From 396bf1a0132dc8c2585a029c1a0cef1bb80e2636 Mon Sep 17 00:00:00 2001 From: Joe Taylor Date: Mon, 17 Jun 2019 11:26:46 -0400 Subject: [PATCH 1/2] Correct a flaw in ft8sim when generating data with large abs(DT). --- lib/ft8/ft8sim.f90 | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/lib/ft8/ft8sim.f90 b/lib/ft8/ft8sim.f90 index bbec600d4..c5dd82bb7 100644 --- a/lib/ft8/ft8sim.f90 +++ b/lib/ft8/ft8sim.f90 @@ -91,7 +91,7 @@ program ft8sim msg0=msg do ifile=1,nfiles k=nint((xdt+0.5)/dt) - ia=k + ia=max(1,k) phi=0.0 c0=0.0 do j=1,NN !Generate complex waveform @@ -105,7 +105,7 @@ program ft8sim if(fspread.ne.0.0 .or. delay.ne.0.0) call watterson(c0,NMAX,NWAVE,fs,delay,fspread) c=sig*c0 - ib=k + ib=min(k,NMAX) wave=real(c) peak=maxval(abs(wave(ia:ib))) nslots=1 From 393b595126bf88490faf1e4a8440255f169a4b88 Mon Sep 17 00:00:00 2001 From: Joe Taylor Date: Mon, 17 Jun 2019 15:47:47 -0400 Subject: [PATCH 2/2] Editorial work on parts of the User Guide related to FT4. --- doc/user_guide/en/introduction.adoc | 6 ++++-- doc/user_guide/en/new_features.adoc | 18 ++++++------------ doc/user_guide/en/protocols.adoc | 9 +++++---- doc/user_guide/en/tutorial-example4.adoc | 3 ++- 4 files changed, 17 insertions(+), 19 deletions(-) diff --git a/doc/user_guide/en/introduction.adoc b/doc/user_guide/en/introduction.adoc index 6da0f7936..f0d8e12e7 100644 --- a/doc/user_guide/en/introduction.adoc +++ b/doc/user_guide/en/introduction.adoc @@ -34,8 +34,10 @@ are possible (by EME and other propagation types) at signal levels 10 to 15 dB below those required for CW. Note that even though their T/R sequences are short, FT4 and FT8 are -classified as slow modes because their message frames are sent -only once per transmission. +classified as slow modes because their message frames are sent only +once per transmission. All fast modes in _WSJT-X_ send their message +frames repeatedly, as many times as will fit into the Tx sequence +length. *ISCAT*, *MSK144*, and optionally submodes *JT9E-H* are "`fast`" protocols designed to take advantage of brief signal enhancements from diff --git a/doc/user_guide/en/new_features.adoc b/doc/user_guide/en/new_features.adoc index 496bef16b..de5c34ff0 100644 --- a/doc/user_guide/en/new_features.adoc +++ b/doc/user_guide/en/new_features.adoc @@ -1,17 +1,11 @@ === New in Version {VERSION} -For quick reference, here's a short list of features and capabilities -added to _WSJT-X_ since Version 2.0.1: - -- New FT4 protocol, designed especially for radio contesting - -* T/R sequence length 7.5 s - -* Bandwidth 80 Hz - -* Threshold sensitivity -17.5 dB - -- Improvements to accessibility +The most important feature added to _WSJT-X_ since Version 2.0.1 is +the new *FT4 protocol*, designed especially for radio contesting. It +has T/R sequence length 7.5 s, bandwidth 80 Hz, and threshold +sensitivity -17.5 dB. Version 2.1.0 also has improvements to FT8 +waveform generation, contest logging, rig control, the user interface, +and accessibility, as well as a number of bug fixes. === Documentation Conventions diff --git a/doc/user_guide/en/protocols.adoc b/doc/user_guide/en/protocols.adoc index fc0dad266..e0d4145e3 100644 --- a/doc/user_guide/en/protocols.adoc +++ b/doc/user_guide/en/protocols.adoc @@ -13,9 +13,10 @@ aim is to compress the most common messages used for minimally valid QSOs into a fixed 72-bit length. The information payload for FT4, FT8, and MSK144 contains 77 bits. -The 5 additional bits are used to flag special message types used for -FT8 DXpedition Mode, contesting, nonstandard callsigns, and a few -other special types. +The 5 new bits added to the original 72 are used to flag special +message types signifying special message types used for FT8 DXpedition +Mode, contesting, nonstandard callsigns, and a few other +possibilities. A standard amateur callsign consists of a one- or two-character prefix, at least one of which must be a letter, followed by a digit @@ -76,7 +77,7 @@ Forward error correction (FEC) in FT4 uses a low-density parity check called an LDPC (174,91) code. Synchronization uses four 4×4 Costas arrays, and ramp-up and ramp-down symbols are inserted at the start and end of each transmission. Modulation is 4-tone frequency-shift -keying with Gaussian smoothing of frequency transitions (4-GFSK). The +keying (4-GFSK) with Gaussian smoothing of frequency transitions. The keying rate is 12000/576 = 20.8333 baud. Each transmitted symbol conveys two bits, so the total number of channel symbols is 174/2 + 16 + 2 = 105. The total bandwidth is 4 × 20.8333 = 83.3 Hz. diff --git a/doc/user_guide/en/tutorial-example4.adoc b/doc/user_guide/en/tutorial-example4.adoc index 762459728..43be6af1a 100644 --- a/doc/user_guide/en/tutorial-example4.adoc +++ b/doc/user_guide/en/tutorial-example4.adoc @@ -14,7 +14,8 @@ frequency limit is approximately 4000 Hz. - Select *File | Open* and navigate to +...\save\samples\FT4\000000_000002.wav+. The waterfall and Band Activity window should look something like the following screen shots. -Most of the decoded messages use the *RTTY Roundup* message formats. +This sample file was recorded during a practice contest test session, so +most of the decoded messages use the *RTTY Roundup* message formats. [[X15]] image::ft4_waterfall.png[align="left",alt="Wide Graph Decode FT4"]