R PI 0 question

My new car cam equipped with a DAB radio & despite living in a major town there are a large number of dead spots what I loose reception

Oh? you should keep it tied up better. Perhaps a boy scout course in Knots and hitches?

-- the biggest threat to humanity comes from socialism, which has utterly diverted our attention away from what really matters to our existential survival, to indulging in navel gazing and faux moral investigations into what the world ought to be, whilst we fail utterly to deal with what it actually is.

Indeed. Which is why the whole "color fidelity" discussion is largely moot, regardless of encoding system.

In my youth, I frequently tried to demonstrate how to adjust a receiver to produce a more "studio"-accurate picture: black level (color brought back the DC restorer), contrast, saturation, hue (for flesh tone), finally, saturation touch-up.

I found that most viewers liked black level set to gray, too much contrast, and oversaturation. Apparently, TV manufacturers understand this, since their default "store" or "vivid" modes recreate this misadjustment.

I wonder how many of you have ever seen a properly adjusted NTSC color picture? They are pretty rare--as are properly adjusted digital sets.

It's also worth pointing out that NTSC color was designed to be fully compatible with post-war B&W TV, so the 6MHz VSB broadcast channel was a given.

The color subcarrier frequency was chosen as an odd multiple of half the line frequency so that a comb filter could separate the chrominance information from the luminance information, even though the bands overlapped.

Economic considerations ruled out the use of comb filters in home TVs, so the luminance bandwidth was usually limited to less than the subcarrier frequency, which dropped the horizontal resolution to less than 300 lines. The chrominance bandwidth was, in principle, 1.1-1.4MHz, but the use of simple filters typically reduced the chrominance bandwidth to less than

1MHz. The lack of comb filters was also responsible for fine luminance patterns resulting in chrominance artifacts.

Studio monitors and today's digital receivers do not suffer from these limitations, which owe more to simple, inexpensive circuits than to intrinsic standards issues.

Now, back to the Raspberry Pi, which is already in progress... ;-)

--
-michael - NadaNet 3.1 and AppleCrate II:  http://michaeljmahon.com

Back in the 70s my brother had a Heathkit TV, which was built to be easy to tweak, and I managed to get realistic skin tones, sensible brightness/contrast/saturation, focus and squareness right across the screen, but not usually at the same time.

Yes, I remember that receiver!

It was a good design, not "cost-reduced" like so many that came later. But it was always a bear to adjust a set "from scratch"--purity, static and dynamic convergence, gun levels and gains, in addition to all the standard monochrome issues of linearity, etc. These problems were quite difficult on shadow mask sets prior to the Trinitron.

IIRC, it shipped with a dot/pattern generator to help with this process (or did I build that separately?).

In any event, once properly set up, it was quite stable. Of course, any NTSC decoding issues affect the whole screen uniformly--unlike dynamic convergence and purity (shadow mask magnetization) problems, which affect localized areas of the screen.

--
-michael - NadaNet 3.1 and AppleCrate II:  http://michaeljmahon.com

There was a generator, although I also don't remember the details. It might have been part of the convergence board. There was a slide switch and a jumper lead that was also part of the adjustment scheme. The kit also shipped with a De-gaussing coil when I built the kit in about 1969-70 or so. The one I had was really "hard" on the HV PS. Heath replaced the whole HV subassembly a couple of times.

I remember borrowing a 400Mhz portable oscilloscope from a Tektronics rep to help chase problems down in the middle 70's.

The TV was finally scrapped in the early 80's. We had a Sony that produced a very good picture, and worked well. It had an early demise when it got knocked off a stand. There were several TV'S after that, all CRT types, and they had relatively short life spans. The current one is a 42' HD 1080 LCD with analog and digital tuners, along with the usual HDMI. DVI, and RGB inputs. It's out of warranty, so I cannot but wonder how long it will last.