[Lowfer] Note from Markus re modifying opds for any frequency

[Garry Hess]

Andy,

When 74 kHz opera rate-64 was first being used, I asked Markus, DF6NM 
how to modify the existing rate-32 opds code to accommodate it. Turns 
out it's not that hard to modify the code to handle any rate. Here's his 
response:

<
you won't need another software version, opds can be configured for 
other speeds. I posted some setup hints on blacksheep yesterday, but 
here's everything in a nutshell:

- SpecLab FFT setup: As the frequency is fixed on 74549.5 I'm not 
watching the full 100 Hz but reduced to a narrower 32k FFT, which keeps 
data files short and speeds up processing ... My settings are for 72 kHz 
"dial",  you'll still have to adapt to your audio center freq, 
samplerate etc.

- Suggested opds.ini edits:
opspeed=64
spotdelay=58
sourcepath=c:\spectrum\data64\  'this was because I'm exporting to a 
separate data64 folder. But you can also use the existing data folder.
pattern=*.txt
myqth=jn59nj    'enter your 6-digit locator for distance calculation
fc=74550.0   'nominal RF center of FFT
sr=11999.9988  'your calibrated samplerate (Hz)
dec=50331648   '96*512k   1536*32k
fignore=74551
ignoretol=1.1   ' lets opds ignore clusters of local qrm lines higher up 
on 74.550 and 74.551
reverseoutput=1  'bottom-to-top
uploadcmd=cleanup.bat  'can be disabled if you don't want to upload and 
delete
timetol=2
- cleanup.bat can stay as is, but you can also do without it.

- callsloc.txt has to contain the WG2XRS stations. We decided to use 
WG4XRS etc instead of WG2XRS/4 which isn't supported by Opera. Here's mine:
WG1XRS fn42hi
WG2XRS fn31ls
WG3XRS fn42ch
WG4XRS fn12lq
WG5XRS em95tg
That should be it... good luck!

73, Markus (DF6NM)
 >

The frequencies noted above need to be adjusted for monitoring 29.499 
kHz rather than 74549.5 kHz. Also, you need to add WH1XBA fn12lq to 
callsloc.txt, or something similar. It depends on what Bob decides to 
enter as his call in his opera program.

Here's my opds.ini file:

*****
'opds.ini for opds2h5 64 version
'df6nm 2013-10-01
'Opera-64

opspeed=64
spotdelay=58

sourcepath=C:\Spectrum\data64\
pattern=*.txt

myqth=en52ta    'enter your 6-digit locator

fc=27950.0     'nominal center for Op-64 (Hz)
sr=12000.170   'calibrated samplerate (Hz)
dec= 50331648   '48*2*512k
'fignore=74551
'ignoretol=1.1

'sr=48000       'alternative SpecLab samplerate and decimation (Hz)
'dec=113246208  '216*512k (instead of desired 196*512k)

'lorangri=8000 6731 7499 'active Loran GRIs in central Europe: Russia 
Lessay Sylt
'lorantol=0.003 'eliminates Loran lines within +-3 mHz

reverseoutput=1 'bottom-to-top

timetol=2       'assign multiple partial detections to same spot (symbol 
durations)

'lower snr thresholds for slightly more sensitivity:
'thresholddbcor=14.5 'default 15
'thresholddbc=5 'default 6
*****

FFT settings in Spectrum Laboratory are:
decimate input by 1536
FFT input size = 32768

Hope that helps.
-- 
73, Garry, K3SIW, EN52ta, Elgin, IL