D is for Digital M is for Mobile R is for Radio in the context of D.M.R., Howard. In actuality, all D.M.R. radios are analog at heart. Various types of modulation are applied to an R.F. carrier to produce a signal that carries information which has been digital ( as in considered to be either a one or zero ) in nature. So in a sense, when you send morse code with a key- you produce a 'sort' of digital radio. You should not advertise this. The reason that you should not advertise the above statement is because it is an over-simplification, and does not meet the standard of new technology for error correction by microprocessors. AX.25 Standard packet would be closer, with A.P.R.S. Yet some folks would not consider AX.25 to be the same as the new D.M.R. standards.... So this would be a good time for some to study FSK, QPSK, and QAM modulation... and think about bandwidth.
Of course, because the radios of today include microprocessors which send the data at a high rate- you have different standards for how this is accomplished in modulation. In the commercial world ( non-ham ), there are a few notable suppliers: Motorola ( MotoTrbo trademark, APCO P.25* ) Tait ( See various DMR levels, APCO P.25* ) Kenwood ( Systems which conform to DMR in the CTCSS subaudible sense of the word *) Hytera Raytheon ( gateway for P.25*, etc. ) Vertex In the amateur radio world, there are other suppliers: Kenwood ( Latest D-Star(tm) equipped radios ) Icom ( D-Star(tm) first U.S. 'Big-three' offering ) Yaesu ( Wires conversion, C4FM modulation ) Alinco Timewave (AX.25 modulation products for use in adding terminal mode controllers to FM radios**) Uniden, G.R.E. ( Trunking scanners, Phase 1 P.25* ) * I hesitate to mention other suppliers, and do not endorse any specific supplier. Analog means that a signal ( such as your voice ) varies in amplitude according to your lungs and vocal cords, and frequency. Digital means that binary has just two states, yet can be modulated in many ways to provide higher throughput over an analog link of sufficient bandwidth. Modulation types are defined by the F.C.C. and include C4FM. Throughput has to do with the amount of information that can pass in a given time, see Baud Rate and Bits per Second (B.P.S. ) Common industry standards: D-Star(R or tm) was created and includes royalties to the Japanese Amateur (JAARL ) folks, as CODECS require the software. Icom had initial offerings in the U.S., yet Kenwood joined. MotoTrbo(tm) is a proprietary C4FM based digital and analog radio standard. Vertex radios share C4FM, as can Yaesu. CODECs convert analog signals ( such as voice or video ) to digital form, and vice-versa. Many radios can do some DMR modes, but are not directly interoperable because of CODEC royalties ( few makers are known to install multiple-types of CODECs in the same hardware). Gateways often allow audio, yet sometimes not video or data to pass- because the CODECS are carefully controlled. Raytheon is one commercial maker of note. ** AX.25 or Packet Radio is sometimes not considered to be D.M.R., but in reality- it fits and accomplishes the same results. See H.D.L.C. protocol for error correction and channels. PSK31 modulation normally does not contain error correction, and thus can be seen as of less use in EMCOMM situations than AX.25 eg. Winlink gateways. P.25 refers to APCO modulation, either Phase 1 or Phase 2, which some would not consider to be D.M.R. in the commercial sense- because it involves 'trunking' as a rule. APCO is a public safety ( governmental support ) agency which promotes the P.25 standard ( Motorola Astro , Tait, E.F. Johnson, etc. suppliers plus others). Jon L. Livingston, Electronics Technician 9520 Wilcrest Drive #3110 Houston, Texas 77099 [email protected] Known for a time as the President of the Unix Users of Minnesota (UUM) General Radiotelephone license PGGB062294 CET Wireless Communications WCM-R185658 Mbr.095007 Amateur Radio license KB0MNM PLEASE REFERENCE THE MESSAGE BELOW from Howard if you choose to elaborate or try to 'correct' the above, Thanks!!! 73 ----- Original Message ----- From: "D. Howard Bingham via BVARC" <[email protected]> To: "Mike Hardwick via BVARC" <[email protected]> Cc: "D. Howard Bingham" <[email protected]>, "Howard Bingham" <[email protected]> Sent: Wednesday, June 13, 2018 4:21:34 AM Subject: Re: [BVARC] BVARC General Meeting - This Thursday June 14th Pardon my stupidity, but WHAT is DMR , is it another name for D-Star, that now Kenwood is also marketing.? 73 D. Howard Bingham KE5APJ - Deer Park, TX ========================= On 6/12/2018 9:54 PM, Mike Hardwick via BVARC wrote: Matt Cline, K3JMC, will bring to us the in-and-outs on Digital Mobile Radio or DMR. DMR is growing fast and Houston already has nearly 15 repeaters operating DMR. Come out to the meeting to find out more on this fast growing digital format. Also staring at the June meeting will be the BVARC raffle 2.0. This raffle is extremely different since the prize is a “station in a box”. This station in a box is everything but the trees so make sure you pick up your raffle ticket to win a new radio and accessories. We will be selling tickets for the station in the box through November’s Chili supper. If you would like to sell tickets, tell Donovan you would like to sell one or two or 20 packs of tickets. It’s up to you on how many tickets you would like to sell. Donovan will have all the specifics on selling the tickets. And don’t forget Field Day coming up on June 22 nd , 23 rd and 24 th . With five groups joining in this year, the combined Field Day is quickly becoming one of the largest Field Day gatherings in Texas. This year it will be held at Duhacsek Park off Old Richmond Road and Voss. The location will give us more than enough room to have a great time. Don’t forget to sign up to operate for Field Day. The web site to sign up is: <https://docs.google.com/spreadsheets/d/1_CoLXpiWzGCTqBPevjCRejNDlf4T4hQYEWmWh2OI6AA/edit?usp=sharing > Allen Brier has done a great job on putting together the signup sheet and it is extremely easy. Also, pass the word around for the July meeting. Kyle Brewer, AE5IJ, will be coming by and telling us what is up with the ISS, its radio communications and the status of the amateur radio equipment. Make sure you make it to the July meeting. And it will then be that time again. Time for Ice Cream at the August general meeting. See you there . Mike N5VCX _______________________________________________ BVARC mailing list [email protected] http://mail.bvarc.org/mailman/listinfo/bvarc_bvarc.org Message delivered to [email protected]
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