[CQ-Contest] Skimmer DR

[Scott Robbins]

>>I'd be interested to see how well in a major contest with a band full of
>>signals the software works.  I don't see (unless I missed it) a dynamic range
>>specification for the software.  What is it?

>         IMD should be very good...on the order of 95 dB at close spacings
>based on the SDR-1000 and SDR-5000.  Where most wideband SDR rigs
>fall apart is BDR.  The SDR-5000 is the best at ~120 dB compared to
>~140 dB for rigs like Orion or the K3.  This means the decoder may not
>work as well while transmitting on teh same band but bandpass filters
>should relieve that problem on other bands.  

>         Again the correct analogy is the Flex SDR...or a classical
>rig like a K3 using SDR on it's wideband IF output.  SDRs can see
>192 kHz of spectrum and still maintain extremely good performance.
>Trying to use SDR on the same band will run into BDR limitations,
>but using one behind a set of bandpass filters should work fine.
>The K3 and SDR of course have these built in, so you still need 2
>real radios.  The Softrock40 wouldn't work very well unless you
>added BPFs ahead of it.

I was wondering what the available DR of the Skimmer itself might be -- there
isn't a claimed specification page.  Outside of Amateur Radio, Ten-Tec provides
receivers that are used for wideband decoding of radio spectrum with a variety
of devices (or software, often both) that are hung off the IF and/or audio
outputs.  

These devices/software have a dynamic range that is inherent and can be the
limiting factor itself in the ability to decode what is heard on the spectrum
-- receiver performance can exceed their available range.  If the software
itself has (picking a number out of the air) 70 dB of available range, the
loudest signals available to it will make the smaller signals unreadable. 
During a contest, that would be certainly a potential issue!

Scott W4PA



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