Software DMR in Chip Microcontroller

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VK3KYY
Posts: 7478
Joined: Sat Nov 16, 2019 3:25 am
Location: Melbourne, Australia

Re: Software DMR in Chip Microcontroller

Post by VK3KYY » Sun Jun 19, 2022 6:32 am

The supported radios, e.g. GD77, MD9600 are not open hardware.

They are commercial radios which we repurpose by writing new firmware.

We have no control about what chips are in these radios

There is no connection between the MCU and the RF or AF in these radios execpt via the C6000 etc.

If you are designing and building your own radio, you can use whatever chips you want.

ok1pt
Posts: 167
Joined: Mon Jul 20, 2020 3:38 am

Re: Software DMR in Chip Microcontroller

Post by ok1pt » Sun Jun 19, 2022 7:40 am

Jozef wrote:
Sun Jun 19, 2022 5:33 am
Hi every one,
I thought a lot about why we using DMR chip like "HR-C5000", "HR-C6000" or any one other.
Can we make our DMR programmatically in chip microcontroller like STM32F or any suitable microcontroller?
Share your thoughts with us.
any one have information or resources please share it with us.

Jozef
Hi Jozef!
I believe I understand you correctly - you want to implement the DMR processing by software emulation on the MCU and not use the hardware chip ?
I'm afraid that it's not possible for a lot of reasons (in the order of their importance):
1) There is not a direct AF signal way to the MCU, so it can't read it and provide software demodulation and the digital processing of the signal.
2) The MCU is not powerful enough to do this - it's just the control unit for user interaction and programming the specialized chips to do their work. There is a lot of very delicious things you have to do, like syncing the receiver perfectly to the transmitted signal, which should be done in parallel with decoding and evaluating the signal, and this MCU simply can't do this, it's a small single-core unit.
3) The program memory capacity is limited, and it's mostly consumed by the current program image. So, there's no space to include such a big piece of software like DMR processing.
4) On receive, the MCU should be working full-time by permanently scanning the signal for the presence of valid DMR etc. So, the battery would be consumed very quickly.
With regards / 73
Pavel OK1PT

ok1pt
Posts: 167
Joined: Mon Jul 20, 2020 3:38 am

Re: Software DMR in Chip Microcontroller

Post by ok1pt » Sun Jun 19, 2022 9:46 am

Jozef wrote:
Sun Jun 19, 2022 8:55 am

Hi ok1pt,
thanks for your sharing , Yes this is which I meant.
all your reasons are reasonable and I aware it`s difficult task, but some microcontroller which has (digital signal processing DSP) property have a good possibilities like OMAP or TMS or even FPGA.
some Expensive digital radio like hytera using OMAP for this purpose.
I do not know if there is possible or not and this is the reason for writing this post.

warm greeting
Jozef
Hi Jozef,
OK, now I'm understanding better. I thought that you want to reimplement the DMR in software in the radios which are used in this project- i.e. GD-77s and its clones.
Of course you can do it in your own design, SDR (Software Defined Radio) is a common practice today and you can find a lot of free projects, which use for example DVB-T USB receivers for the RF part and the rest (of course just the receive part) is then done in SW and they receive most of digital standards, DMR not excluding.
If you will buy a two-way hardware for SDR radios, you can program the transmit path as well. There are open source projects, which can generate GSM, DECT and other public mobile standards, so there will be no problems with DMR, it's possible that such projects exist as well, I just didn't any research in this field (yet ?). But you need to have a standard PC or at least something like Raspberry Pi for the computing performance.
WIth regards,
Pavel / OK1PT

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