Hi fidelity SSB bandwith

Discussion in 'Ham Radio Discussions' started by K1VSK, Feb 27, 2007.

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  1. K1VSK

    K1VSK Ham Member QRZ Page

    I admit I just don't get it.

    I just saw a pic of someone's shack posted here on QRZ.com showing a small rig and lots of audio stuff, all of which results is an audio signal wider than a barn door and of much less quality than traditional AM.

    Given that AM is still widely used, what possible reason(s) are there for producing a poor substitute via processed SSB which only serves to use excessive spectrum?
    As a paranthetical question, this same picture contained a bio written in the third person - are we to infer someone else wrote his boi?
     
  2. KA4DPO

    KA4DPO Platinum Subscriber Platinum Subscriber QRZ Page

    there is no sound technical reason for doing it. I think it has more to do with peer envy like; My audio setup is better than yours kind of thing. It's a lot like CBers with echo mikes and roger beeps.
     
  3. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    Don't know who you mean; you might as well reference a callsign so we can all know who you're talking about.

    "Hi fi" SSB actually can sound very good and needn't occupy excessive bandwidth, when it's done properly. Whether you can actually hear any improvement in "fidelity" when the transmitting station implements such enhancements has a lot to do with your particular receiver.

    Unfortunately, for every station who's done this well, there seems to be more than one who has not, and sounds like crap. [​IMG] [​IMG]

    WB2WIK/6
     
  4. KY5U

    KY5U Subscriber QRZ Page

    Cut them a little slack. It's just another sub interest in AR that adds to the overall flavor. They pretty much stay within 3kHz bandwidth now unless the band is not occupied. And just remember that a full fidelity AM signal can occupy 8kHz bandwidth or more.

    I love AM, but I try to keep my signal within 5kHz. BTW, if you're a SSB user you need to allow at least 4kHz between you and the AM carrier not to interfere. Best advice is to avoid 3880, 3885, 3890, 3725, and 3685 as these are AM watering holes in the SE.
     
  5. N4AUD

    N4AUD Ham Member QRZ Page

    You've expressed my thoughts better than I could have myself.
     
  6. VA2GK

    VA2GK Ham Member QRZ Page

    The amount of audio gear and hardware you have in your shack has nothing to do with your SSB bandwidth, what are you talking about?
    The ONLY thing that determines the bandwidth is your radio, period.
     
  7. AB0WR

    AB0WR Ham Member QRZ Page

    Your claim just isn't true.

    A lot depends on HOW you make your bandwidth wider.

    Even a cursory study on the internet (think google and the search terms "intelligibility" and "frequency") will show that inclusions of frequencies up to 4500hz can add SIGNIFICANTLY to the intelligibility of audio in the presence of gaussian and other masking type noise. While it provides lesser gain, inclusion of frequencies up to 6000hz (usually with some kind of pre-emphasis) can assist significantly in discerning between sounds like "f" and "s" or "d" and "t".

    So there are a LOT of *technical* reasons for modifying your audio.

    Please note that unless you have modified your receiver or have a newer receiver with IF DSP that can pass an extended bandwidth of 4.5khz to 6khz, you'll never be able to adequately judge what the audio modifications accomplish. To you it will sound just like it always did - only wider.

    tim ab0wr
     
  8. K3VR

    K3VR Ham Member QRZ Page

    Ok guys, here's what you're not able to hear, unless you have a radio with the ability to detect what some of the ESSB and AM experimenters are doing. Use a good pair of headphones or good speakers. The download is 2.3 MB and will demonstrate what wider filters sound like.

    Bandwidth Demonstration

    I've found that during periods of very poor propagation and weak signal work, the traditional Collins Radio SSB audio response (300 Hz~2.4 kHz) is sufficient, and sometimes preferable to wider bandwidths.

    However, when rag-chewing, and when signal strengths are very good to excellent, wider bandwidths are more pleasing to listen to. Wider bandwidths offer much better intelligibility and decreased listener fatigue.

    Radio manufacturers have accommodated customer listening preferences with the following radios:

    IC-756 ProIII
    Ten-Tec Orion
    Ten-Tec Omni 7
    Kenwood TS-2000LE
    Flex Radio SDR-1000

    All of the radios above contain significantly wider filters than Dad's KWM-2.

    A large diaphragm condenser microphone requires phantom power and equalization so it won't sound too bassy, or dull and lifeless, hence, the rack of audio equipment. Wider bandwidths have been around since Hams started using voice modes. The previously mentioned radios reflect the surge in ESSB popularity.

    YMMV

    For more information, read the White Paper at the link below.


    Bandwidth and Speech



    .
     
  9. WA9SVD

    WA9SVD Ham Member QRZ Page

    Cut them some slack?

    Sorry, but I respectfully disagree.

    While it IS commendable that any and all of us SHOULD aspire to the best, cleanest signal, we have to remember the intent of Amateur Radio. And THAT is communication, not broadcasting.
    One of the original reasons SSB was adopted and later accepted was that it (usually) limited bandwidth to the necessary frequencies required for voice transmissions, usually thought of as 300-3000 Hz. So with limited bandwidth, SSB signals would require less bandwidth than AM signals, which could be (often, but not always) 10 kHz wide or even more.
    Enter many of the "NEW" HiFi operators, who on SSB boost the Bass AND treble of their audio, (sometimes bypassing or otherwise eliminating the bandwidth restricting filter elementd) so they sound "better."
    The fact remains, that Amateur Radio is a COMMUNICATION medium, and NOT a "broadcast" quality outlet.

    The "enhancements" brought about by "HiFi" proponents are usually at the expense of increased bandwidth, often to a seeming extreme. And (IMHO) they actually sound pretty awful to those of us that choose to use the traditional bandwidth filters on the receive end.

    (More than once I've been told that I can't properly receive a station that's severely distorted because I'm not capable of receiving "enhanced" SSB, and I should get my equipment checked, as it's not "functioning" properly, with the proper filter bandwidth.)

    Amateur Radio is about communication, not broadcast quality sound!
     
  10. K3VR

    K3VR Ham Member QRZ Page

    Actually Larry, this is what Amateur Radio is about:

    §97.1 Basis and purpose

    The rules and regulations in this Part are designed to provide an amateur radio service having a fundamental purpose as expressed in the following principles:

    a. Recognition and enhancement of the value of the amateur service to the public as a voluntary noncommercial communication service, particularly with respect to providing emergency communications.

    b. Continuation and extension of the amateur's proven ability to contribute to the advancement of the radio art.

    c. Encouragement and improvement of the amateur service through rules which provide for advancing skills in both the communications and technical phases of the art.

    d. Expansion of the existing reservoir within the amateur radio service of trained operators, technicians, and electronics experts.

    e. Continuation and extension of the amateur's unique ability to enhance international goodwill.

    .
     
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