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 TX ALC in SDR 
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Post TX ALC in SDR
Just what is ALC in an SDR TX?

From what I can glean, in an SDR the RF drive applied to the PA can be designed not to exceed a certain level plus some headroom. The output of the DAC will not exceed this level, and there is no ALC in the traditional sense at this point. The ALC in an SDR radio is actually applied at the AF input to the ADC to prevent clipping occurring due to excessive level. Is it the case that the ALC meter on my 7300 is showing the control applied by the ALC algorithm at the ADC? If this runs out of range "overdrive" will result in signal distortion, but it's NOT RF distortion from overdriving the PA. That's why winding the mike gain up and down on my IC-7300 doesn't distort the RF output.

Thoughts, guidance?

Anyone know of a good, simple SDR primer? There's lots of info out there, but most of it makes my brain hurt.


Sat Jun 10, 2017 1:08 pm
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 TX ALC in SDR 
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Post Re: TX ALC in SDR
Come on chaps. This is a technical forum, isn't it?

:scratch:


Wed Jun 14, 2017 5:40 pm
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 TX ALC in SDR 
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Post Re: TX ALC in SDR
Does anyone on here actually know anything about SDR techniques, or is it all just users? My question is not necessarily specific to the 7300, so feel free to comment.

I'm not trying to be provocative, but this is an SDR forum.

:rolleyes:


Fri Jun 23, 2017 6:07 pm
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 TX ALC in SDR 
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Post Re: TX ALC in SDR
Certainly what you describe is how it works on the Flex 6000 series. As for overdriving, it used to be the case you could produce traditional overdriven crud on a Flex 6000 albeit thankfully without the splatter due to the way the signal processing chain worked. A customer wrote an algorithm that massively improved things so you could go as far as wicking the mic gain and processing up to 11 and have minimal distortion which was quite a feat and was incorporated into a later version.

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Sun Jun 25, 2017 8:27 pm
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 TX ALC in SDR 
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Post Re: TX ALC in SDR
Hi Connor,

Thanks for the comments.

I'm trying to get a basic understanding of the techniques used in SDR. It's very different to anything I was brought up with in amateur radio, but certainly very interesting. There is a lot of info on the web, but much of it is way over my head at the moment.

Good fun though.

73,

Rob.


Mon Jun 26, 2017 4:30 pm
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 TX ALC in SDR 
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Post Re: TX ALC in SDR
This may help.

https://helpdesk.flexradio.com/hc/en-us ... s-Debunked

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Sat Jul 01, 2017 8:27 pm
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 TX ALC in SDR 
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Post Re: TX ALC in SDR
Very useful.

Thanks.


Sun Jul 02, 2017 6:49 am
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