questionable reasons. (Cell phone jammers are similarly cheap and I've lost count of the times I wish I had on trains with a loud person in the carriage!). If you're in Neptune there will be plenty of people/cars close to you, in range of one of these things. I mean, have you found the problem ends if you move your boat a mile away? Ignore this para of course if the no fix held all the way from Ipswich town to Shotley Just on wiring, I think you'll find the Ray mushroom is on the same seatalk bus as the VHF and any other Seatalk devices. Seatalk is NMEA0183 as annoyingly tweaked by Ramarine
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We were in Fox's Marina when we joined the boat after lunch. No fix all the way down to Shotley. Didn't think of trying my phone GPS as a test. Duh. Leaving tomorrow for an attempt at Snape. I am sitting here doing a very detailed paper chart passage plan! Which, of course, I would do anyway....
 
volvopaul said:
T

I don't suppose you were in th western Solent near or approaching Yarmouth or Lymington? My raymarine always looses its fix in that area every time. I've thought it's a time thing fault say 1 hour after switching on but it's not it's an area problem
Click to expand...

Have had that same problem there and once when in needles Chanel
 
Apart from the length of time taken to get a fix again the symptoms are exactly what I've when a power problem (either completely dead battery or a power surge) has wiped the slate and the almanac has been lost. Wiki reckons that's no longer an issue but either I've come across some old kit in fairly newish covers or it's not as solved as they reckon. I've certainly seen it take hours to get a fix and had an old handheld that could take all day - it's worse if you have poor satellite visibility too.
 
TwoHooter said:
Sorry, I don't know and I don't think that's in the manuals
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Just as a FYI, Furuno used to make both a passive antenna and a NMEA mushroom.
By looking at the rear of your GP33 unit (see below), if its cable is attached to the "ANT" connector it's the first, while the "NMEA" connector is for the latter.
On the matter of possibly scrambled signals, nowadays it's normally easy to double check that, with just about any mobile phone...
GP33-LG8.jpg
 
Sorry for lack of response - could not get a working connection yesterday. I tried until late at night - kept dropping out.

MapisM: Thanks for the picture. Reading from left to right on the picture our connections are:
Ground: Yes
NMEA2000/Canbus data: Yes
NMEA 0183 data: No
GPS Antenna: Yes
Therefore if I understand it correctly (there's a first time for everything) it's a passive antenna.

Yesterday morning I started the engine first, then fired up the GPSs, and both got fixes straight away and worked flawlessly all day.

I think the original sequence of events was a bit different to what I said originally. I recall trying the GPSs before starting the engine and they didn't get a fix. I left them on when I started the engine and as described they didn't get a fix all day.

One possibility is that they were taking time to get a fix, which does sometimes happen, and there was a voltage spike when I started the engine which messed them up completely for 24 hours.

I can't do any proper checks here and we are going walking today. When we get back to a marina I'll run some checks.
 
I am now pretty confident that neither GPS aerial will work if the voltage is low. I haven't yet established what the cut-off point is but I now have a new "intelligent" battery charger and I am making sure that the batteries are fully charged before I turn the two GPS units on. The other cause of the problem may have been a voltage spike, as suggested above, because I had the two units running before I started the engine. I have been keeping the charge up, and starting the units after starting the engine, and have had no further problems.

Thanks again to everyone who offered ideas.
 
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