Re: ping: Jim Thompson

Don Bowey wrote:

On 4/30/06 1:58 AM, in article
9%_4g.65867$F_3.12268@xxxxxxxxxxxxxxxxxxxxxxxxxx, "joseph2k"
<cooltechblue@xxxxxxxxxx> wrote:

Don Bowey wrote:

On 4/25/06 9:49 AM, in article erudncGPy7ioztPZRVn-gQ@xxxxxxx, "Jerry
Avins"
<jya@xxxxxxxx> wrote:

Don Bowey wrote:
On 4/25/06 12:14 AM, in article e2ki8j$cuh$1@xxxxxxxxxxxxxxx, "Steve
Underwood" <steveu@xxxxxxx> wrote:


Joerg wrote:

Hello Jim,


1200 baud FSK changes frequency in a _single_ cycle, so period-type
demodulation goes to crap quickly in the presence of noise.


Zero-crossers are pretty much a thing of the past here, just like
they
are for medical ultrasound Doppler. You can do it in the digital
domain
these days. All it takes is a good uC such as the MSP430. But not a
version with a puny 10 or 12 bit converter. They offer some that
convert
to 16 bits.

What's wrong with a 12 bit converter? The entire telephone network
uses
12 bits.

Steve


No, the telco network is 8 bits, 8000 times each second.

The eight bits are derived via A-law or mu-law from 12-bit data.

Jerry

Only if the bits are being used to provide a voice channel, as
contrasted
to
a 64 kbit/s digital channel or concatinated digital channels.

Don
OK alligator breath, explain v.90 modems.

Well, skunk tail breath, what's that have to do with the current
discussion,
and why should I explain them?

Don

You have been talking big, but have not shown me a good grasp of how
Continuously Variable Slope Delta (CVSD) codec's work. You could really
show me by explaining how they pack 56,000 bits/s down the voice telephone
lines, through the D4 channel banks that does the analog/digital
conversions at 56,000 bits/s with a CVSD and so on th the other end. I
have been watching the CVSD's develop for over 30 years, and i followed all
the way to 28800 baud modems. Some of the tricks necessary for 56000 baud
interact in ways i do not fully understand yet. Enlighten us all please.

--
JosephKK
Gegen dummheit kampfen die Gotter Selbst, vergebens.  
--Schiller
.