On 5/28/2015 5:04 AM, Rick Lyons wrote:
> On Fri, 22 May 2015 10:12:38 -0400, rickman <gnuarm@gmail.com> wrote:
>
>     [Snipped by Lyons]
>>
>> I was a victim of the digital cliff.  I used to receive some half dozen
>> stations on rabbit ears and so eschewed cable with its 100 channels of
>> junk.  The digital conversion made all but one station un-viewable and
>> that one was PBS.  I learned how network TV was comparatively junk.  To
>> me the "quality" of my received signal has only continued to improve.
>
> Rick,
>    You wrote, "I learned how network TV was comparatively
> junk."
>
> I beg to differ with you.  What's wrong with shows
> regarding:
>
>     mentally-defective obese hillbillies,
>
>     "reality" shows where every scene is carefully scripted
>      and rehearsed making the program "unreal",
>
>     a History channel that broadcasts no programs related to
>     history, but rather "unreal" videos of truckers driving
>     on frozen lakes, pawn shops, and catching crabs and alligators,
>
>     watching a naked man and woman camping in the woods,
>
>     news programs that broadcast propaganda rather than actual news,
>
>     home videos showing dogs humping each other.
>
> What's not to like about that?
>
> [-Rick-]
>

I don't know what I was thinking....

Actually I found a few shows on network TV recently that I really like. 
  One is Prime Suspect which is not being renewed.  I watched the last 
episode last night before I lost my Internet access.  I've also viewed 
two seasons of Elementary which I think is very good.

Otherwise most of my viewing is cable programming such as "Black Sails" 
and "Breaking Bad".

I was at a party a couple of weeks ago and I mentioned that I had seen a 
series that only lasted one season but I thought it was really good. 
Before I could finish someone said, "Firefly, right?"  Seems that is a 
running joke about how no one watched it while on the air, but everyone 
loves it now.  lol   Morena Baccarin is pretty schweeeet.

-- 

Rick

On Fri, 22 May 2015 10:12:38 -0400, rickman <gnuarm@gmail.com> wrote:

   [Snipped by Lyons]
>
>I was a victim of the digital cliff.  I used to receive some half dozen 
>stations on rabbit ears and so eschewed cable with its 100 channels of 
>junk.  The digital conversion made all but one station un-viewable and 
>that one was PBS.  I learned how network TV was comparatively junk.  To 
>me the "quality" of my received signal has only continued to improve.

Rick,
  You wrote, "I learned how network TV was comparatively 
junk."

I beg to differ with you.  What's wrong with shows
regarding:

   mentally-defective obese hillbillies,

   "reality" shows where every scene is carefully scripted 
    and rehearsed making the program "unreal",

   a History channel that broadcasts no programs related to 
   history, but rather "unreal" videos of truckers driving 
   on frozen lakes, pawn shops, and catching crabs and alligators,

   watching a naked man and woman camping in the woods, 

   news programs that broadcast propaganda rather than actual news,

   home videos showing dogs humping each other.

What's not to like about that?

[-Rick-]

On Fri, 22 May 2015 07:49:10 -0500, Richard Owlett
<rowlett@cloud85.net> wrote:

>rickman wrote:
>> On 5/21/2015 11:14 PM, Richard Owlett wrote:
>>> a.s. wrote:
>>>> The primary advantage of digital transmission over analog
>>>> transmission is
>>>> Noise Immunity. A digital signal (in comparison to an analog
>>>> signal) is
>>>> inherently more immune to noise. Why the word "inherent"?
>>>>
>>>> Please make it more clear to me.
>>>>
>>>
>>> I see an unwarranted assumption that "Noise
>>> Immunity"/"SNR"/whatever has
>>> perfect correlation with "channel quality". CAVEAT LECTOR -
>>> note liberal
>>> use of quotation marks.
>>>
>>> In my living room I have a daily demonstration that digital
>>> does not
>>> always outperform analog. It's my TV reception.
>>>
>>> In the bad old analog days I could always get a useful signal
>>> on all the
>>> local channels.
>>> Now I get acceptable reception for _all_ channels only under
>>> certain
>>> atmospheric conditions.
>>>
>>> Yepp, there's some peculiar degenerate local conditions
>>> including rabbit
>>> ears at or near average terrain on path to transmitters (I'm on
>>> down
>>> slope of general terrain and there is a 20+ foot high ridge 2
>>> blocks
>>> away). In analog days I could see very prominent ghosts.
>>>
>>> All the discussion in this thread assumes the noise is random. The
>>> "noise" I deal with is inherently coherent.
>>
>> You aren't comparing apples and oranges.
>
><CHUCKLE>
>I think you meant to say I _WAS_ comparing apples and oranges.
>In a sense that was intentional. I'm saying that there is an 
>unstated presumption that something called "noise immunity" is 
>always the appropriate figure of merit for evaluating a 
>communication channel.

That would require a universal definition of "noise" in a
communication channel, which has never happened yet.   This is a
running joke in many comm areas, especially in standard developments,
where a fundamental starting point is trying to get everybody to agree
on the definition of SNR for tha application in question.   It is
often not an easy task.

In your case the presence of "ghosts" indicates strong multipath
reflections, which is a common issue for TV and other terrestrial
systems.   An area of significant difference between various
implementations of receivers for analog and digital TV transmissions
is the ability of the demodulator to acquire and track the signal.
Decades of experience with NTSC signals led to some pretty good analog
demodulators that could lock onto and track signals at a pretty low
thresholds in the presence of strong multipath.  There were even some
good multipath cancellers for the analog signals.  I don't think the
implementations for some ATSC digital demodulators are at the same
levels yet, so, yeah, you may lose lock or content in places where the
analog would still lock and give you degraded content, and since ATSC
is single-carrier, the equalizers are often limited in how much
multipath they can handle.   Sparse equalizers are not unusal in that
application since the multipath delay spreads can be (or may not be)
very, very long.

And now some people want to convert FM radio to digital-only, and some
Scandinavian countries are already legislating that move.   I think
this is a mistake for a number of reasons, but there is a push in that
direction.


>   The digital
>> transmission is capable of providing either a much higher
>> resolution image than the analog signal did or providing multiple
>> channels.  If the extra channel capacity were used for increased
>> error recovery I expect the digital signal would be adequate
>> under a much wider range of conditions.
>>

Eric Jacobsen
Anchor Hill Communications
http://www.anchorhill.com

On 5/22/2015 8:49 AM, Richard Owlett wrote:
> rickman wrote:
>> On 5/21/2015 11:14 PM, Richard Owlett wrote:
>>> a.s. wrote:
>>>> The primary advantage of digital transmission over analog
>>>> transmission is
>>>> Noise Immunity. A digital signal (in comparison to an analog
>>>> signal) is
>>>> inherently more immune to noise. Why the word "inherent"?
>>>>
>>>> Please make it more clear to me.
>>>>
>>>
>>> I see an unwarranted assumption that "Noise
>>> Immunity"/"SNR"/whatever has
>>> perfect correlation with "channel quality". CAVEAT LECTOR -
>>> note liberal
>>> use of quotation marks.
>>>
>>> In my living room I have a daily demonstration that digital
>>> does not
>>> always outperform analog. It's my TV reception.
>>>
>>> In the bad old analog days I could always get a useful signal
>>> on all the
>>> local channels.
>>> Now I get acceptable reception for _all_ channels only under
>>> certain
>>> atmospheric conditions.
>>>
>>> Yepp, there's some peculiar degenerate local conditions
>>> including rabbit
>>> ears at or near average terrain on path to transmitters (I'm on
>>> down
>>> slope of general terrain and there is a 20+ foot high ridge 2
>>> blocks
>>> away). In analog days I could see very prominent ghosts.
>>>
>>> All the discussion in this thread assumes the noise is random. The
>>> "noise" I deal with is inherently coherent.
>>
>> You aren't comparing apples and oranges.
>
> <CHUCKLE>
> I think you meant to say I _WAS_ comparing apples and oranges.
> In a sense that was intentional. I'm saying that there is an unstated
> presumption that something called "noise immunity" is always the
> appropriate figure of merit for evaluating a communication channel.

lol, yes.

I was a victim of the digital cliff.  I used to receive some half dozen 
stations on rabbit ears and so eschewed cable with its 100 channels of 
junk.  The digital conversion made all but one station un-viewable and 
that one was PBS.  I learned how network TV was comparatively junk.  To 
me the "quality" of my received signal has only continued to improve.

-- 

Rick

>  
> > True.  Just as an observation, that applies to wideband FM radio, too, 
> > which is the only analog signal transmission scheme that I know of that 
> > has an input SNR to output SNR characteristic that resembles digital 
> > communications.
> 
> Yes.  I didn't mean to leave that out. 
>  
> > Which makes one wonder if it's the only way, or if major Armstrong was 
> > just an absolutely unique freakin' genius.
> 
> As well as I know the story, he must have been pretty close.
> 
> I don't remember well by now, but I think he used one tube for
> both the oscillator and mixer. Seems detector, too:
> 
> https://en.wikipedia.org/wiki/Regenerative_circuit
>  

Yes and his life story should be a lesson for all of us.

As you probably know, as smart as he was, he did not fair well up against the 
"powers that be".

Mark
 

rickman wrote:
> On 5/21/2015 11:14 PM, Richard Owlett wrote:
>> a.s. wrote:
>>> The primary advantage of digital transmission over analog
>>> transmission is
>>> Noise Immunity. A digital signal (in comparison to an analog
>>> signal) is
>>> inherently more immune to noise. Why the word "inherent"?
>>>
>>> Please make it more clear to me.
>>>
>>
>> I see an unwarranted assumption that "Noise
>> Immunity"/"SNR"/whatever has
>> perfect correlation with "channel quality". CAVEAT LECTOR -
>> note liberal
>> use of quotation marks.
>>
>> In my living room I have a daily demonstration that digital
>> does not
>> always outperform analog. It's my TV reception.
>>
>> In the bad old analog days I could always get a useful signal
>> on all the
>> local channels.
>> Now I get acceptable reception for _all_ channels only under
>> certain
>> atmospheric conditions.
>>
>> Yepp, there's some peculiar degenerate local conditions
>> including rabbit
>> ears at or near average terrain on path to transmitters (I'm on
>> down
>> slope of general terrain and there is a 20+ foot high ridge 2
>> blocks
>> away). In analog days I could see very prominent ghosts.
>>
>> All the discussion in this thread assumes the noise is random. The
>> "noise" I deal with is inherently coherent.
>
> You aren't comparing apples and oranges.

<CHUCKLE>
I think you meant to say I _WAS_ comparing apples and oranges.
In a sense that was intentional. I'm saying that there is an 
unstated presumption that something called "noise immunity" is 
always the appropriate figure of merit for evaluating a 
communication channel.

   The digital
> transmission is capable of providing either a much higher
> resolution image than the analog signal did or providing multiple
> channels.  If the extra channel capacity were used for increased
> error recovery I expect the digital signal would be adequate
> under a much wider range of conditions.
>

rickman <gnuarm@gmail.com> wrote:

(snip on the advantages of digital over analog)
(then I wrote)
>> OK, but that is because we have some convenient channels with
>> appropriate excess bandwidth and noise characteristics.

> The "excess" capacity often comes from the reduced requirements of 
> digital signal transmission compared to analog.  A TV signal, for 
> example, uses less bandwidth once the image is compressed digitally or a 
> much higher resolution digital image can be conveyed over the same 
> channel.

Well, some of that is more recent. The CD standard isn't compressed,
mostly as computer technology wasn't up to it yet. But the available
bandwidth on a CD is much higher than a vinyl disk. 

But yes, as we are most often interested in low entropy data,
compression is very useful.
 
(snip, I also wrote)

>> But the other reason is that the cost of digital electronics, per
>> transistor, is so much less than for analog. If built using discrete
>> transistors in little metal cans, none of what we do today would
>> make sense.

(snip)

> But that complexity is relatively easy to manage compared to the 
> problems analog circuits present.
 
>> Even with integrated circuitry, analog electronics is nowhere near
>> where digital electronics is.

>> A 128GB USB drive, smaller than your thumb, has trillions of
>> transistors.  As far as I know, all the analog electronics ever made
>> so far hasn't used a trillion transistors. Well, maybe close.
 
> And that difference is exactly why the huge complexity of digital 
> devices can be practical and even preferable.

Yes. That is what I was trying to explain to my (non-engineer) brother.
Even though the result is much more complex, (though hidden to the
average user) it isn't so hard to design and build in large quantities. 

I remember when 9600 baud modems were new, it was noted that they
have about the same computational power as the bigger computers
we connected them to.

-- glen

Les Cargill <lcargill99@comcast.com> wrote:
> Tim Wescott wrote:
(snip)
>> Very little, at least.  People were starting to use digital
>> communications, because of the possibility for error correction and
>> whatnot, even when computers were built using discrete transistors in
>> little metal cans.
 
> Telegraphy seems a lot digital.

There is an ISDN book that noted that in the introduction.  That is,
we went from a digital system, to an analog system, and now back to
digital. 

Oh, also Nyquist came up with his popular theorem computing the
telegraph rate though band limited cables. 

-- glen

I would not say a digital signal is inherently more immune to noise
than an analog signal.  Instead I would say that once a signal
is in the digital domain, there are a wealth of techniques that
can improve the noise immunity; in the analog domain, not so much.


S.

On 5/21/2015 11:14 PM, Richard Owlett wrote:
> a.s. wrote:
>> The primary advantage of digital transmission over analog transmission is
>> Noise Immunity. A digital signal (in comparison to an analog signal) is
>> inherently more immune to noise. Why the word "inherent"?
>>
>> Please make it more clear to me.
>>
>
> I see an unwarranted assumption that "Noise Immunity"/"SNR"/whatever has
> perfect correlation with "channel quality". CAVEAT LECTOR - note liberal
> use of quotation marks.
>
> In my living room I have a daily demonstration that digital does not
> always outperform analog. It's my TV reception.
>
> In the bad old analog days I could always get a useful signal on all the
> local channels.
> Now I get acceptable reception for _all_ channels only under certain
> atmospheric conditions.
>
> Yepp, there's some peculiar degenerate local conditions including rabbit
> ears at or near average terrain on path to transmitters (I'm on down
> slope of general terrain and there is a 20+ foot high ridge 2 blocks
> away). In analog days I could see very prominent ghosts.
>
> All the discussion in this thread assumes the noise is random. The
> "noise" I deal with is inherently coherent.

You aren't comparing apples and oranges.  The digital transmission is 
capable of providing either a much higher resolution image than the 
analog signal did or providing multiple channels.  If the extra channel 
capacity were used for increased error recovery I expect the digital 
signal would be adequate under a much wider range of conditions.

-- 

Rick