185 KHz K3SIW G4WGT 1618 m OPERA 3811 miles 7 Feb 2018 @ 23:57:14 #opera


2018-02-07 23:57:13 K3SIW AA G4WGT IO83QO 0 136 [185]  -45 Op32__~45dB

For some reason,  LF reception at my  qth has yet to match  MF, however ..

After a  exchange  of emails with  Gary G4WGT , [who  has a excellent history of VLF and LF reception] ,
around the  possibility of  detecting K3SIW  on the  USA  lowFER  band ,  K3SIW sending on 185185 Hz
using a multi mode  beacon,  one of the  modes being  Opera OP32 , normally  deployed on 136 KHz.

Opera reporting  185  as   136  to the  data  base  and the  psk-map 

Gary  set up watch on 185185 with his home-made up-converter  and IC706 , LF to  4 MHz , after  7 nights ,  the  assumed 
impossible occured, Opera  made a  single  detection  of  K3SIW signal  on 185185 at  -45 dB  s/n 

So the  problem now being ,  as the  spot  was from the  correlation detector , was it  real of  false , not wishing
to rush things , over the  following  days ,  we made a series  of  checks , 

Where  there any  false  detections  during the  7  days  previously ,  NO 
No detections are  showing  for  G4wgt on the  2200  band , before or since 

Was there  a  parallel  detection  or  decode  at the  same  time  slot - YES 
Nk9M , made a  full  decode  at  + 6 dB  s/n, Time stamp is added  by
RX- PC and is  inside  system  expected variation 

23:58 136 K3SIW de NK9M Op32 +6 dB F:4% in Oswego, IL. 1499.7 Hz

23:57 136 K3SIW de G4WGT Op32 Deep Search -45 dB in Chorley, NW England 1500.7 Hz

Was the  detected ''Audio''  frequency  correct ..YES
opera displays the  average  frequency over the  tx time

G4WGT recovered audio  frequency   1500.7 Hz , 
NK9M recovered audio frequency  1499.7
Expected  audio  frequency  1500 Hz 

Was G4WGT  station  frequency correct .  YES 
Testing  with  BBC radio  4  on 198 KHz ,  produced  1500  +/-  fractional  Hz audio tone.

Was path possible ,  YES ,  experience  with  op32 on 136 KHz has shown , that  detections  are possible 
2 or 3  hours before each end of the  path is in  darkness , in this  case , the  time matches , darkness 
tx  and rx.

As to what  amount of  signal  reached  G4WGT cannot be quantified,  as the  correlation  detector , treats the  total  TX  time as 
a single  ''bit'' , but  a minimum  of 40% of the  Tx at a  average of  -45 dB  is required .

Good result all  round ,  stations  wanting  to  monitor  K3SIW  can download  Opera from the  web site listed ,

Settings ,  
Set RIG control to  VOX  , [ not  cat]
Set Frequency  to  136 KHz ,  set's  op32  
Set RX  usb  to    185185  - 1500 Hz  = 183.685  KHz 

web linked  PC is  needed  to  update the  deep search list , of the  call may be  added  
by editing the  opera.ini  file for  stand alone  


Opera download link

Opera on line data base [2200 meter]

Day night  showing   same time  ................................................................................................psk-map  some time  later ,