LF: Re: Re: WSPR

["mal hamilton" <g3kevmal@talktalk.net>]

Tnx Jim for the info but in actual fact 200 hz is required and not only 6 hz 
as some have specified, in other words if there was other acty within the 
200 hz bandwidth it would corrupt the target signal.
mal/g3kev

----- Original Message ----- 
From: "James Moritz" <james.moritz@btopenworld.com>
To: <rsgb_lf_group@blacksheep.org>
Sent: Tuesday, December 23, 2008 7:19 PM
Subject: LF: Re: WSPR


> Dear Mal, LF Group,
>
> The transmited WSPR signal has a bandwidth of about 6Hz.
>
> SSB mode is used for transmission in order to translate the soundcard 
> audio
> to the appropriate RF frequency. But the signal bandwidth remains 6Hz
>
> At the receiver, a 200Hz bandwidth is extracted from the receive audio by
> the DSP routines in the PC. This allows the transceiver to switch from TX 
> to
> RX without changing modes.  (In my case, I have configured the rig to use
> the 250Hz CW filter as the "narrow SSB" filter, so the RX bandwidth is 
> only
> 250Hz anyway).
>
> This 200Hz of bandwidth is then sub-divided into numerous narrow 6Hz
> sub-channels, that can be simultaneously processed to receive lots of WSPR
> beacons operating simultaneously on slightly offset frequencies within the
> overall 200Hz range. That's the beauty of DSP.
>
> Overall, this means one transceiver can alternately transmit a WSPR beacon
> signal and then receive many different WSPR signals within a 200Hz range,
> during different 2 minute time slots.
>
> Cheers, Jim Moritz
> 73 de M0BMU

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