GPS/GLONASS/GALILEO/BAIDOU - How important?

MattS

MattS

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Looking at getting a new NMEA GPS antenna. There is variation between them in terms of which satellite networks they support. You can get a reasonably priced GPS antenna with 9-axis heading/pitch/roll sensor for the same price as another brands GPS only sensor, but you sacrifice support for newer networks like Galileo, Baidou etc.

How much does this actually matter? I guess there's the ultimate argument of "it depends how worried you are about relying on US / Russian satellites", but are there any more practical considerations that are likely to apply to a casual sailor like me?
 
How accurate do you feel you need to be?

My ancient Garmin handheld was accurate to within three metre at one of the published OS marker points.

If I am within 0.5 NM of an object Mark I eyeball takes over.
 
Sandy said:
How accurate do you feel you need to be?

My ancient Garmin handheld was accurate to within three metre at one of the published OS marker points.

If I am within 0.5 NM of an object Mark I eyeball takes over.
Click to expand...

I don't feel the need to be 0.5m accurate, I'm likely already damaging my topsides at that point....

Is that the key benefit of supporting more networks, then? Increased accuracy?
 
AntarcticPilot said:
I'd take lack of support for newer satellite segments as an indicator that the equipment was an old design, and obsolescent. I gather that all modern chip sets support every satellite segment, so anything designed in the last 5 or so years will support them all. My phone (at least 4 years old) supports all of them!
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Ok - thanks - interesting consideration. In that case there are quite a few out there utilising 5+ year old tech it seems!
 
Given that many of these 'other' systems are still being sorted and not full coverage ........... no it doesn't really make much difference.

Most GPS units use only one user set system anyway ... its your choice which to use ...

The reason for these other systems - basically a hangover from USA purposely degrading the accuracy for non military. Plus country's wanted independence from US control of GPS.
US GPS is basically the only one with actual near global coverage ..
Galileo - EU agreed to US demands that if US requests switch off .. Galileo will be switched off !!
Glonass - mmmm very good system - but does suffer from Russian adjustment of areas covered .... to aid their military ... Chechen war was good example when Glonass was refocused
Indian and Chinese systems are also good - but subject to location you are in.

AP says modern gear covers all .... sorry but not true. Most gear today covers 2 maybe 3 systems but not all. Plus most need user to decide which to use.
 
MattS said:
I don't feel the need to be 0.5m accurate, I'm likely already damaging my topsides at that point....

Is that the key benefit of supporting more networks, then? Increased accuracy?
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Regardless of claims by brands ... GPS accuracy is not as great as they claim.

You only need to sit in a marina and let plotter mark position over a few hours. That mark becomes more and more like a 'star snowflake' on the screen ... watch speed and course ... they are not zero ... but because of positional computation varying - speed and direction result.
 
RobbieW said:
That's listed as an NMEA0183 device, you'd need a converter to use it with an NMEA2000 installation
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I have a ShipModul NMEA multiplexer (which although very expensive, I highly recommend incidentally) which I can use to do this conversion when I eventually have some kit that actually uses NMEA2000!
 
RobbieW said:
That's listed as an NMEA0183 device, you'd need a converter to use it with an NMEA2000 installation
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Many 'hobby' GPS units are actually NMEA0183 ..... because Marine use is actually not majority market ..... there's a whole other world out there that uses 0183 for simply connecting GPS units to gear ...

Have a look at Belkin units ... very popular tiny multi channel GPS items ... not much bigger than a Thumbnail ...

Look at prices as well and what they can do ...
 
Refueler said:
Many 'hobby' GPS units are actually NMEA0183 ..... because Marine use is actually not majority market ..... there's a whole other world out there that uses 0183 for simply connecting GPS units to gear ...

Have a look at Belkin units ... very popular tiny multi channel GPS items ... not much bigger than a Thumbnail ...

Look at prices as well and what they can do ...
Click to expand...

Interesting thanks. Don't suppose you have any handy links to viable Belkin devices? Can't find anything that looks feasible on first look
 
If you have an iPad and I assume other tablets you already have pitch, roll, yaw and and an accelerometer and there are a number of Apps that use the data.

Try Scramp - established for marine safety.

Jonathan
 
Refueler said:
AP says modern gear covers all .... sorry but not true. Most gear today covers 2 maybe 3 systems but not all. Plus most need user to decide which to use.
Click to expand...
My understanding is that Russia and China require Glonass and Baidou support (respectively) on any GNSS being sold in their territory, and of course, Europe strongly encourages the use of Galileo. Given that the majority of chips are made in the Far East and marketed world-wide, I've always taken that to mean that modern chipsets will support all the networks. Of course, equipment built on these chipsets may not offer access to all, but I think the basic electronics can support all of them. As I say my phone, which is now an old model and which was not top of the range when I bought it supports all that I am aware of, and I am sure that it will use an industry-standard chip-set.

Of course, comments about the availability of networks are completely correct, and I bow to your superior knowledge when it comes to the implementation in marine devices - you've seen more of them than I have. But I think that the basic chip-set can support all or any of the satellite systems; this is borne out by your comment that the networks used are user selectable. For practical purposes, it doesn't matter, except that I'd still suggest that a device that only offered the US GPS system is based on very old electronics.

You've got me curious about user selection of satellite networks - I must poke around in the more obscure menus on my new recently installed chartplotter!
 
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Neeves said:
If you have an iPad and I assume other tablets you already have pitch, roll, yaw and and an accelerometer and there are a number of Apps that use the data.

Try Scramp - established for marine safety.

Jonathan
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I do have an iPad which I use for primary electronic navigation at the moment. I tend to either use its built-in GPS, or a Garmin bluetooth GPS dongle for that. Not heard of Scramp - will take a look! Truth be told, I don't particularly have a need for pitch and roll data... compass / heading would be of some use though.

The GPS sensor will initially be fed into the NMEA network, and then used by DSC VHF and my OpenCPN plotter that I run at nav desk.
 
The thread was about various systems for location and some one mentioned pitch and roll. It simply happens that we all, I exaggerate, have a device that measures pitch and roll - but we none of actively use it. I understand its used within the device so that the screen is always -right way up.

I'm interested and my granddaughter has made me an accelerometer using aduino boards (as I'm not going to drop my iPad Pro in the sea!)

Jonathan
 
I have a KA-GC9A which is a standard component of the Onwa Auto-Pilot, an Onwa KM12 which has a 'standard' GNSS antenna, a Humminbird Helix 9 with a internal GPS antenna and indeed I also use a GPS Dongle on the laptop. Of course all show different lat/long :). That's because all the antenna are in difference places! But to find the variation you need to look at the third decimal! Who can say which is the most accurate? Typically I get 20 satellites using the Onwa KM12 and a v. good Horizontal dilution of position whereas the Hummin gets 9 sats and poorer HDOP.

$GPGGA,100000,5145.9898,N,00054.5004,E,1,20,0.7,2.5,M,,M,,0000*5A
$INGGA,100000,5145.9865,N,00054.5037,E,1,09,1.1,-5.6,M,,,,*20

If someone can tell us the distance between the two lat/long?

Unfortunately I don't harvest the KA data but typically the difference between the KA and the KM12 is minimal. The system uses the KA for the heading and it finds our wpts. I do like the KA - note it needs to be placed on the centre-line of the boat and needs to be installed dead ahead (easy to adjust).
 
tillergirl said:
note it needs to be placed on the centre-line of the boat and needs to be installed dead ahead (easy to adjust).
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I hadn't appreciated it needed to be mounted on centreline, which would indeed be a bit of a challenge for me given my pushpit construction.
 
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