Interferance

[QM]

I know lots of other people have been suffering interference problems, especially around marshall position 2 and the long straight. The cries 'I'm getting interference' (as their car charges off in to the grass or tyre) are quite frequent.

Personally my son and I have tried all sorts of methods to combat it, including using tin foil to produce a Faraday cage around the receiver. But the best solution came in the form of a new FM radio system with a dual conversion receiver... Not one glitch all day ;D

I have used this type of receiver in flying models for several years now, so I was very glad to see car radio manufacturers now producing them ;D So if you want glitch free operation you know what to do ;)

[sdrcc]

I had a long chat with Rob Nelson about the amount of "interference".

Essentially, it all comes down to receivers and crystals, both fragile components, getting thouroughly bashed around the circuit.

When we race at our clubs, we learn solve any interference issues and assume everything is fine, but when we get to big meetings with lots of "new faces" there, we all suddenly suffer glitches.

90%+ it's down to tired old crystals and/or receivers. Yes they can work when they are on their own, but when trying to decipher the right signals when the airways are crowded, then that's when most problems materialise.

I suffered very badly throughout the day with one receiver, and just decided to go for it in the final. Turns out, I wasn't driving with most of the people who were in my heat, and low and behold, it was faultless. Got 3rd.

I think there is some merit in this theory, and we should all give Mike a call and get some new receivers and crystals. I mean, they don't have to be the most expensive, just the most reliable.

[P. Harrod]

I suffered from interference at the GP and the most common point was just after the banked sweeper. I was suprised to be suffering so bad in the early rounds since I have recently had my radio tuned, along with reciever and crystals all checked. I changed crystals after practise, luckily to the allocated ones but no change. I moved my reciever around the chassis to try and improve things, I ended up with it on it's side on the top deck near the front of the car, which may have helped a little. I found that by standing on the right hand side of the rostrum things were helped, my first and last finals were pretty much glitch free. My middle final was kinda of bad though with nothing changed by me and standing in roughly the same place ???

[bruce]

Have to agree with Dom there. The reciever is usually the root of the problem assuming you have a FM system which shouldn't be giving you problems. A few years ago i spent just about a whole season changing things and the reciever was the last thing i tried. I had had it tuned so i assumed it was ok. Tuning is bound to be carried out with no other frequncies floating about so does not achieve too much. As soon as you go racing interference will probably attack again!

[George Stoker]

Although I agree that 9/10 times it is down to equipment I also have to point out that over the whole day I suffered intermittent interferance.
This was with a Futaba 3VC (fairly new) PCM receiver (brand new) and fairly new crystals - yet - I still suffered. Interestingly reading Peter's post - I too stood at the far right of the rostrum for the Final and had my first trouble free race of the day! - in a time which would have put me well up the A final :(
Also - findings from the past have proved that vehicles parked adjacent to the track do not help - I am not talking about the pitting area - but the corner coming off the banked sweeper - where a lot of people have claimed to have suffered interferance - Parked there were 2 vehicles for most of the afternoon. Reflected signals can cause interferance.
Just my two pennorth - but it was still a great day!

[Bt]

beat me to it george, it has been thought in the past one of the problems at certain SMTCA rounds where there has been alot of cars or other metal object in front of the rostrum on the far side of the track that caused interference.

I only got one little glitch all day so it was fine for me but i used to get alot of intereferance at stonehaven and other SMTCA rounds. Like others have said i've been fine all day in the passed but come the final with other drivers i cant do anything as the car is in control not me.

The biggest solution i foudn to this was your wiring. Make sure any/all reciever wires(antenna esp) are kept off the chasis and away from any power devices such as speedo's/motors. Even keep your speedo wires away from recievers that include closely beside them or hanging over the top of them. I made some changes to my car earlier on in the season(what i just mentioned) and havent had any interference since. I also reloacted my ariel mount so the wire comes out the reciever and goes straight up the tube, none of it is lying about the car or wrapped around anything.

[QM]

George is your Futaba system dual conversion as well as PCM? The earlier PCM only sets suffered from loss of signal and went in to fail safe mode causing loss of control until a good signal was then received. This was solved with dual conversion, as it wipes out the offending bad signal.

There is also the mobile phone problem, they do cause intermittent interference with radio gear and have been known to wipeout computer radio memories.

Mike Henderson can give you the low down on the 23rd channel issue. Basically, anyone on a higher frequency can get interference from a channel 23 places below it, or vica versa :o

[Bt]

the mobile phone issue has already been addressed at the smtca series(brought up by me actually ::)) but it actually states in the brca handbook you arent allowed to be carrying them when on the rostrum. They are completely banned from the track area in our series. only allowed in the pits, not racing, marshalling, anything near the track...

[marcoski]

The biggest problem is people will insist on building metal rostrums!! Also, even if your radio gear is fine, it doesn't mean that someone elses gear is not producing spurious signals. Actually when I calibrate handsets, I have two others on adjacent channels right next to the one in question just cover that problem. I do not calibrate in a radio quite zone!!

[bruce]

Good to hear that it is more thorough than i thought Marcus.

[sdrcc]

This topic has really got everyone going.

The "interference" issue Sunday really got a few people annoyed and distracted, although the effect was maybe as much as 1 person per heat/final (avg).

But this level is not really acceptable at this level of competition.

To this end, I shall be looking to seriously investigate the interference situation at Stonehaven and look for a suitable remedy.

Can anyone provide contact details of specialists in this field that can provide a detailed analysis of the problems and ways to fix them?

They can either post the details to this forum or contact me directly via the Contact info at www.sdrcc.co.uk.

The plan is to diagnose and effect any solutions over the last two meetings and early next year, so by next year, these episodes can be a thing of the past.

Domenick

[Gary Dunn]

I believe the main guy in the BRCA that deals with this is Jim Spencer.

What seems to strange about the problem at Stonehaven is it's apparent randomness. Sometimes people can start races ok then get problems intermittently.
I believe that happened to Kevin Nicolson in the 3rd A final last weekend. Probably decided the result.
According to the A final list no driver changed crystals during the finals, so in theory, no other driver could've affected things.
Unless it could be down to something as spurious as another driver changing position....?

[NOKIA]

Fellow sufferers - I was plagued with intermittent interference throughout sundays racing and found it very frustrating >:(

Now i was one of the more fortunate to have spent most of saturday practicing and setting up my car. I did not have ANY problems at ANY anyware on the track (on saturday) ;D

On race day i stood on the same postion on the rostrum as i did the day before and my car was all over the show starting at point 2 clearing just at the point turning in (for 19T) and then again coming back towards the rostrum. I later moved to the RH side of the rostrum and it was better but still prominant at point 2. It was intermittent and the only way I could find some sort of restbite was to hold my TX way out in front of me and PRAY ???.

Now I have NEVER suffered from this problem until @ Stonehaven and as I'm not the only one to have had problems, something else is underfoot!!!!!

I can appreciate that equipment installation / condition can play a major roll in problems, however, I do feel that most competing at these sort of major events have their equipment in good to perfect condition.

I am also very surprised at how close the frequency spacing being used is, bearing in mind that Dual Conversion Systems where bought out speifically for closer frequency spacing thereby increasing capacity and more choice. I cannot see how the standard systems (non dual conversion)sets are expected to cope when we are (at times) VERY close in frequency, stood in each others pockets, with antennae nearly touching each others and electrics flying around only inches from our recievers :o :o :o I cannot understand why car radio manufacturers have not discontinued the single type sets.

I used to fly RC planes and would NEVER even considder standing so close to a fellow pilot (let alone another 9 or so) as this was looking for trouble.

So whats the answer i hear you say - well I think vigilance on:

Drivers car eqipment, installation & maintenance
Track Set-up and facilities
Race Control ensuring sufficient frequency spacing between drivers,

AND most importantly better TX discipline by all in the Pits!!!!!!!!

Whew that was a mouthfull ;D ;D

[sdrcc]

That's good input Bryan.

I'll look at the frequencies used in each heat, and ask everyone who had a problem with interference at the Grand Prix, to email me with the following:
heat round description

We can look at the frequencies and see if this was a significant factor.

Admittedly, we don't normally suffer much interferance usually, so as you say, something out of the ordinary happened. This seems a most plausible cause.

[QM]

Sorry Dom, I beg to differ on that...Luke and I suffered interference at every club meeting until I went to dual conversion. Luke is still running a single conversion set, as still gets the odd glitch now and then, and especially at marshall point 2. You get used to it after a while and accept the loss of control, just hoping it doesn't veer off the track ::)

I know other club members suffered the same thing during normal club meetings as well, usually the silver foil around the receiver cured it, as well as heavy motor supression.

But do remember the crystal in your receiver, it is the most vulnerable part of the system. If you have ever wondered what it is like, carefully take an old one apart, you will be truly amazed at how a wafer thin bit of crystal can survive the bashing they get. I had one written off in the final when my car was hit very hard, it took a while to discover that was the fault though.

For other high vibe models, i.e. helicopters and aircraft etc, receivers should be very well protected in foam, but no one does it for cars, probably because of lack of space!

[sdrcc]

Well there really isn't a definitive answer, except we all have to learn to handle our receivers a little better.

Don't think it's all down to crystals, but yes, we should think about any internal damage whenever we have a big crash. Yes, it's not just the car that suffers!

Maybe it's the size of Stonehaven that tests the range of the radio equipment used? I mean we are asking close frequencies to stay separated and provide maximum control at 50m+ ranges.

I still want to investigate if people were closely placed to others in their heat, and see if there was a pattern of problem vs. frequencies.

Would even spacing help or hinder? We could establish bays on the rostrum, and number them to the cars? That would evenly space everyone out on the rostrum. Is that bad or good for radio signals? (never mind views or personal preference)

[P. Harrod]

There seemed to be quite a few problems just after the banked corner, one thing I noticed there, it looked like a metal bar , possibly used to block off the track, was sitting next to the track, where there was also an old tyre. Surely that could be reflecting radio waves and causing some of the problems.

[sdrcc]

Not convinced the narrow bars have this reflective effect. I was under the impression it usually requires large surface areas to cause a major problem for receivers.

A narrow guage bar (3 inches diameter) would be unlikely to have such an effect.

However, next meeting we will leave the bars there, till we can establish someone has a problem, then relocate them for the next heat. This way we can lcoate the problems and remove them.

We shall do this for all the suggestions raised on the forum.

[Bt]

We could establish bays on the rostrum, and number them to the cars? That would evenly space everyone out on the rostrum.


I dont think this would help, it would aggrevate the drivers more than anything. As people like to stand in the spot they feel comfortable in, i know i do anyway..

[rotax62]

One thing that I noticed was quite a lot of people in the pits testing there cars >:( whether they checked that it was ok to do so am not sure ::) ??? I only suffered one glitch all day and am sure it came from someone testing their car >:( A Transmitter control would be good for any other big meetings. It would be good the be able to trust each other to be responsible but I don't think we can :-

Gary ;)

[sdrcc]

Transmitter pounds usually require another overhead with people to run them. That means someone else has a very busy day or they don't get to race.

I was very loathe to do that at the GP, but have personally decided that I won't concentrate on running a car at the next one; leaves me free to keep everything organised.

But if I have a volunteer (or a few) then sign up here...

[Bt]

tinkering with your car in the pits is fine during racing as long as people have/use a DSC Lead (connects there transmitter to recieve by wire instead of using radio signals) or if we started using dom's old idea of using the pegboard during racing.

What about not allowing people to switch on transmitters or cars at all (except for DSC leads of course) during racing but waiting until the end of each round where you allocate a 5/10min segment(time forbidding) where people can try there cars using the peg boards.

The other major overhead with transmitter compounds is insurance, you have to make sure the club and individual will be covered in case of any accidental damage to people's equipment.

[QM]

Good point BT, but transmitter control is a safety requirement. All major flying events have a transmitter control (an insurance requirement) as an out of control aircraft kills people, as happened earlier this year in an uncontrolled event :-

Model cars don't often kill people, but boy can they cause serious injuries. So really a transmitter control is essential for large meetings. We even operate one for our regular club meetings, as we couldn't stop people switching on their transmitters during a race. It may not have caused injury, but it did cause damage :-

Yes there is a risk for liability, but that is covered by the individual, as they are responsible for placing their transmitter in the boxes, and collecting it again. We only have a supervisor to check that all sets are off while in the box. Anyone with a very expensive transmitter should have it insured under their household all risks policy, or a seperate insurance policy ;)

[sdrcc]

I would agree with Q.

If the drivers want a transmitter pound, then they have to be liable.

If they don't want to be liable, don't ask for a pound, or don't leave the transmitter. If the attendees at a meeting want a pound (hands vote at drivers briefing) then all transmitters would have to be submitted, not just one per driver.

Unless all transmitters are left with Control, then the pound is pointless. If we run a pound, then anyone with a transmitter in the pits, and are involved in the meeting, will be asked to leave.

That's the only reasonable way of running it. Otherwise we'd just be wasting time and effort. The only people disobeying the pound, are the very people who are likely to switch on regardless.

[Gary Dunn]

The best transmitter pounds are those that don't require supervision/hands-on by the Organising club.
The best I've seen is at Southport. It's part of the rostrum. The driver collects it from 'his' individual pigeon-hole & leaves it there before he leaves the rostrum.
Probably not a practical proposition in this case.
If one is created, it has to have weather protection.

However,I think there's a couple of important points being missed.

Various people are pointing at specific points on the track as being 'problem areas'. The instances of 'glitching',- which is more likely the symptom, are not caused by someone having a transmitter on in the pits.
If someone switches on in the pits on a frequency being used on the rostrum, the car being raced doesn't get wee glitches,- it usually goes out of control.
Similarly, if a car is being tested in the pits, the "rostrum transmitter" will make the "pits car" go bananas, telling the pits user immediately somebody's using that frequency if they've been stupid enough not to check before switching the Tranny on.

More basic still, why should Stonehaven need a tranny compound when nowhere else in Scotland does?
Are the local guys really guilty of ignoring basic procedures? Seems unlikely. And it is not a serious problem at the Scottish Championship rounds, which is what most of the GP 'visitors' will race in. I'm not saying it never happens, but it's pretty rare.

If it continues to happen sporadically at the club meetings then maybe more detailed investigating is required. Such as maybe keeping the drivers on the rostrum after a race & switching off transmitters one-by-one to see if a problem disappears & narrowing it down to someone's kit,- be it tranny or car.

The last I heard, the BRCA used a hand-held portable tester that can identify if a tranny is sending out unwanted 'spikes', which can be picked up by a different car's receiver.
Unfortunately, it's expensive, made in the U.S., & doesn't have EEC approval.
There is other kit in use around Britain, but last I heard it wasn't as comprehensive, or portable.

[sdrcc]

Gary has summed up what I didn't want to say.

It's highly unlikely that a transmitter pound is what is required.

If we all read back through earlier posts, we do have a huge track, which when coupled with the narrow bands of frequencies we use, and mixed with the damage (invisible) that happens to receivers and crystals, it's a more likely cause than blaming the surroundings.

I notice that the majority of problems either occur at the farthest points of the track, and also when there are several transmitters in between your transmitter and the car (you might be far right, the car is at the left of the track).

I am keen to tackle this problem, and see what can be analysed from this feedback. I'll also be investigating hiring such a unit as Gary describes.

But costs may prohibit this. We are not a rich club by any means, and it's a struggle to keep the accounts out of the red each year.

Thanks to everyone's support this year, we are having a really good year, and hope to grow on this next year.

But everyone have a think about the quality of their kit. Remember, even brand new kit can be blocked out by a bad transmitter...