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LF: Rugby and 77.5 kHz

To: [email protected]
Subject: LF: Rugby and 77.5 kHz
From: [email protected]
Date: Tue, 7 Mar 2000 06:45:02 EST
Reply-to: [email protected]
Sender: <[email protected]>
Hi again,

that was another nice xband QSO with M0BMU (71.858). I specially liked that because seeing Jims sigs on 71.8 a couple of weeks ago has stirred up all that activity.
With Rugby off (actually testing apparently, carrier on and off several times
around 10:30), I noticed an interesting structure in the noise. The
time-signal tx DCF77 (77.5kHz nr Frankfurt, 50kW?) has a 645.883 bd (=fc/120)
pseudorandom phase modulation (5 deg). Using correlation to this 512 bit
sequence, special receivers can determine time more accurate than by the 1 Hz
carrier dips alone. 160 km from their site, I normally can see 3 or 4
sidebands on each side of the carrier. Today, 8 sidebands were clearly
visible down to 72.34 kHz (77500-8*646). Truly a spread spectrum!
Now Rugby is back to normal. I've included two spectra with it being off and
on <Rugbyoff.zip, 8kB>, so you can compare.
73 de Markus, DF6NM

Attachment: RUGBYOFF.ZIP
Description: Zip archive

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