Communicating with 433MHz OOK/ASK wireless modules (#88)

[@stevenq4859]

With out a doubt the most comprehensive and best video on communicating with radio frequency I've seen, thank you.

[@MartynDavies]

You are very kind

[@englishrupe01]

This is a really fantastic clear explanation of what is happening in these modules! Thank you so much for taking the time to help us newbies to this field. I really appreciate it!

[@davidederosi6068]

You made difficul things understandable things. You have teaching skills of keeping attention focused and explain the logic of things you are talking about. Thank you.

[@bornach]

433MHz ASK is the protocol used by many remote control electrical sockets such as those made by Status. I hooked up the receive module to an oscilloscope to examine the pulses sent when I pressed each button on the remote control. Reverse engineering the codes allowed me to program an Arduino to send the same codes via the transmit module in place of remote control. I can now create a crude Internet of Things switch to turn on and off anything that you plug into the mains. I think bitluni's channel goes into more detail on how to use these modules to do this.

[@MartynDavies]

I've got some old wireless power switches - I'll have to see if pressing buttons on the remote control results in any messages on the Arduino

[@jeriellopez4927]

Do you need an oscilloscope to do this? Cannot get the code using arduino?

[@harjeetsinghmakkar5177]

I was really looking for such explaination only. You have quality of a good techer. Nice editing too. Explained so well, slowly but surely. i had to listen to it at 1.75 times the normal speed. But worth it. Keep it up.

[@MartynDavies]

I definitely can't understand myself at 1.75 speed

[@bgable7707]

THANK YOU!, for the clear detailed explanation of the ASK and the Receiver mode component back down. It really is quite simple .... when you know what your doing. Cheers

[@AndyMcGeever]

For simpler calculation of wavelength to one Mhz if you don't need to be ultra precise - 300/Freq - 300/433=0.69m or 69 cm. Antennas designed for the 70cm amateur band work well for these transmitters.

[@BalticLab]

I think this is the first time KZbin recommended your channel to me. Good stuff, subscribed!

[@bjornroesbeke]

I know these modules are used in wireless doorbells and radio controlled sockets, so i bought and experimented a bit with these modules. So far i've only been able to get 30cm range with a 1/4 wavelength antenna, and only when the polarization matches almost exactly. The receiver is outputting continuous noise, even when the transmitter is turned off.

[@demef758]

Simple on/off keying communication like this is ideal for standard serial protocols that use stop and start bits to synchronize the data stream. 2400 or 4800 baud should work great. Many uPs are equipped to work with these streams, too. Just make sure both your transmit and receive uPs are set for the same baud rate, and you're in business.

[@MartynDavies]

I agree. For IoT projects a simple radio link is ideal so that you can make things like remote sensors as cheap and simple as possible.

[@the1spyderryder]

The round device on the transmitter is a SAW device not a crystal as one would think of it.

[@nikospapakyritsis3161]

Thank you for this analysis !

[@KT-ut9zg]

Fantastically detailed explanation. Thanks a million. In a rather silly way, I'm going to see if I can create a simple morse transmitter and receiver using the 'binary' on/off to send and receive.

[@MartynDavies]

yes great idea

[@MrBobWareham]

A very good video with lots of information thank you and no banging music how refreshing

[@MartynDavies]

Thanks. Yes, I dislike constant music in KZbin videos also.

[@bitschips]

Martin, thank you for the explanations and for explaining the transmitter and receiver diagrams (yes it is complicated!) Best regads and be safe.

[@MartynDavies]

Glad you liked it

[@craiglarson2346]

You say there are four discrete voltage levels for ASK. I had no idea. That raises the value of binary by a square of 2. I continue to be shocked by the fundamentals. Thank you for your clarity and contribution.

[@MartynDavies]

ASK can have as many levels as you like (with this code I'm using here it is 2, which means the same as OOK), it's all a question of the complexity of the receiver, because of course it gets harder and harder to tell one level from another, the more levels you add.

[@tlangdon12]

As Martyn says, you can have as many levels as your receiver can distinguish between. If your receiver was sensitive enough, e.g. it had eight levels, you could send one byte of data in one time period. This is one way to achieve faster data transmission rates.

[@awaitingthetrumpetcall4529]

Thanks. I always wanted to know about the circuits inside the modules. I designed my method of sending data based on the TV remote method. I use a 'start bit' and a 'start byte'.

[@saikumarv2639]

I Have learned new thing from this video, Good explained .

[@bigbothoee8617]

Very nice info and detail have you used these with your own circuit

[@manashiroy331]

Wonderful, in depth explanation. Thank you very much.

[@mysoul1802]

Thanks for your sharing, I want to use STM8 instead of arduino board but don't know how.

[@MartynDavies]

It's been a while since I used the STM8, so I can't help a lot, but I remember that the interface/programmer boards are cheap and that you have to download a special C compiler to program it. Here's a starter tutorial that talks about that: maker.pro/custom/tutorial/getting-started-with-stm8-microcontrollers

[@grzesiek1x]

I make circuits like those ones for my own :) They are really nice to play with

[@eagleeye389]

You are a good man, thank you for this information

[@cslovell]

Thank you very much for such an informative & quality video. If I may ask: It appeared to me that you did not include the spi library in your receive sketch whereas you did include it in the transmit sketch. Is there any reason it's not required in one but in the other, or was that just an oversight? Also, is the spi library required when specifying the transmit & receive pins?

[@MartynDavies]

SPI is a different type of serial interface - basically some chips have the SPI pins built-in (e.g. LED controller chips) to allow several chips to share a set of control pins to one controller (e.g. Arduino). This is the 'old-school' serial interface, which at its minimal level just has two pins (RX and ground or TX and ground). This kind of serial interface goes back through the decades to even before I started using computers and connects just two things together, here the Arduino and the RF module.

[@9wattd]

Thank you, teacher. Your explanation can help me to create & apply some devices. Already subscribed.

[@douglasheld]

15:57 Thank you, I really like your buffer management and explanation. This code makes much more sense to me than the RH example code with the gratuitous use of the *s. When you slap the buf[buflen]=0; however, isn't this writing beyond the end of the buffer? I can appreciate the clarity but maybe you should expect a message of BUFSIZE-1, and then add on the protective trailing 0 before interpreting the bytes as a string.

[@MartynDavies]

True. Perhaps I corrupted the following item in memory, but I seem to have got away with it this time.

[@douglasheld]

@@MartynDavies Oh, thank you for confirming. I am still learning this language.

combining theory with practice, a great video

[@2Green2Freak]

Wow thank you very much for this very very educational video

[@vaibhavkhurana215]

Thank you so much !! This was really informative

[@HanLok420]

Thank you for the detailed explaination Martyn! Is it also possible to activate and deactivate a 433 MHz power outlet with this, if you collect the data send by the remote before? If yes, how does the transmitted data code have to look like if you send it as binary or decimal code? I have tried the RC-switch library before but it is working very unreliable and before I am buying a new transmitter to exclude a disfunction, I would like to try the RadioHead method.

[@MartynDavies]

I haven't reverse engineered one of those outlet switches before, but yes I would try to capture the transmissions from the remote control and see if I could understand the byte structure. Note that 433MHz is a band (I think about 1MHz wide), so there are variations in frequency between devices, and units from different vendors can be fundamentally incompatible.

[@HanLok420]

@@MartynDavies thanks for responding, capturing the signal of the worked out without any issue. The problem i have is, that I dont know how to write the code to transmit the data with this method so the power outlet receives it.

[@mannnanshaikh7608]

you are god sir . very clear explanation. thank you soo much

[@user-bj4lp3fr1o]

I only get about a 5 foot range even with a 17.3 mm antenna.

[@MartynDavies]

That is poor. I would suspect a faulty module.

[@dronesrus7436]

Your antenna must have 17,3 cm, not mm. More power Addition with higher Transmiter-voltage, e.g. 9 V is better than 5 V... good luck

[@user-bj4lp3fr1o]

@@dronesrus7436 Thanks for the correction. I'll try it with the longer antenna.

[@imtrung5244]

Thank you so much for clarifying me about 433mhz. I bought one receiver and a remote. But I don’t know why the distance is too short (abt 17cm) even I tried to use antenna of 17.2cm. Do you know what happened to my receiver?

[@MartynDavies]

To be honest, I haven't tried to see what distances it will work, but I seem to remember that someone on YT has done a video on this.

[@hadibq]

Brilliant teaching skills! Thanks a lot!

[@cinibar]

Excellent description of this system! Thank You! Which now inspires some questions! PLEASE bear with me here. The frequency number mentioned is 433 MHz. I'm guessing that it is exactly 433.000, correct? So since this is probably right, then if I had more than one of these transmitters, they would all be on 433 and so all receivers are tuned to the same 433.000, correct? If so then if two or more transmitters are transmitting simultaneously, then the receivers would all hear/receive all transmitters at once?! Correct? Since the receivers are not using a crystal for the receive frequency, It appears that the receiver is somewhat wide banded and tunable as you mention. What I would like to do is use this system but have no transmitter/receiver pair interfere with each other. By them all being on the same frequency, 443.000 this has to be a problem. Can the transmit crystal/oscillator be changed to a slightly different frequency and then retune the receiver to that new frequency? I'm thinking it should be able to do this. The replacement 'oscillator' I would use is a SiT8008B programmable IC. What I would like to do is use a few of these in somewhat close proximity of each other without any of them causing interference with the others. Yout thoughts Sir? Thank you very much! Cheers!

[@MartynDavies]

If multiple transmitters send at the same time, then yes interference can happen. However this scheme only sends carrier for 1's, so you might get away with having multiple transmitters as long as they're sending infrequently. Also, stronger signals (e.g. closer modules) will likely get precedence over weaker. These are very simple radios and don't have features for contention, security, acknowledgements etc. For complex scenarios, you might switch to OFDM, bluetooth, Lora etc.

[@cinibar]

@@MartynDavies Thank You! I will also be checking out the HC12 module in which you can program it for slightly different frequencies. That way they should not interfere with others.

[@johnthompson4011]

Thank you bro,Made it crystal clear for, but had to play it at 1.75x speed to not fall asleep, get rid of the umms,errs etc...

[@MartynDavies]

At least I'm not rude

[@johnthompson4011]

Loved ur vid bro,chill @@MartynDavies

[@ithaca2076]

Your handwriting looks amazing!

[@emylrmm]

Some of the designs for the Receiver are very sensitive to noise on the VCC connection. Even a tiny voltage ripple on VCC may cause output to put out a continuous square wave. That will render data reception impossible. Power the receiver from a very tightly regulated 5 volt supply

[@MartynDavies]

That's interesting. My 5V power source (a Riden module) seems very stable.

[@Althu-blog]

Am used this Modyool but one problem. No range 100mr . Haw to boost range in circuit Sir

[@MartynDavies]

You might get improved range with a better antenna, but this module is intended to be a very low power transmitter.

[@SLATEB0Y]

Very interesting and nicely explained.

[@louiswilkinson4258]

An excellent video ! Thank you very much.

[@douglasheld]

5:25 that's only one significant digit!

[@saikumarv2639]

Make more videos like this sir.

[@Dralsoft]

what woud you say it consumes less? ESPNOW protocol or this

[@MartynDavies]

I have not used ESPNOW, but in general low complexity means low power

[@slucas601]

On the receive module in the circuit where the incoming signal is combined with the 433mhz signal generated in the upper part of the circuit diagram before being amplified by the first op amp, how does the combining of these two inputs decode the incoming signal? Also, what is the practical range and data throughput of these types of modules?

[@MartynDavies]

I think this is what is called a 'heterodyne demodulator', where you mix the signal with something close to 433Mhz, and this gives you a 'beat' frequency that is the difference of the two, and this will be in the range that the op-amp can amplify. That's probably all you need, since the aim is to distinguish between 'signal' and 'no-signal' for OOK. I haven't tested the range, but I imagine quite short due to other devices in the band: car keys, mains remotes and so on. Also, the output stage of the transmitter is only one small transistor as you saw, so the output power is low. You could do a lot better in aerial design of course than (cough) my piece of wire. For a range of tens of metres you probably want Bluetooth, or for hundreds of metres Lora. These systems have extra coding in the signal to improve signal to noise ratio and detection of errors.

[@slucas601]

Thanks Martyn. I will investigate more and I have a order placed for these parts to experiment with. Great introduction, you have sparked my curiosity.

[@techinfotahir7912]

Yale battan theek nissan.

[@James_Bowie]

Very good video, thank you. 👍 Re the Tx schematic, what is capacitor C1 with the dotted lines? Also, I bought this Tx/Rx set and the Tx came with only one coil -- the larger one. Is this a manufacturing error or have they somehow done away with it?

[@MartynDavies]

I suppose that C1 allows a low impedance path for high frequencies (i.e. to attenuate them). L1 is in the power rail (is this what's missing?), so this would reduce signals leaking back into the power supply (or microcontroller?). I imagine that both these components could be left out.

[@mekimr9736]

You use subliminal picture in 16:15, why ??

[@MartynDavies]

Just an error in editing. It seems to be the background frame: I composite the screen grabs over the background in the video editor, rather than chroma-key in video sources in real time.

[@mekimr9736]

@@MartynDavies Ok sorry

[@humward888]

Great video, great explanation. Thank you.

[@MartynDavies]

Thanks!

[@simonsalon9478]

MR Martyn Can i transmit with this tx module another freqency? under 433Mhz I mean

[@MartynDavies]

It's an oscillator based around a 433Mhz crystal - I expect if you swapped in another crystal, you could change the frequency.

[@simonsalon9478]

@@MartynDaviesThank you for answer i gor it but Sir for example i wanna transmit a frequenct like 412.2mhz ,so when the module support 433 mhz ,any way with add some other element ? changeable frequency crystal

[@alaanoor3679]

Mr, Davies i have a question i've noticed that we always use two arduino boards , one for Tx and the other is RX for sake of two way communications , can we use a single arduino for tx and RX and the other arduino also have TX and RX so we can exchange data ?

[@MartynDavies]

For two way communication, you might want a radio module that has both Tx and Rx built-in (i.e. a transceiver), so that you minimise the chance of receiving your own transmission. I think these 433Mhz modules are best used in the simplest applications.

[@abubakarrsawaneh1930]

Thanks this is what I was looking for.

[@kamleshchavan7451]

Sir can it be possible for you to explain the RF receiver module circuit diagram more in detail , I mean everything in detail

[@MartynDavies]

I'm not sure that I have more detail

[@kamleshchavan7451]

@@MartynDavies ok sir thanks

[@egyrmexiq1]

Beautiful explanation, thanks for posting..

[@tlangdon12]

Thanks for the video Martyn. Have you done any further experiments with these modules and the library to see what is the maximum data rate that you can get reliable communications with? I think anyone trying to use these modules would benefit from knowing what is realistically achievable with them if you want reliability.

[@MartynDavies]

I haven't experimented with the rate, but I suspect it will be fairly low, firstly because the receiver doesn't use interrupts and so the program is polling for incoming bits, and secondly because the Atmel processor is quite a slow one anyway. I worked on some multi-port serial cards many years ago (also a polling solution), and I think we had the bit rate at 19200 for reliability. Hardware USARTs usually have some kind of buffer (at least a byte) to store incoming bits until the main processor has time to come and service the receive request. The default speed in the RH library seems to be 2000bps.

[@tlangdon12]

@@MartynDavies Thanks Martyn. That’s really useful.

[@ДмитрийНорд-с3я]

Автор, можно скетч для трансмиттера отправки конкретного кода 24 bit?

[@8m405]

Really impressed by your knowledge

[@tonywright8294]

Why did you keep moving the parts ?

[@forthidiot4297]

How to change variable frequency replace components

[@pro-eq9oy]

Very valuable information for me. thnks

[@chenitimohamed4141]

Please tell me the type of oscillator, is it colpitt oscillator or not

[@MartynDavies]

In the receiver? I would say yes.

[@chenitimohamed4141]

@@MartynDavies no in the transmitter.

[@SidhuD_96k]

Kitne metar pe kam karta he

[@ramuvanparti]

I have created same RF modules using encoding and decoding IC HT12 how range of is very less how can achieve it for 100 meters?

[@MartynDavies]

I did not do a range test, but this guy did: quadmeup.com/fs1000a-and-xy-mk-5v-433mhz-rf-modules-overview/

[@kaustubhponkshe6186]

Can I transmitt PWM signal generated from arduino using these RF modules ?

[@MartynDavies]

yes, that should work - the 'on' pulses will get modulated with the 433MHz carrier, and your original PWM waveform should get recovered at the receiver

[@caner8688]

what is the length of the antenna belonging to transmitter? please

[@MartynDavies]

I don't have the unit with me, but the wavelength at 433MHz is 0.69m, so most likely 17cm, which is about a quarter wavelength.

[@demef758]

3*10^8 / (4 * 433 * 10^6) = 17.3 cm, and for both transmitter AND receiver!

[@rongarza9488]

Thank you, Martyn. Where can I get more information on the different amplitude signals you mentioned from minute 9 to minute 10? Is it just a matter of using different resistors between the transmitter's data pin and gnd, and reading the receiver's data pin as an analog instead of a digital signal? I've just got 3 events (off, medium, and high) so I'm trying to get by without a microprocessor on the send side.

[@MartynDavies]

The FS1000A is a very basic transmitter and I assume that the transistor is just switching the oscillator on and off. However, putting different resistors across the base might work. On the receive side you'll need some different software to decode multiple levels - but I suppose that the Radiohead library has something to do that (i.e. Amplitude Shift Keying).

[@rongarza9488]

@@MartynDavies Thanks, Martyn, as soon as I can get them I'll give it a test.

[@rongarza9488]

@@MartynDavies Okay my tests show that on-off works but halfway with resistors doesn't send signals of varying strengths. IMSAI Guy posted a schematic of the transmitter. I wish there were a schematic for the receiver. Could the receiver work better with adjustment? There appears to be a variable resistor in the middle of the PCB.

[@MartynDavies]

@@rongarza9488 I do show the receiver schematic in this video. This receiver won't work unmodified for your application though as the last stage is a comparator that forces the signal into on or off.

[@meszarosistvan197603]

Perfect! Bravo, and thanks....

[@euphoriachemistryclasses1383]

I am facing problem with this FS1000A module. They are not communicating. I noticed one thing that in my Rx circuit there is no 1uH inductor, but I can see in your this video that your Rx module has a green coloured inductor of 1uH ( color code Brown, black, golden,silver). Is this the reason that my Tx and Rx modules are not communicating? Each and every effort I made to communicate them but nothing is happening. Can you help me what could be the possible reason.

[@MartynDavies]

If the inductor is missing, the emitter of the transistor won't be connected to ground, so yes that would stop the oscillator.

[@euphoriachemistryclasses1383]

@@MartynDavies if I use inductor other then 1uH the it work? because I use 3.3uH nothing happened as I have inductor of only this value this time.

[@MartynDavies]

@@euphoriachemistryclasses1383 This looks like a tuned circuit (there's no crystal to set the frequency of the receive side), so I suspect the value is important.

[@euphoriachemistryclasses1383]

@@MartynDavies ok

[@yankovalsky7696]

@@euphoriachemistryclasses1383 , maybe there is an smd coil there?

[@hamidrezanaghshehchi7228]

Thank you for amazing tutorial, i wanna make a receiver how to get schematic circuit?

[@MrBobWareham]

Look on the web for PT2262%20TX-RX%20decoder%20chip.pdf

[@classicryda120908]

hi, i am using the same hardware but i cant send a 433 mhz signal from far distance, it is really strange that my receiver can only receive command when the transmitter is located REALLY close to it, like 2-5cm apart, i mean.. whats the point of having RF receiver if the achievable distance is this tiny? my goal is to receive a signal from a 433 mhz remote/switch from at least 4m distance I also tried to add an antenna for both the tx and rx but still no luck any help?

[@dandwrasan2342]

Great vid nicely done ✅👍🏻

[@surenbono6063]

..can the transmitter work one to many receiver at the exactly same time and data within it's range like normal broadcast..?..I have checked it it's not as good as espnow on esp8266.. ~30m

[@MartynDavies]

Yes you can broadcast, and in fact this is a disadvantage of these simple transmitters - anyone can receive and decode the data. You might not want a simple setup like this to control a gate or door.

[@surenbono6063]

@@MartynDavies ..you can always add a password to verify data reception.. string length check are never good enough...better with espnow broadcast

[@surenbono6063]

@Arnold Rimmer ...of course it's not an important data transmission like a redundant clock info on each reception side..I'm interested in rf clock projects...

[@btzee]

if someone sniffs and copies the transmitter and replays it? Is there any security in these modules?

[@MartynDavies]

No, there's no security. It sends a simple signal and in the clear, so is easily compromised.

[@Willy_Tepes]

Can you use these without a microcontroller, like a pushbutton on the transmitter that lights a LED on the receiver? It is just an on/off signal that is sent anyway.

[@MartynDavies]

Yes. The output of the receiver should be the same as the state at the transmitter input.

[@Willy_Tepes]

​@@MartynDavies Great, I am considering making an early warning system for camping and hiking. We have brown bears and wolves around here :) Trip wire/IR on the transmitter and a buzzer and LED at the receiver should do the trick.

[@gartmorn]

Martyn is your background in software/electronics through work or is it just a hobby as you seem very knowledgeable imho?

[@MartynDavies]

Electronics is a hobby (since my teen years). Software, cloud technology and computer communications is my daily work. I've studied software, electronics and radio; it's great to know some theory but really good to wire things up and actually do stuff; that's what really where you really find that you know what you can do. Thanks for following my videos, I really appreciate your support, and best wishes for the Christmas season!

[@gartmorn]

@@MartynDavies I thought you might have a background in software! I worked as an electrical fitter and as a plant operator in the power industry until getting early, ill health, retirement following a bad accident in the power station! We worked on all kinds of plant and control gear from 17kv downwards but it was mostly relays, contactors etc and any electronics was dealt with by the instrument techs! I did a bit of electronics when I was an apprentice and took it up again when I retired although I have always dabbled a bit! I'm afraid programming is a bit of an Achilles heel for me but I'm trying my best! I love your channel as it's a good mix and you explain things well and assume nothing of your viewers! Keep up the great work! Davy

[@saikatd9037]

Why D11? May I change Transmitter pin or Receiver pin in arduino code? Please describe the library functions

[@MartynDavies]

The documentation is online (www.airspayce.com/mikem/arduino/RadioHead/classRH__ASK.html), where you can see that 'rxPin' has a default of 11. You can of course override that in your RH_ASK declaration, as I do for the transmit side (see 14:29)

[@batkotivalio]

Hi, is this set suitable for proportional controlling of two brushed motors on rc car and Is it possible to run motors in opposite directions at the same time for drift?

[@MartynDavies]

Sorry, but I don't know a lot about circuits for radio control.

[@matheokoning4456]

I tried to copy the transmitter module but I can't get it to work. I tried the schematic you show in the video and several others on the web that are similar but with different resistor values. When I connected the ground pin of the resonator to L1 inductor, it worked for a short while. Did you or someone manage to copy the transmitter module to process in a pcb or does anyone have any tips what I can do to get it working? Is there a way to test if the resonator is still good? Would really like to be able to do this myself but have no idea how to troubleshoot.

[@MartynDavies]

No, I just used an off-the shelf one. I suspect the finished ones from China are cheaper than I could get the components for.

[@matheokoning4456]

@@MartynDavies That's right. The modules are indeed cheaper than if you make it yourself. But I want to learn and like to make my own projects in my own pcb. Unfortunately I can't find much information about this on the internet. Or am I looking wrong :-)

[@ekamautomation1567]

Can we use multiple transmitter and receiver in one room with different address mode

[@MartynDavies]

Receivers will likely receive every transmission, but you could code every message sent, then in software decide which codes to act on in any given receiver.

[@eandecraftsceylon5360]

Great information

[@channel1-u8z]

Can i use the receiver to receive data from a HC 12 transceiver? I have read that HC 12 uses gfsk. Will it be able to communicate with the receiver which is ook/ask?

[@MartynDavies]

No, these simple modules only have one carrier frequency and can't support FSK.

[@channel1-u8z]

@@MartynDavies Thank you for replying. Last question, the receiver i got which is the same model as this uses 315 mhz. If I use it alongside with a HC 12 transceiver which is 433mhz, will they interfere each other?

[@MartynDavies]

@@channel1-u8z I don't have any equipment for measuring RF emissions so I don't know, but the FS1000A has no kind of shielding so it could be quite noisy. I would just try it and see how it goes; they are on very different frequencies so that is in your favour.

[@channel1-u8z]

@@MartynDaviesThanks

[@bjgminten]

How do you know how long the period is for one bit in the on/off switching? Can you compare it with a baudrate that you can set to a value in advance? Or does this work totally different?

[@MartynDavies]

In this case, the bit rate over the radio link is set to 2000 when the RH_ASK object is created - so the assumption is that this bit rate is fixed and known to both ends of the communication. In some radio systems it's more dynamic than this - for example you can transmit a preamble with a known bit pattern (e.g. 10101010), which allows the receiver to measure the length of a bit so that it can interpret the rest of the message correctly.

[@bigbothoee8617]

How far will they work apart without antana Im hoping to have less than 1 meter apart

[@MartynDavies]

I didn't experiment much with the distance

[@alidemir8434]

i need to do this without rh_ask or i need a rh_ask lib for stm32 on cubeide

[@pupupupu448]

Hello Martyn, thanks for this great Video! But one question i have.. i cant get any results on google.. so what happends if there is a sender which always sends an signal, so always voltage on.. Now you have a receiver near, but how now the receiver can get other signals then 1, if one is permanently sending 1.. (or sending permanently waves) how a receicer can now get any 0's? The wave which the receiver becomes will look always ^^^^^^ because another sender is permanently on? Now if another sender want to send waves the reveiver cant get any offs, because of the sender which permanently sends? Or do i missing something? Thanks you!

[@MartynDavies]

Yes, this rather simple form of modulation can be jammed quite easily. A more sophisticated scheme, like spread spectrum, allows the energy to be distributed so that sending a single jamming signal has a limited effect on the system, and the signal can still be received despite the additional noise.

[@pupupupu448]

@@MartynDavies Okay, thanks :) how you mean it exactly? use a range of frequencies?

[@MartynDavies]

@@pupupupu448 It's rather complicated, but spread spectrum technologies add a spreading code that makes the signal use a much wider frequency band, such that when you despread the signal, the overall effect of noise (and other signals) is less. This simple radio module cannot do that.

[@MariaSouza-mg8bs]

Tem como colocar um amplificador de áudio no receptor mudar a bobina para escutar aviação?

[@MartynDavies]

No

[@kaustubhponkshe6186]

@12.07 , do we need to remove insulation from antenna wire ?

[@tlangdon12]

No, the insulation can remain on the antenna wire.

[@saavedra29orig69]

I wish all the videos where informative, educating and useful like this and not reproducing already known recipes of how to do this and that.

[@MartynDavies]

Thank you very much

[@saavedra29orig69]

I thank you for the video. @@MartynDavies

[@deepakkoirala2296]

How can we increase the strength of sender and receiver? Like around 500 meters?

[@MartynDavies]

I'm not sure that this module can broadcast over that kind of range, I haven't tried to evaluate it.

[@deepakkoirala2296]

Or may be like 150 meter ?

[@AravindAnirudh595]

Nice work. Can you share the detailed schematic diagram?

[@MartynDavies]

If you go to google images and search for 'fs1000a schematic' and 'xy-mk-5v schematic', you will find them.

[@asharampatel8429]

Please explain ht12e & ht12e with logic circuit

[@MartynDavies]

I don't have these chips at the moment, but this might be what you are looking for: www.instructables.com/Make-a-RF-Transmitter-and-Receiver-With-HT12E-HT12/

[@jeffbeck6501]

Awesome video.

[@Anhad1313]

Buy link?

[@MartynDavies]

Type the part number into Google?

[@kabirsharma4820]

Hey, great video.. I m trying bidirectional communication using these sensors. I have a transmitter and receiver on remote and a transmitter and receiver on robot. The robot will send the battery voltage to the remote, (only if the voltage is in acceptable limit the remote should work), then the remote will send command to the robot to move (forward backward sideward etc). I m doing this using arduino nano but bidirectional is not working. have you tried bidirectional communication, is it working?

[@MartynDavies]

No, I haven't tried bi-directional with these modules. I can see that it might be a problem that both directions will be using exactly the same carrier frequency, so the sender will hear its own signal (and probably quite loud). It's quite common in radio technologies to use slightly different frequencies for the two directions.

[@SAURABHKUMAR-vk5xb]

Sir, my modules are not working, please can you suggest something what should I do. I'm doing a project on gesture control robot with accelerometer and making it wirelessly using rf 433mhz modules but I'm not receiving anything on the receiver side, what should I do please help ! Thank You

[@windowsxseven]

🇮🇳🤮🤮🤮🤮🤮🤮

[@SAURABHKUMAR-vk5xb]

@@windowsxseven Well sucks to you. I had completed my project and it works. Need Anything ?

[@windowsxseven]

@@SAURABHKUMAR-vk5xb defensive

[@jimver04]

4th unused pin is analog receive?

[@MartynDavies]

Just joined to the other centre pin

[@eclecticlife]

Thanks for the great video!! I am trying to connect the transmitter to a smoke detector, so that when the sensor goes off, it will transmit a signal. I was just providing 9volts to the data pin but it doesn't send any signal. Any help would be greatly appreciated. Thanks in advance

[@drjwilber]

Memory of between 200 hz and 3khz to data pin at 5v -

[@kibonumwemedia7474]

Thank u bro

[@ItsMeK99]

Can i get a voltage signal and plot it from these antennas ???

[@MartynDavies]

Yes, but the OOK signal isn't so interesting; either the carrier is present, or it's not.

[@ItsMeK99]

@@MartynDavies can you help with the code for the transmitter and receiver

[@rypr_lobo]

Please sur i need shèma reciver all valeur capacitor please

[@MartynDavies]

For the transmitter, search for the schematic online. For the receiver, I don't know.

[@rypr_lobo]

@@MartynDavies Thank you sur

[@e1Pr0f3ss0r]

Can I receive an 433 MHz Freq RF code and reply back with this module? If not will u plz help me for How to make that kind of module..by using Arduino...plz it's request.

[@MartynDavies]

One module is a transmitter and the other is a receiver, so no you can't reply back. You can get combined transmitter/receivers (transceivers); they're a little more expensive. Search on ebay or aliexpress for '433 transceiver' and you will find some choices.

[@dronesrus7436]

@@MartynDavies this is a intressting point. With 4 modules (2 transmitter and 2 receiver) is a full-duplex-reply possible, but one transmitter has to be a master and must wait for the reply to avoid frequency-mismatch. The other transmitter is a slave and transmit data only on demand from the master...

[@MartynDavies]

@@dronesrus7436 Probably desirable to disable your own receiver while transmitting, to avoid receiving your own TX.

[@dronesrus7436]

@@MartynDavies yes, that's right. It's all a matter of software. As long as the current consumption of the receiver module is less than 20 mA, this module can simply be powered by an I/O pin from the Arduino - and switched on and off if necessary... it's just one idea out of many...