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PostPosted: Tue Jan 10, 2017 8:34 pm 
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Do you have a flashcart?
Nope. I don't really have an overview of which one to get for a 60-pin system.


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PostPosted: Tue Jan 10, 2017 8:57 pm 
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For a 60-pin system, the EverDrive N8 should be good enough.


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PostPosted: Tue Jan 10, 2017 9:32 pm 
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NewRisingSun wrote:
color $31 at 319.9 degrees (nominal: 330)
color $36 at 113.1 degrees (nominal: 120)
Since I bothered to play around with the Pac-Land image and write down some numbers:
Blue $31 at 316-323° (nom: 330)
Blue $11 at 323-335° (nom: 330)
Magenta $15 at 84-90° (nom: 90)
Peach $36 at 109-117° (nom: 120)
Brown $07 at 150-158° (nom: 150)
Orange $27 at 140-146° (nom: 150)
Green $1B at 268-274° (nom: 270)

I clearly need to put more effort into filter design to reduce those ranges.


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PostPosted: Wed Jan 11, 2017 7:57 am 
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I don't use Matlab, but I can post the C source to my NTSC decoder that takes the .raw captured file and outputs a .rawraw RGB file, if that helps you.


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PostPosted: Wed Jan 11, 2017 2:55 pm 
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NewRisingSun wrote:
Quote:
Do you have a flashcart?
Nope. I don't really have an overview of which one to get for a 60-pin system.

The Everdrive N8 has a Famicom 60-pin option, though I can also confirm that the PowerPak and Everdrive N8 72-pin both work on a Famicom using simple 72-60 pin converters.


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PostPosted: Wed Jan 11, 2017 6:37 pm 
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You need to perform two simple soldering mods to get the most out of your PowerPak with just about all 72-to-60 pin converters and it the stacked PowerPak and converter can get a bit wobbly, but otherwise you will be good.

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PostPosted: Wed Jan 11, 2017 8:05 pm 
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NewRisingSun wrote:
I don't use Matlab, but I can post the C source to my NTSC decoder that takes the .raw captured file and outputs a .rawraw RGB file, if that helps you.
Eh, the matlab/octave fragment was more for proving to myself that your methodology is correct. It clearly is, and now I think the only remaining parameter to be explored is just how much variation we should anticipate across all the hardware variants.

Is there an easy way to calculate how "non-ideal" either not a square wave or not a sine wave this is? Is the "skewness" test the right one?

Skewness of 10000 points of a sampled ideal sine wave appears to be approximately 0, but skewness of the huge patch of color $31 is 0.126 and the mean is very slightly higher than the median (Δ=0.336).


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PostPosted: Thu Jan 12, 2017 5:27 pm 
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Skewness is a measure of asymmetry. A square wave with non-equal duty cycles is indeed asymmetrical, though I am not sure how this translates to the phase of the fundamental frequency. Tepples suggested hue-specific phase shifts resulting from hue-specific duty cycles. If non-equal duty cycles of a square wave translate into phase shifts at the subcarrier (fundamental) frequency, then the phase shift amount should be correlated with skewness in sign and magnitude.

For the record, I have used the same setup to measure the composite video output of a Tandy 1000 computer. It can output six hues at two luminance levels. The two levels are different for each of the hues. I measure no level-specific phase shift beyond the noise level between the two luminance levels of each hue:
Code:
Color 1: 0.008638 (blue, nominal: 0)
Color 2: 223.742996 (green, nominal: 225)
Color 3: 269.025116 (cyan, nominal: 270)
Color 4: 92.503235 (red, nominal: 90)
Color 5: 46.509937 (magenta, nominal: 45)
Color 6: 180.940750 (yellow, nominal: 180)
Color 9: 359.858380 (blue, nominal: 0)
Color A: 223.127350 (green, nominal: 225)
Color B: 268.470940 (cyan, nominal: 270)
Color C: 91.619957 (red, nominal: 90)
Color D: 46.090595 (magenta, nominal: 45)
Color E: 179.678253 (yellow, nominal: 180)
This tells me that whatever I am measuring from the Famicom is not an artifact introduced by my capturing hardware, otherwise I would be measuring level-specific phase shifts in the the Tandy 1000's composite video output as well. I have attached that capture as well, in case you want to try your skewness test on that file.


Attachments:
RGBI16.zip [162.59 KiB]
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PostPosted: Fri Jan 20, 2017 11:42 am 
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I have received my Everdrive N8. I have used "Blargg's Full Palette" to make raw capture files that show all 52 colors. The attached archive contains three files:
  • Palette-RP2C02E-RCA.raw: Signal from the yellow RCA socket at the back of the Sharp Twin Famicom AN-500B (PPU: RP2C02E-0)
  • Palette-RP2C02G-PPU.raw: Signal from the PPU's output pin of the Sharp Twin Famicom AN-505BK (PPU: RP2C02G-0)
  • Palette-RP2C02G-RCA.raw: Signal from the yellow RCA socket at the back of the Sharp Twin Famicom AN-505BK (PPU: RP2C02G-0)
I was unable to get any signal from the output pin of the RP2C02E-0.

I am posting these files without comment for now, because I am curious about what conclusions other people draw from them, before I share mine.


Attachments:
FullPaletteRaw.zip [604.33 KiB]
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PostPosted: Fri Jan 20, 2017 12:16 pm 
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My biggest observation is what I see in the first scanline of the 2C02E output of colors $1x :

At this point, I have no idea what to think any more. Colors $12, $16, and $1A are a different phase offset than the other ones, not restricted to just even or odd phases.


Attachments:
RP2C02E-scanline41.png
RP2C02E-scanline41.png [ 35.7 KiB | Viewed 1268 times ]
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PostPosted: Fri Jan 20, 2017 12:57 pm 
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Do the affected colors remain $12, $16, and $1A even across resets? Perhaps the phase might get distorted more when signal level transitions coincide with the pixel clock.


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PostPosted: Sat Jan 21, 2017 6:23 am 
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As far as I can tell, they remain the same. Attached find four different capture files from the RP2C02E, each taken after another RESET. Note that the Everdrive UI appears between the RESET and the palette test program.


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Palette-RP2C02E-RCA-4times.zip [756.13 KiB]
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PostPosted: Sat Jan 21, 2017 1:27 pm 
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I have captured the output (see attachment) of a PAL NES with an RP2C07 PPU, from the yellow RCA socket. I have not modified the capture program itself, which is why it only captures five sixths of the 1000 ms/50Hz field. Note how the RP2C07, unlike the RP2C02, never illuminates the border area with background color 0.

The first picture shows the result I get when I use my "Simple PAL" decoder --- properly accounting for the phase shift in the V channel from scanline to scanline, but not averaging each scanline's demodulated chroma signal with the delayed previous scanline's demodulated chroma signal. If the signal is affected by phase distortion, then we should see Hanover bars - opposite hue errors from scanline to scanline:
Image
The second picture shows the result I get when I use my "Full PAL" decoder --- averaging each scanline's demodulated chroma signal with the delayed previous scanline's demodulated chroma signal:
Image
These results indicate to me that the PAL NES is just as susceptible to considerable phase shifts as the NTSC NES, but because the PAL system is designed to eliminate the effects of phase shifts, PAL televisions will display colors that are almost exactly the nominal hues minus 15.0 degrees.

Capturing regular television pictures and decoding them with my "Simple PAL" decoder exhibits only very slight Hanover bars, indicating little phase distortion:
Image


Attachments:
SMB-Title-RP2C07.zip [163.84 KiB]
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PostPosted: Wed Jan 25, 2017 6:19 pm 
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RAW... OK... but how to parse the file, as RGB or any other format?


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PostPosted: Wed Jan 25, 2017 6:22 pm 
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In case it isn't obvious to others reading this, the reason you don't get Hanover bars from a broadcast signal is the 90 degree swing of broadcast TV's color burst compared to the nonstandard 120 degree swing from the 2C07.


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