On 2019-05-19 9:50 AM, Wes wrote:
FT8 reports negative SNRs number but we both know those are bogus.
All of the modes that quote negative SNRs are doing so by using SNR
in a voice (2500 Hz) bandwidth *NOT* SNR in the detector bandwidth
(bandwidth of the final filter whether than be a narrow IF filter,
the "ear-brain" filter or a software [computation] filter).
If one looks at the SNR thresholds of the various Joe Taylor "slow"
modes, 80% of the "negative" SNR can be attributed entirely to the
difference between the occupied bandwidth and the [excess] measurement
bandwidth. The remainder can be attributed to software processing
algorithms that take advantage of the fact that noise is random while
the signal is not - in essence reporting using a "peak noise" level
while actually decoding against a "minimum noise" level (like copying
CW through static crashes - one looses a dit/dah during the crash but
fills that in from the context).
73,
... Joe, W4TV
On 2019-05-19 9:50 AM, Wes wrote:
I feel like I'm gonna be slappin' a tar baby by responding.
Since we are discussion HF radios, I was assuming HF. I realize
JT65(-HF) and JT9 have been used on HF, but the QSOs are hardly random.
If your computer clock is off, sorry, no QSO. FT8 reports negative SNRs
number but we both know those are bogus.
Wes N7WS
On 5/19/2019 5:58 AM, Ed W0YK wrote:
JT65, JT9, FT8.
73,
Ed W0YK
-------- Original message --------
From: Wes <[email protected]>
Date: 5/19/19 07:49 (GMT-06:00)
To: [email protected]
Subject: Re: [Elecraft] Sensitivity - Was K4 Observations
What current modes hear below the noise level?
Wes N7WS
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[email protected]
This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[email protected]
This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
