Recommend me a GPS/Glonass Antenna

[Porthandbuoy]

Up until now I have been using a GPS Bluetooth puck providing position data to a netbook with OpenCPN and a USB/NMEA0183 adapter from Digital Yacht sending data to my DSC radio. Obviously that requires the netbook to be 'on' if the VHF is to know its position; not always what I wanted or required. This season I've changed the netbook from XP to Linux and am using QtVLM navigation software
Now I want an external, rail-mounted GPS/Glonass antenna with NMEA0183 output. There is a bewildering choice on chandleries, and other on-line outlets, with prices ranging from the sublime to the ridiculous with little apparent difference in spec.
So what to get?
I require NMEA0183 input to my Standard Horizon DSC VHF and I'll Tee that off to the netbook using the same USB/NMEA adapter.

 

[PaulRainbow]

Cheap one from Ebay or the like, if you stick it in a cupboard close to the deck, chances are it'll work fine, no need to mess around rail mounting and running wires through the boat. (assuming not a steel boat.)

 

[rogerthebodger]

I use a GPS mouse for my SH DSC VHF which has an RS232 output connected to the NMES 0183 input.

I also have a USB GPS mouse connected to my PC running OpenCPN.

Having a steel boat the mice need to be outside to gt best signal but alo being steel the magnet of the mice stich to the cabin just outside the companionway.

 

[TernVI]

If you're happy with the indoor aerial, can you not just provide the USB thing you have with 5V?

I think an outdoor aerial is the proper thing to do.
Ublox are probably the best GPS/Glonass modules IMHO, although it's a few years since I've designed any stuff with GPS in.
There are loads of Ublox -based modules out there.
You need to be sure the baud rate is compatible.

 

[prv]

If you're happy with the indoor aerial, can you not just provide the USB thing you have with 5V?

The OP’s “USB thing” is an external serial port. It’s nothing to do with GPS per se. His existing GPS receiver is a Bluetooth device which is no use for his VHF.

Paul has it right.

It’s true that “it seems to work” in good conditions isn’t proof of adequate installation. But for what it’s worth, I tried my new AIS transmitter’s GPS antenna both on deck and stuck to the underneath of the deck, while looking at the satellite signal strength graphs in its setup software, and the difference was negligible. That was a foam-cored fibreglass deck with a bucket of water poured over it before the inside test.

Pete

 

[Porthandbuoy]

The OP’s “USB thing” is an external serial port. It’s nothing to do with GPS per se. His existing GPS receiver is a Bluetooth device which is no use for his VHF.

Paul has it right.

It’s true that “it seems to work” in good conditions isn’t proof of adequate installation. But for what it’s worth, I tried my new AIS transmitter’s GPS antenna both on deck and stuck to the underneath of the deck, while looking at the satellite signal strength graphs in its setup software, and the difference was negligible. That was a foam-cored fibreglass deck with a bucket of water poured over it before the inside test.

Pete

I've checked the satellite signal graphs for both the Bluetooth puck and a usb receiver inside and outside the cabin. In both cases there a significantly weaker signal, and often fewer visible satellites, with the receivers inside. Ladybird was built in 1966, the deck is pretty thick GRP & ply and the windows triplex glass. I do admit the Bluetooth GPS puck is old and the usb one was very cheap.

 

[PaulRainbow]

I've checked the satellite signal graphs for both the Bluetooth puck and a usb receiver inside and outside the cabin. In both cases there a significantly weaker signal, and often fewer visible satellites, with the receivers inside. Ladybird was built in 1966, the deck is pretty thick GRP & ply and the windows triplex glass. I do admit the Bluetooth GPS puck is old and the usb one was very cheap.

But it isn't a proper comparison when they are two different devices.

 

[Porthandbuoy]

But it isn't a proper comparison when they are two different devices.

Slight misunderstanding here. Two devices, yes. Both tested inside and outside. Both show weaker signal and sometimes fewer satellites when inside. Both devices old, so probably not as sensitive as modern ones.

 

[PaulRainbow]

I think an outdoor aerial is the proper thing to do.

Almost every chart plotter made today has an internal GPS. Many AIS transducers have an internal GPS. When fitting AIS with separate antennas i have always fitted them below decks and every single one of them has worked flawlessly. My phone, tablet, laptop all have their own GPS and all work perfectly well below decks.

20 years ago it might have been "the proper thing to do", but GPS antennas/receivers have come a long way since then.

 

[rogerthebodger]

I've checked the satellite signal graphs for both the Bluetooth puck and a usb receiver inside and outside the cabin. In both cases there a significantly weaker signal, and often fewer visible satellites, with the receivers inside. Ladybird was built in 1966, the deck is pretty thick GRP & ply and the windows triplex glass. I do admit the Bluetooth GPS puck is old and the usb one was very cheap.

But it isn't a proper comparison when they are two different devices.

I interpreted that as checking both devices inside and outside so he was comparing like devices twice.

 

[PaulRainbow]

Slight misunderstanding here. Two devices, yes. Both tested inside and outside. Both show weaker signal and sometimes fewer satellites when inside. Both devices old, so probably not as sensitive as modern ones.

Ah, my mistake.

Modern ones are definitely better than they used to be. Some of the early plotters with built in GPS struggled on some boats.