> -----Original Message-----
> From: amps-bounces@contesting.com [mailto:amps-bounces@contesting.com] On
> Behalf Of Michael Tope
> Sent: Monday, August 14, 2006 10:41 PM
> To: Joe Subich, W4TV; garyschafer@comcast.net; amps@contesting.com
> Subject: Re: [Amps] Checking for IMD
>
>
> ----- Original Message -----
> From: "Joe Subich, W4TV" <w4tv@subich.com>
> To: <garyschafer@comcast.net>; <amps@contesting.com>
>
> >> Even if there is some receiver IM generated it only needs to
> >> be a few db below what we are looking for to be masked.
> >
> > However, absent AGC to prevent overload, the dynamic range of
> > many IF strips (particularly where the primary filtering is
> > provided by DSP) is less than 30 or 40 dB. If you are looking
> > at - 35 dB 3rd order and - 40 dB 5th order, that is pushing the
> > real dynamic range of the IF.
> >
> >> By the way most spectrum analyzers have filters with a rather
> >> broad shape factor compared to our receivers and seem to do
> >> just fine.
> >
> > Most spectrum analyzers have much better IF strips (and fewer
> > conversions) that the typical amateur receiver. They are
> > optimized for dynamic range and not selectivity ... they have
> > to be.
> >
> > 73,
>
> Sounds like the Flex Radio SDR-1000 would be ideally suited
> for this task. It has very a simple conversion scheme, high
> dynamic-range, and no analog AGC (either derived or applied).
> With a 44 KHz sampling rate sound card it should easily provide
> 15 to 20 KHz of useable spectrum viewing with good dynamic
> range.
>
> 73, Mike W4EF...........................................................
Isn't that an FM radio? If so no good for a spectrum analyzer front end.
By the way the HP141 has no less than 4 conversions.
73
Gary K4FMX
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|