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Shouldn't the newer digital voice modes on VHF and UHF be put elsewhere?

Discussion in 'Ham Radio Discussions' started by KC0BUS, Aug 8, 2017.

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  1. KC0BUS

    KC0BUS Ham Member QRZ Page

    I wasn't entirely sure which sub-forum to post this in, so I'll post it here and it can be moved to wherever if need be.
    Considering FUSION, DMR, D-Star, NXDN and P25 digital systems; since they are in fact "digital" by definition, shouldn't these systems be placed in the "digital" or "data" portions of "the band plan" and not the "standard, analog repeater and simplex" areas where everyone seems to be putting them?
    Thank you
  2. K7MH

    K7MH Ham Member QRZ Page

  3. K7JEM

    K7JEM Ham Member QRZ Page

    Repeaters are only legally operated in certain band segments, so if these are repeaters, they have to go there.
    KD8ZMN and WU8Y like this.
  4. WB2WIK

    WB2WIK Premium Subscriber QRZ Page

    I give them all a digital salute.:)
  5. KK5JY

    KK5JY Ham Member QRZ Page

    In the US, as long as voice operation (digital or otherwise) doesn't happen in the CW-only portion of the band, there are no restrictions on where they are operated. VHF and UHF aren't divided up into "analog vs digital," and for that matter, the only division is "CW only" vs. "anything goes," with the former being only 100kHz wide at the bottom of the bands.

    VHF and UHF band plans are no more than helpful suggestions, and they differ from region to region.
  6. K0RGR

    K0RGR Premium Subscriber QRZ Page

    There is no digital band plan for those bands. This is part of the problem with getting the digital voice modes to be accepted - a new DV repeater either has to replace an analog repeater, or as with the FUSION repeaters and some custom built D-star machines, be able to do more than one mode. A lot of the Yaesu repeaters out there are capable of FUSION, but being used for analog. There have been situations where two repeaters were on the fringe of each other, and nobody complained about the occasional interference between them. But when one switches to DV, the resulting cacophony of howls emanating from the FM side is deafening. The problem could be fixed if the FM repeaters all transmitted a tone, but most don't.

    When I travel, I hear lots of busy repeaters that have converted from FM to digital voice, and of course, if it's not the flavors I have, I can't copy it.
    G7BND likes this.
  7. WD8T

    WD8T Ham Member QRZ Page

    Have to keep those bands alive somehow or the FCC will start auctioning it off.
  8. KA0GKT

    KA0GKT Ham Member QRZ Page

    DMR occupies about 6.5 KHz; D-Star occupies 9 KHz at 8kbps and 5KHz at 2.4 kbps. NXDN is either 12.5 or 6.25 KHz wide; P25 (APCO 25) fits into a 6.25 KHz channel.

    Carson Bandwidth Rule states that the occupied bandwidth of an FM signal is 2x (peak deviation + highest modulating frequency) so 5 KHz peak deviation with 4 KHz peak modulating frequency would occupy 18 KHz.

    RTTY occupies, IIRC (and would certainly stand corrected) 1.2 x frequency shift (in Hz) + the Baud Rate in Bits / second, so if you're running 300 baud, the occupied bandwidth will be 470 Hz. RTTY is a bit of a digital bandwidth hog, PSK31 uses about 100 Hz of bandwidth.

    I would agree with your suggestion if the occupied bandwidth of the digital audio signal was no broader than the widest bandwidth currently allowed in the digital or data portion of the band, so once there is a digital voice modulation system which occupies 470 Hz or less, the rules should be changed. Until that time (I'll never sat "Never", but we're going up against physics here) Digital voice should remain in portions of the band with modes which use similar bandwidth.
    KD4MOJ likes this.
  9. KD4MOJ

    KD4MOJ Platinum Subscriber Platinum Subscriber QRZ Page

    Actually 12.5 Khz.:) It's 6.25 per slot.

  10. KC1HOX

    KC1HOX Ham Member QRZ Page

    I dont know what the issue is. I live in connecticut and we have over 100 repeaters and plenty of room for more. Dozens of fm , dstar ,dmr some fusion nxdn and p25 all live happily.

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