• Spread Spectrum

    From k9zw@700:100/69 to All on Sat Jul 23 12:00:20 2022
    The use of changing frequencies complicates reception of even an in-the-clear message.

    Lots of techniques when you mix digital communications and SS frequency hopping.

    --- Steve K9ZW via SPOT BBS

    --- Mystic BBS v1.12 A48 2022/02/11 (Linux/64)
    * Origin: SPOT BBS / k9zw (700:100/69)
  • From debian@700:100/69 to k9zw on Tue Aug 16 01:31:32 2022
    It is technially FM - the signal modulates the frequency, just not an analog type of FM (like what broadcast FM is for example).

    Very wide bandwidths do make it more difficult for (atleast some of the cheap) receivers to demodulate the signal.

    To the untrained ear, it sounds like either tones or static - depending on the method of modulation used and the method of demodulation used.

    KG7UJH
    Debian

    How ya gonna do it? PS/2 it!

    --- Mystic BBS v1.12 A48 2022/02/11 (Linux/64)
    * Origin: SPOT BBS / k9zw (700:100/69)
  • From k9zw@700:100/69 to debian on Tue Aug 16 07:14:19 2022
    Spread Spectrum is not limited to FM or any particular sort of modulation scheme. https://en.wikipedia.org/wiki/Spread_spectrum

    What I had in mind was a subset of the whole area, Frequency Hopping Spread Spectrum. https://en.wikipedia.org/wiki/Frequency-hopping_spread_spectrum

    Any interesting HFSS tidbit "In 1942, actress Hedy Lamarr and composer George Antheil received U.S. Patent 2,292,387 for their "Secret Communications System", an early version of frequency hopping using a piano-roll to switch among 88 frequencies..."

    Earlier Tesla mentioned the basic concept in patent 725,605 from 1903.

    The later Zinn enhancements are interesting, as they reduced the need to externally sychronize RX with TX.

    Lots going on here, so hoping I haven't pointed you down a rabbit-hole...

    --- Steve K9ZW via SPOT BBS

    --- Mystic BBS v1.12 A48 2022/02/11 (Linux/64)
    * Origin: SPOT BBS / k9zw (700:100/69)
  • From debian@700:100/69 to k9zw on Wed Aug 17 01:25:41 2022
    What I had in mind was a subset of the whole area, Frequency Hopping Spread
    Spectrum. https://en.wikipedia.org/wiki/Frequency-hopping_spread_spectrum

    From the wikipedia article -

    "...spread spectrum techniques are methods by which a signal...generated with a particular
    bandwidth is deliberately spread in the frequency domain, resulting in a signal with a
    wider bandwidth".

    I suppose something like this would be fine for local comms. Wider bandwidth means more
    data/inforamtion can be transmitted. A form of trunking could be done with this as well.
    Wider bandwidth = more trunk channels. If I am not mistaken, 802.11b/g/n utilize spread
    spectrum?

    One down side, depending how you modulate the data, could be distance of transmission.
    Wider bandwidths usually don't transmit far as narrower bandwidths do. but maybe this
    could be overcome with a slow baud/symbol rate?

    Just some thoughts rattling in my head

    Lots going on here, so hoping I haven't pointed you down a rabbit-hole...

    eh, I have allot of irons in the fire in my own life - it is nice to take a break at times
    ;). I think, though, we should be talking about how to utilize this for offgrid and emcomms.

    Are there any radios that you know if that a Radio Amateur could use that can transmit
    spread spectrum?

    73, de KG7UJH
    Debian

    How ya gonna do it? PS/2 it!

    --- Mystic BBS v1.12 A48 2022/02/11 (Linux/64)
    * Origin: SPOT BBS / k9zw (700:100/69)
  • From k9zw@700:100/69 to debian on Wed Aug 17 07:58:04 2022
    On 17 Aug 2022, debian said the following...

    Are there any radios that you know if that a Radio Amateur could use
    that can transmit
    spread spectrum?

    Would think most any that could do digital mode work would be able to do some forms of Spread Spectrum.

    If the radio can do ALE, which is a form a freqency-hopping, it would also do some forms.

    --- Steve K9ZW via SPOT BBS

    --- Mystic BBS v1.12 A48 2022/02/11 (Linux/64)
    * Origin: SPOT BBS / k9zw (700:100/69)