Reply by glen herrmannsfeldt●January 24, 20072007-01-24
Randy Yates wrote:
(snip)
> According to the BTSC specification, the pilot tone is nominally
> 15734 Hz (+/- 2 Hz), not 15734.26 Hz.
It is the color subcarrier divided by 227.5, which rounds to
15734Hz. It is supposed to be synchronous to the line rate.
I suppose the receivers might have a +/- 2Hz tolerance, but
I don't believe that broadcasters can do that.
I tried to find the tolerance for broadcast color subcarrier
on fcc.gov, but I didn't find it. I believe it is around 100Hz
for the main carrier, and I thought close to 1Hz for the subcarrier.
-- glen
Reply by Andreas Lobinger●January 22, 20072007-01-22
Aloha,
Ralph A. Schmid, DK5RAS wrote:
> "Clay" <physics@bellsouth.net> wrote:
>>Cellphones are speced at -117dBm.
> Not for GSM, with GSM you must be lucky when the cellphone achieves
> -106dBm. With UMTS my personal experience is, that at least around
> -100dBm are necessary...
To pass conformance testing you have to have at least -115dBm in GSM
and ~113dBm in UMTS. If both your telephones cannot archive this,
throw them away and replace by real receivers.
>>But nobody is going to operate them
>>at that low a level,
> People do this all day, when they are out in the woods or inside
> buildings, where coverage is not as in urban areas.
In range problems usually the UL is the problem, not receiver
sensitivity in DL.
>>since cellular and pcs operate as interference
>>limited and not noise limited systems.
> This is only valid with high density of cells and overlapping
> coverage.
> I just wanted to point at the digital lie - more range, and higher
> capacity.
There is no digital lie. There maybe range problems with limited
basestation power... But reusing the resource and having measurable
capacity is only archievable with digital.
Wishing a happy day
LOBI
Reply by Jerry Avins●January 22, 20072007-01-22
Randy Yates wrote:
> Jerry Avins <jya@ieee.org> writes:
>
>> Randy Yates wrote:
>>> Jerry Avins <jya@ieee.org> writes:
>>>
>>>> How would the meter be read?
>>> With your eyes? Seriously, I don't know what you're
>>> asking.
>>>
>>>> It's an advantage for the audio itself to be the indicator.
>>> Why?
>> There's no meter to look at. Eyes are more often occupied that ears,
>> and their directionality properties differ.
>
> There are advantages to using analog communications when a human needs
> to be in the feedback look because that allows us to use our ears
> rather than our eyes so that our eyes won't be distracted. So, even
> though we may gain an advantage in range of several miles using
> digital, it isn't worth the occasional glance at the power meter that
> would be required from our eyes.
>
> Is this the gist of your argument?
It may not be worth it. What is and isn't worth depends on circumstance.
Aside from that caveat, that was my argument. We see only what we look
toward. and both eyes move together. We hear all around.
Jerry
--
Engineering is the art of making what you want from things you can get.
¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯
Reply by Ralph A. Schmid, DK5RAS●January 22, 20072007-01-22
"Clay" <physics@bellsouth.net> wrote:
>Cellphones are speced at -117dBm.
Not for GSM, with GSM you must be lucky when the cellphone achieves
-106dBm. With UMTS my personal experience is, that at least around
-100dBm are necessary...
>But nobody is going to operate them
>at that low a level,
People do this all day, when they are out in the woods or inside
buildings, where coverage is not as in urban areas.
>since cellular and pcs operate as interference
>limited and not noise limited systems.
This is only valid with high density of cells and overlapping
coverage.
I just wanted to point at the digital lie - more range, and higher
capacity.
Reply by Ralph A. Schmid, DK5RAS●January 22, 20072007-01-22
Vladimir Vassilevsky <antispam_bogus@hotmail.com> wrote:
>-120dBm per how many bits per second?
Just Voice, no bits :-)
Reply by Randy Yates●January 21, 20072007-01-21
Jerry Avins <jya@ieee.org> writes:
> Randy Yates wrote:
>> Jerry Avins <jya@ieee.org> writes:
>>
>>> How would the meter be read?
>> With your eyes? Seriously, I don't know what you're
>> asking.
>>
>>> It's an advantage for the audio itself to be the indicator.
>> Why?
>
> There's no meter to look at. Eyes are more often occupied that ears,
> and their directionality properties differ.
There are advantages to using analog communications when a human needs
to be in the feedback look because that allows us to use our ears
rather than our eyes so that our eyes won't be distracted. So, even
though we may gain an advantage in range of several miles using
digital, it isn't worth the occasional glance at the power meter that
would be required from our eyes.
Is this the gist of your argument?
--
% Randy Yates % "Rollin' and riding and slippin' and
%% Fuquay-Varina, NC % sliding, it's magic."
%%% 919-577-9882 %
%%%% <yates@ieee.org> % 'Living' Thing', *A New World Record*, ELO
http://home.earthlink.net/~yatescr
Reply by Jerry Avins●January 21, 20072007-01-21
Randy Yates wrote:
> Jerry Avins <jya@ieee.org> writes:
>
>> How would the meter be read?
>
> With your eyes? Seriously, I don't know what you're
> asking.
>
>> It's an advantage for the audio itself to be the indicator.
>
> Why?
There's no meter to look at. Eyes are more often occupied that ears, and
their directionality properties differ.
Jerry
--
Engineering is the art of making what you want from things you can get.
¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯
Reply by Randy Yates●January 21, 20072007-01-21
Jerry Avins <jya@ieee.org> writes:
> How would the meter be read?
With your eyes? Seriously, I don't know what you're
asking.
> It's an advantage for the audio itself to be the indicator.
Why?
--
% Randy Yates % "Ticket to the moon, flight leaves here today
%% Fuquay-Varina, NC % from Satellite 2"
%%% 919-577-9882 % 'Ticket To The Moon'
%%%% <yates@ieee.org> % *Time*, Electric Light Orchestra
http://home.earthlink.net/~yatescr
Reply by Jerry Avins●January 21, 20072007-01-21
Randy Yates wrote:
...
> If I had a "rigging meter" that accurately indicated the load,
> and I had knowledge of the "hard" limit, then I think I'd take
> that 3-ton advantage.
The only to accurately determine the strength of a chain is to break it.
All other measures are statistical. A chain that deforms well before it
parts has a built-in load meter that always works.
> To get back to radios, this type of behavior is only useful when a
> human closes the loop based on the audio signal. In what modern
> scenario would a power meter not serve the same purpose, and therefore
> render digital still advantageous?
How would the meter be read? It's an advantage for the audio itself to
be the indicator. Whether that advantage is worth its cost is an issue
I'm not able to address.
Jerry
--
Engineering is the art of making what you want from things you can get.
¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯
Reply by Randy Yates●January 21, 20072007-01-21
Jerry Avins <jya@ieee.org> writes:
> Randy Yates wrote:
>> "Mark" <makolber@yahoo.com> writes:
>>> [...]
>>> And re the discussion of analog vs digital, digital may have several dB
>>> advantage in a static situation near threshold like in a space system,
>>> but for a walkie talkie etc, the digital system cliff effect causes the
>>> audio to simply stop
>> That's true, but the edge of digital's cliff is quite a bit further
>> away than the bottom of analog's hill.
>
> That's not always a good trade. Riggers prefer a chain that yields at
> five tons and breaks at seven to one that snaps at ten without
> warning. Digital systems may be stronger, but they're brittle.
If I had a "rigging meter" that accurately indicated the load,
and I had knowledge of the "hard" limit, then I think I'd take
that 3-ton advantage.
To get back to radios, this type of behavior is only useful when a
human closes the loop based on the audio signal. In what modern
scenario would a power meter not serve the same purpose, and therefore
render digital still advantageous?
--
% Randy Yates % "How's life on earth?
%% Fuquay-Varina, NC % ... What is it worth?"
%%% 919-577-9882 % 'Mission (A World Record)',
%%%% <yates@ieee.org> % *A New World Record*, ELO
http://home.earthlink.net/~yatescr