Editorial work by Dave, KC3GPM.

doc/user_guide/en/decoder_notes.adoc

@@ -1,19 +1,21 @@
-[[AP_Decoding]]
+// Status: edited
+
 === AP Decoding
 
-The _WSJT-X_ decoders for FT4, FT8, JT65, and QRA64 include optional
+The _WSJT-X_ decoders for FT4, FT8, JT65, QRA64, include 
-procedures that take advantage of naturally accumulating information
+procedures that use naturally accumulating information during a
-during a minimal QSO.  This _a priori_ (AP) information increases
+minimal QSO.  This _a priori_ (AP) information increases sensitivity
-sensitivity of the decoder by up to 4 dB, at the cost of a slightly
+of the decoder by up to 4 dB, at the cost of a slightly higher rate of
-higher rate of false decodes.
+false decodes.  AP is optional in FT8, JT65, and QRA64, but is always
+enabled for FT4.
 
 For example: when you decide to answer a CQ, you already know your own
 callsign and that of your potential QSO partner.  The software
 therefore "`knows`" what might be expected for at least 57 message
-bits (28 for each of two callsigns, 1 or more for message type) in the
+bits (28 for each of two callsigns, one or more for message type) in the
-next received message.  The decoder's task can thus be reduced to
+next received message.  The decoder's task is thus reduced to
 determining the remaining 15 bits of the message and ensuring that the
-resulting solution is consistent with the message's parity symbols.
+resulting solution is reliable.
 
 AP decoding starts by setting AP bits to the hypothesized values, as
 if they had been received correctly.  We then determine whether the
@@ -21,12 +23,12 @@ remaining message and parity bits are consistent with the hypothesized
 AP bits, with a specified level of confidence.  Successful AP decodes
 are labeled with an end-of-line indicator of the form `aP`, where `P`
 is one of the single-digit AP decoding types listed in Table 1.  For
-example, `a2` indicates that the successful decode used *MyCall* as
+example, `a2` indicates that the successful decode used MyCall as
 hypothetically known information.
 
 [[FT8_AP_INFO_TABLE]]
 .FT4 and FT8 AP information types
-[width="50%",cols="h10,<m20",frame=topbot,options="header"]
+[width="35%",cols="h10,<m20",frame=topbot,options="header"]
 |===============================================
 |aP | Message components
 |a1 | CQ   &#160; &#160;   ?   &#160; &#160;   ? 
@@ -49,7 +51,7 @@ be attempted in each state.
 
 [[FT8_AP_DECODING_TYPES_TABLE]]
 .FT4 and FT8 AP decoding types for each QSO state
-[width="50%",cols="h10,<m20",frame=topbot,options="header"]
+[width="35%",cols="h10,<m20",frame=topbot,options="header"]
 |===========================================
 |State        |AP type
 |CALLING STN  |   2, 3
@@ -60,14 +62,12 @@ be attempted in each state.
 |CALLING CQ   |   1, 2
 |===========================================
 
-Decoding with _a priori_ information behaves slightly differently in
+Decoding with _a priori_ information behaves slightly differently
-JT65.  Some details are provided in Tables 3 and 4.  Notations such as
+in JT65.  Some details are provided in Tables 3 and 4.
-`a63`, use a second digit to indicate the number of Rx intervals
-averaged to obtain the decode.
 
 [[JT65_AP_INFO_TABLE]]
 .JT65 AP information types
-[width="50%",cols="h10,<m20",frame=topbot,options="header"]
+[width="35%",cols="h10,<m20",frame=topbot,options="header"]
 |===============================================
 |aP | Message components
 |a1 | CQ   &#160; &#160;   ?   &#160; &#160;   ? 
@@ -81,7 +81,7 @@ averaged to obtain the decode.
 
 [[JT65_AP_DECODING_TYPES_TABLE]]
 .JT65 AP decoding types for each QSO state
-[width="50%",cols="h10,<m20",frame=topbot,options="header"]
+[width="35%",cols="h10,<m20",frame=topbot,options="header"]
 |===========================================
 |State        |AP type
 |CALLING STN  |   2, 3, 6, 7
@@ -93,7 +93,6 @@ averaged to obtain the decode.
 |===========================================
 
 
-[[Decoded_Lines]]
 === Decoded Lines
 
 Displayed information accompanying decoded messages generally includes UTC,
@@ -110,7 +109,7 @@ summarized in the following Table:
 [width="50%",cols="h,3*^",frame=topbot,options="header"]
 |===========================================
 |Mode    |Mode character|Sync character|End of line information
-|FT4     | +            |      | ? &#160; aP
+|FT4     | ~            |      | ? &#160; aP
 |FT8     | ~            |      | ? &#160; aP
 |JT4     | $            | *, # | f, fN, dCN
 |JT9     | @            |      |
@@ -126,10 +125,12 @@ Sync character::
 
 End of line information::
  `?` - Decoded with lower confidence +
- `a` - Decoded with aid of some a priori (AP) information +
+ `a` - Decoded with aid of some _a priori_ (AP) information +
  `C` - Confidence indicator [ISCAT and Deep Search; (0-9,*)] +
  `d` - Deep Search algorithm +
+ `E` - Size of MSK eye diagram opening - if negative, the eye is closed + 
  `f` - Franke-Taylor or Fano algorithm +
+ `H` - Number of bit errors corrected +
  `M` - Message length (characters) +
  `N` - Number of Rx intervals or frames averaged +
  `P` - Number indicating type of AP information (Table 1, above) +
@@ -140,7 +141,7 @@ Table 6 below shows the meaning of the return codes R in QRA64 mode.
 
 [[QRA64_AP_INFO_TABLE]]
 .QRA64 AP return codes
-[width="50%",cols="h10,<m20",frame=topbot,options="header"]
+[width="35%",cols="h10,<m20",frame=topbot,options="header"]
 |===============================================
 |rc | Message components
 |0  | ?    &#160; &#160;   ?   &#160; &#160;   ?