Message-ID: <F2DBE89BE47F43C9B384F873F753785A@Black>
From: "Markus Vester" <markusvester@aol.com>
To: <rsgb_lf_group@blacksheep.org>
References: <F4E8A04C3CBA4C67AE9C3318F2F40C4F@JimPC> <496E6B45.5020100@usa.net> <0F3DBBAC61C545AE85525CD884B642EC@Black> <20090114231729.6b8aea4f@lurcher> <2AD1A31DF27448F495C0CE7FF33CE9DE@Black> <C4F6E432D5814955A1FDD42B0279F472@AGB> <1E6D0A88C4DE49E5A2AF05911187E7A3@Black> <424931F60B3D4F41AB7DCB9E9FCAB3C5@big7368b9a7d3d> <E68E6C5A539A4838ADAC20BE903CBC68@JimPC> <002e01c9770b$35b63910$8d01a8c0@JAYDELL>
In-Reply-To: <002e01c9770b$35b63910$8d01a8c0@JAYDELL>
Date: Thu, 15 Jan 2009 23:33:31 +0100
MIME-Version: 1.0
Subject: LF: 136khz WSPR and Loran notching
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Hi Jay and all,

thanks for this information. Your strongest lines are apparently from Nantucket which is dual rated on GRIs 5930 and 9960. I have 
slightly adjusted my WSPR transmit center frequency to 137567.8 Hz, which would just barely squeeze the signal between 565.261 and 
570.281.

It may be helpful to try notch filters on the Loran lines. As I have only weak Loran lines on 137 kHz, I have experimentally set the 
RX somewhere near 100 kHz and tried to apply SpecLab's new multiple autonotch feature from the FFT filter dialog box. Even though 
this was originally intended to dynamically remove 50 Hz hum harmonics for VLF listening, it proved quite effective on Loran lines 
when the FFT size was set high (> 64K) and agressive threshold parameters were chosen. It did require some fiddling, but resulted in 
a very audible rejection of the strong Loran clatter. Alternatively, the older SpecLab "IIR2" DSP-filter is also very effective to 
place narrow notches on a few discrete frequencies. The main point is that the nulls will hardly affect the desired signal as long 
as the notch width is much narrower than the modulation symbol rate (1.47 Hz). A noise blanker in front of the notch filters will 
prevent ringing after a strong impulsive excitation.

The straightforward way toapply this to WSPR would be to have one PC running SpecLab, and use an oldfashioned audio cable to feed 
the DAC audio output to a second PC running the WSPR decoder.

Best wishes
Markus, DF6NM


----- Original Message ----- 
From: <jrusgrove@comcast.net>
To: <rsgb_lf_group@blacksheep.org>
Sent: Thursday, January 15, 2009 1:17 PM
Subject: LF: Re: Re: 136khz WSPR


> Marcus
>
> Info on 137.570 kHz.
>
> 137565.036 9610 - South Central U.S.
> 137565.261 9960 - Northeast U.S.
> 137565.337 7270 - Newfoundland East Coast
> 137565.392 9940 - Western U.S.
> 137566.890 5980 - Russian American
> 137567.568 9990 - North Pacific
> 137568.922 7980 - Southeast U.S.
> 137569.095 7960 - Gulf of Alaska
> 137569.361 8290 - North Central U.S.
> 137569.677 8970 - Great Lakes
> 137570.239 9610 - South Central U.S.
> 137570.281 9960 - Northeast U.S.
> 137570.423 9940 - Western U.S.
> 137570.952 5990 - Canadian West Coast
> 137571.669 5930 - Canadian East Coast
> 137572.215 7270 - Newfoundland East Coast
> 137572.573 9990 - North Pacific
> 137575.188 7980 - Southeast U.S.
> 137575.251 5980 - Russian American
> 137575.251 8970 - Great Lakes
> 137575.301 9960 - Northeast U.S.
> 137575.377 7960 - Gulf of Alaska
> 137575.392 8290 - North Central U.S.
> 137575.442 9610 - South Central U.S.
> 137575.453 9940 - Western U.S.
>
> Jay W1VD  WD2XNS  WE2XGR/2
>