Re: DDS spurs

---------

From: Leon Heller (leon_heller@hotmail.com)
Date: Sat Sep 28 2002 - 13:19:25 CDT


>From: "Matthew Balmer" <matthew@thebalmers.freeserve.co.uk>
>Reply-To: matthew@thebalmers.freeserve.co.uk
>To: "Low Power Amateur Radio Discussion" <qrp-l@Lehigh.EDU>
>Subject: DDS spurs
>Date: Sat, 28 Sep 2002 17:32:30 +0100
>
>Hi,
>
>This is a second attempt at sending this so apologies if it doubles.
>
>I am interested in experimenting with DDS operating at 14 and 22MHz,
>control
>via a PIC. Spurs seem to be a problem with DDS VFOs, most sources I've
>read
>seem to suggest around -50dBc for the spurs.
>
>Just how much of a problem are these going to be to a high performance
>receiver? It is obviously going to be a problem with the spurs mixing with
>other signals, and clearly the problem it will cause will depend on the
>strength of the signal it mixes with.
>
>I know I could use a "clean-up" PLL but I'm interested, if it won't harm
>the
>performance too much, in just using a simple DDS VFO.
>
>Any comments/experiences would be greatly appreciated.

ADI has some software for the AD9850 that tells you where the spurs are. I
forget what it's called, but I've got a copy somewhere. You could use it to
adjust things so that you don't have too many in the bands you are using.

73, Leon

--
Leon Heller, G1HSM Tel: +44 1424 14790
Email:leon_heller@hotmail.com
My web page: http://www.geocities.com/leon_heller
My low-cost Altera Flex design kit: http://www.leonheller.com

_________________________________________________________________ Send and receive Hotmail on your mobile device: http://mobile.msn.com


Search QRP-L Archives

[ QRP-L Archive | ]
[ 1993 | 1994 | 1995 | 1996 | 1997 | 1998 | 1999 | 2000 | 2001 | 2002 ]

---------

This archive was generated by hypermail 2b29 on Sun Oct 13 2002 - 10:40:05 CDT

kd4ab@kd4ab.org