Car Navi Speedpulse
Speed Pulse signals in car navigation, some models need them some don’t. What’s going on?
When in car navigation units were first introduced a few years ago, we were told that speed pulse information was vital for the system to work, the reasons given seemed valid and sensible to me.
The way these units worked was to have a detailed road map in the system which was interrogated by a computer aided by a gyroscope and speed pulse signals which between them made it possible for journeys to be plotted by the car making a few movements (drive forward, turn left, turn right). These movements would be unique and once overlaid and matched to the map the journey destination could be calculated and the only need for satellites was to give the map a clue where in the world the vehicle was in the first place. The satellites were thereafter only needed as backup or to correct position occasionally since the system could work out where the car was by the gyroscope and speed information combined with the map.
These early systems were sometimes difficult to fit to some vehicles since not all cars had speed pulse. Before all cars had ECU computers or CanBus systems we sometimes had to install speed pulse generators. So what’s changed?
When new units started to appear from Pioneer and Clarion and we were told there was no need for speed pulse, I was confused. A bit like when the manufacturers started to show us tiny cheap amplifiers with output ratings and frequency responses that defeated the laws of electronics, I was confused then but my service engineering training told me these super amps had to be rubbish and it was all advertising hype, I was of course proved right but how do you argue with a navigation that appears to work without speed pulse? Well I told myself it was because there were many more satellites now and the rendering engine in these navi systems was vastly superior to the old ones so maybe you really didn’t need speed pulse??
Have you ever been using your portable or fixed navigation unit on a journey when the cursor on the screen suddenly jumps to an adjacent street? Or driven into a tunnel to find the cursor is miles behind your position when you drive out the other end? And just forget it if you end up in a multi story car park, ever wondered why it takes ages for your system to resume its journey after you leave that underground car park? These are all symptoms of lack of speed pulse. When you rely on satellites only and you lose sight of them, you lose accuracy.
Alpine have introduced the INE-S900R and I am glad to see they have returned to the vastly more accurate system requiring a speed-pulse but the dangers here is that since the internet is full of non specialist dealers, who don’t understand, never mind warn you about the dangers of finding a Speed Pulse in a modern car so please be careful, you could cause hundreds of pounds worth of damage to your pride and joy. Always us a specialist or at least ask for advice on which interfaces to use for your car make, year and model. I would always recommend professional fitting but if you own a VW then Alpine have made it easier for you with their VW fitting facia and VW Steering wheel Can adaptor.
If you need any further help with this contact us or call 0845 166 7104
