Cheap 433MHz Modules Increase Range

Hello all

I would be glad if anyone could help me to increase the range of my 433mhz modules. I am planning to set up a moisture, temperature and pressure sensor for my plants. The data should be sent zu the receiver about 15-20 meters away. Most probably in line of sight. There wont be too much in between. The best I have been getting so far was about 10 meters (probably even less) line of sight. With inconsistent results and more often than not much less than 10 meters.

Here is what I am using and what I have done so far. To test I just want to transmit a string of 18 letters.

I have these 433mhz modules (I have heard they are crap, but I have also read from many people that have been able to get good results with similar modules):
https://www.amazon.de/gp/product/B076KN7GNB/ref=ppx_yo_dt_b_asin_title_o01_s03?ie=UTF8&psc=1

Transmitter attached to Arduino pro mini and Receiver attached to Arduino Nano. Both running on 5V. Unfortunately I wont be able to use more than 5V.

At first I used the following library, because the description sounded very promising:
https://andreasrohner.at/posts/Electronics/New-Arduino-library-for-433-Mhz-AM-Radio-Modules/

After a while I tried the RadioHead library, which increased the range considerably:
http://www.airspayce.com/mikem/arduino/RadioHead/

I tried all of those antennas:

Coil loaded antenna:

Commercial antenna:

and a 4/Wave straight and coiled antenna.

I don't know what else I should do to increase the range even further without using a dipol antenna or a lora module.

Does anyone have an idea how to get a much better range? I have heard of people talking about 50 or more meters.

Your help is greatly appreciated.

Cheers,

moses

Many of these devices are very poor performance. Very low sensitivity, poor selectiviy.

Proper RF transceiver is the way to go - its not as if they are expensive, something like the RFM12

Yes you have the worst modules that money can buy, and there are lots of limitations many of which cant be easily fixed.
If you live in suburbia, the 433.92 Mhz band is usually congested as there are so may household items that use this frequency, so interferance can be a big problem and only better radios will solve this.
Lora radios are the best for dealing with interferance issues and have the best range.

mauried:
If you live in suburbia, the 433.92 Mhz band is usually congested as there are so may household items that use this frequency, so interferance can be a big problem and only better radios will solve this.
Lora radios are the best for dealing with interferance issues and have the best range.

Therefore better take a module with a frequency other than 433.92MHz? Are there other frequencies that might give problems?

Those cheap modules work fine with a balanced dipole antenna, as shown below (33 cm tip to tip). Connect one inner end to ANT, the other to GND.

I get 300 meters line of sight range.

Thank you jremington

I heard of that but never tried it so far. Its quite cumbersome. I would prefere a smaller alternative.

I played with the type of transmitter / receiver you have. Had very poor luck, finally ended up throwing them in the trash out of frustration.

I ended using a pair of RFM69HW transceivers. They required more code but the performance was like going from a moped to a Mercedes.

With the 433Mhz I could barely get 5 meters from my room to the outside.

With the RFM69HW’s I had one transceiver in my basement (cement walls, below grade) and could communicate reliably with the other transceiver 50+ meters away on the opposite side of another building. I could have gone further but I was so blown away by the performance I had just seen.

The RFM69W can be had on eBay for about $5 each. Be sure to get the proper frequency for you region. Mine was 915MHz.

The RFM69W migh seem a little overwelming at first but the Arduino libraries work fine and once you get the code working the radios just work, no extra attention is required. BTW I used the antenna that looks like a spring, they are also on ebay.

John

moserroger:
Therefore better take a module with a frequency other than 433.92MHz? Are there other frequencies that might give problems?

Check your local regulations - not all those frequencies are legal in just any country. Some places allow the 868 MHz band, others the nearby 915 MHz band, for example.

You can get 1000+ feet with cheap 433MHz OOK transmitters and receivers if it's line of sight.... (it looks my record was 1400')

Just not those awful green receivers - they are pretty terrible. I found that they were unreliable at >50 feet (which is under 20 meters).

Search ebay for RXB12 or RXB14. Little yellow PCBs, a buck and change a pop, shipped. They are based on the Synoxo SYN470/SYN480 superhet receiver IC (the RXB14 uses the smaller 8-pin SYN480 - this is identical except that some of the pins that set operation mode are hardwired instead of being broken out; the RXB14 is smaller and has 3 pins (Vcc, data, gnd) while the RXB12 is bigger, but pin-compatible with the cheap green units, having 2 data pins in the middle instead of 1). They were the champions of the range tests I conducted a while back - and they work well on 3.3v (while the cheap greens don't work at all)

The RXB8 was nearly as good - but is more expensive. RXB6 and SRX882 were both about half the range of RXB12. The RX-433-AT from Applied Wireless outperformed the RXB12 by about 20% - but they are $30 plus shipping!

The cheap green transmitters are actually pretty good (in stark contrast to the receivers they're sold with), though the STX882 outperformed them at very low operating voltages (I tested down to 2.1v according to my notes - simulating two just-about-dead alkaline cells)

And as noted above, a wire antenna of the correct length makes a huge difference. Don't use those spring antennas they sell on ebay often bundled with the 433MHz transmitter/receivers; they are beyond awful. I've put them on an antenna analyzer and it agrees that they are abysmal antennae.

I found that they were unreliable at >50 feet (which is under 20 meters)

Mine work at 1000', using a balanced dipole antenna. See photo in reply #4.

The importance of a good antenna and proper impedance matching cannot be understated.