Hi Steve and all,

In case you have built WSJT-X v1.7 from r6329 and used it on the HF 
bands, you'll surely see many more false decodes than usual.  As 
committed, the code uses aggressive values for the parameters d_0 and 
r_0.  These values may be appropriate for EME-like conditions, but 
surely not for HF.

On a trial basis, with r6330 I've introduced a table lookup for limits 
on nhard, d_0, and r_0, using the user-selectable "Aggressive decoding 
level" as the table index.

Here's the table, as implemented in jt65_decode.f90:

Aggr  nhard  d_0    r_0
-------------------------
0       41    71    0.70
1       42    72    0.72
2       43    73    0.74
3       43    74    0.76
4       44    76    0.78
5       45    77    0.80
6       46    78    0.82
7       47    80    0.84
8       48    81    0.86
9       48    82    0.88
10      49    83    0.90

I changed the early-exit condition in ftrsd2.c to nhard_min <= 41, 
ntotal_min <= 71.

Normal operation at HF should set "Aggressive decoding level" to 0.
If you try operating on HF with higher values, be sure to set Ftol=1000. 
  With higher values of Aggressive decoding level you will see a few 
more decodes, and also some false decodes.

Let me know if you have different ideas about how these parameters might 
best be set, for different operating conditions.

        -- Joe

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