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Transmitter / receiver at or around 418 MHz

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lilimike

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I need a single on/off data line transmitter / receiver with a range of around 1000 feet.
It can transmit a status (on/off) once every 2 or 3 seconds and must be operated by batteries and if possible around 418MHz. I do not have line of sight.

I found the simplest solution to be from Linx Technology using TXM-418LC, RXM-418LR and using their encoder chip LICAL-ENC-LS001 and its matching decoder.

Perhaps the simple solution is the most expensive specially for the $15 RX chip.

Can anyone guide me to a cheaper solution?
It doesn't have to be as simple as above but my device will operate outside at temperatures between -30F to 90F.

Mike
 
Hi Andy,

Do you have a specific product or link?
Doing a quick search on Google I found only a TX for $29
My first solution described above comes to around the same price but for RX and TX.

Mike
 
The price for the Linx modules doesn't seem to bad for what you want, But getting 1000 ft. range from any low power module may be difficult.
 
Google "car alarm relay remotes" or "garage door remotes". Andy
 
Google "car alarm relay remotes" or "garage door remotes". Andy

That will give Mike reliable, 1000 feet, non-line-of-sight range? Do you any specific links?

Ken
 
1000' non-line-of-sight is impossible with any of the legal in the USA license-free low-power modules, period.
There are some higher power 433MHz TX modules being sold in other countries. You will have to check the legality of using those in Canada.
 
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I've been Googleing a bunch but I only find FM transmitters or bulky units that operates on 12 volts.
I am not looking for something off the shelf, I want to build something and hopefully manufacture and sell it. I don't want to copy other people's devices but to see which chips they use would be a start. The Linx chips would make manufacturing cost extremely low and it would also give my product a very good quality but $30 on components is too high. I am not able to manufacture more than 100 units at a time and I was looking more fore something that would cost around $15 (components) for both the TX and RX.

1000' non-line-of-sight is impossible with any of the legal in the USA license-free low-power modules, period.
There are some higher power 433MHz TX modules being sold in other countries. You will have to check the legality of using those in Canada.

I plan to transmit my status once per 2 or 3 seconds and I can deal with reducing the range to 200 feet. I think I will start with designing something and then I will tackle FCC (US) and CRTC(Canada)

Thanks for any help.

Mike
 
I have used the ABACOM modules which I linked to in my previous post.
 
To DIY an RF transmitter with a reliable 1000' range will require government approval, possibly even a license to manufacture.

Most modules are maybe at best 100' but generally much lower.
 
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Thanks for the info Bill.

I am aware I will have to deal with permits, licenses and move mountains but I have to start somewhere so I will design the best system I can and then attenuate to comply with regulations. Hopefully there is a midpoint that will workout. The one thing I can not do is quit in case it gets too complicated.

Mike
 
I am surprised no one came up with an rfPIC12F675 as a suggestion... It is obviously more complicated but a lot cheaper even with the required components. I still need to do many hours of reading but so far it looks like a good solution.

Anyone have pros and cons?

Mike
 
I am surprised no one came up with an rfPIC12F675 as a suggestion... It is obviously more complicated but a lot cheaper even with the required components. I still need to do many hours of reading but so far it looks like a good solution.

Probably because it's so complicated :D

I had a look at it a good few years ago, but dismissed it for that reason.

I agree with Bill, check what is and isn't allowable before getting involved in the design.

You might have a look at RF Solutions?, I seem to remember they have some longer distance licence free modules, check their specs out.
 
I think I found the ideal chip, SI4421, it needs few components, it has lots of functions, it is programmable and it goes for about $3 CAD so I get a complete 2 way communication for around $10 including two MCUs.

Mike
 
at a power out of 2 to 7dbm, you will be lucky to 30' of range, regardless of what they say in their advertising.

Learn how to use **broken link removed**.
 
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Thanks for the link I will play with this.
On Silabs they also provide a range calculator which showed around 30 meters but maybe I entered a wrong variable.

I've ordered a few samples so I will do some tests an see how it goes. I also ordered the Linx modules and as a third choice I was looking at RFM12b from Sparkfun
Too bad Xbee is so expensive.

Mike
 
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