Radio beacon with as PIC

Guest · Guest

Hi,
I want to make a radio beacon / security tracking type device using a PIC, I have gathered all the PIC parts I need including the CCS compiler but I am overwhelmed by the RF side of things, can anyone help?

Spec.

UK / Europe Legal RF (433mhz I think is OK)
programable frequency (can be a set that are selected from)
3.5v
1km range (I think this equates to about 100mw)
Simple drop in module ideally.

Thanks

Pete

newguy · Joined: 24 Jun 2004 Posts: 1907

Linx has quite a number of different modules available, at quite an assortment of frequencies and output powers. Their modules range from "drop-in" pre-certified types to basic building blocks.

Digi-key carries their products, and they're quite reasonably priced.

http://www.linxtechnologies.com/

drh · Posted: Fri Nov 12, 2004 8:00 pm

Look at www.rfsolutions.co.uk
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David

Guest · Guest

I am hitting brick walls looking for my RF module, I have started to ask companies via email for such a device, but I would like to ask you guys if I'm barking up the wrong tree with this spec.

Range 2miles urban, 10 miles open
Programmable frequency (can be selectable from a set of say five pre-set freq’s)
Easy connection / programmable via MCU
License exempt UK/Europe
3.5v ideally

Can anyones say "you will not find such a device" or "yes this is acceptable, and if you keep looking / asking I'm sure you will find one"

Ttelmah · Guest

SLomas · Guest

You're going to have trouble meeting your requirements.
The European license free bands have tight limits on the output power to levels that will make it almost imposible to acheive the ranges you desire.
Remember that manufacturers often quote unreasonable range figures.
You will not reliably get the range you want, especially as most of the regulations for license free also restrict the transmitter aerial efficiency.
Most license free modules are made to a price and this is achieved at the expense of features such as selectable frequency.

I have in the past spoken to John Fairall at RFSolutions who I have found to be most helpful. I suggest that you speak with the manufacturers directly & explain your requirements.

Steve.

johnl · Joined: 30 Sep 2003 Posts: 120

If you want to stay in the license-free band, I suggest using spread-spectrum transceiver modules. There are several which will meet your range requirements. I am currently using one from Aerocomm and so far am pleased with the reliability in harsh indoor industrial environments. Another company I strongly recommend is Maxstream.

Using spread-spectrum technology will give much more reliabillity than using a single-frequency system.

Most modules are easy to interface to a PIC with simple serial commands.