Hello Joe, Paul, VLF!
It is not easy to believe but I can try now to say:
looks like I have decode of VO1NA 1-char message: "S"!

(But may be it is false decode? :-/ )

So this decode taked from individual files of 24 Dec and 26 Dec transmissions and also from stacking procedure of all seven files without any other false decodes.

Stacking of 24Dec and 26Dec with phase shift 60 deg give me strongest decode with rank 0:

ebnaut-rx V0.7a
input file C:\EbNaut\VLF_EBNAUT\VO1NA-dec2017\sum.wav
sample rate 0.342935 per second
rx frequency 8270.1
file start time 2017-12-26 20:32:18.390
polynomial 16K21A
crc size 8
number of chars 1
block size 14
symbol period 60.000
number of symbols 544
list length 2000
start offset 1672.000
freq offset -0.092500
cores 1
skipped 1670.870573 seconds to start
initial reference phase 48.3
---------------------------------------------
found S
list rank 0
reference phase 0 0 0 0
carrier S/N 12.20 dB in 30.6 uHz, -32.94 dB in 1Hz, -66.92 dB in 2.5kHz
carrier Es/N0 -15.16 dB
carrier Eb/N0 4.64 dB
info bit period 5726.32 seconds
symbol error rate 209/544 = 38.419 %
Es/N0 from symbol errors -13.6 dB
Eb/N0 from symbol errors 6.2 dB
Shannon capacity 2.6 bits/hour
Shannon efficiency 24.2 %
symbols file C:\EbNaut\VLF_EBNAUT\VO1NA-dec2017\sum-symbols.csv
elapsed 7 seconds
---------------------------------------------
found S
list rank 0
reference phase 30 30 0 0
carrier S/N 12.62 dB in 30.6 uHz, -32.52 dB in 1Hz, -66.49 dB in 2.5kHz
carrier Es/N0 -14.73 dB
carrier Eb/N0 5.06 dB
info bit period 5726.32 seconds
symbol error rate 214/544 = 39.338 %
Es/N0 from symbol errors -14.3 dB
Eb/N0 from symbol errors 5.5 dB
Shannon capacity 2.9 bits/hour
Shannon efficiency 22.0 %
symbols file C:\EbNaut\VLF_EBNAUT\VO1NA-dec2017\sum-symbols.csv
elapsed 78 seconds
---------------------------------------------
found S
list rank 0
reference phase 0 0 -30 -30
carrier S/N 12.62 dB in 30.6 uHz, -32.52 dB in 1Hz, -66.49 dB in 2.5kHz
carrier Es/N0 -14.73 dB
carrier Eb/N0 5.06 dB
info bit period 5726.32 seconds
symbol error rate 208/544 = 38.235 %
Es/N0 from symbol errors -13.4 dB
Eb/N0 from symbol errors 6.4 dB
Shannon capacity 2.9 bits/hour
Shannon efficiency 22.0 %
symbols file C:\EbNaut\VLF_EBNAUT\VO1NA-dec2017\sum-symbols.csv
elapsed 102 seconds
---------------------------------------------
found S
list rank 0
reference phase 30 0 0 -30
carrier S/N 12.93 dB in 30.6 uHz, -32.21 dB in 1Hz, -66.19 dB in 2.5kHz
carrier Es/N0 -14.42 dB
carrier Eb/N0 5.37 dB
info bit period 5726.32 seconds
symbol error rate 208/544 = 38.235 %
Es/N0 from symbol errors -13.4 dB
Eb/N0 from symbol errors 6.4 dB
Shannon capacity 3.1 bits/hour
Shannon efficiency 20.5 %
symbols file C:\EbNaut\VLF_EBNAUT\VO1NA-dec2017\sum-symbols.csv
elapsed 318 seconds

All files for reprocessing are here: http://rn3aus.narod.ru/VO1NA-1char.zip 

73 de rn3aus/Alex