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Creating RF Circuit without using RF modules

Discussion in 'Radio and Wireless' started by KevinMorris, Nov 13, 2018.

  1. KevinMorris

    KevinMorris

    2
    0
    Nov 13, 2018
    Hello everyone.
    So i have this scenario where i have to develop a RF transmitter and receiver. There are various tutorials available for developing it but all of them use a ready made RF Module.
    But i want to build it from scratch i.e without using the ready made modules as most of them have a fixed frequency which interfere with other modules. Also it proves to be expensive for mass production.
    Any help would be appreciated.
    Thank you.
     
  2. Externet

    Externet

    632
    131
    Aug 24, 2009
    RF modules were developed to fight against the size, labor, reliability, interactions, calibration, tuning, components count and pricing of 'discrete' circuitry.
    Choosing one method or the other carries the good and the not good of each. You have to deal with them.
    Explore an amateur radio manual which provides tutorials and schematics for several circuitry methods. A mix of methods, modular and 'discrete' is also possible, fitting the convenient type at a convenient stage.
    A cellular telephone would be like a brick size without modular RF, oscillators, tuners, duplexers and power amplifier. And that is not considering display driving.
    Perhaps you are looking at sophisticated overpriced RF modules vendors, instead of the ones used in mass production.
     
  3. KevinMorris

    KevinMorris

    2
    0
    Nov 13, 2018
    Thank you for replying.
    But maybe i was clear enough to describe my question.
    I want to develop my own rf module from scratch using all the components that are used in the ready made module. Your point is right that modules are developed to reduce their cost, size etc. But there are limitations to that.
    As most modules have same frequency which interfere with other modules and also the module has a 4 channel triggering.

    But my application requires more than 4 channels. I dont know whether rf modules with more than 4 channels are already available or not. But if they are, then the prices will be high.
    So i want to build my own rf module so that i can decide the frequency and also increase the number of channels
     
    Last edited by a moderator: Nov 13, 2018
  4. kellys_eye

    kellys_eye

    4,289
    1,143
    Jun 25, 2010
    Do you know the range, bandwidth etc of the signals you wish to transmit/receive (don't forget you might have to design the receiver circuit to match).

    Discrete RF design is very complicated - a primary reason for using ready-made modules where all the hard work is done for you - not to mention the LEGAL design parameters you have to consider. You can't use 'any old' frequency/band/power/modulation etc.

    If you need multiple channels then look at multiplexing your data before transmission. Modern transmit modules incorporate channel hopping, burst transmission and error correction techniques to minimise interference, increase range and lower power consumption.

    There is (practically) zero chance of you designing a system that will out perform any standard ready-made module.
     
  5. davenn

    davenn Moderator

    12,996
    1,661
    Sep 5, 2009

    You cannot just decide on a frequency .... as the freq's you choose MUST still be within the band allocated for such things.
    Therefore you will still have the channelling problems

    Unless you are a skilful circuit designer and RF technician, then, seriously, you would be nutz to use anything other than commercial modules ...
    many of them are designed to cover many dozens of channels that are selectable by a little programming and microprocessor control, eg .
    a PIC controller. Many others can also use sets of DIP switches to select one of many channels

    trying to design and build from scratch would be a serious job for an unskilled person

    there's a zillion multi-channel RF modules, matched TX and RX pairs on eBay for dirt cheap prices

    https://www.ebay.com/sch/i.html?_nkw=rf+modules

    specifically .....

    https://www.ebay.com/itm/2PCS-Ardui...h=item3ad3d47c4e:g:YP4AAOSwLzdWTYYk:rk:3:pf:0



    2PCS Arduino NRF24L01+ 2.4GHz Wireless RF Transceiver Module New



    Maximum operating speeds up to 2Mbps, GFSK modulation efficiency, Anti-interference ability, Particularly suitable for industrial control applications.
    125 Channels, Multi-point communication and frequency hopping to meet the communication needs
    Built-in hardware CRC error detection, Multipoint communication address control.
    Low-power 1.9 ~ 3.6V, only 1uA on Power down mode
    Built-in 2.4Ghz antenna
    Available software to set the address, only received local Address when output data(Provide interrupt instruction), can be directly connected to a variety of microcontrollers, Software programming is very convenient.
    Built-in voltage regulator
    Standard DIP Pitch Interface for embedded applications
    size: 34mm X 17mm X 1mm

    you could NEVER build it as small or as cheaply as that


    Dave
     
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