There was a change to the top qrg of
the band a while back , which is why the mid
band was moved , not sure its a while
back , who was testing at the time ? , was it
the USA that changed ? other than that , the
decoder only needs the signal from a sound card inside
the pass band to give -50 dB Op -55/6 wspr decode
levels
G,
Sent: Friday, December 27, 2013 6:46 PM
Subject: VLF: Opera frequency range
Hi Graham, Peter, VLF,
there seems to be conflict in the VLF
frequency selection: Somewhat arbitrarily, EA5HVK hardcoded Opera-VLF
to ~ 8910 Hz, while I would rather stick close to 8970 Hz. Direct Opera-4H audio generation from Opera software won't
work well with the deep search, because
- most transmitters and grabbers are currently
set up for 8970 Hz, and we can easily reuse "6000" and "60000"
SpecLab instances for opds data export,
- frequency instability from a raw soundcard (ie
without continuous samplerate correction) is typically a ppm or so. This
is not really sufficient to produce a coherent peak
in about 60 uHz,
- searching a wide frequency range
(yes, 22 Hz is vast!) for with uHz resolution would be unnecessary and
inefficient with the SpecLab / opds combo.
If one would like to try decoding 8970 Hz
signals with standard Opera software, one solution would be audio
frequency conversion through SpecLab and VAC. Or we could ask José for
a software version with user definable frequency
assignments.
Best 73,
Markus (DF6NM)
Sent: Friday, December 27, 2013 5:27 PM
Subject: Re: LF: Opera RX active 24/7 - de PA1SDB
The Op decoder limits are 8900 Hz > 8922 Hz
mid band 8911 Hz
There was a change of band some time
back , the Op software is correct tx/rx soundcard
SDR
73-G,
Sent: Friday, December 27, 2013 2:57 PM
Subject: Re: LF: Opera RX active 24/7 - de PA1SDB
Hi Peter, all,
Blacksheep seems to be responding
again...
Hmm, 8.925 kHz would be way out of
range of my SpecLab instances. I am currently looking for Opera signals
near 8.97 kHz:
opds-32: 8968.5 - 8971.5 Hz
(Stefan?)
opds-4H: 8969.8 - 8970.2 Hz
(Uwe?)
Sent: Friday, December 27, 2013 1:57 PM
Subject: LF: Opera RX active 24/7 - de PA1SDB
Hello VLF,
Opera RX on 8KC, 24/7 now.
Also Spectogram available.
The frequency band is 8895 - 8925 Hz, right
?
