From Newsgroup: comp.dsp

On 09/04/2019 07:26 PM, Eric Jacobsen wrote:

[snip]

Due to circumstances I must use an indoor antenna and local topography
puts it not far above average terrain. In days of analog TV I had
impressive ghosts ;}!

The weather related issue I referred to was how I have to place/orient
the antenna which varies with:
1. incoming strong frontal system {PS this is Tornado Alley ;}
2. season

Two Wikipedia articles I read mentioned improvements in receiver design. >>[snip]

The "improved equalizer design" is just that they can afford to make a
more complex equalizer with more taps since gates on silicon have
gotten a lot cheaper over the years. So they throw complexity at it,
and it does perform better and doesn't really add any significant cost
or power consumption.

I think you're right that TVs are pretty cheap these days and it's
likely that the performance will be better than what you currently
have in that particular characteristic (and maybe some others!). If
you have decent internet and a WiFi access point, get a smart TV and
you can get content over the internet, too, and not be stuck with the over-the-air stuff.

Turns out my existing set is newer than I thought - only 4 years old.
Bought a new one anyway. Performance seems pretty much the same. Due to
space restrictions it was the smallest offered, therefore on the low end
of the price range.

I'll have to figure out a practical method of adjusting both antenna
elevation and orientation (optimal values of *BOTH* have been
demonstrated to vary with conditions). As I live in Tornado Alley, I'm
not considering an outdoor antenna.


Mark had written:

you may want to buy a low cost USB-PC based type RF spectrum analyzer
and observe the signals. Dynamic multi-path is the primary impairment.

I can see the spectrum analyzer as a tool for observing, on a per
channel basis, the signal _strength_ as a function of antenna elevation/orientation. I don't understand what multi-path artifacts I
might be able to observe.

And the design of the adaptive equalizer in your particular receiver is critical to overcoming that impairment.

Understood. But I have no control of that.
Now if I had the work-space I had 50 years ago, who knows what I might attempt?

When I did an internet search I found more links about using a spectrum analyzer than that useful information on where to obtain one and
relative cost/performance trade-offs.

Suggestions? [I avoid Ebay and Amazon with a passion ;]

TIA




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From Newsgroup: comp.dsp

On Monday, September 2, 2019 at 10:39:51 PM UTC-7, boB wrote:

(snip regarding analog television vestigial sideband modulation)

Very interesting point ! I wonder if they make use of that extra bit
of information ? I would think that if they needed to use the
vestigial part that the main sideband would be messed up enough that
it would be unusable ?

Never even asked why that sideband was there at all before... Maybe
because it's easier than filtering or cancelling out all the way ?

In the case of NTSC VSB, the lower sideband is filtered out with
a specific frequency range. The result, then, of demodulating the
signal as a normal AM signal is that the frequency response isn't
flat. The lower sideband is cut off at about (I don't know the exact
shape) 1MHz. The result is that the demodulated signal is reduced
by half past 1MHz. The IF amplifiers, then, are designed to compensate
for this.

Getting the frequency response in audio may seem more obvious, but
it is still considered important in video.


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