Re: LF: RE: comparison OP8 477KHZ opds(DF6NM)--OPERA 1.5.6 LAST NIGHT

["Markus Vester" <markusvester@aol.com>]

Thanks Dionysios for sharing your results. Well done picking up VO1NA again in Greece!

 

Have a look at the bandwidth indication, which (besides possible drift) basically tells us whether a station is transmitting coherently with continuous phase. Specifically, VO1NA, G0NBD and G8HUH seem to be doing so. My impression is that the detectivity of Opera Dynamic and opds are pretty much on par for incoherent (random-phase) signals, but  opds seems to have an edge for coherent and stable ones. This is presumbly a benefit from opds's synchroneous demodulation, which (according to my measurements) can gain another 3 dB for a "perfect" signal.

 

Note that the % output from opds is not related to the correlation quality but only indicates the temporal overlap of the stepped 35-minute detection window with the 32.6-minute duration of the detected transmission. Values less than 100% just indicate partial overlap. The quality of the detection shows only in the last column, displaying the dB SNR of the  time-domain correlation peak. Detections just above the 15 dB threshold should be regarded as possible false positives and checked by other criteria, like operating frequency and time.

 

Despite my sub-optimal MF noise background, I also managed to snatch a single detection of VO1NA here.

2015-01-24 02:38:20 VO1NA   4563km 478477.028Hz  11mHz -37.4dBOp  93% 16.0dB
Sorry about the slightly inaccurate frequency readout, which is due to the free running Si570 crystal oscillator in the FiFi-SDR receiver.

 

Best 73,

Markus (DF6NM)

 

From: Rik Strobbe

Sent: Saturday, January 24, 2015 11:06 AM

To: rsgb_lf_group@blacksheep.org

Subject: LF: RE: comparison OP8 477KHZ opds(DF6NM)--OPERA 1.5.6 LAST NIGHT

Hello Dionysios,

 

thanks for the very interesting comparisation.

If the decodes from Costas are removed (at 7km his signal must be S9+++) it looks like this:

 

sv8rv km07ks Opera-8 477khz correlation   (DF6NM)

   date      time   call   distance  frequency bandwidth  snr    correlation

2015-01-24 01:15:31 G0NBD   2526km 478500.708Hz   8mHz -40.7dBOp  95% 16.2dB

2015-01-24 00:46:23 M0PPP   2446km 478513.832Hz  42mHz -42.8dBOp  81% 16.0dB

2015-01-24 00:25:37 G0NBD   2526km 478500.710Hz   8mHz -39.7dBOp  86% 16.6dB

2015-01-24 00:11:06 VO1NA   5905km 478477.530Hz   8mHz -40.6dBOp  90% 15.5dB

2015-01-23 23:37:30 G8HUH   2395km 478455.648Hz  11mHz -40.5dBOp  87% 16.9dB

2015-01-23 23:07:56 G8HUH   2395km 478455.643Hz   8mHz -41.8dBOp 100% 17.2dB

2015-01-23 22:42:33 G8HUH   2395km 478455.641Hz  11mHz -39.8dBOp  99% 15.0dB

2015-01-23 22:01:51 SO5AS   1598km 478496.870Hz 122mHz -35.0dBOp  99% 19.8dB

2015-01-23 21:36:53 SO5AS   1598km 478496.866Hz  44mHz -36.7dBOp  87% 15.8dB

2015-01-23 16:39:11 G3KEV   2449km 478507.023Hz  72mHz -38.9dBOp  66% 15.9dB

 

OPERA 1.5.6

***********  24/01/2015  *********** 

23:38    477 G8HUH Op8 Deep Search -36 dB  

22:43    477 G8HUH Op8 Deep Search -37 dB  

22:01    477 SO5AS Op8 -29 dB   |  ---------- -----  ---- ------------------------------------------------ ---------------------------------------------| Fade: 6%

17:05    477 G3KEV Op8 Deep Search -36 dB  

16:15    477 G3KEV Op8 Deep Search -37 dB

 

 

73, Rik  ON7YD - OR7T