RF transmitter range

I’m working on an RF transmitter and receiver project using the cheap 433mHz transmitters and receivers and RcSwitch library. Currently, the receiver works at upto 7 metres with a masonry wall obstruction. But beyond the 7 metres, it looses communication. Please can someone advice me on which transmitter to use to achieve at least 20 metres regardless of obstructions. Thanks. The transmitter and receiver are attached below.

RF device.jpg

Hi,
Welcome to the forum.

Please read the first post in any forum entitled how to use this forum.
http://forum.arduino.cc/index.php/topic,148850.0.html

Have you connected an aerial to the Tx and Rx.

This link may help.

Tom.. :slight_smile:

Actually, I have connected an aerial to the Tx and Rx. I also powered the Tx with a 12 volts power source.

JVT:
Actually, I have connected an aerial to the Tx and Rx. I also powered the Tx with a 12 volts power source.

I would say you have damaged your Tx, they are only rated for 5V
Can you please post a copy of your circuit, in CAD or a picture of a hand drawn circuit in jpg, png?

Thanks… Tom…

The FS1000A Tx is supposed to take upto 12v. I have attached a hand drawn circuit. It simply transmits “112” to the receiver.

Hi,
What data rate are you sending?

Ops circuits.
c2b3798400e48fedbd5983614992cf0ce2118817.jpg

Tom… :slight_smile:

It sends "112" every 5 secs. Apologies for my rusty sketch.

JVT:
It sends “112” every 5 secs. Apologies for my rusty sketch.

But what bit rate are you sending the “112”?
Can you please post a copy of your sketches, using code tags.
Tom… :slight_smile:

/*
  Example for different sending methods
  
  https://github.com/sui77/rc-switch/
  
*/

#include <RCSwitch.h>

RCSwitch mySwitch = RCSwitch();

void setup() {

  Serial.begin(9600);
  mySwitch.enableTransmit(6);
  
}

void loop() {  
  mySwitch.send(112, 24);
  delay(5000);  
}

JVT:
I'm working on an RF transmitter and receiver project using the cheap 433mHz transmitters and receivers and RcSwitch library. Currently, the receiver works at upto 7 metres with a masonry wall obstruction. But beyond the 7 metres, it looses communication. Please can someone advice me on which transmitter to use to achieve at least 20 metres regardless of obstructions. Thanks. The transmitter and receiver are attached below.

Transmitters are limited by law to a certain RF output. Higher voltage doesn't change this. There may be output steps available in the programming of the transmitter, investigate what you are setting it to. The receiver is where you should pay attention. Better antennas, lower noise receiver, gain antenna rather than a bit of wire.

Actually better antennas on both will help.

Paul

To maximize range with those cheap modules, dipole antennas work great. I get over 300 m line of site range with the setup below.

Tip to tip length is 33 cm. Connect one end to "ANT" and the other to "GND".

The receiver pictured in the original post is a regenerative receiver. Superheterodyne receivers perform considerably better and are drop in replacements.

MrMark:
The receiver pictured in the original post is a regenerative receiver. Superheterodyne receivers perform considerably better and are drop in replacements.

jremington:
To maximize range with those cheap modules, dipole antennas work great. I get over 300 m line of site range with the setup below.

Tip to tip length is 33 cm. Connect one end to "ANT" and the other to "GND".

Are you saying that attaching an aerial to the Gnd pin helps reception. Can you tell me how long the aerial would have to be if it has to be coiled.

  1. Yes, GND is actually the "other antenna connection".
  2. No

JVT:
Are you saying that attaching an aerial to the Gnd pin helps reception. Can you tell me how long the aerial would have to be if it has to be coiled.

If the antenna has to be coiled you are wasting your time and ours.

Paul

Those receivers are trash.

Search eBay for rxb12 or rxb14, the ones with the yellow pcb material (some with red look like good ones in the photos, but arent), get one of those. They're about a buck shipped, and the range is much, much better. Those transmitters are fine - not the best, but not trash. But those receivers are crap.

I got like 10 meters tops with those receivers, vs hundreds of meters with rxb12

Paul_KD7HB:
If the antenna has to be coiled you are wasting your time and ours.

Paul

Thanks, I think I've got the message.

DrAzzy:
Those receivers are trash.

Search eBay for rxb12 or rxb14, the ones with the yellow pcb material (some with red look like good ones in the photos, but arent), get one of those. They’re about a buck shipped, and the range is much, much better. Those transmitters are fine - not the best, but not trash. But those receivers are crap.

I got like 10 meters tops with those receivers, vs hundreds of meters with rxb12

Thanks a lot. I’ll go for them.