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Thread: Interesting DMR Digital Radio Development by Ham Roger Taylor

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    Default Interesting DMR Digital Radio Development by Ham Roger Taylor

    One of the Australian developers of the MMDVM (SDR Radio) firmware used in Amateur Radio hotspots (Jumbo Spot / Pi-Star) has embarked on an interesting project to directly interface the PiStar platform to a Radioddity GD-77 radio directly via USB interface.

    This work will allow the actual radio hardware to be used directly with a Raspberry Pi running Pi-Star. He's got early prototype code working with two slot DMR at this point.

    This work could eliminate the need for a SDR radio hat for implementing hotspots.

    https://www.rogerclark.net/opengd77-...alpha-version/

    Roger Clark calls the project OpenGD77.

    One of the problems Roger is dealing with is reverse engineering the Chinese DSP being used to process DMR AMBE and digital audio within the GD-77 handheld radio. The chip, designated HR-C6000 by it's developer, looks like a firmware personality burned on a standard TI DSP chip. Documentation is next to impossible to find, so the work has been trial and error.


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    Quote Originally Posted by mrerick View Post
    One of the problems Roger is dealing with is reverse engineering the Chinese DSP being used to process DMR AMBE and digital audio within the GD-77 handheld radio. The chip, designated HR-C6000 by it's developer, looks like a firmware personality burned on a standard TI DSP chip. Documentation is next to impossible to find, so the work has been trial and error.
    Wonder if that's the one DVSI is pissed at...

    dvsi.jpg

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    DVSI's scare tactics are really lame. Immature even.

    Saying something about the illegitimate manufacturer is one thing, but threatening to come after people who buy the radios, unknowingly, is another. Okay there, Motorola legal team wannabes.

    With respect to the FBI nonsense, it is not criminal copyright infringement unless the following criteria can be proven:

    https://www.justice.gov/jm/criminal-...nd-18-usc-2319

    There's also this thing called jurisdiction.

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    Considering the retail pricing of the multiple Chinese radios using the D-5000 and D-6000 DSP chips, it would not surprise me.

    Here is a translation of the documentation they were able to locate:

    https://raw.githubusercontent.com/ro...translated.pdf

    Roger isn't investigating the internal firmware used with the DSP, just loading a binary copy as released by the radio manufacturer.

    This blog entry discusses the process so far: https://www.rogerclark.net/dg4klu-gd...v-0-1-rx-only/

    I have not seen if the Chinese manufacturer that created the chip / firmware is licensed for the AMBE encode / decode technology. I don't remember the names mentioned above being associated with the HR-C6000 chip he's trying to understand.

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    From the data sheets that they have located, the HR-C5000 and HR-C6000 DSP used in many of these Chinese radios is made by Hangzhou Hongrui Communications Technology Co. Ltd.

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    The HR C5000 / C6000 chips only do the DMR layer 2 & 3 stuff. No vocoding ie: AMBE. In CCRs that is most often done in the radio's MCU... which also explains why the radio's MCU firmware is frequently encrypted. Some might say it's to protect the vocoder contained within, others say it's to hide the fact that the vocoder could be pirated. The exceptions that I know of are the Anytone radios where L2/L3 & vocoding are all done in the one chip, which is DVSI licensed, and a new HongRui chip starting to appear the HR-C7000 which apart from the RF transceiver and flash memory, is nearly a one chip radio solution (and not a very good one at that). Even worse is the HS8850 which has everything on the one chip: RF transceiver, MCU, flash memory, speech synthesis, audio PA. DMR audio out of that nasty little slab of silicon sounds like an 1980s speak 'n spell kids toy.

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    Quote Originally Posted by duggerd View Post
    Wonder if that's the one DVSI is pissed at...
    Now I know exactly where to go for cheap vocoder ICs.

    Thanks, DVSI!

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    The Chinese don't give a rat's Shiff hole about copyright. They are copying everything as fast as they can. Most of the companies in this realm in China are either owned and/or controlled by the Chinese Government. They even sponsor college students to come to the USA to learn our tech and then take it home.

    We are our own worst enemy when it comes to espionage. Going to the FBI about foreign enemy countries stealing our tech is laughable.
    "God as my witness" - Jeremy Dewitte - Felon

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    A users guide to Rogers Open GD77 has been posted at:

    https://www.rogerclark.net/opengd77-user-guide/

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    The OpenGD77 project has continued work. Right now, Roger has added multi-language voice prompts to the CPS (to upload voice files) and the Firmware. it's going through some revisions right now, but the first iteration is working well.

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