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13

As others have said, PAL and NTSC are analog and have virtually no latency. This is extremely important when flying FPV drones at high speeds. Having latency will tell you where you’ve been, not where you actually are. I have a large video/photography drone (Yuneec Q500 4K). It transmits the video digitally on 5.8 GHz using the 802.11A protocol. (Just ...


10

Yes, it is related. In early TV implementations, it was not easy to remove all of the AC line ripple from the DC power circuits that drove the CRT, and this resulted in a slight variation in intensity from top to bottom. It was found that if the vertical frequency of the TV signal was the same as the power line frequency, these intensity variations would ...


10

It's an analog signal in time domain- what you would see on an oscilloscope. The horizontal blanking interval is when the electron beam would retrace back to the left side of the screen (but it is normally blanked so that there is no trace on the CRT screen). All the information is transmitted in a single analog signal with NTSC- color, luminance and ...


7

I upvoted Nettle Creek's answer, but here is a quick explanation about why latency matters: Piloting a drone is a feedback system with you in the loop. As in any other feedback system, the usual Nyquist stability critera apply. Video latency adds lag in the feedback loop, and the effect is the same as on any other feedback system (you are the opamp): it ...


6

Setup, or pedestal, was a 'feature' that helped engineers align the raster on the monitor: it made an active video extent visible by turning up the brightness. When's the last time you did that? Never. So the later PAL and SECAM standards didn't use it. PLUGE is used instead. Setup requires that the video be 'squished' to allow for the 7.5 IRE added to it ...


5

To answer your actual question, no, "modern" TV sets will not be very forgiving. Older TVs and monitors (analog signal path, CRT display) were very forgiving. Anything that had approximately the correct vertical and horizontal sync frequencies would display something useful. Any modern set (i.e., digital signal path, flatscreen display) will be sampling ...


5

The only way to know if 1 Vpp is too high is to consult the datasheet. At the very least, the chip must be specified to operate over the resulting supply voltage range. For example, if the supply voltage is nominally 3.3 V, then the chip is seeing 2.8 to 3.8 volts. Is the chip specified to operate over that range? Even if it is, it may still not be OK. ...


5

There (was) an IC for that: https://www.renesas.com/us/en/general-parts/1523-video-clock-synthesizer-i2c-programmable-delay. Obsolete now... no thanks to Renesas. Basically, multiply up by 455 to get 2fsc or 910 to get 4fsc (that is 14.31818MHz.) The latter is available as a crystal. Another option is to 'crash lock' a crystal oscillator to regenerate the ...


4

Wikipedia provides the following information (see NTSC, PAL and SECAM Overview PDF for an in-depth look): An NTSC television channel as transmitted occupies a total bandwidth of 6 MHz. The Rigol DS1052E has a bandwidth of 50Mhz, which is sufficient. It also has special video triggering modes, which will be useful. There is a tutorial from Rigol on ...


3

They choose this protocol, because it is universal so you can use different accessories from different manufacturers. Also, they choose it, because it is simply faster and needs less computing power to decode the image. And a third reason is that a digital signal is less reliable in fast moving objects where you need low latency.


3

Depends how clear you want the image to be on an LCD, and whether you're using that same crystal for sync timing or just for reading pixels out of a buffer. The 12.272MHz you reference is an older standard for digitising NTSC video specifically, before MPEG came along and everyone standardised on 13.5MHz instead (which works equally well for PAL, and meant ...


3

You can generate an NTSC compatible monochrome signal from a 12 MHz dot clock, but you will end up with an atypical horizontal resolution, and you will not be able to exploit any easy relationships to the colorburst frequency to do simple digital color. With a fully analog monitor like a CRT, horizontal resolution is more a question of bandwidth than ...


3

I offer an additional reason to the others given (of established and extremely cross-compatible standards, mature affordable low-power chipsets, latency etc)... one of signal robustness. An analogue video signal can be quite badly degraded before it can no longer be received in some form, or understood to a sufficient extent for flight control (or review) by ...


3

The luminance ("Y" or brightness) signal was FM modulated onto a high frequency carrier and written directly onto the tape. The chroma ("C" or color) signal was hetrodyned down to a sub-harmonic of the color subcarrier and combined with the luminance signal. Because the tape speed is a couple orders of magnitude too slow to record such high frequencies, ...


3

This is just a short recall of what I remember. The H sync tip, and chroma burst are stripped off and then restored with a standard sync tip after reading. Since the sync tip corresponds to past the the edge of the tape with some guard edge, there is a precision servo to sync the spinning head and tape speed to the standard rate derived from the Hsync ...


3

one family of computers that was highly regarded for its graphics capabilities in the age of NTSC, considered 192 to be into overscan, and 160 color clocks per scan line to be the normal safe value. That sounds about right. To get a consensus you could look at other computers which had NTSC output. For example the Commodore Amiga had a 'low-res' (...


3

I have just taken apart a low cost IP camera made by Dahau and it appears to be based on a SoC made by Ambarella, part number S2L-M-A1-RH. Details are here. The SoC includes just about everything you need to make an IP camera: ARM A9 processor camera front end video processor AES cryto engine H.264 video encoder Ethernet MAC Most of these IP cameras run a ...


3

PAL and NTSC are colour encoding systems and are not necessarily related to horizontal and vertical scan frequencies. The choice to make the vertical scan frequencies the same as the local power line frequency was to make the picture disturbance due to poor power supply filtering, and power current magnetic fields less obvious. With the power line ...


3

There's a trick that is used in NTSC that I believe also applies to PAL. If you look at the fine detail of the spectrum of the luminance signal, you find that most of the energy is concentrated at multiples of the horizontal sweep frequency, with relatively little energy in between these peaks (this energy represents diagonal edges in the image, which are ...


3

In this case AC coupling does not mean that the signal DC bias is zero or floating. The receiver can and will bias any DC voltage it wants, for example using sync tip clamping. The voltages for blank, black, white etc are referenced as AC peak-to-peak voltages referenced to sync tip, so DC bias is really not defined on cable anyway.


3

AC coupled means the receiver will take care of DC clamp to avoid ground errors. DC Offset will cause a shift in bright/darkness. Gain affects Contrast relative to 50%. simulate this circuit – Schematic created using CircuitLab


3

Two points worth looking at: 1) Switching between crystals is accomplished by applying DC voltages to D207/D213.When the diode is forward biased, it is low resistance to AC and therefore "switched on"; when reverse biassed, it is switched off. It is worth checking DC levels around both diodes in both modes, looking for differences or anything odd. 2) In ...


3

Of course not. You always have the option of running the MCU's main clock at the required frequency (or a multiple thereof) so that everything else can be derived by simple counters. The MCU datasheet will show you the external clock input along with the range of frequencies that you may apply to it. Pick a frequency within that range for your external ...


3

In PAL (and NTSC), the color information is deliberately bandlimited and undersampled in order to reduce the analog signal bandwidth requirements while maintaining "reasonable" picture quality. This is based partly on the fact that the human eye has greater spatial resolution for intensity than for color. So yes, any attempt to create a compatible ...


3

There are basically no pixels in an analog PAL (or NTSC) signal. While the subcarrier is 4.43361875 MHz (or 3.579545 MHz for NTSC), the video information is still analog. The color information just can't change as fast as the luma due to chroma being bandwidth limited to about 1.3 MHz in PAL (NTSC is different). And the color hue information is sent as the ...


2

The answer is to use a DA video encoder that supports PAL/NTSC. the encoder converts parallel digital inputs (e.g. 10 bits) to composite signal for example the: ADV7393


2

Actually, using a suitable micro you could get 12-bit colour and reasonable resolution. For example, the STM32F407 has two 12-bit DAC's that can be continuously loaded by DMA to generate composite video. Allocate a section of RAM (it has 200kB) to be a frame buffer, fire up the DAC and DMA and off you go - reasonable video from an MCU for zero CPU cycles. ...


2

Dave Tweed's answer is largely correct. But it wasn't just AC ripple on the DC power circuits that caused the variation. The signal cicuits in early TV used tubes (a.k.a. valves). The cathodes usually had a heater filament that was often driven by low voltage AC (typically about 6 V). This caused the temperature of the cathode, and consequently the gain of ...


2

That signal encodes timing, brightness and colour for an entire line of video. It dates from the days of the CRT monitor which used magnetic deflection to scan the raster, hence the rather long horizontal retrace time (Changing currents in coils takes time), there is also a vertical retrace interval and a (rather longer) vertical blanking interval ...


2

Yes, it does. That's why the next step is usually DC restoration, which clamps the sync peaks to a specific voltage. (The component following the blocking capacitor is a diode, rather than a resistor.) This then establishes the correct relative voltages for "black" and "white".


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