AIS connected to "hot battery bus" - why?

[Sandy]

Sandy, I just had a quick look at your GX1700 manual online. Perhaps when it's next acquired it's position, go into the GPS status page (page 20 of the manual linked below) and see how many satellites it can see.

From the same page, it looks like your early device doesn't contain a lookup table as it says "When the GX1700 is first turned on, it may take several minutes to compute a fix of your position. This is normal as the GX1700 is downloading 'alamanac' information from the GPS satellites".

https://standardhorizon.co.uk/wp-content/uploads/2019/08/GX1600_GX1700_OM_USA_EM048N161_5292013.pdf

The boat is ashore at the moment, when I'm next down I'll turn it on with stop watch in hand.

 

[Plum]

The VHF has never been 'quick' and I am sure it is because it is by the nav station.

I think Vespa have been taken over by Garmin and the model is discontinued, while I've had fantastic service from Vespa in the past it is not the end of the world if it takes time to build its tables.

As I said I'm not that fussed as I've got an easy fix as I do need to keep the Navtex powered up and it is just a matter of moving a wire a maximum of 20 mm.

I have a SR GX1700 and although I have never timed it I would be very surprised if it ever took more than 30 seconds to get a gps fix

 

[wonkywinch]

No need to time it that accurately Sandy, it's going to be the number of satellites it can see when it's running, that will give a big clue as to how good it can see the sky from the front panel where it's internal antenna is located. The number and strength is going to be a huge clue to the initialisation delay.

 

[PaulRainbow]

Sandy, I just had a quick look at your GX1700 manual online. Perhaps when it's next acquired it's position, go into the GPS status page (page 20 of the manual linked below) and see how many satellites it can see.

From the same page, it looks like your early device doesn't contain a lookup table as it says "When the GX1700 is first turned on, it may take several minutes to compute a fix of your position. This is normal as the GX1700 is downloading 'alamanac' information from the GPS satellites".

https://standardhorizon.co.uk/wp-content/uploads/2019/08/GX1600_GX1700_OM_USA_EM048N161_5292013.pdf

First time refers to the first time out of the box, not each time you turn it on, from "cold" it should be about 1 min after that.

 

[wonkywinch]

First time refers to the first time out of the box, not each time you turn it on, from "cold" it should be about 1 min after that.

My money is on a dead button cell inside the box or insufficient view of the sky from the installed location inside Sandy's boat.

 

[PaulRainbow]

My money is on a dead button cell inside the box or insufficient view of the sky from the installed location inside Sandy's boat.

I'm not aware of a replaceable battery in the VHF (not impossible though), so you may be correct that Sandy starts off in a poor reception area, which he did say very early on. Looking at the satellite page, as you say, might give a clue. The fact the AIS is also affected is a bit of a clue too.

 

[Refueler]

I am pretty sure that the reason that the initial fix is not instant is I use the internal antenna on both bits of kit,

Sandy ... I have various GPS gear inside the boat ... most sitting next to each other at nav station. They all perform normally. The only possible cause of slow lock-on - could be if there is various metal or Carbon Fibre items between the GPS antennae and the 'sky' ...

Many people do not realise that Carbon Fibre is a serious inhibitor of RF ... and it does not take much to cause problems.

 

[Sandy]

I'm not aware of a replaceable battery in the VHF (not impossible though), so you may be correct that Sandy starts off in a poor reception area, which he did say very early on. Looking at the satellite page, as you say, might give a clue. The fact the AIS is also affected is a bit of a clue too.

Yip, no button battery in the VHF or AIS.

 

[Caladh]

I really don't have an issue with the '20 min syndrome' as I have a solution. I am pretty sure that the reason that the initial fix is not instant is I use the internal antenna on both bits of kit, as I said in a previous post I am not a fan of loads of antenna doing their best to make the boat look like a hedgehog and get in the way. You will have seen the amount of ironwork, some of Mr Brunel's finest, that is just to to the north of the mooring in post #31 that 'might' have an impact on getting a good initial fix and as Plymouth is a military port who knows what they might be doing with electronic countermeasures at anytime? If I was concerned I'd make a brew before setting off, it is just nice to know what big stuff is moving about, especially if it is military and avoid the 'men in black' asking you nicely, but firmly to move out of the way.

My ancient Garmin chart plotter is situated in the cockpit and gets a fix by the time I get back to the wheel from letting go of the mooring lines- it is not as if I struggle navigating my way down the Tamar out to Plymouth Sound as I still use things like charts, 2B pencils, a Breton plotter and an eraser.

The kit works once an initial fix has been acquired. On trips nether is switched off as it allows family and friends to either know where I am, or more pleasantly meet up for a beer. To date My longest longest passage was was six weeks and both worked flawlessly 24/7.

But for what it is worth:

• Standard Horizon GX1700E
• VespaMarine AIS Watchmate

Out of interest and ref the ironwork in your area of mooring, does the 20 mins syndrome show its self as an issue when you’re not on your regular mooring ?

 

[Sandy]

Out of interest and ref the ironwork in your area of mooring, does the 20 mins syndrome show its self as an issue when you’re not on your regular mooring ?

Really difficult to say as once I have switched it on I don't switch it off until I return to the mooring.

I use AIS as a way of letting my non-sailing family know where I am.

 

[Refueler]

Really difficult to say as once I have switched it on I don't switch it off until I return to the mooring.

I use AIS as a way of letting my non-sailing family know where I am.

Would be an interesting check to see if its gear / installation or location ...

 

[wonkywinch]

Really difficult to say as once I have switched it on I don't switch it off until I return to the mooring.

I use AIS as a way of letting my non-sailing family know where I am.

Checking the satellite signal level as mentioned above will be a good indicator of what's going on. If it's weak when you're in the open, it will be a local antenna problem (ie front face of device can't see enough sky). An external antenna would be an option to fix this and it can be mounted discreetly, perhaps even still inside the boat.

 

[Refueler]

Checking the satellite signal level as mentioned above will be a good indicator of what's going on. If it's weak when you're in the open, it will be a local antenna problem (ie front face of device can't see enough sky). An external antenna would be an option to fix this and it can be mounted discreetly, perhaps even still inside the boat.

Its not unknown for GRP to have CF or even metal in the layup ... this can easily interfere with signal reception.

For most people antena placed against 'window' sorts it ... my SR25 - the antena is just put behind curtain without any need for fixing.

My 38 - antena is just at nav table ...