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SSB Carrier Supression

Discussion in 'General Electronics Chat' started by Space Varmint, Dec 3, 2008.

  1. Space Varmint

    Space Varmint New Member

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    Has that coil doing? :D
     
  2. wasssup1990

    wasssup1990 New Member

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    Just a bit of a joke. Have a laugh! ;)
     

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  3. Space Varmint

    Space Varmint New Member

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    Hey, my best bud from down under! I feel stupid whining over that accident. Got into the happy sauce and it had a reverse effect me...lol.

    Anyway, flat5? Did you get that coil working yet? What's UP? Not you...him.
     
  4. dave

    Dave New Member

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  5. Space Varmint

    Space Varmint New Member

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    Hey thanks Mikey :)

    Not to worry. I try to be a good Christian but I still get mad. I'm only human.

    Yes Frank.....How do you do?
     
    Last edited: Apr 26, 2009
  6. Space Varmint

    Space Varmint New Member

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    Yes that is good, but like my friend Johnny pointed out....pi r round.
     
  7. flat5

    flat5 Member

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    Waiting on trimmers from Futurlec and still have not bought wire or cores/toroids. Guess I'm not in a hurry at this time.
    I'll post when I do something :)
    Don't hold your breath.
     
  8. Space Varmint

    Space Varmint New Member

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    Gasp! Oh thank God! I can breath now ;)
     
  9. Leftyretro

    Leftyretro New Member

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    This thread morphed to be the thread from hell several months ago, do try and keep up. ;)

    Lefty
     
  10. Sceadwian

    Sceadwian Banned

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    Wizard it's definitely too late for this thread, turn around and run away fast before it get you too! Some of us have been trapped here for months.
     
    Last edited: Apr 26, 2009
  11. Mikebits

    Mikebits Well-Known Member

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    Who would have thought that stun guns would have taken a back seat? :)
     
    Last edited: Apr 27, 2009
  12. Mikebits

    Mikebits Well-Known Member

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    Fair enough. :)

    Oh, and I do fine, Thanks for asking.
     
    Last edited: Apr 27, 2009
  13. Space Varmint

    Space Varmint New Member

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    LOL! Actually me & flat5 are working on an rf energy beam we call the "Round-Up". It can go through walls and find you and suck you into this thread. :eek:
     
  14. Space Varmint

    Space Varmint New Member

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    There actually is a conclusion to the original question or thread topic.

    It was found that there are many factors that will effect the amount of carrier suppression. One of the most critical turns out to be almost a side issue and that is "copper" or "skin" effect. Because rf frequency travels through the air, then even at minute power levels the same thing will happen with circuits in close proximity. Therefore the shielding techniques must be strategically thought out. Consider the circuits involved in creating an SSB signal. We have:

    1. A carrier oscillator

    2. A balanced modulator circuit

    3. Audio amplifiers from the microphone

    When looking only at the skin effect, we should not consider the crystal or digital filter at this point. What we want is the cleanest most suppressed double sideband signal as possible. It was found that one of the best methods is to isolate the balanced modulator from the audio & carrier oscillator. They should be in separate grounded compartments. This way the carrier rf energy can be directed to the proper port of the balanced modulator through shielded coaxial cable.

    Another key area to consider is the output of the crystal filter. Even with a small level of rf carrier signal being fed to the balanced modulator, the rf skin effect can ride around the crystal filter and manifest itself as undesired carrier energy. The solution I used was to amplify the output of the balanced modulator thereby creating an DSB signal with a much greater power level with its minute carrier ratio that is much larger than the in coming carrier oscillator signal to the balanced modulator. Now the skin effect is at a much lessor db level and becomes negligible. Any amount of attenuation used will attenuate both to where the skin can be brought to zero if fed into another shielded compartment through coax.

    Then the only other consideration becomes the width and offset of the crystal filter and the efficiency of the balanced modulator. In a diode ring type like single balanced or double balanced modulator the diodes can be replaced for maximum suppression.
     
    Last edited: Apr 28, 2009
  15. Electronman

    Electronman New Member

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    Hi.

    I do not know what's the story here which caused this thread to reaches to 47 pages!!
    But I have a question regarding to SSB with Carrier in contrast to the subject of this therad.
    I just want to know the ways of creating SSB-WC.

    Thanks
     
  16. Space Varmint

    Space Varmint New Member

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    Well, essentially SSB is an extremely efficient form of AM transmission both in power consumption and frequency bandwidth. It was actually discovered many years back. I think about the 1940's but others may have an exact date for that.

    The actual subject of this thread was to be what to look for in producing best results for suppressing the carrier and one sideband. Today there are many methods to do this but probably the most common is to use a balanced modulator circuit to null out the carrier and by using a crystal filter set for about 2KHz bandpass the carrier can be further attenuated along with the undesired sideband. Without the carrier the transmitter will have no output unless voice modulation is applied which makes it highly efficient though the power amps and final must be biased to something more linear than a class C amplifier as is used in FM. Usually you want class A amplification with SSB.
     
  17. audioguru

    audioguru Well-Known Member Most Helpful Member

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    Speech goes up to 14kHz for the very important consonants. Vowels go up to 2kHz. Can anybody be understood if they are speaking only in vowels?
    I heard some ducks quacking when some SSB recordings were played. I heard only a couple of English words.
     
  18. Space Varmint

    Space Varmint New Member

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    Well you should love it then because everybody sounds like Scrooge McDuck.

    Merry Christmas Audioguru and everyone! :D
     
  19. killivolt

    killivolt Well-Known Member

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    SV, Good to still have your SSB input.

    Guru, as expected. Quack Quack.

    With "guru's" explanation I can hear it without even knowing what the h... their talking about.,


    Either way, Merry Christmas to everyone.

    kv

    Edit: SV you were faster than me.
     
    Last edited: Dec 24, 2009
  20. audioguru

    audioguru Well-Known Member Most Helpful Member

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    Merry Christmas everyone.
     
  21. killivolt

    killivolt Well-Known Member

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    You too my friend you too.

    May I hope to shine. As well.


    kv
     

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