From c2cfce23733b649a9370c73d5d2737596266921c Mon Sep 17 00:00:00 2001 From: Andreas Eversberg Date: Tue, 10 May 2016 19:23:11 +0200 Subject: [PATCH] wip: docs --- docs/c-netz.html | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-) diff --git a/docs/c-netz.html b/docs/c-netz.html index c3a4b12..0bf8a8f 100644 --- a/docs/c-netz.html +++ b/docs/c-netz.html @@ -148,12 +148,14 @@ Let it run again for one hour and you will see that signal is now below 1 PPM.

-C-Netz uses FSK by directly modulating the carrier, rather than modulating an FM tone. +C-Netz uses FSK (Frequency Shift Keying) by directly modulating the carrier, rather than modulating a transmitted tone. The advantage is much higher data rate. -A phone will only detect the correct polarity. +The base station's carrier frequency is raised by 2.5 KHz to transmit a logical "1" and lowered by 2.5 KHz to transmit a logial "0". +(The mobile station transmits reversed polarity.) +The mobile station will only detect the correct polarity. The three sync words of "11100010010", is shown in the picture above. In the picture above, the polarity is wrong. -The "1" points down and the "0" up. +(The logical "1" points down and the logical "0" points up.) You must check, with what polarity your transmitter is doing a positive frequency deviation. Also you must check your sound card's polarity on positive value beeing sent. To change polarty, use command line option '-F' or '--flip-polarity'. @@ -161,8 +163,8 @@ To change polarty, use command line option '-F' or '--flip-polarity'.

-This software does not care about what polarity it receives. -It just checks for sync words at both polarities and chooses right polarity automatically. +This software does not care about what polarity it receives from the mobile station. +It just checks for sync words with both polarities and chooses right polarity automatically.

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