From 4213e029054f79785792360fd69570dd59d68bea Mon Sep 17 00:00:00 2001 From: Joe Taylor Date: Tue, 14 Jul 2020 13:45:32 -0400 Subject: [PATCH] Editorial work by Dave, KC3GPM. --- doc/user_guide/en/decoder_notes.adoc | 45 ++++++++++++++-------------- 1 file changed, 23 insertions(+), 22 deletions(-) diff --git a/doc/user_guide/en/decoder_notes.adoc b/doc/user_guide/en/decoder_notes.adoc index 4227b408c..afa46e820 100644 --- a/doc/user_guide/en/decoder_notes.adoc +++ b/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 -procedures that take advantage of naturally accumulating information -during a minimal QSO. This _a priori_ (AP) information increases -sensitivity of the decoder by up to 4 dB, at the cost of a slightly -higher rate of false decodes. +The _WSJT-X_ decoders for FT4, FT8, JT65, QRA64, include +procedures that use naturally accumulating information during a +minimal QSO. This _a priori_ (AP) information increases sensitivity +of the decoder by up to 4 dB, at the cost of a slightly higher rate of +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 -next received message. The decoder's task can thus be reduced to +bits (28 for each of two callsigns, one or more for message type) in the +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,