>>>AA6YQ comments below
-----Original Message-----
From: Topband [mailto:topband-bounces@contesting.com] On Behalf Of John K9UWA
Sent: Sunday, October 29, 2017 12:03 PM
To: topBand List
Subject: Re: Topband: FT8 - the end of 160m old school DXing? (long)
Someone will develop a software program that takes the human voice or CW and
packetize it much the same as cell phones already do
into digital packet form. Then it will be added to the carrier or lack thereof
similar to SSB and or CW. On the receive end the
software will convert it back to analog. Once again we will hear the signal
after it is processed into analog coming out of our
speakers in either CW or Phone sounds. Perhaps a 7 to
10 second delay for all the processing to take place.
>>>That was accomplished long ago, and without significant encoding or decoding
>>>delays. For example:
https://en.wikipedia.org/wiki/D-STAR
This FT8 program has the ability to extract the digital signals from the noise
and process them up to 10-15 dB below the noise
level. So why can't the human voice be processed in a similar manner?
>>>Besides callsign and gridsquare information, FT8 can convey only 13
>>>characters of arbitrary alphanumeric text with each message;
this is less than what would be required to convey a meaningful snippet of the
(encoded) sender's voice. Technical details are
provided in an article by Joe K1JT et al in the November issue of QST.
>>>The K1JT modes employ ruthless encoding and error correction to enable
>>>constrained communications when signal-to-noise ratios are
far lower than what's required by other digital modes, CW or SSB. In terms of
information content, human voice is quite inefficient;
thus the developers of these modes are unlikely to extend them to convey voice.
73,
Dave, AA6YQ
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