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hello

i only no about 27 ghz transmitter and receiver and crystals . can anyone please explain 2.4 ghz and why there is no crystals and how they connect please

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i've only ever used 27mhz Acoms controllers but i have all 6 bands now so last week i bought a 40mhz set up to move on to but my mate has convinced me to use a 2.4ghz set-up for my nitro truck

all my 27mhz and single 40mhz gear cost a few £ each, used off eBay, but the 2.4ghz is more expensive as i'll be buying it brand new. I'm looking forward to comparing it, particularly when i'm running at the same time as he is on the same frequency

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i've only ever used 27mhz Acoms controllers but i have all 6 bands now so last week i bought a 40mhz set up to move on to but my mate has convinced me to use a 2.4ghz set-up for my nitro truck

all my 27mhz and single 40mhz gear cost a few £ each, used off eBay, but the 2.4ghz is more expensive as i'll be buying it brand new. I'm looking forward to comparing it, particularly when i'm running at the same time as he is on the same frequency

I've got the Acoms Technisport 0555 2.4GHz, and it's awesome for my purposes/ Recievers are cheap and it's got tons of adjustability. I'm using it for both a Jugg2 and a TA02

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I started right from the beginning with 2.4G radio gear. The range is decent, there's no Servo/ESC glitching, and trim/EPA data is stored digitally in the transmitter memory chip even with some cheaper transmitters (look out for digital trim buttons instead of "analogue" rotary knobs). Plus, theres no worrying about crystals and shared radio channels. One disadvantage of cheaper 2.4G receivers is however they are often missing a BEC, so it should be included in the speed controller, which is not the case with Tamiyas TEU 101BK and 104BK.

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Hi,

I used to think that 2.4Ghz was all just about marketing, but now I think that aside from the convenience of getting away from crystals, they might even help you lap faster -

http://rcarduino.blogspot.com/2012/03/read...o-you-need.html

Duane B

;)

"Walk-away" test is just about signal strength, not about how fast you will lap. And putting a 27MHz AM radio in a built-up environment is bound to cause interference - the frequency is open to many uses so there are lots of potential sources of interference, and AM is very prone to interference anyway (you can tell that from the radio reception in your own house).

A good quality FM radio, preferably on a dedicated RC frequency (40MHz in the UK) is effectively interference free and just as fast in response as an 2.4GHz system - many top racers still use FM. 2.4GHz will also get interference in some situations, especially when there are wireless video signals around.

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"Walk-away" test is just about signal strength, not about how fast you will lap.

Admittedly, I'm arguing the hypothetical here, but if poor signal strength is introducing "chatter" and therefore reduced steering control, it's probably going to affect your line and therefore your times.

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Admittedly, I'm arguing the hypothetical here, but if poor signal strength is introducing "chatter" and therefore reduced steering control, it's probably going to affect your line and therefore your times.

It's going to make you crash. Interference won't slow you down without your realising - you will definitely know about it.

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Hi,

Having measured signal variance and observed it in the form of steering chatter and ESC stability I can assure you that it is going to reduce grip in the corners.

near.PNG

The reason we don't crash is that when we learned to drive our RCs we were already compensating for this in our cornering speed - I am sure that you learned what speed you could corner at by reducing the speed until you stopped crashing ?

With 2.4Ghz systems I have measured the signal as having no variation at typical racing distances there is also no steering chatter.

I am quite certain that I can get a car around a corner at a higher speed when there is not someone sat next to me randomly waggling the steering wheel, I am puzzled that you would disagree.

Duane B.

rcarduino.blogspot.com

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Hi,

Having measured signal variance and observed it in the form of steering chatter and ESC stability I can assure you that it is going to reduce grip in the corners.

near.PNG

The reason we don't crash is that when we learned to drive our RCs we were already compensating for this in our cornering speed - I am sure that you learned what speed you could corner at by reducing the speed until you stopped crashing ?

With 2.4Ghz systems I have measured the signal as having no variation at typical racing distances there is also no steering chatter.

I am quite certain that I can get a car around a corner at a higher speed when there is not someone sat next to me randomly waggling the steering wheel, I am puzzled that you would disagree.

Duane B.

rcarduino.blogspot.com

So what your saying is the glitches you are getting from your AM radio in your house trump my 20 years experience of actually racing the cars? I was practicing at a track with a 60m straight last week with a car that is probably pushing 50mph top speed and the car ran dead straight using an FM radio. I still run 27MHz AM cars in my back garden which is 20-30m long and don't get any glitching.

I'm assuming you have a background in science - surely you can see that putting your radio in an atypical situation is going to give you an irrelevant result? Glitching in your house has no relevance to the radios performance in actual driveable conditions - unless you are trying to maximise the corner speed around your sofa.

Do your measurements at the track. Then drive the car back to back with the 27MHz radio and the 2.4GHz radio. Then drive the 2.4GHz radio back to back with a good quality AM or FM radio. Then report your results.

Very cheap 27MHz radios can be unresponsive but that is bad design, not a flaw with the method of transmission. Futaba is good quality and I doubt you could tell the difference in response speed or consistency between a Futaba 27MHz AM set and any of the top end 2.4GHz radios, I know I can't. I've seen drivers race at the sharp end at regional level using decade-old AM Futaba Attack radios.

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I certainly notice the difference between my Futaba 2PK 29mhz AM systems (29mhz is Australian surface RC AM frequency with nothing else on the same bands), and my Futaba 3PKSs 27mhz FM (27mhz in Aus shares with toys and household devices), especially when the 3PKSs is in HRS mode and you're using digital servos. The AM set is laggy by comparison, but you compensate for it and after a few laps your lap times are no different than with the better radio. You notice it the most when you've been using the 3PKSs with either the 2.4ghz modules or FM synthesised modules installed and then straight away pick up the AM set. Another example is when you're using a ballistically fast model, the AM set is just too laggy for the amount of control you need.

I notice very little difference between FM and 2.4Ghz.

I get no interference on AM, FM or 2.4ghz, all except for one spot on my track where they all play up (I have another thread on this and still not found a reason why or a solution).

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Hi,

As you know from reading my suggestion for the walk away test, what I am suggesting is that in a typical environment, the street I live on, there are surprising amounts of chattering in the Servo and the ESC at only moderate distances. The street I live in is very similar to most of the environments we race in, I can think of tracks that are in the basement of shopping centers, underground car parks, school halls, all environments with similar or worse characteristics than the average street.

As you also know from my blog, the test I have suggested can be repeated by anyone in any environment that they choose to race in, its a very simple test and you will either come away from it thinking 'hey thats great, my radio is very stable' or you will walk away thinking 'wow, thats a bit surprising, I really didn't expect my signal to be this bad at the far end of the track'

If your in the later camp then you can judge for yourself whether the amount of chatter in your steering and esc is sufficient that you could be faster if you were able to eliminate it.

My background or experience is irrelevant to such a simple test that can be done by anyone and might surprise a few -

Do you need a new radio

Duane B

rcarduino.blogspot.com

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Hi,

Having measured signal variance and observed it in the form of steering chatter and ESC stability I can assure you that it is going to reduce grip in the corners.

near.PNG

The reason we don't crash is that when we learned to drive our RCs we were already compensating for this in our cornering speed - I am sure that you learned what speed you could corner at by reducing the speed until you stopped crashing ?

With 2.4Ghz systems I have measured the signal as having no variation at typical racing distances there is also no steering chatter.

I am quite certain that I can get a car around a corner at a higher speed when there is not someone sat next to me randomly waggling the steering wheel, I am puzzled that you would disagree.

Duane B.

rcarduino.blogspot.com

You do realize the interference you have recorded could easily be the fault of the Arduino which you have packed into the car right by the receiver.

For those who don't know, the Arduino runs at 16MHz and is completely un-shielded so it will put out interference. Since 27MHz is a lot closer to 16MHz than 2.4GHz, as well as being lower frequencies and the proximity to the receiver antenna, I would expect the results you got and suspect the glitching to be caused by the Arduino. Although the radio frequency has a part in this, it would not be the direct cause of the problems.

In the interest of science and finding the truth, I would suggest running the same test on a 40/75MHz set and look at what the results are.

BTW, what are you measuring and what are the units on the graph? The x-axis looks like time in secods, but what is the other one?

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Hi,

The test really is very simple, all you need to do is put your transmitter on the ground and walk away from it with your car. You don't need to walk miles away, just to the far edge of the area you would normally drive in.

What you are looking for is 'chatter'. In my tests with or without additional equipment in the car, the steering servo would begin to move erratically back and forth. This movement was quite sever at the far end of my usual running area using a 27Mhz set up, with a 2.4Ghz there was no movement at all.

Based on the number of people that have responded to this thread you have far more equipment than I do so how about doing the test and sharing your experience.

Stu22,

The Y-Axis is microseconds, the Arduino is well decoupled and all traces are shielded, the results are the same whether the Arduino is in the car or not.

Duane.

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Usually when you buy transmitter and receiver as a set they're already bound and can be used straight out of the box. If you buy an extra Rx you'll need to bind it to the transmitter. This is usually a simple push-button exercise that take about 30 seconds. It'll be explained in the radio's manual anyway, just make sure you don't bin it!

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