FSK Modulator Carriers 45/55MHz

Discussion in 'Wireless & RF Design' started by Alvaro M, Mar 23, 2017.

  1. Alvaro M

    Thread Starter New Member

    Mar 21, 2017
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    Hey Everyone,

    I'm having trouble by finding suitable ICs for my project. I need a FSK or GFSK modulator with data input of 10Mbps and Output of 45 and 55MHz for the 0 and 1 binary values correspondingly. It really is my first electronics project and have been looking for it for a week and can't find anything suitable.

    Thank you for the help.
     
  2. DickCappels

    Moderator

    Aug 21, 2008
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    The simplest solution would be to switch between two signal sources with a multiplexer. How well would that fit your needs?
     
  3. Alvaro M

    Thread Starter New Member

    Mar 21, 2017
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    May be a solution but how's the continuity with that? Thought about a VCO, where the binary data selects which frequency is in its output. Any thoughts about that?
     
  4. BR-549

    AAC Fanatic!

    Sep 22, 2013
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    You are looking for a device with a 10 Mbps, fsk, input and a 45-55 MHz fsk modulated output?

    Please re-state clearly what you are doing.
     
  5. DickCappels

    Moderator

    Aug 21, 2008
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    Maybe a single counter with 45MHz and 55 MHz outputs.

    A PLL can do it. TI has a few set up for FSK but you would have to divide the several hundred MHz output to get down to around 50 MHz. One problem I can see with using a PLL is that the modulation frequency is about 20% of carrier frequency, making getting a snappy response but clean response difficult. Shifting the input voltage open loop into a VCO should work very well.

    There were or are some VCOs that can operate well around the frequencies in which you are interested -most of these are in PLL chips today.
     
  6. BR-549

    AAC Fanatic!

    Sep 22, 2013
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    You mean you want a 44 MHz out for space and 55 MHz out for mark?

    I have a little DDS chip with 3 independent outputs. You could set one for 44 continuous and one for 55 continuous and then gate the two with the third output.

    https://www.adafruit.com/products/2045
     
  7. Alvaro M

    Thread Starter New Member

    Mar 21, 2017
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    Thanks for the reply. What I need is a device with a binary data input of 10Mbps, which modulates that data using FSK, setting the value '0' to a frequency of 45MHz and the binary value '1' to 55MHz.
     
  8. Alvaro M

    Thread Starter New Member

    Mar 21, 2017
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    Thanks for the rely, I will look for those PLL chips and their specification and will keep you updated
     
  9. Alvaro M

    Thread Starter New Member

    Mar 21, 2017
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    Actually your solution is good but I couldn't find the way to switch between the two output frequencies, according to the data stream.
     
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