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Thread: DMR

  1. #1

    Default DMR

    Hi all,

    Is anyone on here operating on DMR? I'm shortly to be joining the network and was wondering if there might be anyone around to chat with. ;-)

    Jason G7RUX

  2. #2

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    Hi Jason,

    Well, I did a little research on the mode for the United States and our Federal Communications Commission allows the use of DMR ONLY for the use of Part # 90 Business Band Two-Way Radio NOT to be used for the Amateur Radio Community which falls under Part # 97. This Digital format sounds much like the Motorola iDEN TDMA technology that was sold to NEXTEL in the 1990s although Motorola design used a 25 KHz Channel assignment, split between Voice Two-Way / Telephone Interconnect / Data Signalling and accomplished using 30 Time Slots total. It was a fairly well secure system because of the TDMA format and the business community really liked the product. When Sprint bought out the NEXTEL System, they wanted to switch it to the CDMA format but that would have required a completely different design so Sprint has let the TDMA slide into the garbage can and they'll be tearing out all of the Tower Sites with the RF Hardware & Mobile Switching Offices in the next 3 to 5 years. Someone in Sprint certainly didn't understand the technology before buying the former NEXTEL System.

    Dan

  3. #3
    Super Moderator 2E0FVL's Avatar
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    Seems to be a few repeaters coming along looking at this: http://www.ukrepeater.net/index.html
    From the DMR Site: New Repeaters on the network
    WD9IEV Milwaukee, WI
    KG4GOQ Lake Worth, FL
    W2GGI Delray Beach, FL
    K4KTR Bardstown, KY
    NH7CY Minneapolis, MN
    N9KYB Galveston/Kokomo, IN
    N9KYB Frankfort, IN
    W9AMT Indianapolis, IN
    VE6VPR Edmonton, AB
    VE2RCM Montreal, QC
    VA3RFD Ottawa, ON
    WD5ETD Tulsa, Oklahoma
    XE1LM Mexico City, Mexico

    Looks like it's building up!!
    Pete - 2EFVL
    The QRM Formally Known As M6PAP!!
    www.selseylifeboats.co.uk
    www.amberleymuseum.co.uk

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    Quote Originally Posted by WA9WVX View Post
    Well, I did a little research on the mode for the United States and our Federal Communications Commission allows the use of DMR ONLY for the use of Part # 90 Business Band Two-Way Radio NOT to be used for the Amateur Radio Community which falls under Part # 97.
    interesting. There are an awful lot of people using that mode for amateur communications: http://dmr-marc.net

  5. #5

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    Quote Originally Posted by WX4LTG View Post
    interesting. There are an awful lot of people using that mode for amateur communications: http://dmr-marc.net
    Okay, Well I stand corrected but the way the document was written, DMR uses 6 or 8 Time Slots and the MotoTrbo uses 1 Time Slot out of 30 Time Slots at least here in the United States, and I do remember reading that the F.C.C. Approved the use of MotoTrbo technology for the Amateur Radio Community. A Time Slot refers to the use Telco lines allowing the Network to exist between all of the states and/or countries . and for the most part it also determines the RF Channel Bandwidth being 6.25 KHz wide. I've heard that most people prefer MotoTrbo versus D-Star Audio but I've never heard either Narrow Band technology in real time use. I do remember when Shaumburg (IL) Campus did a study or comparison between iDEN / Nextel (TDMA) versus P25 (FDMA) Audio in 1997, the P25 Audio won hands down but when they compared the Spectrum Efficiency, the iDEN / Nextel had them beat every which way than up so every technology has its own trade offs.

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    Quote Originally Posted by WA9WVX View Post
    I've heard that most people prefer MotoTrbo versus D-Star Audio but I've never heard either Narrow Band technology in real time use.
    I've heard the same thing - and France apparently declared D-STAR illegal because the codec is non-public, so they've classified it as "encryption" and not "encoding."

  7. #7

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    Quote Originally Posted by WA9WVX View Post
    Well I stand corrected but the way the document was written, DMR uses 6 or 8 Time Slots and the MotoTrbo uses 1 Time Slot out of 30 Time Slots at least here in the United States, and I do remember reading that the F.C.C. Approved the use of MotoTrbo technology for the Amateur Radio Community.
    I suspect that you may be confused with the system we call TETRA in Europe; DMR Tier 2 (what DMR-MARC kit uses) has two timeslots. The RF channel BW is still 12.5 kHz but is often referred to as half that because of the two timeslots; a misnomer in my opinion.

    Anyway, back to my original question; is there anyone on here who uses DMR; my DMR MARC ID is 2351657 and would welcome a call (or a text!)

    Jason G7RUX

  8. #8

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    Jason,

    I've been very much aware of the TETRA System over in Europe as I worked with both the Motorola iDEN / Nextel and the TETRA Systems while at the Schaumburg, IL Campus. I did do field implementation of the iDEN / Nextel Mobile Switching Offices. MotoTrbo was just on the verge of being introduced in 2004 and the Base Stations are the MTR3000s. You're absolutely correct about the 2 Time Slots for a 12.5 KHz Channel but some how Motorola Solutions, Inc. managed to sell the idea that the MotoTrbo was Narrow Band Digital for Type Acceptance. I think of Narrow Band Digital as a 6.25 KHz RF Channel and that explains why the MotoTrbo would have a better audio than the D-Star.

    Dan

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