[Lowfer] 136 KHz Opera

[Garry Hess]

There was more opera32 activity on 136 kHz last night so a second 
comparison of v1.5.5 vs DF6NM deep search was made. Unfortunately, while 
reception was simultaneous, the antennas were different. Eprobes fed 
both sdr-iq receivers, but the one used for v1.5.5 is known to be a bit 
more sensitive than the other at LF.

Decodes for v1.5.5 were:

11:13    136 VO1NA Op32 Deep Search -41 dB
10:38    136 VO1NA Op32 Deep Search -41 dB
10:03    136 VO1NA Op32 -38 dB   |---------| Fade: 3%
09:28    136 VO1NA Op32 Deep Search -42 dB
08:53    136 VO1NA Op32 Deep Search -42 dB
07:08    136 VO1NA Op32 Deep Search -43 dB
06:33    136 VO1NA Op32 Deep Search -41 dB
05:58    136 VO1NA Op32 Deep Search -42 dB
05:23    136 VO1NA Op32 Deep Search -42 dB
04:48    136 VO1NA Op32 Deep Search -42 dB
01:04    136 WD2XNS Op32 -16 dB  |---------| Fade: 0%
00:32    136 WD2XNS Op32 -17 dB  |---------| Fade: 0%
00:08    136 VO1NA Op32 Deep Search -40 dB
***********  08/01/2015  ***********
23:59    136 WD2XNS Op32 -21 dB  |---------| Fade: 0%
23:33    136 VO1NA Op32 Deep Search -40 dB
23:26    136 WD2XNS Op32 -22 dB  |---------| Fade: 0%
***********  07/01/2015  ***********

Detections for DF6NM deep search were:

2015-01-08 10:38:54 VO1NA   2836km 137476.981Hz  12mHz -48.1dBOp  94% 16.6dB
2015-01-08 10:03:53 VO1NA   2836km 137476.978Hz   2mHz -48.9dBOp  98% 16.4dB
2015-01-08 04:48:52 VO1NA   2836km 137476.999Hz  17mHz -49.2dBOp  94% 16.0dB
2015-01-08 01:37:48 WD2XNS  1268km 137479.996Hz   3mHz -24.3dBOp  97% 16.4dB
2015-01-08 01:05:03 WD2XNS  1268km 137479.996Hz   2mHz -23.0dBOp 100% 20.7dB
2015-01-08 00:32:15 WD2XNS  1268km 137479.999Hz   5mHz -21.3dBOp  93% 20.8dB
2015-01-08 00:08:48 VO1NA   2836km 137477.004Hz   3mHz -49.3dBOp  94% 17.2dB
2015-01-07 23:59:29 WD2XNS  1268km 137480.003Hz   1mHz -28.0dBOp  92% 21.2dB
2015-01-07 23:33:47 VO1NA   2836km 137477.004Hz   3mHz -45.9dBOp  97% 16.2dB
2015-01-07 23:26:44 WD2XNS  1268km 137480.003Hz   3mHz -28.3dBOp 100% 21.4dB
2015-01-07 22:58:46 VO1NA   2836km 137477.001Hz   4mHz -47.1dBOp  94% 16.7dB

Last night was very cold here (-11F) and the noise floor was raised 
compared to the previous night. Thus, VO1NA generally required "deep 
search" detection with v1.5.5 and that code yielded more detections than 
the DF6NM code. As mentioned earlier that was at least to some extent 
because the former receive setup was more sensitive than the latter. 
Neither code gave any falses, but I noticed that v1.5.5 produced "03:09 
    136 UW8SM de WD4KPD Op32 Deep Search 7863 km -43 dB in WASHINGTON, 
NC. with 0.1w + T-ant." Indeed UW8SM was active earlier in the evening 
but this was almost certainly a false because no Europeans reported 
reception at that time.

Next time I'll switch the eprobes and see what happens.
-- 
73, Garry, K3SIW, EN52ta, Elgin, IL