To: rsgb_lf_group@blacksheep.org
References: <5B911389.9080807@posteo.de>
 <165aeea613a-1ec0-427@webjasstg-vab55.srv.aolmail.net>
 <CAA8k23Qs9aRiSuKoXaEpSENOVn8wLJZav9yNiggx78Zega3yag@mail.gmail.com>
From: N1BUG <paul@n1bug.com>
Openpgp: preference=signencrypt
Autocrypt: addr=paul@n1bug.com; prefer-encrypt=mutual; keydata=
 xsFNBFqj1+0BEACggWlaH8oG/AiXSUG3CeQwZ1NrVEP4U7YsA9N9XEffjCDEsnTjHF2BJSgS
 2AicyomkmTGvghEHxrNFfFw07jwgJl97ae/VtNxpERPSE98mb4sPOMpJbwddioMazMDXwhKA
 wpg5fse+Ru8OrIT04KK919xL/pZuAP6pY6d2kVoizjJOfS71pHpiU6N6q3d9cl+w7d2LKhAE
 a3A1ZgDquPvn0WQlrN8K5D66xVrwTRhf1b5H4Ozl8/mMJzCeLG1ZIsDB3Pu2flwE81P8dCJA
 y1azwgY8pTEshVk4em/se9uRiZaDJr/qUSCf6hrV7AGa8g1jpAQDmdGpDNYMqyDqXen4jNi1
 8kNFVu1BMl2vjaI8skw/YPxIxlk/0ROHYhN6SuoDq1mt4AW4FryNa7k3A8dM8Bt7udBoTv0i
 uw4j9R/bmh2vl/QaHRUhDco0xn2z6geWvXkKqha++vzXDrEKUuqgB85SDZPs5W/phs9p0pz1
 xA61d1gn8FQJtpou5dQuAucqMo8eKQY5LUcbC+MH5pebH+M2wIuDCBmFPJHQDSPNepeaxJ4o
 G/HU1hrpzlgLiTTSKR8DcwtMQwYywnCTlm8MgL4jXuPzoGyKDMYyKIjC51G+3AAOJ6oXJAGR
 g0ehhCPtmnCGBaRlUIoUSpbgc4B+onqFKZmDiVm9CRNJhKIWrQARAQABzRZOMUJVRyA8cGF1
 bEBuMWJ1Zy5jb20+wsF9BBMBCAAnBQJao9ftAhsjBQkJZgGABQsJCAcCBhUICQoLAgQWAgMB
 Ah4BAheAAAoJECRS/J8srRGjPBsQAIh+Haz9gqrQJ0OlMI5xmQ0A5nsVWcatWF/Ea4mucNjL
 4n4jmW+Z4Ukn3OVss55chWwrOVMRNWU2d2zRc92ZF7yJhLCoJFV870bZfxNYwdJ3GEBLIu6/
 anmQYX0oXFx8UBsx5K6egNqbeflPA7zrLiQkWrz6JApECdiA1rHDjyJdS7PDxBCG9cKgr/5b
 r4Rn/JlUl9pRPnxlSwHXsV+J6JtFYtWI69MWIVD7Y7OY1wO9+684uOnzeDANzeIwpBDcSm6p
 0D5u0b1hfPl2TD0ozVs6P0NvxkMbimXUhRR1QD0FvydyxmZTLAo+XZDGR8GqWYrYrauoRZ1h
 3m23+bNT2T4AuoFnWekpsZu+sxIf0LKPtEZCa51O65jZ810ROpXg9Lx71gEoQD+kbjO69+kq
 9r7wjytDq/jyhpOGrGYV6kgcQrISY86t9YvkA9Of2HDzZLih3GwecW6fkeV1AO5w4RteE9nL
 zIs2siGw2YqavF6LpTH71Db7cUYyZWn5hkKpwfpLNnPEuqgZACovpH1WUHx+KMqqIL4rMVCH
 GcSLqnH2KF4cEDb6OeTbwuLfpGlN+I3j24eQnB2uz5rDa7/IBjsClLl8S/wdDTP8IikBGixX
 06v3k06tk/OF4UsfJ0cY/ASGP5+kjT4ASMZAIikwVMpKi5A5be77vecKNYlJQ2a6zsFNBFqj
 1+0BEACaujZXo3F17v7QTnub4DjjYvm+nr8J0uU5pPc1UMEz9eWjmtmITm15fx1hPKNtVW+I
 VlT+DG+ShNnYmO2M4CFBoc7PwkAOc70aDxfHz20kotvj1HhXG7oBiqPkN3TK4C7qWV1HUEPA
 V960qPdhsoCqmtkvNwj39w1T0ZR5qwwaqDogs9UwBib7zseQ3OXHG32xYYCMcxM35hgXGkkz
 R7wFL4ZnAPOeFb8LnWtZcrGpwXdsYkXuCxm+A+u9KlFY+w3ZCzZt1F9Ie+/PSZnFIUtbXt2i
 mfc+VkRwOLz5BDAeWuDL09TN81+gbrR3kXlymDcCbuduO/yHOQK085qzE3LuImdy+JNb7oDf
 1C/hvpRvtB02vVy33rzIXT8644SJzFY/mw/W39/BgHKCoL1FrBbfgf0UoIFw5M752i7jQwmv
 j5yFfnVAXIPpCuusMwWMGVpZcGV7QxJxh0HBEhYgOo9v3zKwzNIPm9V/LA67u/rj4a/MlCE0
 mpd6IHaePE1vXDaboPZHZdhAziru5/Jd7KQI0k+HmM/HRANPRNDZ4UeBpgj9PzS6hDN5GHlZ
 fRUbI8JAg9wSaQtEn0bjyaR7lw0yngZTvvjT1Qqt5zGwm1IAall2STes5xK0aS7p+UJJMVbf
 ydZ5VOnocvUkwYxbiqoyuVtGxi4tpWW9CRstYXMkAwARAQABwsFlBBgBCAAPBQJao9ftAhsM
 BQkJZgGAAAoJECRS/J8srRGjTDMP/18q7uhac/naxoFsOqhgXIlvaPgu6GX7s/QOh+bcSV1F
 y50lxo51P/C95H2TVME/CtCjk2xWQcNjWtXloMEsZpl7T3qWgJHvyZYkDtgh3M6UNY+zb08U
 K9E2+rR0AZ6zdMKio7Z1xA9BtbUpSZpvy2NgjoYVqo35NllUWMZJq0u+88PvE5WeCIqLipNI
 EZmUcG9UwolQbPkrRc42ReL+bFbuXGXDA5GbQ0RudXbugI8iUwaw3ftaKElIZtuHW0hw1VrU
 9tVHsxKyEoKgNNT1hr+dgRmvCHmA87Pi4R5cMV0ZkLVOYfPX1motedag7HmSNPi2PkYLts4z
 kyvPEJe2IvaPvjvK1ShRWWgje3uytrhfwyjUZcIuA76RWEfBbwT2Mbrn9O7LvrYtbTiTlsLo
 Zdk2uocuefBvPd2oI7mTn5eLy/VDy2JVnlb9vpZZhriXI4KtCcP6mYyuPxlxqj/30Kn1fU5b
 C4EpnKy6hW1CHM42DbwzT+ChjBpFbX9bfwT4qn6d42+T4mN5wkmfnBRHfcn8Wf1ezRSK3Ome
 Esa3ZDssj23CZHe11uec6Ln14qoB7JyRT9qM3Q99tzvAlmWFM3GrSsG94g4JponQjQWHmr8B
 eMYezwJHzSI7zWElJpzs/OuohstTYfYTy16FygUOEinc1K4ywjEklgRpXRtjKvqc
Message-ID: <33e4331a-6c57-3040-0c49-74840cbf4a1f@n1bug.com>
Date: Fri, 7 Sep 2018 06:28:00 -0400
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101
 Thunderbird/52.9.1
MIME-Version: 1.0
In-Reply-To: <CAA8k23Qs9aRiSuKoXaEpSENOVn8wLJZav9yNiggx78Zega3yag@mail.gmail.com>
Content-Language: en-US
Subject: Re: LF: Slow JT9 modes...
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: 8bit
Sender: owner-rsgb_lf_group@blacksheep.org
Precedence: bulk
Reply-To: rsgb_lf_group@blacksheep.org

Sounds interesting, Andy. Please correct me if I am wrong, but
doesn't PSK require linear amplification? If so, it would eliminate
many potential QSO partners.

Regarding EbNaut, my understanding was that OCXOs aren't good enough
and that a GPSDO or rubidium standard is needed. If that's not true,
someone please correct me on this also.

As for someone who is interested in LF either joining the JT
development team or writing code independently, if I had the
relevant skills and development tools I would leap at the
opportunity to bring back the slower JT9 submodes. Unfortunately I
have enough trouble getting my head around simple things these days,
as you've seen with my construction projects...

73,
Paul N1BUG


On 09/06/2018 09:21 AM, Andy Talbot wrote:
> As good as JT9 is, in whatever speed-flavour, at LF it throws away one
> aspect of LF propagation that isn't not really availalble for HF, phase
> stability over longer periods, at least suited to a few characters.   JT9
> is a purely power-based system with heavy FEC.
> 
> So while slower versions of JT9 would be good for LF in  the short term,
> they will not make the most of what propagation can offer.  NO one on the
> WSJT-X development team is interested in LF, so it's no good looking
> there.    However, I'm sure they'd be amenable to someone else joining the
> team and adding an LF users perspective and writing / developing the
> relevant submodes.   Or do it independently using the open-source code.
> 
> EBnaut carries phase signalling to the extreme, carrying no sync / timing
> info in the on-air symbols and being completely reliant on high stability
> frequency sources and people accurately starting and stopping.   This
> complex manual setting is, in my opinion its downfall;  high stability
> sources are less of a problem these days as OCXOs are now so cheap and
> readily availalble.
> 
> What we need is an intermediate slow PSK or QPSK based scheme that carries
> its own timing and sync.   FEC is something that could come later, we first
> of all want a simple PSK decoder scheme that search over a modest span in
> frequency - say 0.2Hz and with unknown timing .   I suggest differential
> BPSK as a stat, where the data depends on teh phase change from one symbol
> to the next.   That removes the need for absolute clock recovery, and also,
> provided tuning error is appreciably lesss than symbol rate, even for
> carrier recovery.   Just compare one block of digitised data (of a symbol's
> length) witjh the previous one and look for a peak every so often to get
> the boundary .  Some framing will be needed in order to guarantee a few
> phase changes for alignment.
> 
> A block / timed scheme like WSJT would probably work best as it reduces the
> searching for sync.  It also makes the soundcard driving software easier as
> a fixed length block can be recorded to a .WAV file more easily than
> continuous real time data reading from the s-card.
> 
> Once the signalling and signal recovery is proven, then is the time to
> think about adding FEC but even a none error-corrected scheme ought to have
> a fair bit to offer in testing.
> 
> The only real downside to PSK is its spectrum is you switch rapidly.   But
> its no worse than on-off keying, and if the signal is being generated by
> upconverting from a soundcard phase ramping could perhaps be used to reduce
> sidebands
> 
> 
> 
> 
> 
> Andy
> www.g4jnt.com