- Jun 9, 2008
I used to work for a Sat Nav company a few years ago.Does it matter where it’s mounted? Is under the tank ok or does it need to be ‘visible’ to the sky?
Is there a long delay whilst it finds satatiltes when switching on?
How good is coverage? It would be a pain for it to not work in places.
What happens in tunnels?
Oh dear, you’re learned opinion seems to back up my Luddite hunch almost perfectly!I used to work for a Sat Nav company a few years ago.
We came out with an aluminum shelled windshield mount device, and there was significant interference to the GPS chip compared to the plastic shelled version. I wouldnt put the it under the tank. Also, best reception is due to the orientation of the chip. So, on side may be worse than flat, updside down, etc.
GPS modules are dependent on "seeing the satellites" (usually need two) , but can be compensated for with software or hardware.
For example, you get significant "bounce" in an urban (or other) canyon where there is high signal reactivity and an indirect signal path (such as satellite low on horizon - which is almost always the case in the Southern Hemisphere). This can be stabilized with an accelerometer and/or software.
The same is true of being in a tunnel - you will lose the signal once a bit inside, but an accelerometer will keep track to a reasonable degree whilst in it.
As for signal acquisition time, it depends. There are timecodes in the GPS signals from the satellites, and the chip manufactures sell features to enable those to be re-used so that you dont have to re-download the acquisition data from the satellite on each re-start. But, those chips cost more. And if the tables are older than ~4hrs or so, the satellite has moved on and you need to reacquire anyhow. There are also chip sets that acquire the data more quickly than others. Those chips cost more. This can also be compensated for by re-using "last known good" position and assuming that as a start point while you re-acquire a satellite signal - so you can effectively hide acquisition time.
I wouldn't buy a GPS speedo for my Commando.
Aircraft avionics have the same problem due to battery volts drop during the start cycle. The solution is a DC-DC (boost) Converter which holds up the supply voltage to key equipment. There seem to be a few automotive converters out there, but I haven't got any answers as to which one would be most suitable - not sure how many watts the GPS needs?I've had a GPS speedo on a bike (not a Norton) for several years now, and have mixed feelings about it. The sensor is mounted on top of a plastic rear fender behind the rider, and has a good field of view. It does take a while to acquire the sats when first started, and you can't move the bike during that period, or it doesn't acquire. I don't find that a big problem, but it is kind of annoying. It does lose the signal sometimes in the local canyons, but by then I usually know how fast I'm going by looking at the tach, so that's not really a big issue either. The real inconvenience is when the bike dies at a stop light, and has to be re-started (electric starter). For some reason it loses the signal during the re-start, but I can't usually just sit there stopped in traffic to wait for it to re-acquire. The bike is a highly tuned ex-race bike, and does occasionally die at abrupt stops, so I find this property kind of annoying. Still, overall, it mostly works ok. The real solution would be to do some fabrication so the original mechanical speedo works again (changes to the rear wheel deleted the speedo drive), but the GPS works well enough that I haven't put much priority on doing that.
As I said, it is several years old now, so the newer designs might be significantly better. I don't think mine has all the features described above by other users.
I'm not going to take the chance. I'll have my bike back in a week or two and I'll be applying the silicon.Has the lack of waterproofing been addressed in later releases of the electronic speedo? I don't want to shell out the bucks for something that needs an immediate modification to make it work as intended. Silicone, as applied by me, is never a neat or pretty sight.