Jay, I have only a
single spectrogram which covers 137774 to 781 Hz. The two grabber viewing
slots are just two subbands, which Chris and I chose more or less
arbitrarily, and which are sometimes being shifted
around.
For simplicity, I would suggest that Chris and
I simply move the upper slot down to 137780, and leave the other one around
the Russian Loran on 137775:
I think this would also work for others, like Scott
in VE7. My secret hope is that someone in VK will catch on, although
common darkness for us may be rather shorter.
The catch is that we will still need well separated
subbands for simultaneous east-west and west-east operation. For that reason, I
would suggest 136170 Hz for Eu transmit work.
Scott, the slow SpecLab settings are fairly
straightforward - I use 11025 Hz samplerate, complex decimation by
768, FFT size 32768, and 600 seconds per FFT. The center
frequency and display offset will depend on your receiver's precise LO
frequency (watch out for DDS rounding errors). Finally you will want
to inject a known audio tone for samplerate tracking
(eg. GPS-derived 5 kHz), or alternatively 1-pps pulses plus NMEA
(which I haven't tried yet).
Best 73,
Markus (DF6NM)
Sent: Saturday, September 17, 2011 9:34 PM
Subject: Re: LF: T/A ... and uHz grabber
Markus
Have to admit I didn't pay much attention to your #
2 uHz grabber. One option would be to use it for uHz bandwidth
work.
Jay
----- Original Message -----
Sent: Saturday, September 17, 2011 7:19
AM
Subject: Re: LF: T/A ... and uHz
grabber
Hi Jay, Chris, LF,
first option: To check sensitivity
and frequency lock, I like to keep a Loran
line in at least one of the two display slots. In Europe,
the Sylt + Lessay line on 137778.37045 would be my natural
choice.
Another option would be to simply move
down to 137780.00 center. Integer Hz multiples would allow to build
a relatively simple GPS-synchronized TX, based on a
sample-hold at 1pps. Of course this QRG could then only be used
by one station at a time.
In case someone overseas would like to set up
a narrow grabber, I'd suggest 136170.00 center for European TA
transmissions. Looking into the other direction, I guess the prospect of
sub-millihertz grabbers in the Far-east or Pacific areas might stimulate quite
a bit of activity.
Best 73,
Markus (DF6NM)
Sent: Saturday, September 17, 2011 12:14 PM
Subject: LF: T/A ... and uHz grabber
...
Marcus
We previously discussed moving the uHz
grabber to avoid QRM to QRSS30 beacon MP (VE3OT) on ~137780.3 - 137780.4.
Do you and Chris have a new frequency in mind?
Jay W1VD WD2XNS
WE2XGR/2
