[Elecraft] Quantization noise and DSPs

[Lyle Johnson]

Hello Jerry!

> ...In reference to quantization noise, there are
> more serious limiting factors once you reach a
> true 16bits in the codec.  External noise, grounding,
> cabling, resistive thermal noise, external audio
> transducers, etc all come into play.

It may not be clear in the photographs, but great care was taken in the PCB
layout of the KDSP2 to divide power and signal ground at the location where
the connectors plug into the K2 control board.  The DSPx module also has
carefully isolated analog and digital sections including separate analog and
digital section voltage regulators, and grounding that ties analog and
digital together at the CODEC chip.

The results of this care are such that, in the DSP-10 Software Defined Radio
project, the DSPx module has about 10 dB better analog-to-digital dynamic
range performance (primarily due to reduced noise floor) over the Analog
Devices EZ Kit Lite product around which the radio was originally designed!


> ...If you have a copy of MATLAB, the filter design
> tool enables you to graph the quantization effects
> of 16, 24 etc. bits.

You can also download a free evaluation copy of scopeFIR from
www.iowegian.com, design a filter and then look at the quantization effects.
Yes, the commercial version of this product was used to design the filters
used in the KDSP2's DSP code.  No, I have no pecuniary interest in Iowegian.

73,

Lyle KK7P