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A Station Owner Tinkers With an AM's Response Curve Reviving Vintage Processors

Discussion in 'Amplitude Modulation' started by K5UJ, Jan 15, 2019.

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  1. AA5CT

    AA5CT Ham Member QRZ Page

    re: "It's a bit more complex than that for AM's 75 us curve"

    Well, I've (a) Never had to deal with the 'curve' for AM and (b) never even had a need or opportunity to review the applicable standard and (c) whereas I have had to for commercial 2-way/amateur FM for the purposes of new design or modification of equipment in the field or (d) for production test and verification of test set design and function for testing of 2-way FM gear.

    But again, I've never addressed the "AM curve". At today's rate of progress, I likely never will either. Fortunately, and hopefully, we have a talent pool who can in the broadcast industry! :)
  2. AC0OB

    AC0OB Platinum Subscriber Platinum Subscriber QRZ Page

    1) Cool! I got my start in communications at a Communications Service Center in the late '60's through early 70's.

    2) There are many people in the industry qualified to address pre- and post emphasis issues.

    3) Just curious why you posted non-AM Broadcast preemphasis data?

  3. AA5CT

    AA5CT Ham Member QRZ Page

    (3) It is a subject too few hams ever see addressed or mentioned, and, someone had addressed broadcast FM earlier. To bring out such subjects allows some, like myself, to reinforce our holographic memories on related subjects.

    Even now, as I speak, there is a network of inter-connected repeaters in the DFW area where the individuals involved have limited grasp of this subject, and in some of there implementations ignore this aspect altogether. I've even seen mistakes in commercial product involving this subject. This subject therefore, deserves some exposure, and awareness. Not everybody is even aware of this aspect!

    As to (2), you are no doubt aware of the dying-off of a large talent pool that got us where we are today. Those are the individuals, the dedicated broadcast engineers and technicians who spend time on standards committees or working out in the field maintaining systems, who understand the technical reasons why decisions were made the way they were.

  4. AC0OB

    AC0OB Platinum Subscriber Platinum Subscriber QRZ Page

    Every communication's engineer within the AM broadcasting community I know of is quite aware of the bandaid NRSC solution.

  5. AA5CT

    AA5CT Ham Member QRZ Page

    It would help if in this discussion if we were arguing in the same hemisphere, or on the same planet even. The number of really good, sharp RF engineers familiar with AM broadcast are a dying breed.

    Take Charles Shoemaker, president and owner of MSW Corporation, Now retired and no longer in the business ... he was my mentor ...
  6. N1BCG

    N1BCG Ham Member QRZ Page

    It was *amazing* how good even the Gates BC1G sounded on the Motorola C-QUAM monitor when the stereo matrix CRL peak limiter was switched to PROOF. Yeah, kinda wide, but it was late on Sunday nights when the weekly L+R/L-R delays were tweaked.

    Did I mention we sounded *amazing*? The NRSC filter was like a prophylactic for AM.
  7. WA3VJB

    WA3VJB Ham Member QRZ Page

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