Re: LF: Rugby LORAN measurement? Continued

["Andy Talbot" <actalbot@southsurf.com>]

I should have said, by pulse I mean a break in carrier,  so the actual pulses are 900ms, 800ms and a few at 700ms.  On Alberto's plot the main zero at 10Hz is very clear, and there is adefinite dip at 5Hz caused by some of the pulses having a 200ms (800ms) period.  The spectrum caused by the few 300ms pulses won't be visible since a) there are very few, if any of these and b) its first zero would be at 3.333Hz so wouldn't be visible in the line spectrum.

 

Andy  G4JNT

www.scrbg.org/g4jnt/

 

----- Original Message -----

From: Andy Talbot

To: rsgb_lf_group@blacksheep.org

Sent: Tuesday, April 11, 2006 5:13 PM

Subject: Re: LF: Rugby LORAN measurement?

The pulses have a width of either 100, 200 or 300us.  The time/date  is carried by pulse width mod :100ms = 0,  200ms = 1,  with a framing code at the 52 - 59 second interval of '01111110'.  Parity checks and DUT info are carried in a 'second level' pulse during the framing code, so some of the pulses are extended from 200 to 300ms.  The seconds marker is 500ms long.

 

So...

Your answer is that all pulses are a multiple of 1/ (10Hz) hence there is a  sin(x) /x  pattern is based on 10Hz and 5Hz convolved with the 1Hz PRF

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