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Understanding GPS activated digital speedo

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tvrgeek Avatar
tvrgeek Silver Member Scott S
Hillsborough, North Carolinia, USA   USA
1965 MG MGB
"You would think that modern cars, with their electronic speedos would be right on, that's not always the case." Sure was not in my Mini Cooper!. But my Acura and Hondas were spot on. My GTI, not so.
Of course, tire wear and inflation does make a difference.

30cm for civilian! Wow. Kind of scary actually. But it is what is needed for autonomous trucks and buses as well as the pizza delivery drones. The future is inevitable. Of course, we need maps at better than that for it to be useful.



Cogito ergo sum periculoso

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Wray Avatar
Wray Gold Member Wray Lemke
., SC, USA   USA
Most everyone thinks about how GPS is used in speed and positional information. But, if that system went down most of the high speed communications on the planet, including your cell phones, would be SOL in a big way. GPS affects your life a lot more by the way it's used for a universal source for time and synch reference.

There has been noise about resurrecting the Loran-C system again, morphing into a Loran-e system. Lots of benefits to that at a fraction of the cost of GPS.

MGUK Paul Wiley
Watton, Norfolk, UK   GBR
The main GPS system is/was developed for the American military to use. But Bill Clinton accepted the claim that civilian use would benefit end users and equipment manufacturers. So he ordered the restriction on high accuracy use be removed. I don't know if current military systems are capable of providing even higher accuracy or other benefits but the standard GPS service is very handy for getting round particularly where you are travelling to unknown territory.

The European Space Agency decided a few years ago - probably under instruction from the EU Commission - to develop an independent system. So Galileo was designed amid futuristic claims for all sorts of advanced benefits. Anyway, it is now at a point where it is coming into use. A European electronics company - Thales - has just got an order to build receivers for civilian aircraft to use both Galileo and the US GPS system. There are probably all sorts of military systems coming into service as well.

It is claimed that Galileo will provide 1 metre accuracy to everyone but we will see. I expect personal and car systems using both services will appear before too long. But they will have to offer a significant improvement on the established American service if there is to be much impact on the market. IF there is a significant take up of Galileo, the price of equipment should fall as it has done with the American GPS receivers.

You can find a write-up on Galileo if you Google; GPS Galileo.

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melbaver Avatar
melbaver Gold Member Chris Howells
Broadwater NSW, Australia   AUS
1968 MG MGB "Moneypit"
1996 Jeep Cherokee "Shopping Trolley"
And of course there is (or was???) Glonass.



Chris Howells

1968 MGB Purchased already dis-assembled but which is largely back together so I'm a lot less ignorant.

sweep Avatar
sweep Gold Member Chris W
Gosford, NSW, Australia   AUS
1966 MG MGB "Basil"
2013 Volkswagen Tiguan
2015 Audi A3
GPS only receive information for their display. They're passive. Multiple GPS should have no interactions with each other.



The secret to creativity is knowing how to hide your sources.

To the intelligent person, life appears infinitely mysterious, but the stupid have an answer for everything.

ron neal Avatar
Coastal, SC, USA   USA
1962 MG MGA MkII
1968 MG MGC
1969 MG MGC
1969 MG MGC    & more
In reply to # 3695982 by Wray Most everyone thinks about how GPS is used in speed and positional information. But, if that system went down most of the high speed communications on the planet, including your cell phones, would be SOL in a big way. GPS affects your life a lot more by the way it's used for a universal source for time and synch reference.

There has been noise about resurrecting the Loran-C system again, morphing into a Loran-e system. Lots of benefits to that at a fraction of the cost of GPS.

Loran-A and Loran-C bring back a lot of memories. When we used a sextant for a "navigation fix" and were within a couple miles it was considered good. Now you just plot the dots.
Ron

Wray Avatar
Wray Gold Member Wray Lemke
., SC, USA   USA
Ron, as an old sea dog you know about Loran-A. We had them on the tugs, never could get fixes that were worth using so we continued to navigate using mostly dead reckoning. Loran-C changed navigation in a major way. I remember when the first handheld GPS came out, a unit by Magellan. They debuted it at a big marine show in Chicago, we all swarmed the booth.

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ron neal Avatar
Coastal, SC, USA   USA
1962 MG MGA MkII
1968 MG MGC
1969 MG MGC
1969 MG MGC    & more
Wray
I am sure that the first handheld GPS was a very hot ticket.
In conjunction with Loran-C we used early Sat Nav which were doppler fix satellites in the 60's. On submarines we had to be more accurate if we wanted to hit a target with our ICBM's so we had SINS, Sat Nav, Loran C but did away with the internal periscope sextant due to its inherent inaccuracy for this particular job. Loran-A was on older non capital ships and auxiliary vessels. There were Loran-A stations around the world but somewhat stone age and I would probably trust a good sextant fix first.

We seem to digress from the OP so I will be the first to apologize and move on but will add with the cost of rebuilding the orig. gauges I am beginning to look more at the new GPS gauges the say Smiths and are have old style faces to fit a MG dash.
Ron

Taddeo Avatar
Taddeo Gold Member Todd V
Batesville, GA, USA   USA
My '12 GTI reads 2 mph lower than two different Garmin's showed. When I set the cruise at 77 the Garmins show 79. Used on my Harley Fatboy both Garmin and speedo read the same, as did the MGB.

In reply to # 3695637 by tvrgeek On the Garmin, I had an old one that compared exactly with a stop watch and mile markers as well as the big radar speed signs. Then after an "upgrade" it consistently read one MPH higher. My current one is the same. I have not had enough miles on my VDO GPS speedo to test. The things I don't like about it are in the sunlight, you can't see the odometer and it does take a block or so to sync. I had one of those cheap HUD speedos in my GT for a while and it read right with the Garmin. It was a lot more flaky though.

I suspect this is from the Federal regulations that a speedo can be as much as 10% +/- 2 MPH off as long at it does not read low. This I got from BMW when they were defending their worthless speedo in the Mini. It was more than 10% off. That said, I found out the hard way my GTI speedo is 4 MPH low at 77. ( The speedo was more accurate than the fuel gauge though)



No original work of art was ever created by carefully coloring inside the lines.
1974 MGB No a/c, o/d, pw, pdl, ps, tilt, cruise, zoned heating, collision avoidance, backup cameras, or radio. Hey, that sounds like my Harleys!

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ohlord Avatar
ohlord Gold Member Rob C
North of Seattle, N.W., USA   USA
1957 Land Rover Series I "EYEYIYI"
1971 MG MGB
1971 MG MGB "Bedouin 2"
Thats a chip/equipment issue.
As noted the next Gen chips are going into cell phones currently and I suspect into other gps devices that is 30cm accurate horizontal and vertical.



"I'm a long way gone down this wild road I'm on
It's gonna take me where I'm bound
It's a long way around"



"These are the days that must happen to you"

RD2 Radar/ Electronic Warfare Technician
Vietnam 1969-1972

tvrgeek Avatar
tvrgeek Silver Member Scott S
Hillsborough, North Carolinia, USA   USA
1965 MG MGB
I believe the 1 MPH faster display on our Garmins is to be sure they do not run afoul of Government regulations. VW does not seem to care. As I mentioned, my old one was dead on until a firmware upgrade, then 1 MPH faster. Not a chip issue, a software decision. For a speedo, we are still dealing with averaging and dithering. My Garmin and VDO speedo respond far faster than the cheap HUD GPS speedo. It lagged by 3 or 4 seconds. You could pull up to a light and watch the numbers count down. grinning smiley Still, a quick fix for a bad drive gear inside the trans. not to mention the PO put on tires three sizes too large.



Cogito ergo sum periculoso

ohlord Avatar
ohlord Gold Member Rob C
North of Seattle, N.W., USA   USA
1957 Land Rover Series I "EYEYIYI"
1971 MG MGB
1971 MG MGB "Bedouin 2"
Speedhut !



"I'm a long way gone down this wild road I'm on
It's gonna take me where I'm bound
It's a long way around"



"These are the days that must happen to you"

RD2 Radar/ Electronic Warfare Technician
Vietnam 1969-1972

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