Raido Hams "Slipstreaming" 30 years ago

Discussion in 'General Hardware' started by dave holbon, Dec 6, 2002.

  1. dave holbon

    dave holbon Moderator

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    Many years ago before the advent of the Internet a process called ”slipstreaming” was used in the old (but now) re-invented technology called “wireless” communications.

    Wireless technology relied on a carrier frequency to send and receive, upon which an audio signal was superimposed. It was only a matter of stripping out the carrier frequency and what was left was in effect directly transmitted to the speakers (after some processing using filters) and amplification.

    Before the advent of the digital computer an “analogue computer” was envisaged. This in concept was far more powerful than any digital machine as it could process a factor of ten to a thousand more “bits” of information per clock cycle. It used sine waves, which had (digital) steps in them; or a form of a saw-toothed wave carried by a sine wave.

    The receiver still received the correct (if somewhat distorted) signal, which it processed in the normal way, throwing away using filters, what it thought was distortion. Indeed “high quality” receivers threw away all but the original signal leaving no distortion at all, well in theory. As radio works by generating a carrier signal at a certain frequency upon which the actual signal is superimposed (usually not to low) it was a relatively simple task to “slipstream” a resonant harmonic of this frequency (30 years ago) containing you own data. Even digital communications can take place in this way and at incredible speed; if you can (in effect) distort the carrier wave (or one of it’s harmonics) just enough to produce a sinusoidal wave distorted to a stepped sawtooth that the receiver can still process without error, then for every high to low trough (the carrier wave frequency) can contains two to three hundred or even hundreds of thousands of digital signals on the actual carrier (or harmonic) wave itself, then your “slipstreaming”.

    This was impossible to decode though until recently as the switching frequency of the detecting and transmitting transistors had to be incredibly high (more than 16ghz) and had to accurately track the carrier wave itself, which involved switching digital ground at enormous speed. The carrier wave itself might also be slightly distorted so error checking had to be used which lost another 5ghz.

    The analogue computer will be here soon which will be a factor of one thousand times faster than current machines thanks to the old radio hams “slipstreaming” technology.
     
  2. damnyank

    damnyank I WILL NOT FORGET 911

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    Dave - don't get me wrong - you have a veritable wealth of knowledge - but sometimes I wonder if it is worth it!

    "detecting and transmitting transistors" - man some of the kids on this site never heard of transistors - let alone "saw-toothed wave carried by a sine wave" or "distort the carrier wave (or one of it’s harmonics) just enough to produce a sinusoidal wave distorted to a stepped sawtooth " - the kids are wondering what you are smoking!

    Of course us "oldies" remember studying that kind of "state of the art" stuff in basic and advanced electronics training with the military (back in the 60's). It's sorta like sending a new troop out looking for some "flight line" or "a can of grid leak bias"
    :p :p
     
  3. dave holbon

    dave holbon Moderator

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    Damnyank: -

    I had to laugh at you response. You’ve been so kind to my post over the last months where everyone else seems to have stopped or attacked me in some way. I’m sure I’m a thread killer of some sort, maybe I’m just too old.

    My.. my.. what sort of world do we live in where my own nephew (who was here when I submitted the post) has just graduated with a Phd in Computer Science and mathematics and has never heard of either harmonics or standing waves or “slipstreaming” as applied to “radio” as it used to be known.

    We both know it’s all been done before and some. What comes around goes around.

    Be lucky.
     
  4. chastity

    chastity Moderator Political User

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    Well I will say that I never heard of the term slipstreaming in regards to radio waves and that some of the terms you used are a bit over my head or what you want to call it but I do find your post to informative and yes I've heard of transistors. I will also say its a good read and more interesting then some of the problems people have. So Dave I say feel free to enlighten folks.