RF Transmission in Remote Areas (Multiple Transmitters, one Receiver)

Discussion in 'General Electronics Chat' started by Chris Walker, Feb 5, 2015.

  1. Chris Walker

    Thread Starter New Member

    Feb 5, 2015
    4
    0
    Hi all!


    I have a project that requires measuring temperatures at remote areas around a farm. I have already designed the sensing section of the project. There will need to be ten sensing modules around the farm all transmitting to one receiver unit. The sensing circuit when triggered will output an AC voltage which can be interpreted for the temperature.


    The trouble I am having is with the transmission. I am new to RF design so PLEASE help. I need a way of transmitting and reproducing the voltage signal from each sensor at the receiver to then process and output the temperature. Key points to consider:

    • Each sensor module will need a individual ID
    • Transmission will need to be around 200 metres.
    • Transmissions need not be simultaneous.
    • Possibly incorporating a repeating unit to forward on signals to the receiver would be a good idea. This way sensors could be located further away from the receiver by creating a network of sensor modules.
    • Power consumption should be reasonably low as these will need to be battery powered though size is not a big factor.
    Here's a link to the sort of thing I am looking for:

    http://www.cdt21.com/parts/files/press/PR00204.pdf


    Specific part names would be greatly appreciated.


    Additionally the voltage signal could be evaluated at the sensor module if this was easier. However in an attempt to lower power consumption I aimed to do all of the processing at the receiver.


    Any help would be greatly appreciated!!!


    Cheers


    Chris
     
  2. crutschow

    Expert

    Mar 14, 2008
    12,972
    3,219
    What's wrong with the one in your reference?
     
  3. Chris Walker

    Thread Starter New Member

    Feb 5, 2015
    4
    0
    Hi Crutschow,

    My interpretation of the pair in the reference was that they only send switch signals. Sort of like garage openers, when a button is pressed it sends a signal to open the door. I'm unsure how to make use of these with a variable voltage. My sensory circuit outputs a voltage depending on the temperature. Therefore I require an RF system which could send the value of the voltage or reproduce the voltage at the receiver end. If you can think of a way I can incorporate the pair in my reference I would be happy to use them.

    Cheers

    Chris
     
  4. Chris Walker

    Thread Starter New Member

    Feb 5, 2015
    4
    0
    Hi #12,

    No i'm not looking to beat those statistics, the ones in my reference would be perfect but I'm unsure how to use these for my purpose. Sorry I may be interpreting what they do incorrectly but I need to send more that a 1 or 0 and it seems that's all they do. Do you think I could use a combination of multiple switches to refer to different voltages/temperatures?

    Cheers

    Chris
     
  5. Rolland B. Heiss

    Member

    Feb 4, 2015
    236
    40
    How about just simple store bought wireless digital temperature monitors for each location in any way you see fit? Set up the receivers on a certain wall in your home or garage and glance at the temps when you need to.
     
  6. Chris Walker

    Thread Starter New Member

    Feb 5, 2015
    4
    0
    Hi Rolland,

    Due to the specifications of the client, some of the sensors may be underground, may be kicked by cattle and many other conditions. I could buy wireless monitoring systems however I would have to modify the products for each situation so I have decided to design the system from scratch instead. I have already developed the robust casings and sensing components, I have just hit a snag with the RF side of things.


    Any help with the transmitting and receiving of data would be greatly appreciated.

    Cheers

    Chris
     
  7. crutschow

    Expert

    Mar 14, 2008
    12,972
    3,219
    How about these from the same company.
    They can transmit data at 2400bps.
    Now you just need a temperature sensor that can send a serial data stream.
     
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