433 Mhz Transmission

Projects General Guidance
1

Dear all,

for a project I have in mind the 433 Mhz transmitter/receiver modules below seem very well suited.
433Mhz
I just wonder, whether you could attach a sensor like this speed sensor
speed sensor
directly to the transmitter and then send the data to the receiver, which would be hooked up to some arduino or whether you need a second arduino to collect the sensor data and then send them to the receiver. So basically the question is: do I need two arduinos or would one be sufficient?

Any help would be highly appreciated

M.

2

You would need just one Arduino to handle the sensor and transmission. And, of course, another for the receiver and associated decoding.

3

Thank you, Terry, for the clarification! Am I correct to take it, that for handling the data and transmission one of the small arduinos would do, any recommendation?

4

I doubt the radio is capable of that amount of data, AND it's probably illegal.

5

It is rare, that anything sold by a an online store in Germany is illegal and if it is this is specified. Since nothing of that nature is found on the pager I take it using it does not pose problems. As for the data rate that does not seem to be a problem either since if I use a small arduino to collect the data, as Terry proposed, I can process them and limit the amount of what is to be transmitted, can't I?

6

I’ve only recently started playing with similar Tx/Rx pairs to yours myself. For compactness and versatility I’m using Nanos.

@sonofcy:
The devil as usual will be in the details. For example, @maplesd has not yet said how frequently the speed measured by his opto-coupler must be transmitted.

7

The device itself is legal, how you use the ISM band has rules and part of that is that it should be low bandwidth. How much data that is of course is fuzzy, but sending a temperature once a minute will be ok, sending it once a second will not. Sorry, I don't make the rules.

8

Something like 20-30 float values per second would be fine. Would that be too much to transmit?

9

In Germany, the limitation is on transmit power (10 mW) not duty cycle.

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10

Hi Emily, thanks for chiming in! The spec says you could have a range of up to 200m with 12V. I actually need something like 1.5m so transmitter power perhaps shouldn't be a problem.

11

Depending on the difference they yes it should work. I have just been working with 433Mhz for a remote sensor.

You will need an Arduino board for the transmitter. As this pair is an On/Off type the receiver will receive as much noise as there is signal. Therefore you will need to put you data in some recognizable form.

This will give you some idea of how a typical remote sensor works.

12

I wouldn't think so.
In Germany it's the 868MHz band that has a 10% duty cycle limitation.

13

I’m not sure. My last project was simply to transmit and receive the message ‘Terry’ as I increased the distance between Tx and Rx, and report a a success rate of 0 to 9. The transmission frequency was about 10 Hz.

We’ll have to wait for feedback from anyone who has more practical experience with higher rates.

14

Sorry, that is not how I remember it, but at 82 and ASD who knows what I remember.

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15

Thanks for the great feedback everyone! It just occurred to me that I could bring the transmission distance down to less than 0.2m. Perhaps that might help. Basically I want to transmit data to a rotating object and I once read that slip rings for data transmission are an invention of the devil, so I wanted to go wireless.

16

I suspect it might do the opposite! I’d regard a metre as a minimum.

17

Ups, that's unexpected! At least my remark might have helped to avoid some newbie mistake. Why do you think 1m would be better?

18

You may be thinking of North America where the non licensed usage is much stricter.

19

Could be, but I thought I saw similar or identical info on the Swiss Guy's YT channel, but maybe not. I live in northern Canada and I doubt there is even one other user nearby, much different in EU and USA is growing.

20

I'm too lazy to look up Switzerland but they are not in the EU so maybe that is the difference.

I know in North America there are different regs for licensed use both north and south of the Canadian border as well as east and west in the USA.

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