Digital Mobile Radio (TDMA) comes to Ham Radio.....

Discussion in 'Survival Communications' started by BTPost, Jun 11, 2014.

  1. BTPost

    BTPost Stumpy Old Fart,Deadman Walking, Snow Monkey Moderator

    FCC officially gives the green light to DMR for US hams
    Filed in DMR, FCC by Don Trynor, VA3XFT on June 10, 2014

    On June 9th, the US Federal Communications Commission, commonly known as the FCC, officially approved the use of Time Division Multiple Access (TDMA), the modulation type used by Digital Mobile Radio (DMR), for ham radio use.

    In FCC Decision FCC 14-74 issued on June 9, 2014, the FCC outlined its decision to officially approve TDMA for ham radio use, as in doing so would be “consistent with the basis and purpose of the amateur service”. While this is great news for the nearly 3,600 US hams who are currently using DMR, it will serve more as closure to the longstanding issue of technical non-compliance of TDMA with the FCC’s Part 97 Rules. To address this technical non-compliance, the FCC issued a blanket waiver in 2011 at the request of the Amateur Radio Relay League (ARRL) for ham radio use of TDMA, however speculation within the ham radio community as to whether TDMA and by association, DMR, would officially be permitted in the Part 97 Rules has ranged on until now. With this decision, clarity has now been provided to US hams, which should allow DMR to gain even more traction within the US ham radio community.

    For more information about DMR, check out the DMR page.
    Airtime, kellory and Georgia_Boy like this.
  2. techsar

    techsar Monkey+++

    Too bad the digital signal, at same ERP levels, is about 6db down from an analog signal, received about 35 miles away. Real world, not "it works on the test bench." This is a big drawback for nearly all digital communications. Same reason tv stations had to roughly quadruple the output power to maintain the same coverage area as they enjoyed while in analog...

    After seeing the failures of digital systems (700 and 800 mhz) during tropical storms or even just overloading the systems, I am not a fan of most of these digital modulation schemes. They have an annoying propensity to fail when they are needed most.

    It also gives the FCC a way to save face for not acting on the non-compliance issue, rather than just a waiver.
  3. BTPost

    BTPost Stumpy Old Fart,Deadman Walking, Snow Monkey Moderator

    True enough, Techsar.... I have been telling the folks that I consult with, these facts for Years, and watching many get sold, Pig in a Poke Digital Systems, by the Big Boys, and after a couple of months of Poor Performance, they just disappear, looking for the next Sucker Muni.... I insist that a provision in the contract, be added, That if the new System does NOT preform, as well as the Od System, after 6 months, they are REQUIRED to replace their New Crap, with the Old Stuff and Refund ALL the Money spent. You can't imagine the looks on the Salesman's Faces, when they read that clause. Many just walk away from the negotiations. Saves a lot of small Cop Shops and Muni's from massive Comms Grief.... .......
    kellory likes this.
survivalmonkey SSL seal warrant canary