[Ham-Mac] cocoaModem Observations & ?

[Brian K.Short]

On Mar 31, 2007, at 6:42 AM, James Duffey wrote:
> I am seriously considering adding a digiKeyer or microKeyer to the 
> setup. In the information on the web site, I have not located what the 
> conversion dynamic range (A to D bits) is on the CoDec sound chip they 
> employ. Do you or anyone else on the list know what this is? If it is 
> an improvement over the iMic's 16 bits, I may spring for the 
> digiKeyer, otherwise as a primarily CW op, the microKeyer seems to be 
> more useful.
>
> I think that you will be happy with CocoaModem. - Duffey

Yes, this was my dilemma and it is too bad that the DigiKeyer
which has the USB codec doesn't also have the K1EL keyer.

My primary motive was to be able to switch between eMac
and XP laptop with just the 1 cable.

Previously, I built all of my own interface - CAT with PTT/CW
on RTS/DTR, FSK with PTT/CW, and audio isolation.

After attending the same SDR lecture as you last summer,
I began casually looking at some of the specialty external
sound adapters like Roland etc.  As I recall (and you likely
better), in those applications the dynamic range of the I/Q
codec establishes the fundamental parameters of the receiver.
As available/affordable codecs improve in performance, so
do SDR receivers, fundamentally.

I do have a tiny SDR receiver and a Firefly kit to play
with some day.  If I am not being too nosey, is this what
you have in mind for the increased dynamic range?

Someone here said that the DigiKeyer has the lowest
noise level (presumably in the world).      I don't know
the basis of that specification or comparison.

I would enjoy to see a comparison of sound cards and
the significance of relevant specifications among the
built-in, external, and specialty high performance varieties.

My decision to get a Digikeyer was based more upon
convenience and expediency.

Personally, I don't have a real feel for how much improvement
24-bit A-to-D would improve copy of 45 baud 170 Hz shift RTTY.

Obviously, though, you are asking the fundamental questions.
What would the relevant specifications be? Dynamic range,
noise, sampling rate, and ?

Speaking of sampling, I would also be curious what sampling
rates folks use effectively?

--
Brian --> http://users.wildblue.net/k7on/
"Blessed are the cracked, for they shall let in the light."