whit3rd <whit3rd@gmail.com> wrote:> On Wednesday, November 29, 2017 at 12:07:07 PM UTC-8, Rob wrote: > >> I really can't see a use of NTSC (or PAL, for that matter) in the modern >> world. Yes, people clinging on to their old TV set... > > One use is for closed-circuit television. To make a simple camera-wire-display > ensemble. > > DVI is short-wire-only (ditto HDMI and DisplayPort) > USB options are driver-crippled and short-wire-only > IP variants don't function in real-time > VGA takes too many wires, and there's no camera so equipped > ATSC encoders aren't available in a camera: that digital > transmission standard is fast to DECODE, but not to ENCODE. > > Find something OTHER than composite video that can drive a > 20-meter video link, which doesn't delay to boot an operating system > and navigate the internet. Tell me that the cable it uses is as easy > to buy as BNC-terminated coax. Tell me that the cameras and monitors > are interchangeable with multiple vendors. > > Composite video is sometimes the only candidate.Well, our CCTV system in the building is now completely IP. True it is not real-time, but it is much more flexible: instead of requiring a dedicated coax from every camera to the "recorder" box, and a power connection at each camera, it now uses an ethernet network with 801.11AT PoE and every camera is only wired to the closest switch. (and it can be done over WiFi when desired) It is not related to internet, the camera's and the recorder are on an isolated VLAN that has no link to internet. (those devices are to insecure to connect them to internet, especially from the company network) The picture is Full HD, a big improvement over the old PAL based system. (which of course was better than an NTSC based system) The only point that holds is that it is not real-time. There is a delay of 1..2 seconds.
Freescale fractional clock divider paper
Started by ●November 28, 2017
Reply by ●November 30, 20172017-11-30
Reply by ●November 30, 20172017-11-30
bitrex <bitrex@de.lete.earthlink.net> wrote:> On 11/29/2017 04:44 PM, whit3rd wrote: >> On Wednesday, November 29, 2017 at 12:07:07 PM UTC-8, Rob wrote: >> >>> I really can't see a use of NTSC (or PAL, for that matter) in the modern >>> world. Yes, people clinging on to their old TV set... >> >> One use is for closed-circuit television. To make a simple camera-wire-display >> ensemble. >> >> DVI is short-wire-only (ditto HDMI and DisplayPort) >> USB options are driver-crippled and short-wire-only >> IP variants don't function in real-time >> VGA takes too many wires, and there's no camera so equipped >> ATSC encoders aren't available in a camera: that digital >> transmission standard is fast to DECODE, but not to ENCODE. >> >> Find something OTHER than composite video that can drive a >> 20-meter video link, which doesn't delay to boot an operating system >> and navigate the internet. Tell me that the cable it uses is as easy >> to buy as BNC-terminated coax. Tell me that the cameras and monitors >> are interchangeable with multiple vendors. >> >> Composite video is sometimes the only candidate. >> > > I think "Rob" might be confusing composite with RF-modulated composite, > like you'd plug into the antenna jack of an old tube TV set and select > channel 3 or channel 4. I'm not modulating anything, just baseband video > + sync. The cable with the yellow plug.RF-modulated composite is of course even worse than direct composite video, but for color the difference is small. The limitation of the picture quality is mainly in the standardized parameters of NTSC (or PAL). For BW video the extended bandwidth of a direct composite signal would help, but of course the small number of lines limits the vertical resolution. Where I wrote "composite" in the posting upwards from this one (not quoted above), I meant to write "component". Another standard that provides better quality than NTSC/PAL composite. It works over similar distances but of course requires 3 coax cables.
Reply by ●November 30, 20172017-11-30
On Wed, 29 Nov 2017 18:49:18 -0500, bitrex <bitrex@de.lete.earthlink.net> wrote: [snip]>> >I noticed that it looks like the designers of this FPGA were thoughtful >enough to bury an edge-detection functional block way down in the manual >that can be configured to fire on the rising and falling edges of a >clock simultaneously, thank you for your kind offer, though! ;-) > >For reference here's the patent where a logic configuration similar to >what it looks like the writers in the original paper (which I still >don't follow) are talking about is described: > ><http://www.google.si/patents/US5335253>A programmer of FPGA's wouldn't know how to do that with an XOR plus a D-Flop... without there being specifically "an edge-detection functional block"?? ...Jim Thompson -- | James E.Thompson | mens | | Analog Innovations | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | STV, Queen Creek, AZ 85142 Skype: skypeanalog | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | It's what you learn, after you know it all, that counts.
Reply by ●November 30, 20172017-11-30
On 11/30/2017 10:46 AM, Jim Thompson wrote:> On Wed, 29 Nov 2017 18:49:18 -0500, bitrex > <bitrex@de.lete.earthlink.net> wrote: > > [snip] >>> >> I noticed that it looks like the designers of this FPGA were thoughtful >> enough to bury an edge-detection functional block way down in the manual >> that can be configured to fire on the rising and falling edges of a >> clock simultaneously, thank you for your kind offer, though! ;-) >> >> For reference here's the patent where a logic configuration similar to >> what it looks like the writers in the original paper (which I still >> don't follow) are talking about is described: >> >> <http://www.google.si/patents/US5335253> > > A programmer of FPGA's wouldn't know how to do that with an XOR plus a > D-Flop... without there being specifically "an edge-detection > functional block"?? > > ...Jim Thompson >I haven't really used FPGAs/PALs/programmable digital hardware before. First time for everything, right?
Reply by ●December 7, 20172017-12-07
tabbypurr@gmail.com wrote:> On Thursday, 30 November 2017 06:22:36 UTC, Michael Terrell wrote: >> NT wrote: > >>>> It's a while since I played with such things but could one not just feed the signal to an oscillator running at around 1/2.5th the frequency and have it lock. With the right amplitude it should lock on the voltage extremes but not the centre voltage of the osc input. >> >> >> 4X colorburst crystals are easy to find, and cheap. 14.318180 MHz. >> They were common in a lot of video equipment. > >>> My memory says no, only whole multiples, but I can't think of any reason why. > > maybe no-one can answer the question :)Maybe the question needs fixed? Most of the broadcast NTSC color equipment had a 14.318180 MHz crustal that was then divided down to every needed signal National Semiconductor even mad a simple color sync generator IC. It used 14.318180 MHz/7 for it's reference, but it provided all of the snc and balnking signals needed for color TV cameras. <http://ee-classes.usc.edu/ee459/library/datasheets/MM5321.pdf>
