IT10 Posted August 31, 2006 Share Posted August 31, 2006 Hi all, I noticed today that there seems to be a difference of a couple of MPH between the MPH shown on the speedo and the digital speed readout on the dash pod. Eg Pod shows 57, speedo reads 60. Not sure if anyone else has noticed this or gets this? I know the difference is negligible, but does anyone know which would be the more accurate? Cheers Ian Quote Link to comment Share on other sites More sharing options...
Kennydies Posted August 31, 2006 Share Posted August 31, 2006 I use my Road Angel as both are inacurate. Quote Link to comment Share on other sites More sharing options...
Removed Posted August 31, 2006 Share Posted August 31, 2006 digital out of the 2 in the car, but yeah a GPS device will be more accurate Quote Link to comment Share on other sites More sharing options...
davidbaker8130 Posted August 31, 2006 Share Posted August 31, 2006 Hi Ian, As the guys have already said, GPS will normally be most accurate but as far as Pod V Speedo it states in the manual that "The speed indicator in the trip computer indicates the reference speed. The actual speed indicated by the speedometer may differ from the one in the trip computer" Hope that helps. Quote Link to comment Share on other sites More sharing options...
Removed Posted August 31, 2006 Share Posted August 31, 2006 comparing the 3 (in fact 4 including the GPS on the B2 as well as the GPS on the TOMTOM) at the same time and assuming GPS is the most accurate, the digital speed read in the trip computer seems to be closer to the actual speed as opposed to the speedo Quote Link to comment Share on other sites More sharing options...
davidbaker8130 Posted August 31, 2006 Share Posted August 31, 2006 How many speedos do you need!!??!! My speedo/pod always seem to read the same anyway. Like you guys, most of the time I use Tomtom - then you can go faster. Quote Link to comment Share on other sites More sharing options...
Removed Posted August 31, 2006 Share Posted August 31, 2006 just comparing them for the sake of it a couple of times Quote Link to comment Share on other sites More sharing options...
Rob_Quads Posted August 31, 2006 Share Posted August 31, 2006 Remember for GPS to sit on cruise control as its normally a 2/3 second delays unless its something like drayton timing year. I had a strange one where speed showed 80mph, digital speedo = 80mph. Sitting on cruise control for 30 minutes solid - av. speed = 76mph? Quote Link to comment Share on other sites More sharing options...
Liam's Z Posted August 31, 2006 Share Posted August 31, 2006 Digital and Analogue the same wrt I’d always trust digital first Quote Link to comment Share on other sites More sharing options...
Guest prescience Posted August 31, 2006 Share Posted August 31, 2006 Digital and Analogue the same wrt I’d always trust digital first Why's that then? Quote Link to comment Share on other sites More sharing options...
Liam's Z Posted August 31, 2006 Share Posted August 31, 2006 Why do you think Dorian??? Do we measure say the 100m sprint on a analogue instrument!!! Quote Link to comment Share on other sites More sharing options...
Guest prescience Posted September 1, 2006 Share Posted September 1, 2006 Why do you think Dorian??? Do we measure say the 100m sprint on a analogue instrument!!! Well they both use the same information from the wheel sensors - I think its that the analog speedo is made to overead (as other manufacturers do) to avoid charges of it reading incorrectly if people get nicked for speeding. There is no othe reason I can see that the digital and analog would not read the same, as it can't be manufacturing tolerances because the analog ALWAYS reads higher Quote Link to comment Share on other sites More sharing options...
lomoto Posted September 1, 2006 Share Posted September 1, 2006 you shouldnt look at any of em !! you should be looking where your going Quote Link to comment Share on other sites More sharing options...
Stew Posted September 1, 2006 Share Posted September 1, 2006 I noticed this but assumed it was paralax (sp) error. It is possible for the digital and analogue to read different speeds even if the reading is coming from the same place. I don't know how the Zed is hooked up but the digital speedo will have an analogue input converted (speed at gearbox or wheel) into the digital reading via a scale such as 4-20mA or something. This in turn could vary (as all electronics do) due to temperature etc. Thus giving a different output from the analogue one that isn't converted! If I'm speaking sh*t let me know. Quote Link to comment Share on other sites More sharing options...
hanel Posted September 1, 2006 Share Posted September 1, 2006 I noticed this but assumed it was paralax (sp) error. It is possible for the digital and analogue to read different speeds even if the reading is coming from the same place. I don't know how the Zed is hooked up but the digital speedo will have an analogue input converted (speed at gearbox or wheel) into the digital reading via a scale such as 4-20mA or something. This in turn could vary (as all electronics do) due to temperature etc. Thus giving a different output from the analogue one that isn't converted! If I'm speaking sh*t let me know. Just to confuse things even further...... Tyre tread depth and pressure also must make a difference to the reading on all the readings! Quote Link to comment Share on other sites More sharing options...
Guest prescience Posted September 1, 2006 Share Posted September 1, 2006 Certainly rolling radius will affect the 'true' speed. Stew if the A/D converter was quantised as you suggest, surely on average it would read higher and lower equally. As it is, the digital reading has a positive bias rather than a pseudo-random quantised variation. I still believe it is deliberately set to over-read Quote Link to comment Share on other sites More sharing options...
Stew Posted September 1, 2006 Share Posted September 1, 2006 I was just throwing in my tuppence worth - I have no idea how they do it at Nissan! It could be deliberate, I generally just go for the digital one as it seems in a more natural position! Quote Link to comment Share on other sites More sharing options...
Guest prescience Posted September 1, 2006 Share Posted September 1, 2006 I was just throwing in my tuppence worth - I have no idea how they do it at Nissan! It could be deliberate, I generally just go for the digital one as it seems in a more natural position! Same here Quote Link to comment Share on other sites More sharing options...
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