Wireless Computers

Wrightstuff

A littlebit more.
When I posted about my observations I got this excellent reply from "mountainpro" which I have copied below. Many thanks.

your wireless computer uses an infrared diode and photo transistor as an emitter/detector. The ir diode is basically an led that emits light in the ir wavelength that us silly humans cannot see. The transistor will pick up stray infrared radiation from any source. Your light LEDs shouldnt emit radiation at any other wavelength other than red/white/blue (depending on the colour of the diodes) but unfortunately due to impurities in the semiconductors the wavelengths arent very narrow and they do start flashing in infrared wavelength as well. There is nothing you or the manufacturers can do about it.

your flashing light LEDs frequency is being interpreted by your cycle computer and converted into speed. The computer thinks the light is coming from your ir led on the wheel and the speed of your flashing LEDs will equate directly with the speed of a wheel for the speed being diaplayed on your computer....pretty clever really.
If you stop using leds and use halogen or krypton bulbs instead this should reduce ir radiation.

flipper

Thanks for that info Wrightstuff, very interesting how it all works.
I've got a CatEye Cordless 7 that's driving me nuts at the moment as it's dropping signals all over the place (if I'm doing say 30kph, it'll show 30 for a second, then maybe 11, then up to 20 or so then back to 30... on a 50km ride, it can read as far out as 5km on distance alone)
It worked fine for over 12 months then slowly got worse. I've read elsewhere that there were a bunch of faulty sensors (1 in 10) that CatEye were happy to replace but so far I've been waiting a couple of weeks now for CatEye Japan to get back to me. (not holding my breath)

Never had any interference problems with it from either HRM's or lighting.

__________________
"I think the only rule is that if someone is a big fat bastard its fairly safe to assume they aren't going to be pwning anyone on a climb" ~ classic1

artemidorus

My Polar 720i gives me a speed of 104km/h and an HR of 230/min randomly and when I ride past the aeroport or over the Harbour Br. (I think that radar and television towers both mess with it). It only annoys me when I really wanted to know my true maximum speed.
The Polar uses a radio frequency, not IR.

SEGFTG

I got a reading of 94km/h the other day on my Polar 725, didnt notice anything nearby that could interfere. Thats the only problem I have ever had, I think they are a great unit all round.

malcomm

The V100 is a great comp plus has temp.
The only thing wrong with it is that it does not wake itself up from wheel rotation and goes to sleep rather quickly to conserve batteries.
This can mean that you might forget to trigger it on when you start off or if you stop for a rest etc it may go to sleep and you don't start it again. Either way you will loose lots of your data.
This problem forced me to buy the cateye cd300dw doulbe wireless.

Its a good comp if you don't mind loosing data occasionally.
BTW Vetta assured me they would be changing the firmware to increase the timeouts but I couldn't wait.

cheers
Malcom