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MMDVMHOST FM mode implementation
Posted: Mon May 11, 2020 9:39 am
by IZ8GUR
Hi,
Are you planning to add FM mode that has been added to mmdvmhost?
73
Re: MMDVMHOST FM mode implementation
Posted: Mon May 11, 2020 12:40 pm
by M1DNS
One thing to be aware of, it is only applicable to repeater installs or installs using external transceivers as the AD 7021 Rf chips used in most hotspots can't 'do' FM.
The MMDVM boys are still testing it mostly headed up by Geoff F4FXL So prob. best to give them chance to iron it all out there first, but it seems a very popular inclusion as Jon says a lot of MMDVM users have asked for it.
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Re: MMDVMHOST FM mode implementation
Posted: Mon May 11, 2020 1:16 pm
by IZ8GUR
The main target for me is create a hybrid analogue/digital repeater made easy, is the only use that i can imagine.
Re: MMDVMHOST FM mode implementation
Posted: Mon May 11, 2020 6:27 pm
by G8SEZ
Don't forget that somewhere there has to be an AMBE encoder for analogue FM modulation before it is possible to pass FM users' audio through the system. I think that has to be local, so unless you have a Pistar setup where such a thing exists then FM won't work for you.
Re: MMDVMHOST FM mode implementation
Posted: Mon May 11, 2020 7:56 pm
by IZ8GUR
G8SEZ wrote: ↑Mon May 11, 2020 6:27 pm
Don't forget that somewhere there has to be an AMBE encoder for analogue FM modulation before it is possible to pass FM users' audio through the system. I think that has to be local, so unless you have a Pistar setup where such a thing exists then FM won't work for you.
I don't think it works as you described, it's unusefull!
first of all, in this case the users that will pass over my hotspot/repeater will show in the network with mi callsign everybody, and this is inacceptable.
Second, in the MMDVM.INI file is not mentioned anyting of this, but only a CTCSS decoder that was used for enable this modality when received.
I think the mmdvm will be used only for CTCSS decoder and make an FM audio passthrough, so.....it will be operate like a analogue repeater COR with ctcss dacoder and programmable hangtime (like the configuration extracted below)
So, is not a strange crossmode from analogue to digital and the other way around.
at the end...what sense have to use an ambe for decoding something is already analogue?
Code: Select all
[FM]
Enable=1
# Callsign=G4KLX
CallsignSpeed=20
CallsignFrequency=1000
CallsignTime=10
CallsignHoldoff=0
CallsignHighLevel=50
CallsignLowLevel=20
CallsignAtStart=1
CallsignAtEnd=1
CallsignAtLatch=0
RFAck=K
ExtAck=N
AckSpeed=20
AckFrequency=1750
AckMinTime=4
AckDelay=1000
AckLevel=50
# Timeout=180
TimeoutLevel=80
CTCSSFrequency=88.4
CTCSSThreshold=30
CTCSSLevel=20
KerchunkTime=0
HangTime=7
UseCOS=1
COSInvert=0
RFAudioBoost=1
MaxDevLevel=90
ExtAudioBoost=1
Re: MMDVMHOST FM mode implementation
Posted: Mon May 11, 2020 9:26 pm
by M1DNS
G8SEZ wrote:Don't forget that somewhere there has to be an AMBE encoder for analogue FM modulation before it is possible to pass FM users' audio through the system. I think that has to be local, so unless you have a Pistar setup where such a thing exists then FM won't work for you.
It isnt built intended to pass FM users to digital networks. So the AMBE is irrelevant as there's no transcoding intended.
Its adding FM repeater control, to the list of modes repeater users can make use of.
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Re: MMDVMHOST FM mode implementation
Posted: Tue May 12, 2020 8:11 pm
by G8SEZ
Given that the thrust of MMDVM is to unify the various flavours of digital system as much as possible, it seems to me that there is a strong likelihood that someone will write code that could integrate analogue users with network-linked digital systems.
Just sayin'!
Re: MMDVMHOST FM mode implementation
Posted: Tue May 12, 2020 8:24 pm
by M1DNS
That code already exists. I use it daily with my all-star link.
I'm sure users might want to do this, but as said the FM support will be written mpstly intended for repeater use.
The MMDVM devs intend to include a UDP 'link' interface with the FM controller for other systems to interface with, but any code controlling 'the other side of that' will be left to other devs.
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Re: MMDVMHOST FM mode implementation
Posted: Thu May 14, 2020 2:37 pm
by G8SEZ
M1DNS wrote: ↑Tue May 12, 2020 8:24 pm
That code already exists. I use it daily with my all-star link.
I'm sure users might want to do this, but as said the FM support will be written mpstly intended for repeater use.
The MMDVM devs intend to include a UDP 'link' interface with the FM controller for other systems to interface with, but any code controlling 'the other side of that' will be left to other devs.
Fair enough, it's just that on another hotspot-related forum there are loads of requests for a hotspot that makes an FM radio into a multi-network digital-capable system. People never want much, but especially they want other people to actually do it
Re: MMDVMHOST FM mode implementation
Posted: Thu May 14, 2020 6:06 pm
by M1DNS
Yeah as said the mmdvm hotspot rf chips (adf7021) won't do FM. It's a limitation of that hardware.
There is progress being made with a project creating a Pi hat hotspot. I'm watching that one currently with interest. when complete you'll end up with a Pi SVXlink hotspot. (It doesn't use the 7021 trx chip)
That group are already selling a interface pi hat to connect to external mobile radios, aka pi hat repeater boards, but their svx hotspot pi-hat is gonna make it v.interesting.
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