RadioBanter - View Single Post - A more rational approach -- how I would like to change the cell phone industry.

Don Bowey

On 8/16/07 7:29 AM, in article
, "D Peter Maus"
wrote:

Brenda Ann wrote:
"John Navas" wrote in message
...
On Thu, 19 Jul 2007 18:43:58 -0700, Don Bowey wrote
in :

On 7/19/07 4:42 PM, in article ,
"John Navas" wrote:

On Thu, 19 Jul 2007 14:45:00 GMT, wrote in
:

In rec.radio.amateur.antenna Radium wrote:
Digital cell phones should stop using the compression they use and
start using monaural WMA compression with a CBR of 20 kbps or less and
a sample rate of at least 44.1 KHz. In addition, the following must
also apply:
The audio bandwidth of the phone system is about 3 KHz.
Actually more like 10 KHz.
If he is commenting on the bandwidth of a message network channel/circuit,
including cellular, it is about 3 kHz.
Audio. Suggest you read more carefully.

--
Best regards, FAQ FOR CINGULAR WIRELESS:
John Navas http://en.wikibooks.org/wiki/Cingular_Wireless_FAQ

POTS phone lines are very limited. IIRC from my work with those systems,
about 300-3600 Hz. Strictly human voice range, not meant for hi-fi. Special
lines are still available for hi-fi use as audio STL's.

I engineered a remote in Chicago a number of years ago, and the
client wouldn't spring for ISDN, or equalized lines. ATT provided a POTS
line and we got 8k analog audio out of it. Then again, we were next to
an ATT store. Similar performance was observed at my condo in Heather
Ridge. Here at the house, not two miles away, I'm lucky to hit 14.4
modem speeds, and 3k audio on a good day with my POTS line.

Guaranteed performance, you're right, is only 300 to 3600Hz,

I can't think of even one US Telco that would (or could) guarantee that for
a POTS line.

and
14.4k modem speed. But real performance varies from company to company,
CO to CO, line to line. And surprisingly good audio and high modem
speeds, are possible with POTS technology. The instruments, themselves,
are bandwidth limited. But the lines are often, but not always, much
wider than the instrument. That's why, when addressing the phone with a
hybrid, or repeating coil, directly, I have always been able to get
passable audio on a POTS line. With AM audio bandwidth limited anyway, I
could usually exceed the stations audio performance from the field and
you couldn't tell we weren't using high performance lines. But that
experience hasn't been limited to AM. I've been able, when lines were
clean enough, to hit FM stations with audio wide enough, that the losses
were ignorable. Hardly negligible, but certainly ignorable. And in at
least two cases, better audio than was possible with Comrex, or with the
POTS digital dialup systems out now.

It just depends on who's providing the line, and how it's routed.

BTW, equalized lines are being phased out. They're still available,
but carriers are moving to make them prohibitively expensive to install
and maintain, anymore, and carrier noise, which was never a problem
before, is becoming a problem now. It's easier, more cost effective and
requires less installer activity to drop in an ISDN line for broadcast.
So carriers are really pushing that. Not that they're making it that
much easier on the broadcaster. When I put in my ISDN link here at the
house, I very nearly had to wire it for them.

When the Florians owned WNIB, Bill got tired of all the carrier
noise, and administrative crap that went along with his equalized
studio-transmitter lines, and had ATT install a second set of control
loops for his remote transmitter control. Control loops are copper,
unequalized, and are designed to carry control voltages, down to DC and
control databus output. They're basically just twisted pair. And
dramatically less cost than broadcast lines.

Bill got his own equalizers and set up his own equalized lines on the
extra control loops and put his studio-transmitter audio there.

It was the sweetest sounding audio on the dial. Right up there with
WFMT, but less limiting.

ATT threw a fit. Control loops are NOT for carrying program audio.
Bill fought them on it. And never did return to ATT broadcast lines. He
and Sonja eventually sold out to Bonneville for nearly a half a billion
dollars.

AT&T didn't sell local channels. What Telco are you calling AT&T?

Sometimes the bear gets you, sometimes bear steaks are so tasty at
the end of a long ride.