FT8 was never supposed to have the same sensitivity as JT65 .. you can't
not with only 13 or 14 seconds of Tx time. As was pointed out,
you can have -24 reports on FT8 but its more a result of the noise floor
in your location or the receiving station's location.
Not to mention that the suggestion leaves out provisions for the various
contests that the updated protocol will cover.
Neil, KN3ILZ
On 8/8/2018 11:03 AM, Wolfgang wrote:
Re: [wsjt-devel] WSJT-X 2.0 possible new mode/protocol Neil, you have
to read before you snap back!
Igor wrote, that we miss the sensivity of JT65 in FT8 !
So, we have -21 db in FT8 and in JT65 of around -27db
(92% decoded at -27db, 58% at -28db and 17% at -29db)
And the new proposed FT 2.0 will be another 0.2db (in math) less in
sensivity to the existing FT8. Igor suggested a FT8 protocoll that
could be at around -25 to -26db in sensivity - so again near to the
one of JT65.
Wolfgang, OE1MWW
Wednesday, August 8, 2018, 3:04:19 PM, you wrote:
*> Frankly, I don't see where you're getting the idea that JT65
> sensitivity is missing?
> It is still much more sensitive than FT8, and will be for the
> foreseeable future, as are the other WSJT-X modes. JT9A is at -27,
> JT65A is at -25, and QRA64A is at -26. FT8 is -21 .. all this is
> based on a average noise floor.
> I don't see what your 'new mode' is going to accomplish.
> Neil, KN3ILZ
> On 8/8/2018 2:29 AM, Игорь Ч wrote:
>> Hello Joe and all,
>> .
>> We all have been missing JT65 mode sensitivity and proposed WSJT-X 2.0
>> new FT8 approach with 0.2 dB sensitivity penalty can make things even
>> worse.
>> .
>> I would like to ask you to consider a new protocol where callsign hash
>> would be used instead of the real callsign in all messages but CQ and
>> incoming call, this way we can get back to -25..26dB SNR sensitivity
>> although will get more limited with the free message length.
>> .
>> CQ message: 28 bit callsign1 + i5bit + 12 bit CRC = 45 bit
>> incoming call: 10 bit call1 hash + 28 bit callsign2 + i5bit + 12bit
>> CRC = 55 bit
>> report message: 10 bit call2 hash + 10 bit call1 hash + i5bit + (10
>> bit call3 hash for DXpedition) + 6 bit report + 12 bit CRC = 43(53)
bit
>> roger+report message: 10 bit call1 hash + 10 bit call2 hash + 6 bit
>> report+ i5bit + 12bit CRC = 43 bit
>> 73 message: 10 bit call2 hash + 10 bit call1 hash + 15 bit GRID +
>> i5bit + 12bit CRC = 55 bit
>> RR73 message: 10 bit call1 hash + 10 bit call2 hash + 15 bit GRID +
>> i5bit + 12bit CRC= 52 bit
>> .
>> Spare bits can be used for nonstandard(special) callsign transmission
>> in CQ message. call1 hash could be omitted in the incoming call
>> message if this message is originated by the nonstandard(special)
>> callsign.
>> .
>> Probably we can optimize protocol even better while a main idea is to
>> transmit a full callsign only once per each QSO and to transmit not
>> more than one full callsign in the message.
>> .
>> 73 Igor UA3DJY
>
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73 de Wolfgang
OE1MWW
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