Reduced Carrier? Not here..

Discussion in 'Amplitude Modulation' started by W2NBC, Mar 9, 2019.

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  1. W2NBC

    W2NBC Ham Member QRZ Page

  2. K4KYV

    K4KYV Subscriber QRZ Page

    Just a fancier version, using an algorithm, of plain old controlled carrier. One system runs at reduced carrier, increasing it to full licensed power at high percentages of modulation. Another starts out at a full strap unmodulated carrier and at low percentages of modulation, reducing it at intermediate percentages and then increasing it back to full carrier at high percentages.
  3. N1BCG

    N1BCG Ham Member QRZ Page

    I’m selling underwriting sponsorships of my QSOs. As I interpret the rules, soft-sell announcements are OK...

    “This hour of N1BCG brought to you by...”

    No calls-to-action of course. That, and brokered programming on my 60Hz subcarrier. Gotta pay for this hobby somehow.

    Btw, I’m good on QRZ for advertising rates...
    W1TRY likes this.
  4. AA5CT

    AA5CT Ham Member QRZ Page

    Article: The downside to this approach is that the overall audio signal to noise-and-distortion ratio perceived by the listener may be reduced at longer distances from the transmitter site.

    It isn't just "distances" that are the problem, the man doesn't realize that sometimes the receive location is a compromise location, whether it is inside a building that is noisy *and* attenuates an AM BCB signal or the receiver is operated in and amongst noise making devices common in both office and home environments.

    I have trouble receiving 50 kW 'blowtorch' WBAP inside a Kroger near my home north of Dallas for instance ...
  5. W2NBC

    W2NBC Ham Member QRZ Page

    As this pertains to our operating:
    What signal signature is easier to copy? Full carrier and 100% or more modulation, OR filling in the "gaps" with maximum sideband energy with reduced carrier?
    As Don referenced, it is "controlled carrier".
    As the article suggests, saving overall energy costs and still getting the content heard is the point.

    What I can say is that a signal with DFQ carrier and fully modulated is fantastic to copy..
  6. K5UJ

    K5UJ Ham Member QRZ Page

    For ham AM, the most carrier power possible at 100% modulation with peak limited high average compressed audio is absolutely the way to go. If the positive peak is a bit over 100% that's fine, but for ham skywave, the highly asymmetric stuff is not good. Big channel quieting carrier with audio density is what we want. This is an example of another situation in which modern technology makes something easy to do (extremely high positive peaks) but just because it can be done, doesn't mean it is a good thing to do.
    N1BCG and W2NBC like this.
  7. WA5VGO

    WA5VGO Ham Member QRZ Page

    We have a 50KW here running modulation dependent carrier. I can’t tell any difference between it and all of the other local stations. Outside their 60dB contour there might some difference.
  8. N2DTS

    N2DTS Ham Member QRZ Page

    Fun to play with the controlled carrier on small screen modulated rigs.
    It CAN sound ok if not pushed too hard and the audio is otherwise good.
    In the past, on stock Drake and Heathkit rigs, it was pushed to the limit with restricted and distorted audio as well, but if you have good clean audio and
    reduce the carrier a bit and not a lot when not modulated, it sounds ok and can allow more power output before the 6146 or sweep tubes melt down.
    Makes it easy on an amplifier also.

    I would think a broadcast station would rather just change to a modern efficient transmitter to save electricity costs....

    On a big rig, 300+ watts, it seems better to run lots of carrier and 100% modulation with a bit of compression to maintain average audio levels.
    The guys that just run a mic into a big rig often go soft on the audio as they move around or back away from the mic.

    If you want a really big signal, you put up a killer antenna and run a KW of carrier and use a multi band compressor out to 10 KHz, from say a 24 fet rig.
  9. K5UJ

    K5UJ Ham Member QRZ Page

    They have. carrier reduction is to save even more money.
    I've worked those fellows. It's pretty annoying.
    I'm okay with all of that except the 10 kc part.
  10. N2DTS

    N2DTS Ham Member QRZ Page

    Yes, me too!
    Worked N4RXV on 40 meters tonight running 4 watts out of my little hand held 928 sdr on batteries, what fun (for me, maybe not for him...).

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