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LF: RE: Re: Frequency errors on PSK31

To: [email protected]
Subject: LF: RE: Re: Frequency errors on PSK31
From: "james moritz" <[email protected]>
Date: Mon, 13 Dec 2004 11:13:48 -0000
Importance: Normal
In-reply-to: <[email protected]>
Reply-to: [email protected]
Sender: [email protected]

Dear Andy, Wolf, LF Group,

 

But what effect does an error in the bit clock have, i.e. if the period of each bit is not exactly 32ms?

 

Cheers, Jim Moritz

73 de M0BMU

 

As PSK31 uses differential coding, it is the phase change over the 32ms signalling period due to freqeuncy error that is important.  If for BPSK, we need to maintain the phase to less than 90 degrees to remove the ambiguity, so 90/360 / 32ms = 7.8Hz freq error permissible.

 

For noisy signals, the determination of correct phase becomes worse, so error rate will progressively worsen with tuning error.

 

Andy  G4JNT

 

 

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