sjonley

Hi Is the guy doing the install a CCTV installer? If not there a couple of questions that need answering firstly. What type of distortion is occuring. describe it? 1. Is the cable a true CAT5 and not just a twisted pair. Does the spec say CAT5? 2. Are the problem cameras using passive or active baluns? 3. Are the baluns single or part of a hub? 4. How long are the cable runs for the cameras showing distortion? 5. Are there any "kinks" or very sharp bends in the cable run that may cause breakage? 6. Do the baluns terminate at the same point or are you trying to "breakout" at different points on the cable run? Possible Solutions? 1. If the cable is not a true CAT5 specification, such as BT twisted pair, the "twists per inch" may not occur at the correct spacing. 2. With a passive balun the total distance including coax should not exceed 300m for a colour camera. If the cable run on CAT5 is up at the 300m mark and additional coax is then added both ends, lack of video content may occur. When using active baluns, past experience has shown that when they are powered, if the distance is under 300m the signal can be overdriven and no adjustment to turn a bright image down is possible. A mixture of passive and active may be possible but consult the balun supplier/manufacturer. Also with active baluns, only use one twisted pair, per CAT5. if more than one pair is used within the same CAT5, near and far end crosstalk can occur distorting images. Running four CAT5's next to each other (1 pair, per video signal) has enough spacing to stop near and far end crosstalk. 3. Have the Baluns been checked on a short length of CAT5 to test signal integrity? The reason that when the signal is plugged into a monitor the image seems fine, is that the monitor is less tolerant to the 1v p-p signal than the pc dvr may be. If there is a slight dc offset on the camera signal, the pc dvr will be seeing more black level than the full 0.7v signal range, but the monitor may be tollerant upto 2v, hence a clear image.