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Trying to build something. A remote for the car that runs at about 7mhz to 9mhz


liamblack

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1 hour ago, liamblack said:

Firstly, how do i know what range my remote control operates at?

 

Secondly, is it possible to change it to a specific frequency?

 

Thank you.

 

They quite often quote ranges for equipment but it depends on so many factors you have to take it with a pinch of salt.

With old systems that were crystal based in the 27mhz range you could change crystals in the transmitter and receiver to alter is it slightly but there were only 6 options in the 27mhz range that could be used.

These days 2.4ghz chooses automatically what is supposed to be the strongest channel as well as not interfering with anyone else.

While it might be technically possible to change frequencies manually somehow you have to consider if it is legal to do so, certain bands are used primarily for certain things and adding a signal into that band to use a piece of equipment that isn't supposed to be used in that band is illegal and could land you in hot water.

Edited by markymarky
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iirc land use

is old school.27mhz

40mhz became a 2nd option

 

then it went to the "interference free 2.4ghz"

 

there are 2 types of 2.4ghz systems if I remember correctly

fixed and FAST

 

Fixed is 1 frequency within the 2.4ghz range

fast jumps around the 2.4ghz scale to keep you in the best signal

 

any other isn't intended for use with RCs

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  • 2 months later...

Checking the range.

(Best to have an accomplice to reset the model after each operational test.)

Put the model on the ground and switch on the TX then the model.

'Bind' them.

Then take a walk with the TX and a stick, or similar marker, every 10 steps operate the model if it responds then it is within range.

When the model does not respond push the stick into the ground and walk back to the model counting the number of steps.

Do this three times and then divide the total number of steps by three and multiply by around 0.6.

This will give a very approximate range in ONE direction.

If you have a long surveyors tape measure you can take a more accurate measurement which you can double.

(Normally operators operate from a 'mid-point' so the distance will be doubled giving you 60-100metres of range.)

Most surface models will be good for 30-50mtrs in one direction, which can be a challenge to the MKI eyeball even with a 1:12 scale model.

Your Transmitter will theoretically operate a model within a hemisphere of 30-50meters in every direction.

(My experience with 16mm narrow gauge model locomotives suggest that 75metres is a practical maximum in ideal line of sight control for a surface model - running on metal rails may provide a degree of 'RF coupling' to the model.)

If you need to extend your operations I would suggest that a standing on a pick-up truck or substantial roof rack on a Transit would offer closer to that 75metre range as you will raise the transmitter relative to the receiver. Usually competition driver positions are elevated by 2-4 metres to ensure a good view of the track and ensure that radio signals are reliable when the track topography may compromise signal quality.

I am inclined to think that with some of the brushless models capable of 80-100kph (50-63mph) out of the box you could be running into range issues very quickly if you are pursuing maximum speed runs. (Hopefully the ESC is set up to stop the model if RF connection is broken.)
Modellers operating in sports halls and similar have a space from 12m x 20m to 35m x 20m so RF range is or rather shouldn't be an issue.

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for speed running we use rx boosters 2.4ghz can be boosted to well over 500m of range, out the box some radiolink say 150m range with higher end 500m.

tho these cars are also doing 200mph and most runs happen with the driver up a 2m tower thus more range and nothing blocking line of sight on the runway to break signal.

on the road i find decent signal range as it bounces off houses, basically unboosted my signal is worse on the runway.

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