trying again...

From: Markus Vester

Sent: Thursday, September 01, 2011 10:47 PM

To: [email protected]

Subject: Re: Microhertzing at LF:

Hi Chris,

 

thanks for this! The Saudi Loran traces (GRI 8830) look very accurate on your 4X grabber. I will try to appear there tonight, and have started to send a straight carrier on 137780.30. TX power is now reduced to about 100 mW EMRP.

 

Best 73,

Markus

From: Chris 4X1RF

Sent: Thursday, September 01, 2011 1:34 PM

To: [email protected]

Subject: Re: Microhertzing at LF:

Markus, LF,

As a newcomer to LF I find this as an interesting experiment for real low power or long distance tests for those who can achieve the necessary frequency stability requirements. I found this to be quite a challenge...

I have followed your initiative and started similar windows on my grabbers in YO: http://dl.dropbox.com/u/10280270/YO/TA3600.jpg and 4X: http://dl.dropbox.com/u/10280270/4X/TA3600.jpg

The 4X grabber is currently using the Mercury HPSDR receiver (http://openhpsdr.org) which is GPSDO locked. However, the audio is routed to SpectrumLab using Virtual Audio Cable as a virtual sound card. I have no info regarding VAC sample rate accuracy or how I can automatically adjust it so this may be a limiting factor, further experimentation is needed. In the worst case, a real sound card could be used but then it also has to be locked to GPS.

The YO grabber is usually using GQD as a reference for the sound card sample rate calibration in SpectrumLab and the LF receiver is based on a laboratory grade VTCXO. GQD being off air, I was forced to use DHO which is not very reliable during the night for me as can be seen on the 137.775 Loran line.

Thanks for the challenge!


73s
Chris 4X1RF

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