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How does one feed a two channel transmitter inputs from a tekronix generator ?

  1. Dec 15, 2008 #1
    Hey guys

    I've done my transmitter. it works fine. But, I need to know how to feed it with input from a generator within taking into account that such a transmitter has two channels R+L. shall i use two different generators to feed every single channel ? I really need some help.
     
  2. jcsd
  3. Dec 15, 2008 #2

    berkeman

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    Staff: Mentor

    Are you referring to the WiFi transmitter you asked about a while back?

    https://www.physicsforums.com/showthread.php?t=215867

    What are R+L? Right and Left channels? Is this a stereo something?

    If you want to take the one single-ended output from a typical 50 Ohm signal generator, and feed two 50 Ohm single-ended inputs, you can use an RF splitter (the two outputs are about 3dBm down compared to the input). You can make your own splitter with a transformer that woeks in the frequency band of interest. You can also make one with just capacitive coupling, if you don't need a DC component in the signal.
     
  4. Dec 15, 2008 #3

    berkeman

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    Staff: Mentor

  5. Dec 16, 2008 #4
    Thanks berkeman for ur comments.


    dude you kinda misunderstood my question. I meant that i wanna test my transmitter using a generator and a spectrum analyzer. Ok, I will need to feed such a transmitter with for example a 10 KHz sine wave from the generator and then I''ll be able to see the modulated signal in the spectrum. My question is for the fact that I am using two channels, How can I feed the both channels with a 10 KHz from one generator ?? becaus all I know that i hook every channel to a different generator with the same 10 KHz. Is there any way to use one ? I hope you got my question ..
     
  6. Dec 16, 2008 #5
    Just parallel the inputs. All you will see are sidebands at 10 kHz spacing (and 19kHz pilot town). I would guess the TX is hi-z in and the generator is lo-z out so levels will not be affected. Vary the audio level and you will see the individual sidebands change in level. I think at some levels the carrier disappears and this can be used as a crude way (but expensive as it requires a spectrum analyser - suppose a narrow band receiver could be use if the TX is highly stable) of testing performance. --- Bessel functions. Pre-emphasis may complicate things if different auidio freqs are used.

    http://www.ycars.org/EFRA/Module B/fmanalysis.htm

    The proper way of testing a TX is with a demodulator and stereo decoder (with correct de-emphasis or off if TX pre-emp is turned off) of known high performance and test the R and L channels separately for frequency response and linearity. Check channel separation also.
     
    Last edited: Dec 16, 2008
  7. Dec 16, 2008 #6
    Thanks Pumblechook that's clear enough.
     
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