Hi Helmut,
May be you will remind our reports about our intensive tests (HB9EPU and me)
in 2016 and 2017. Everything is absolutely fine, when the communications
channel is clean, stable and undisturbed. On HF this can't be assumed.
Thank you for those tests, however 700D is not the same algorithm.
Digital voice is under continuous development, and is steadily improving.
SSB development (perhaps apart from noise reduction) has stopped, it is
a 50 year old algorithm. It will not get any better.
I added 2 mp3-file to show the effiency of NR2:
https://www.dropbox.com/s/scyced9ac5p4ryn/Weak_no_nr_no_nr2.mp3?dl=0
https://www.dropbox.com/s/qk63lyvz6uk86wz/Weak_no_nr_yes_nr2.mp3?dl=0
Thanks. I find the second sample is improved, but still has significant
noise, and has distortion added to the audio, a little like a speech
codec :-) It is a little nicer to listen too, but I wonder if the
overall intelligibility has improved?
Cheers,
David
73, Helmut, DC6NY
-----Ursprüngliche Nachricht-----
Von: David Rowe <da...@rowetel.com>
Gesendet: Sonntag, 6. Mai 2018 15:31
An: freetel-codec2@lists.sourceforge.net
Betreff: Re: [Freetel-codec2] 700D vs SSB Comparison
Hi Helmut,
Could you pls process the analog parts of Mark's sample using the HPSDRs
noise reduction algorithms and post the results here for comparison?
Another gentleman tried the NR2 algorithm last year:
https://www.rowetel.com/?p=5472#comment-80095
However the NR2 algorithm at that time was not effective at such low SNRs.
Thanks,
David
On 06/05/18 22:38, Helmut Oeller wrote:
Thanks Mark! This result would be impressive, if reproducable. We
refer to our tests with 700C together with innovative HPSDRs using
high efficient noise reduction algorithms. As you see, we trust in
digital solutions, where we can detect possible improvement.
73, Helmut, DC6NY
*Von:*Mark Jessop <lenniethelemm...@gmail.com>
*Gesendet:* Sonntag, 6. Mai 2018 14:40
*An:* freetel-codec2@lists.sourceforge.net
*Betreff:* [Freetel-codec2] 700D vs SSB Comparison
A comparison between 700D and SSB, recorded over a 40m path, with
approximately the same TX power (100W PEP).
https://soundcloud.com/mark-jessop/freedv-700d-vs-analog-comparison
I've spliced in the decoded 700D audio into the analog recording where
the 700D transmission started...
73
Mark VK5QI
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