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NXDN™ specification released

Discussion in 'Amateur Radio News' started by G4TUT, Jul 18, 2012.

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  1. G4TUT

    G4TUT Ham Member QRZ Page

    NXDN™ specification released

    The technical specification for NXDN™, a FDMA digital voice technology supported by ICOM and Kenwood, is being opened to the public domain.

    For the past 5 years both ICOM and Kenwood have been producing VHF/UHF mobiles, handhelds and repeaters to the NXDN™ standard. The equipment has a transmitted bandwidth of 4.0 kHz and is typically used in 6.25 kHz channel spacing systems.

    The specification is currently available in response to an email request but the NXDN™ Forum indicates it will be available for direct download later in the year.

    The NXDN™ press release reads:

    The Chair of the NXDN™ Forum announced that the Forum Steering Committee will open the NXDN technical standards to the industry public.

    Interested companies can obtain the information for the NXDN technical standards by following the instructions on the NXDN Forum web site

    NXDN Digital products are deployed throughout the world in hundreds of thousands of professional radio applications. As NXDN’s popularity continues to grow it will easily become the primary next generation narrowband two-way radio digital protocol and increase demand in the market for products from multiple vendors. To accelerate the spread of NXDN and to expand on the opportunities it provides, the NXDN Steering Committee has agreed to open the technical specification to the public domain.

    The NXDN Forum will continue to accept new members after opening the technical specifications and will govern the NXDN specification and related interoperability testing and certification.

    NXDN™ Forum

    2005 Icom and Kenwood demo 'Very Narrowband Digital Communications Technology'


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  2. N0NB

    N0NB Ham Member QRZ Page

    The company I work for has plenty of Kenwood NXDN capable radios in its fleet now. I have not sat down and tested the mode as of yet as we have not deployed it, choosing only to employ the "narrowband" 2.5 kHz analog FM required at the first of the coming year.

    Will NXDN have the same limitation as D-Star where the protocol is open but the codec is patent encumbered? Still, opening these protocols is a Good Thing (TM) and will make interoperability possible down the road.
  3. KN4X

    KN4X Ham Member QRZ Page

    Throw in C4FM FDMA and D-Star and we get another VHS vs Betamax fiasco. Might as well save our pennies and let the elite decide which one will be "best for us".
  4. KA9UCE

    KA9UCE Ham Member QRZ Page

    If business and private concerns would come together and work in partnership instead of singly. Too many protocols are attempting to become the defacto standard in the land mobile marketplace, and we are seeing the fragmentation. With Open Sky, D-Star, P25 and all its iterations. The vocoder 'standard' is not really a standard, but an accepted format.
    From the earleir VSELP vocoders, to IMBE and AMBE+ Etc.. Digital prtocols should be adhered to, with a single platform in which everybody has a stake, and not a single entity calling all the shots. Digital is a great migration path, but the FCC is also strangling operators, both commercial and private to go full narrowband, without thinking this through.
    Narrowband mandates are full of holes, as the actual equipment that can open channels for use by TDMA and even CDMA standards has not really 'hit' the land mobile market.
    With all the talk of placing two or more voice channels within a single channel spacing, or splitting up a segment of time within a apecific channel, there are no marketable radios capable of what the FCC has been saing is possible. Sure, it is possible, but why push everybody to narrowband and even purchase new radios simply because they want us to make allowances for the upcoming mandate. Frankly, many in the industry see this as a tactic to force operators to spend money on radios they do not need, and to inject cash into specific businesses, which by the way, are probably those very companies that spend a lot of money to buy sectrum and help put pressure on the FCC to strip amateur radio bands from us. Think of 220, and what a mess that became. The FCC is playing politics that it really has no lawful authority to be involved in. we need to join and come to an agreement as to what is also best for us, and not let large corporations make the choices for us. This rarely works, and looking at the playing field at this time shows they too, do not understand each other, so how are we to as well?
    I like the IMBE/C4FM protocol, and prefer it over all others, and if I had to select one, this is what I would choose. It is stable, proven and effective. WIth signal processing and low BER, in most cases, it is a good choice. Royalties need to be addressed, as this is not acceptable if you are going to make a product for sale. it doesn't make good business sense to keep charging higher prices and limiting the options.
  5. KA5LQJ

    KA5LQJ Ham Member QRZ Page

    This NEWS is all well and good, but what about including HF frequencies? This would be a good option in case of severe wx or disaster to give HF'ers clear and clean communications that could be understood. D-Star requires having a 2 meter or 70 cm cross-band to work. The new protocol would just need the hf rig and FM capability. :cool:

    Respectfully submitted,

    Last edited: Jul 18, 2012
  6. N0SSC

    N0SSC XML Subscriber QRZ Page

    Too many digital modes! We'll have to see how they fight in the ring. Meanwhile I feel like the linux community/hackerspace is hard at work making a truly open radio standard.

    NXDN is already in use by Icom (IDAS) and Kenwood (NEXEDGE). It is very much patent encumbered, and will probably remain a protocol for land mobile and professional systems.

    Hurray it's on the way! Not quite hackerspace, but definately open source. Currently Codec2 is great for HF, and takes up 1.1 KHz using FDMDV
    Frequency Division Multiplexed Digital Voice
    ). The audio can be sent through FM on VHF/UHF but they're working on implementing it on a C4FM or GMSK modem to allow others to build radios that use it.

    A worthwhile watch:
    Last edited: Jul 18, 2012
  7. K8WHB

    K8WHB Ham Member QRZ Page

    ALL the commenters have brought up some excellent points. D-Star is a dead end for a number of reasons that are well covered in the literature from Yaesu and the NXDN folks, so for the future of digital ham radio I don't even consider it.

    C4FM-FDMA I think makes the most sense. The TDMA formats (DMR, for example, or Yaesu's new digital system, which is a modified version of DMR) don't give the same spectrum efficiency without a repeater to "play time slot traffic cop". 4-level FSK as a transmission medium has been used in the real world since the late 1980s (2400 baud POCSAG paging & Flex are both 4-level FSK systems, though they use 2.5 KHz/5.0 KHz deviation). Some of the digital transmission systems require linear amplifiers, which reduces efficiency - C4FM can use existing FM mode RF systems (just as a little sidebar, don't overlook old paging transmitters as good candidates for ham digital transmitters. Mototola & Quintron/Glenayre units going back to the 1980s do 4-level FSK quite well, and they are made for 100% duty cycle service).

    At this point ALL the commercial digital systems (as well as D-Star) are encumbered by patented codecs, and some of the licensing fees are nothing short of extortion (why do you think D-Star radios cost so damn much - the patent fees Icom has to pay are a good chunk of the premium). Developing an open source patent/royality free codec system for amateur digital that works as well as the AMBE+ codec and can be transmitted using C4FM has to be "Job #1".

    The work that Sterling talked about is VERY encourging: the trick is going to be turning such an open system into actual hardware (I do NOT consider "ANY" system with patented components, even with a public spec like NXDN or D-Star, to be an "open" system, even though JVC-Kenwoord & Icom misuse that term in their description of NXDN).

    The next few years will be VERY interesting.


    Bill K8WHB
  8. KY5U

    KY5U Premium Subscriber QRZ Page


    Many of these modes require more than 3khz of bandwidth desirable on HF. There are modes being used now on HF that are more compatible than these VHF/UHF modes. One group of users is called HF Pack, and I am sure other readers can give you info on others. But remember, look at the bandwidth required and use 3kHz or less to be compatible with other voice modes.

    BTW, many Amateurs don't like AM used because it uses 4-6Khz of bandwidth nor do they like "enhanced SSB" which has bandwidths usually around 4kHz due to voodoo audio.
  9. WX1DX

    WX1DX Ham Member QRZ Page

    Like some of the comments I to believe it is time to figure out what actually works best,is widely deployable, can be used on HF, VHF, UHF alike. A good sauce to make a comparison is simple easy to remember readily available and recognizable to the user/consumer. these are the things that matter most.
  10. KB8O

    KB8O Premium Subscriber QRZ Page

    "D-Star is a dead end for a number of reasons that are well covered in the literature from Yaesu and the NXDN folks, so for the future of digital ham radio I don't even consider it".

    I love ignorance ...

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