Experimental version with option to disable CC filtering

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VK3KYY
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Experimental version with option to disable CC filtering

Post by VK3KYY » Sat Feb 22, 2020 1:01 am

Thanks to some research from Colin G4EML, we have been able to disable the Colour Code filtering inside the HR-C6000 DMR chip

I've modified the DMR filtering in the options, so that the list is now

NONE
CC
CC,TS
CC,TS,TG
CC,TG,Ct

when CC filtering is disabled, the Colour Code display e.g C1 is shown in inverse video


Notes.

When CC filtering is disabled, occasionally there are some DMR noises at the end of the received signal.

I'm not sure if it will be possible to get rid of these, because the datasheet for the C6000 chip seems to say that CC filtering is always enabled and the received signal is also checked my the software to ensure the correct Colour Code has been received.
I'm not sure how , with the CC filtering enabled inside the C6000 that it could output data that was on a different CC, but I suspect there may be a design flaw in the chip, which can allow this to happen under some circumstances, hence the data sheet says the CC should be checked by the CPU.

Also.
There is no shortcut to change the radio to the Rx signal CC.

So if CC filtering is disabled, you may transmit on a different CC to the Rx CC, even though you can clearly hear the signal

I think possibly we may be able to speed up the CC scan function, by briefly disabling the CC filtering and then checking the received CC over several frames and then calculate which is the most likely CC for the Rx signal to be using.
I don't think we can simply use the first CC on the Rx signal in this case, as the received CC value may not be 100% accurate when the CC filtering is disabled.

Edit.

I've uploaded a slightly improved version of the CC filter, using a change supplied by Colin.

This is just a temporary fix, I need to completely review call acceptance criteria in the code to fix the ID display problem etc
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Ik0nwg
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Re: Experimental version with option to disable CC filtering

Post by Ik0nwg » Sat Feb 22, 2020 5:04 am

Excellent Roger and Colin!!! it works very well !!! some small noise when the CC filter is disabled as you specified and then I noticed that no communication data (no TA and no DMR ID) is displayed only audio. Thanks to you and the whole group.
Sal
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VK3KYY
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Re: Experimental version with option to disable CC filtering

Post by VK3KYY » Sat Feb 22, 2020 5:08 am

Ik0nwg wrote:
Sat Feb 22, 2020 5:04 am
Excellent Roger and Colin!!! it works very well !!! some small noise when the CC filter is disabled as you specified and then I noticed that no communication data (no TA and no DMR ID) is displayed only audio. Thanks to you and the whole group.
Sal
I think it needs more work ;-)

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Ik0nwg
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Re: Experimental version with option to disable CC filtering

Post by Ik0nwg » Sat Feb 22, 2020 5:24 am

in fact this feature is very useful for discovering the CC in a scan. once the CC has been identified, it is possible to memorize everything and deactivate the filter and in this way the TA or DMR ID is correctly displayed again. So that's fine too. thanks again this function is very very very useful !!!
Ciao Roger
Sal
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Re: Experimental version with option to disable CC filtering

Post by VK3KYY » Sat Feb 22, 2020 5:25 am

Doing some more testing, I think TA is not always working if the CC does not match.

I'm not sure why this is happening at the moment.

Edit.
It looks like the ID is OK, but its the TA that is not being decoded.

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Ik0nwg
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Re: Experimental version with option to disable CC filtering

Post by Ik0nwg » Sat Feb 22, 2020 5:33 am

I will test throughout the day using this feature intensely. I will update you on the results.
Ciao Roger
Sal
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VK3KYY
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Re: Experimental version with option to disable CC filtering

Post by VK3KYY » Sat Feb 22, 2020 5:58 am

Signals from my local repeaters seem OK, except for the noise at the end of the transmission.

But using my Duplex hotpspot is a lot worse.

I think colin had it working quite well, but I don't think he had TimeSlot filtering also disabled, and this probably makes things worse.

I'll need to modify the filering options so that TS filtering acan be enabled but CC filtering disabled.

IK8JHL
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Re: Experimental version with option to disable CC filtering

Post by IK8JHL » Sat Feb 22, 2020 8:32 am

VK3KYY wrote:
Sat Feb 22, 2020 1:01 am



I think possibly we may be able to speed up the CC scan function, by briefly disabling the CC filtering and then checking the received CC over several frames and then calculate which is the most likely CC for the Rx signal to be using.
I don't think we can simply use the first CC on the Rx signal in this case, as the received CC value may not be 100% accurate when the CC filtering is disabled.
Good job!
In fact, I was wondering why CC scanning is so slow, compared to CTCSS scanning instead,? is there a limit within which it cannot find the CC? Indeed the compromise would be to create small interruptions to find the right CC

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Re: Experimental version with option to disable CC filtering

Post by VK3KYY » Sat Feb 22, 2020 9:04 am

IK8JHL wrote:
Sat Feb 22, 2020 8:32 am
Good job!
In fact, I was wondering why CC scanning is so slow, compared to CTCSS scanning instead,? is there a limit within which it cannot find the CC? Indeed the compromise would be to create small interruptions to find the right CC
CC scanning is currently slow as the DMR chip needs to be set with each of the 16 possible Colour Codes and then we need to wait for the DMR chip to receive enough data to pass its CC filter.


Personally, I think disabling the CC causes the reception algorithm a lot of problems, so I don't know how useful this option would be, unless we can improve its operation somehow.

IK8JHL
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Re: Experimental version with option to disable CC filtering

Post by IK8JHL » Sat Feb 22, 2020 10:18 am

Right, it is better use as two separate options, hoping to find some new command for the C6000

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