Question on receiver SR rates.

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AdrianH
Posts: 78
Joined: Thu Jul 18, 2019 2:46 pm

Question on receiver SR rates.

Post by AdrianH » Thu Apr 15, 2021 8:54 am

I would just like to ask a question on the various receiver options that are out there at present as I am getting a bit confused regarding capabilities when it comes down to the low SR rates, it seems to be a rapidly changing scene.

Am I correct in thinking that at present if you wish to receive the lower such as 33 and 25 and 20KS signals that are tried at present you need to use the F6DZP software on a Minitiouner 2/Pro.

I use an elderly Minitiouner-express with Longmynd and it appears to have a lower limit of 66KS. I was wondering if that limitation is part of the software or my hardware, has things improved with the Ryde and Winterhill tuners/receivers which from reading the WIKI's are based on Longmynd.

Being a Linux only type person I was wondering what is available at present or near future?

Adrian

G8GKQ
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Joined: Sun Mar 22, 2009 1:21 pm

Re: Question on receiver SR rates.

Post by G8GKQ » Thu Apr 15, 2021 10:54 am

Hi Adrian

The Longmynd software used in both Portsdown and Ryde has a lower limit of 66 kS.

Dave, G8GKQ

AdrianH
Posts: 78
Joined: Thu Jul 18, 2019 2:46 pm

Re: Question on receiver SR rates.

Post by AdrianH » Thu Apr 15, 2021 11:05 am

OK so at present it is a restriction of the software, thanks for the information.

Adrian

g0mjw
Posts: 1581
Joined: Sat Sep 20, 2014 9:15 am

Re: Question on receiver SR rates.

Post by g0mjw » Thu Apr 15, 2021 11:33 am

Hardware and software. As a Linux user you are expected to be able to develop your own solution. Take a look at the Longmynd source code and see if there might be a way to configure the NIM to work at lower symbol rates. The hardware appears able to do it but it might require some trial and error with register settings. There is no reason a software demodulator will not work at lower SRs, in fact it might work better as the CPU resource should be lower. There are some Gnuradio examples which could be adapted. Normally it is getting the tuning correct that's hardest.

Mike

AdrianH
Posts: 78
Joined: Thu Jul 18, 2019 2:46 pm

Re: Question on receiver SR rates.

Post by AdrianH » Thu Apr 15, 2021 12:00 pm

g0mjw wrote:
Thu Apr 15, 2021 11:33 am
As a Linux user you are expected to be able to develop your own solution.
Mike
I think you are asking a lot of all Linux users there. You sound very much like a software engineer that worked at the same company I was in years ago and assumed everyone could do the same as him.

I have looked over the source code, but understanding it is another thing all together. A bit of bash scripting is nothing like C programming at least not to me. But I will dig further as a means to get more knowledge of how things work.

Adrian

g0mjw
Posts: 1581
Joined: Sat Sep 20, 2014 9:15 am

Re: Question on receiver SR rates.

Post by g0mjw » Thu Apr 15, 2021 4:35 pm

What I mean by that is if you follow the linux route, you often find you are on your own with respect to support. That's just the way it is and as a result Linux users are often more knowledgeable while having far fewer turnkey applications available because even now, the majority of applications are made for windows because that's what 75% of users use. Linux is apparently only on around 2% of desktops, I thought it was much higher, I am sure it is higher in technical hobbies, but it just doesn't have the critical mass of users windows has. There are plenty of good linux applications of course, but when it gets down to highly specialised applications you have to choose the OS that supports the application you want. That's how it is and it isn't any good expecting developers to cater for a minority, or to open source their IPR if they don't want to. Mac users have it worse, despite having 15% or so of desktops, almost nobody develops DATV software for macs. When you don't have the skills, I know I don't, or don't have time, few of us do, then it is best to follow the crowd. That might be Linux on a PI as in the Portsdown/Longmynd or Windows PC for Minitioune. We are quite lucky to have developers developing for both. By restricting yourself to one platform, you halve your options.

Mike

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