High power light and computer/speedo interference?????

[sittingbull]

Last night I had my first ride with a Moon XP500 light. It's impressive and opens up the possibility of riding unlit country lanes at a decent pace

However I noticed my Cateye Micro Wireless computer was either showing 0 mph or approx. half the actual speed when the light was on either of the 2 lowest settings. As I rotated through the 5 light sequence modes the Cateye malfunctioned on those same 2 modes each time

By the end of a 22 mile ride the Cateye was 7 miles short of my Garmin Edge recorded distance. I realise it just may be one of those coincidences when the Cateye might have malfunctioned anyway but I've read at least one other case where something similar has happened. I don't necessarily need both the Edge and the Cateye but it helps to see my speed continuously on my Cateye whilst following a breadcrumb trail on the Edge. Having said that I could live without the Cateye if it meant being able to see the road.

It got me thinking though, assuming the Cateye radio signal from my forks to the bars has been corrupted by the Moon XP500, can I have confidence in the accuracy of the Edge 200 based on the GPS signal it receives?

Anyone have any experience/thoughts based on these or other units?

 

[Cubist]

My wireless computer didn't lile strobes or private hire radios. I had some led under unit lights in the kitchen, and saw the computer was doing 72mph on the breadbin.

Can you set up the edge to give waypoint turns so you can keep the cockpit function visible?

 

[HLaB]

Its a common problem with wireless speedos and LEDs interference, my microwireless would do similar if the batteries weren't 100%. It can sometimes be overcome by using the light on solid (rather than flashing) or spacing the units further apart.

 

[Bodhbh]

They don't like certain stuff I've noticed. Mine used to go nuts at the shopping till at Tescos, I think iit was the scanner.

 

[sittingbull]

Can you set up the edge to give waypoint turns so you can keep the cockpit function visible?

Unfortunately not, or at least not that I'm aware of.

It can sometimes be overcome by using the light on solid (rather than flashing) or spacing the units further apart.

I would have thought the same but strangely the Cateye appeared OK with the Moon XP on flash, it was the 2 lowest solid settings which caused the problems and I'd rather use these to conserve battery power as I've no external battery pack.

They don't like certain stuff I've noticed. Mine used to go nuts at the shopping till at Tescos, I think iit was the scanner.

I've had the odd 65 mph and even 95 mph. I've always associated it with emergency service vehicles or temporary roadworks.

Can I assume my Garmin is unaffected?

 

[HLaB]

I would have thought the same but strangely the Cateye appeared OK with the Moon XP on flash, it was the 2 lowest solid settings which caused the problems and I'd rather use these to conserve battery power as I've no external battery pack.

The MoonXP probably flashes at a different frequency from the Cateye where as the solid runs at a frequency which interferes, I'm not a lighting expert but I think its just the way LED's work; perhaps you can move the light and computer a little bit further apart.

 

[02GF74]

interesting but not unsurprisingly.

high power LED lamps have a drver that supplies constant current to the LED, thbetter one can take a wide range of voltage battery pack e.g. 8 to 24 V.

Downside is thy work by chopping the current i.e. turn the current on and off so the average value is within the specification for the LED. That is how the dimming is done: the current is off for a longer period so the average is less. Switching relatively large currents will create electormagnetic radiation i.e. radio waves that seem to interfere with the wirelessspeedo; the speedo receives a radio signal from the sensor.

You would need to google to see what can be done to improve the situation

 

[Shut Up Legs]

Can you set them up to fool the bike computer into showing higher speeds!?

 

[Stonepark]

My fluxient does the same on the lower settings.

 

[sittingbull]

........ perhaps you can move the light and computer a little bit further apart.

They're already on opposite sides of the stem and I use the full width of the bar tape to maintain a comfortable grip.

........ Switching relatively large currents will create electormagnetic radiation i.e. radio waves that seem to interfere with the wirelessspeedo; the speedo receives a radio signal from the sensor.

You would need to google to see what can be done to improve the situation

I couldn't have explained it but figured something like that was occurring. I've used the same model of Cateye on 2 bikes, on the MTB there are 2 cheapo blinkies (4 x 3AAA batteries in each) and they don't interfere. On the Allez, prior to the Moon XP was a Cateye EL-135 (2 x AA batteries) without interference, but presumably Cateye do compatibility checks.

The only solution I can think of is to revert to a wired unit.

My fluxient does the same on the lower settings.

That's cheered me up a bit thanks (sorry ) as I very nearly bought a Fluxient U2 Mini 1100 lumens unit. I asked the seller which would be brighter, the 1100 lumens Fluxient or the 500 lumens Moon XP, his reply was they would be about the same saying: "the problem is, most manufacturers take the maximum output of the led (usually requiring 3A current), but most are driven at around 1.4A which produces around 500 lumens". From which I deduced the optimum unit to purchase is one of 500 lumens output as others may claim more lumens but are still only putting out 500.

 

[HLaB]

They're already on opposite sides of the stem and I use the full width of the bar tape to maintain a comfortable grip.

Yip can be awkward, especially on a road bike. I switched to GPS when I realised my Cateye Microwireless and Raleigh Echo were getting interference but I had always intended to upgrade computer anyway.

 

[sittingbull]

You would need to google to see what can be done to improve the situation

I've done this and interference appears to be a common problem. Indeed it has previously been discussed at least once on CycleChat such as here.

One possible solution is to shield the source of interference with tin foil. I'd rather swap to a wired Cateye than pursue this.

I would still like a definitive answer on whether my Garmin could be affected. There is less information available on this (in comparison to Cateye computer interference) but it does appear possible. It would appear that the GPS radio signal is on a different frequency range to that used by Cateye, although frequencies don't have to be a match to interfere. One case does mentions a loss of GPS signal when using 2 Cateye Nano Shots. The Garmin site have a brief section on GPS interference and cite possible sources as cell phones and MP3 players.

I can only assume interference to Garmin GPS's by high power lights is not a significant problem or there would be more reported cases.

EDIT: I don't know whether Garmin GPS interference from LED lights is a significant problem or not, but I've just read a couple of reviews where it is a problem.

 

[PatrickPending]

EMI, electromagnetic interference, worse on low power settimgs because often leds ae pulsed to give this. the pulsing results in a wide spectra emi...constant usually doesnt have any pulwing hence less emi and less likelyhood of it interfering with your milometer.........

 

[02GF74]

I would still like a definitive answer on whether my Garmin could be affected.
I can only assume interference to Garmin GPS's by high power lights is not a significant problem or there would be more reported cases.

EDIT: I don't know whether Garmin GPS interference from LED lights is a significant problem or not, but I've just read a couple of reviews where it is a problem.

If memory serves me will, GPS signal uses spread spectrum which has higher tolerance to interference. So would be less susceptible, guess you need to try it to see.

 

[sittingbull]

If memory serves me will, GPS signal uses spread spectrum which has higher tolerance to interference. So would be less susceptible, guess you need to try it to see.

The current plan is to set up a wired Cateye, calibrate it over a "sufficient" number of rides against the Garmin (Moon XP turned off). I know from over 12 months of using the Cateye and Garmin together that there is always some discrepancy between them but this is nearly always less than 1% in distance over 100 miles. Then I'll introduce the Moon XP into the equation........