Willie 0 Posted June 24, 2006 I have just had a security gate installed for my driveway. Part of the gate electonics includes a color CCTV camera referred to as a “Low Lux camera†Share this post Link to post Share on other sites
jisaac 0 Posted June 24, 2006 this information is from FM Systems web site. Here is the link. http://www.fmsystems-inc.com/tech_cctvqual.htm LINES BANDWIDTH TRANSMITTED REQUIRED 330 3.1 MHz 331 3.6 MHz 400 3.7 MHz 460 4.3 MHz 470 4.4 MHz 480 4.5 MHz 570 5.3 MHz 700 6.5 MHz 800 7.5 MHz RELATIONSHIP BETWEEN 'LINES' AND CABLE LENGTH One frequently used measure of picture quality loss, is when more than ½ of the energy at that frequency is lost. Thus at the cable length that ½ the energy at the desired quality level is lost, that defines the maximum length of cable that can transmit that level of quality. This leads to the following limits for maximum cable length at given picture quality levels. LINES RG59/U COAX UTP PAIR 330 686 Feet 282 Feet 400 615 Feet 254 Feet 470 585 Feet 234 Feet 570 521 Feet 215 Feet 700 471 Feet 189 Feet 800 444 Feet 175 Feet These un-equalized cable length limits can, of course, be exceeded, but only by decreasing the number of "Lines" of definition as viewed at the receiving location. HOW TO INCREASE CABLE LENGTH WITHOUT QUALITY LOSS Both Coaxial and UTP cables can be extended far beyond the limits shown on the previous table by amplifying and equalizing the video signal, while at the same time insuring the highest possible picture quality. While these Amplifier/Equalizers can improve the resultant pictures by simply adjusting the Amplitude and Equalization controls for the best looking picture, to obtain the best possible picture requires some Test Equipment. This Test Equipment not only saves many hours otherwise wasted in "knob twisting", but also results in perfect picture alignment every time, the first time out ! TEST EQUIPMENT NEEDED FOR PERFECT EQUALIZATION The VLTG-800 Video Line Test Generator creates a NTSC test signal that contains a Color Burst signal and 100,200,300,400,500,600,700, and 800 "Lines" patterns for observation on Monitors to measure system performance. This Video Line Test Generator signal may be inserted at any 75 Ohm location in a CCTV system as a quality testing signal for trouble shooting or quality testing purposes. The CM-1 Camera Master numerically measures CCTV system performance and enables precise Amplifier/Equalizer adjustment. The CM-1 is a small, battery operated digital meter that measures Sync amplitude, Color Burst amplitude, Composite Video amplitude, and Camera Focus. The Sync and Color Burst amplitude measurement enable the user to precisely set Amplifier/Equalizers to flat frequency response and correct amplitude. WHAT ARE IRE UNITS ? IRE Units are used worldwide to measure video signal amplitude instead of Volts Peak-to-Peak. This system of measurement is much easier to use than Volts Peak to Peak and can be directly measured on the CM-1 hand-held, battery-operated Camera Master instead of a bulky Wave Form Monitor that requires 120 VAC power. The following table defines the amplitude of various parts of a video signal. In terms of IRE Units and Volts. MEASUREMENT I.R.E. UNITS VOLTS Sync Pulse 40 0.285714---- Color Burst (p-p) 40 0.285714---- B/W Picture 100 0.714285---- Color Picture 120 0.857142---- B/W Composite (p-p) 140 1.000000---- Color Composite (p-p) 160 1.142857---- Note that a 50% grey (B/W) is 50 IRE, but 0.357142 Volts Peak. Difficult to measure on a scope, but very easy to measure with a CM-1 Camera Master. Also note that a composite Color picture is 1.142857 Volts, not 1.0Volt. An additional complication is that many Automatic Shutter Cameras are set at the factory to produce as much as 1.3 Volts Peak-to-Peak output in an effort to overcome cable losses . Since this level is sometimes not adjustable at the Camera, there must be a provision , such as an Amplifier/Equalizer, to reduce the composite video level to 140 IRE Units prior to a Digital Recorder to prevent digital overload that will cause the Digital Recorder to cease operation. Many failures of digital recorders are simply due to digital overload on high video levels. Placing an Amplifier/Equalizer ahead of a digital recorder and correcting the video level will usually correct this type of failure. TYPICAL EFFECT OF UNEQUALIZED UTP CABLE LOSS As the UTP or Coaxial cable gets longer, of course the picture becomes weaker (due to low frequency cable loss), and the picture detail becomes fuzzier (due to high frequency cable loss), unless an Amplifier/Equalizer is provided to compensate for these losses. The following table shows the sort of losses that can be expected for various lengths of 24 gauge UTP facilities. 24 GAUGE UN-EQUALIZED UTP CABLE SYNC (Low Frequency) COLOR BURST (High Frequency) LENGTH I.R.E % LOSS NOTES: I.R.E. % LOSS NOTES: 0 Feet 40 0% 40 0% 500 Feet 35.2 12 % #1 21 47.5% #6 1000 Feet 31 22.5 % #2 11 72.5% #7 1500 Feet 27.4 31.5% #3 5.8 85.5% #8 2000 Feet 24.1 39.8% #4 3 92.5% #9 3000 Feet 18.7 53.3% #5 0.5 98.0% #10 NOTES: #1 Slight brightness loss #2 Moderate brightness loss #3 Serious brightness loss #4 Possible loss of sync #5 Probable loss of sync #6 Weak Color, 50% detail loss #7 Very weak color, poor detail #8 Color faded out, very poor detail #9 Color gone, low quality picture #10 No color, very poor quality picture Share this post Link to post Share on other sites
Willie 0 Posted June 24, 2006 Thank you for the information. That was exactly what I was looking for. Share this post Link to post Share on other sites
jisaac 0 Posted June 24, 2006 well i was just passing information given to me. Man if you want all your questions answered in regards to video and signal and transmission then call the tech support at fm systems and let them load you with info. I am telling you they are extremely helpfull. Share this post Link to post Share on other sites
kensplace 0 Posted June 25, 2006 Seriously, IGNORE SPECS... This may sound insane, but specs are just that, specs written by people in a perfect world, with perfect components, with X amount of perfect whatever interference thrown in. In the real world, experience will tell you what works and what does not, I remember when people said a parallel printer cable could not be more than X meters long (cant recall the exact length, but say 10 or 15 meters) and I went to a job where a 50m+ lead was installed (whatever the exact lenghts were, lets just say it was at least 3+ times the max ever length it SHOULD work at) and it worked perfect, and had worked perfect and continued to work perfectly. Cable is cheap, experiment, even specs can fail, as the camera you are trying to hook up may not be up to spec, and may need a shorter cable, or amp, only way is to test. If you go by specs your just guessing that all will be perfect. Share this post Link to post Share on other sites
Thomas 0 Posted June 25, 2006 The max length according to the specs is 35ft or just a hair over 11m. You can run it further, and use some cables that are rated for 2x that length. But you start running the risk of packet loss. You can always exceed any spec. Specs aren't writen to be the absolute answer. What they are writen to is the most likely place in which you will start seeing trouble. Going by the specs with decent to good gear generally means that everything will work. If you buy crap, well you bought crap. It's why being stupidly cheap costs you money in the long run. Share this post Link to post Share on other sites
CSG 0 Posted June 27, 2006 You can run rg-59 in 1000 foot runs, i've done it before. That's why they sell coax cable in 1000' reels :^) Share this post Link to post Share on other sites
