K5ESW said:
"The difference in the FT8 reported SNR and how most hams think of SNR
seems explained well by Jim, KC5RUO.
http://www.arrl.org/forum/topics/view/1957
https://tapr.org/pdf/DCC2018-KC5RUO-TheReal-FT8-JT65-JT9=SNR.pdf
Thanks Paul. I had read one of those articles before. I didn't
Jerry,
The difference in the FT8 reported SNR and how most hams think of SNR
seems explained well by Jim, KC5RUO.
http://www.arrl.org/forum/topics/view/1957
https://tapr.org/pdf/DCC2018-KC5RUO-TheReal-FT8-JT65-JT9=SNR.pdf
He says for FT8, the noise bandwidth that impacts FT8 software´s
behalf of K4SAV
Sent: Thursday, August 1, 2019 5:09:55 PM
To: topband@contesting.com
Subject: Re: Topband: FT-8 performance
I'm not sure how FT-8 calculates the reported S/N number. I found very
little information on the subject and what I did find was not easily
understandable. What
On 8/1/2019 1:27 PM, James Wolf wrote:
I think there is some misunderstanding of bandwidth using FT-8.
The power limited Shannon limit I posted about today is
independent of equivalent noise bandwidth
The equivalent noise bandwidth of an FT8 detected tone is only 6.25 Hz. So
-26 dB
I'm not sure how FT-8 calculates the reported S/N number. I found very
little information on the subject and what I did find was not easily
understandable. What I did was an experiment in which I was able to get
close to the same number being reported. According to what I have read
about
If anybody's interested in trying my version of the python FT8 decoder with
a more sensible SNR
implementation just go here: https://github.com/mcogoni/weakmon
I modified the code to look for the lowest power bin within the input
bandwidth and each
individual signal is compared to this.
To obtain
It is instructive to calculate the Shannon
maximum theoretical data rate (power limited case)
(refer to wikipedia page for Shannon-Hartley theorem).
If S/N ratio (BW=2,500 Hz) = -24 dB,
then S/N ratio (BW=1Hz) = -24 + 10 log 2,500 = -24 +34
= +10 dB. 10 dB converted to a dimensionless ratio is
Do either JT9 or FT8 *really* need a wide SSB filter? What happens if we
use a good narrow CW filter instead?
73, Mike
www.w0btu.com
On Thu, Aug 1, 2019, 2:03 PM K4SAV wrote:
> W0BTU directed a question to me about JT-9. I have never tested JT-9 so
> I don't have any information to supply on
W0BTU directed a question to me about JT-9. I have never tested JT-9 so
I don't have any information to supply on that subject.
The S/N number supplied by FT-8 was only a curiosity to me because I
could see a huge disparity between what was being reported versus what I
was observing on my
You might want to listen to this TAPR presentation on Noise and Noise
calculations.
https://youtu.be/xXXj1Ko4ZXg
I found it pretty interesting.
Mike va3mw
On Thu, Aug 1, 2019 at 2:12 PM uy0zg wrote:
> Is the main problem here in efficiency?
>
> The main thing here - the signal is not heard
Is the main problem here in efficiency?
The main thing here - the signal is not heard by a person!
---
Nick, UY0ZG
http://www.topband.in.ua
Tim Shoppa 2019-08-01 20:40:
The "work signals way down in the noise you could never work otherwise"
myth, is just part of the myth that FT8 is an
We went thorugh a similar discussion here a year ago about the "cooked" S/N
statistics. Or at least they are cooked in a way that no CW operator would
cook them, by considering a bandwidth 50 times wider than the FT8 signal.
On a quiet WARC FT8 band (no interfering carriers) signals that are -18dB
Good morning
Do we know if the SNR is calculated over the RF passband filter width, or
is is calculated over AF filter bandwidth in the WSJTx engine, which it
knows? There is a big difference.
Mike va3mw
On Thu, Aug 1, 2019 at 11:09 AM Marco Cogoni wrote:
> Hi,
>
> I agree with Jerry. I
Very interesting. How does JT9 compare, especially in regards to the noise
floor issue that Mark raised?
73, Mike
www.w0btu.com
_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
I meant Jerry, not Mark. Sorry.
On Thu, Aug 1, 2019, 10:15 AM Mike Waters wrote:
> Very interesting. How does JT9 compare, especially in regards to the noise
> floor issue that Mark raised?
>
> 73, Mike
> www.w0btu.com
>
_
Searchable Archives: http://www.contesting.com/_topband
Hi,
I agree with Jerry. I spent a few weeks trying to use FT8 to obtain
antenna radiation patterns and I discovered how the SNR is computed:
it's totally flawed. Basically WSJTX computes the number in two steps:
the first one estimates how strong the adjacent frequency bins are with
respect
I get the feeling that I must be the only person that has ever tested
FT-8 to the extreme to see what it can do. It seems that everyone else
just assumes it will do what the published information says. It will
not. Below is a summary of my testing.
First I did a bunch of testing to see if I
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