[TenTec] AM Receiver distortion in Orion II

[Dr. Gerald N. Johnson]

On Wed, 2007-01-24 at 19:33 +0000, Rob Atkinson, K5UJ wrote:
> Hi,
> 
> I'll try to explain this. think of a dsb circuit as a data processing 
> circuit.
> 
> If you have two circuits, one using 16 bit processing and the other 24 bit, 
> but they both have the same clock speed, then the 24 bit circuit processes 
> more data for a given amount of time.

NOT AT ALL! The words are wider which makes the dynamic range is greater
but the 24 bit processor works one instruction per clock cycle just like
the 16 bit processor. Sometimes the wide processor word makes a wider
instruction word (but its a characteristic of DSP that the instruction
bus/memory and the data bus/memory are independent) that can do more
complex operations per clock cycle but that's not a given going from 16
to 24 bit DATA.

> That means the digital simulation of 
> an analog waveform for a fixed time period has greater precision because it 
> is sampling at the same rate, but processing it more rapidly, 1/3 more for 
> each clock tick.    Processing bigger chunks of data at a time means you can 
> do things like employ more complex processing algorithms that can result in 
> a more faithful analog result.

Not so.
> 
> Assuming a CD player is a 16 bit system, it could be extremely high 
> fidelity, if it's clock speed is extremely high because then, it would be 
> sampling and processing more data than a 24 bit circuit on a much slower 
> speed for a given amount of time.

NOPE.
> 
> So besides the word length, we also need to know the clock speed for the dsp 
> circuits, which I for one, do not know off hand (I think the 870 dsp runs at 
> 10 MHz but don't hold me to that).
> 
> a few folks have mentioned that  the Orion is (depending on who you talk to) 
> a 24 or 32 bit dsp processor.   That's great and I humbly apologize for 
> implying anything else, but its clock speed is also important and in any 
> event, there seem to be other components that limit its flat frequency 
> response.

Like the A/D and D/A word widths.
> 
> 73,
> 
> rob / k5uj
> 

-- 
73, Jerry, K0CQ,
All content copyright Dr. Gerald N. Johnson, electrical engineer