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Re: LF: T/A ... and uHz grabber

To: <[email protected]>
Subject: Re: LF: T/A ... and uHz grabber
From: <[email protected]>
Date: Sat, 17 Sep 2011 18:13:25 -0400
References: <58BF19DEE3D54EB5A3A4F5911BD506FF@White> <002201cc7458$09677160$8d01a8c0@JAYDELL> <C744292960794ECC95143BA154033783@White> <000e01cc74ae$20e398e0$6d01a8c0@DELL4> <[email protected]> <002d01cc7522$a1eccb90$8d01a8c0@JAYDELL> <733EF991BB354216A53A3485493442A3@White> <001301cc7570$e0b8b4d0$8d01a8c0@JAYDELL> <87921B1A33264C65B0A8BBEBBCBD1A04@White>
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Markus
 
Let's give 137780 a try.
 
Jay W1VD  WD2XNS  WE2XGR/2
 
 
----- Original Message -----
Sent: Saturday, September 17, 2011 4:54 PM
Subject: Re: LF: T/A ... and uHz grabber

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    
 
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