How to design a long range(500m-1km) remote control?

[pradeep_k_b]

Hi.I am trying to design a long range remote control,I need an operating range of at least 500m.This remote control is using to operate a wild animal repellent and I want to turn ON and OFF the the device from my home.And the distance between home and field is around 550m,so the range is really important

I have already tried different methods like 433Mhz RF module and 2.4Ghz NRF24l01 module,but didn't get enough operation range.With 433Mhz I got around 100+m but nrf24l01 only 6-15m

I greatly appreciate if you can suggest some solutions

Thank you

 

[D.A.(Tony)Stewart]

Path loss increases with √f, so try 21MHz or similar LF license free radio channel. >100 mW with line of sight to target or more mW and suitable error detection.

 

[pradeep_k_b]

@SunnySkyguy ..Thank you very much for your reply.By the wy I could see some long range RF modules on the web with freqyencies 433MHz and 2.4Ghz,and the manufactures description they mentioned there modules have a range of 1km+.Then how these modules work?.if you don't mind please check this links https://www.seeedstudio.com/depot/2KM-Long-Range-RF-link-kits-w-encoder-and-decoder-p-321.html
https://www.ebay.com/itm/NRF24L01-P...ommunication-module-2-4G-1100m-/310651702557?

 

[D.A.(Tony)Stewart]

Not very reliable.. Roof top. no interference, no rain, high gain antenna or perfectly wound helix with experience and SA to tweak.

 

[ravindragudi]

On the frequency of communication selection, you have to review and select it carefully as there are restrictions on its use. Refer to National Frequency Allocation Plan of GoI. pages 66 and 153.
**broken link removed**

Having said that, to meet your ~1km range, you may have to choose an RF module with max allowed Tx power may be 10dBm or so for that frequency and directional antenna to increase the gain in given direction and possible repeaters in between if required. A combination of these methods....

 

[Audioguru]

My 2.4GHz radio controls for model airplanes go reliably farther than I can see. They do not cost much and are on sale for lower prices each time a new feature is added. The antennas are small and are not directional but work best when parallel with nothing in between.

 

[pradeep_k_b]

@ravindragudi ..I know about this..but its for a rural area,so I don't think it will not interfere any other systems...actually its a place near to the forest that is why I am trying to design a system like this

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@Audioguru ..what type RF modules are you used for this?..Have you designed a remote control from scratch?I think for model airplanes the ready made radio systems are using..right?

 

[godfreyl]

Another approach would be to use a cellphone link or GSM modem.

 

[pradeep_k_b]

@godfreyl..That wont work.So time I need to use multiple numbers of repellent devices in different parts of the field...

 

[jiripolivka]

@godfreyl..That wont work.So time I need to use multiple numbers of repellent devices in different parts of the field...

I think what you need is to learn how to design and adjust a good communication system. You may use any ready-made "module" at any frequency from 27 through 2.4 GHz. You must calculate the propagation loss from transmitter to receiver antenna over your distance at a chosen frequency, then knowing the transmitter power and receiver noise figure, you can obtain a needed antenna gain for a reliable function.
The best way to make a good system is then using directional antennas. Yagis are easiest to make and use, and a six to ten element Yagi offers a gain close to 10 dB. With a power of +10 dBm your system should reliably work over several kilometers. But you need a line-of-sight for frequencies higher than 430 MHz. Using the RC model frequency of 27 MHz gives an extended range with only quarter-wave monopoles as antennas.

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Also I remember using a pair of toy "walkie-talkies" sold for less than $10. They operate at 430 MHz and have a line-of-sight range of more than one kilometer. If you add a pair of Yagis, you can have a good system for a low cost. Only remember to use fresh batteries.

 

[Audioguru]

I need to use multiple numbers of repellent devices in different parts of the field...

The 2.4GHz radio controls for model airplanes I talked about automatically selects vacant channels (spread spectrum technology) and can have up to 40 operating at the same time.