w4kek/WSJT-X
1
0
Fork 0
mirror of https://github.com/saitohirga/WSJT-X.git synced 2025-04-22 11:20:16 -04:00
Code Issues Packages Projects Releases Wiki Activity

Add the file describing bit packing for SuperFox message types.

Browse Source
This commit is contained in:
Joe Taylor 2024-09-24 09:59:14 -04:00
parent 1c37576885
commit b571f63d98
1 changed files with 65 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

65
lib/superfox/superfox_qpc_2.txt Normal file
View File

@ -0,0 +1,65 @@
Bit packing of SuperFox QPC Messages
-----------------------------------------------------------------------------
The IV3NWV Q-ary Polar Code has parameters (n,k) = (127,50). The last
three 7-bit information symbols convey a 21-bit CRC based on the first
47 symbols. Thus, each Super Fox transmission carries a payload of
47*7=329 bits. On a modern x86 processor the decoder executes in
deterministic time around 5 ms per decode, and always produces a
result. The CRC test rejects all but around 1 in two million false
decodes.
Bit fields are labeled with tags as defined in the QEX article "The
FT4 and FT8 Communication Protocols" by Franke, Somerville, and Taylor
in QEX for July/August 2020, available on the WSJT web site here:
https://wsjt.sourceforge.io/FT4_FT8_QEX.pdf. As one example, the tag
'c28' denotes a standard callsign, which requires 28 bits.
=============================================================================
i3 = 0: Standard message: FoxCall, up to 9 HoundCalls, up to 4 signal
reports, "MoreCQs" flag, a digital signature, and a 3-bit message type.
-----------------------------------------------------------------------------
F H1 H2 H3 H4 H5 H6 H7 H8 H9 R6 R7 R8 R9 U Q D M Type
c28 c28 c28 c28 c28 c28 c28 c28 c28 c28 r5 r5 r5 r5 u5 q1 d20 i3=0 Std Msg
280 300 305 326 329
=============================================================================
i3 = 1: If Fox uses a compound callsign we have space for only 8 Hound calls.
Otherwise like type i3=0.
-----------------------------------------------------------------------------
FC H1 H2 H2 H4 H5 H6 H7 H8 R5 R6 R7 R8 U Q D M
c58 c28 c28 c28 c28 c28 c28 c28 c28 r5 r5 r5 r5 u3 q1 d20 i3=1
58 282 302 305 326 329
=============================================================================
i3 = 2: A free text message with up to 26 characters can be transmitted along
with messages to as many as 4 Hounds conveying either reports or RR73s.
-----------------------------------------------------------------------------
F H1 H2 H3 H4 R1 R2 R3 R4 T T U Q D M Type
c28 c28 c28 c28 c28 r5 r5 r5 r5 t71 t71 u3 q1 d20 i3=2 FT+4H
140 160 302 305 326 329
=============================================================================
i3 = 3: Message "CQ FoxCall Grid <Free text>"
-----------------------------------------------------------------------------
FC G T T U Q D M Type
c58 g15 t71 t71 u90 q1 d20 i3=3 CQ FT
58 73 144 215 305 326 329
=============================================================================
D Digital signature (20 bits)
F Fox call (28 bits)
FC Compound Fox call (58 bits)
G Grid locator (15 bits)
H Hound call (28 bits)
M Message type (3 bits)
Q MoreCQs flag
R Report, (5 bits: -18 to +12 dB, or RR73)
T Free text, up to 26 characters total
U Unused bits
Unused callsign slots are set to 2, the numerical value for CQ.
Unused report slots are set to 0 (-20 dB). "CQ FoxCall" will be
displayed along with other messages if the "q1" bit is 1.
The SuperFox decoder displays its results with a separate line for each Hound.
Thus, the old-style message "K1ABC RR73; W9XYZ <VP8PJ> -14" becomes
K1ABC VP8PJ RR73
W9XYZ VP8PJ -14