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Audio or Video Transmitter

Discussion in 'Audio' started by Electro132, Jan 1, 2015.

  1. Electro132

    Electro132

    261
    3
    Feb 12, 2013
    Hi,

    I am building an audio and video transmitter. So far I have a 3 stage transmitter PCB circuit which consists of a common audio emitter, RF Oscillator and RF Amplifier. However, i still need to place a log somewhere to control the amount of voltage/current flow. I wasn't sure whether i should place it just before Q2 or Q3 (Please see the diagram) so i need some help with this please.

    Also to get Video, I'm thinking i'll be needing to get a mixer (for both the audio and video input) to be in place before Q2 (RF Oscillator) Stage. Can anyone please check if i am right with this? I just don't want to get this wrong. On top of that, i'll be needing some help with video quality or has that got to do with the camera resolution itself?

    Thanks
     

    Attached Files:

  2. davenn

    davenn Moderator

    13,328
    1,769
    Sep 5, 2009
    That doesn't make sense ???

    lets start at the start .....
    1) why are you wanting to TX audio and video ( ie. what are you trying to achieve) ?
    2) what are you intending receiving it on ?
    3) receiving device will determine the complexity of the transmitter
    4) what frequency did you propose to use ?
    5) what frequency is that circuit supposed to work on ?

    Dave
     
  3. Electro132

    Electro132

    261
    3
    Feb 12, 2013
    Ok, sorry for the delay of response but here are my answers:

    1) I want to achieve video surveillance
    2) I'm intending on receiving it on a receiver which can present the audio and video on a TV screen in HD
    3) How does it determine the complexity of the transmitter? i thought receivers should have a RF Amplifier (which amplifies the incoming/outgoing wave from the antenna) which then goes through the AM/FM/UHF/VHF Modulator passing to the RF Oscillator (which chooses the freq) which then should go out to the end device.
    4) VHF or UHF - not sure yet but either will do
    5) the frequency for the circuit i have given is just for radio. So far i have experimented with it and have managed to change the freq from 90.5 to 98.6. Now i want to add more control over how much amplification the RF can gain as well as change the freq to a different freq.
     
  4. davenn

    davenn Moderator

    13,328
    1,769
    Sep 5, 2009
    why don't you just use commercially available modules ?
    its going to save you a lot of headaches and frustrations
    you will still need to case them, build/purchase power supplies for them
    the circuit you initially supplied is pretty crap particularly if you want good quality video
    what sort of distance do you need to TX/RX over?
    I assume the video is coming from a HD camcorder etc ?

    Dave
     
  5. Electro132

    Electro132

    261
    3
    Feb 12, 2013
    I think understanding how the components make the TX/RX is way cooler. And besides, i learn a little about how HD/HQ video transmission works on a circuit level.
    How would i be able to make better HQ video with the circuit? Is there a component i need to add?
    I was only going to do a small demo distance of about 20 meters tops.
    Yes, one of my experiments will use a HD camera but i have also a night vision cctv camera which i would like to try out. It has 30 fps and can see up to a range of 25 meters so it is quite good.

    You know i initially thought that the video signal would just mix with the audio signal and then be placed on top of the carrier signal which is the RF oscillator and then amplified so the signal is strong enough throughout the antenna. Can i ask what am i missing to make the video HQ? I'm guessing it would have to be components added at the video/audio emitter circuit at stage 1 but what exactly?
     
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