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Re: LF: CW 477.7 kHz

from [Andy Talbot] [Permanent Link][Original]
To: [email protected]
Subject: Re: LF: CW 477.7 kHz
From: Andy Talbot <[email protected]>
Date: Sat, 23 Sep 2017 12:12:06 +0100
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WSPR works with a noise bandwidth of 1.46Hz, and by virtue of the strong FEC, allows copy at a S/N IN THAT BANDWIDTH  of about +4dB.    This equates to -24dB S/N in 2.5kHz

10WPM morse has a noise bandwith of about 8Hz, and as you are only using audible / visual human interpretation needs probably a S/N of perhaps +6dB to +10dB depending on the operator's experience to decode perfectly.    That equates to about -20dB S/N in 2500Hz best case

So 10WPM CW is going to be at least 4dB worse, and possibly as much as 10dB  if operator experience is lower.

Andy  G4JNT


On 23 September 2017 at 12:00, Roelof Bakker <[email protected]> wrote:
Hello Joe,

The signal was much better last night.
I have attached an audio clip.

This is made with Linrad using a 10 Hz wide filter.
The keying sidebands are well within the filter passband.

I believe slow Morse, say 10 WPM, received with a 10 Hz filter will
achieve about the same signal to noise ratio as WSPR. In this case
this is 24 dB compared to a 2500 Hz SSB bandwidth.

73,
Roelof, pa0rdt

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