meyerside 0 Posted May 27, 2011 I hope someone can help me. We have an installation of PTZ camera over 200m distance using RG-6 coax cable (one continuous wire). The video has horizontal shift & induces tearing on the top of the screen. These horizontal shifting does not roll over the screen. We thought it was a ground loop problem and installed ground loop isolator on RX side, TX side and both, but to no avail. Upon careful examination of the video, we found that the tearing only happens when we are looking at bright object (i.e. sky). When we move the PTZ to look at dark object (i.e. ground pavement), then the tearing artefact goes away. As such, at night time, we see the tearing artefact less than compared to day time. Any ideas? It could still be ground issue as we measured 6Vac between BNC shield and our DVR ground. After installing Ground loop isolator, this value went down to 0.5Vac, but as stated earlier video did not improve. Any help or guidance would be appreciated. Share this post Link to post Share on other sites
hardwired 0 Posted May 27, 2011 Make sure the viewing side is properly terminated with a 75 Ohm load, a signal level that is too high can cause this (voltage peaks in the video waveform are higher with brighter images). Share this post Link to post Share on other sites
Nimrod 0 Posted May 27, 2011 Was the RG6 rated for CCTV use, what was its full RG6 number. CCTV coax will have a copper core and copper braid of copper plated aluminum braid. If you are unsure use a magnet. The magnet will not be attracted to real CCTV cable. Share this post Link to post Share on other sites
meyerside 0 Posted May 28, 2011 Thank you for the replies. First - Yes, the coax is properly terminated with 75 ohms. It's going to a DVR and we switched the cable to known good channel, but the problem follows the camera. Second - as for cable. All I know is that it's made by "provo". I will try to find the model number. Share this post Link to post Share on other sites
buster40 0 Posted June 17, 2011 Could it be a applicaion that requires a wide dynamic range camera sounds like the Luminance is causing the the video signal to clip Share this post Link to post Share on other sites
valboosky 0 Posted June 17, 2011 What brand of camera is this? model? could help. I know of certain problems with cameras like this when camera blocks overheat and the difference in brightness can cause this. Share this post Link to post Share on other sites
tesc_cctvpro 0 Posted June 17, 2011 I hope someone can help me. We have an installation of PTZ camera over 200m distance using RG-6 coax cable (one continuous wire). The video has horizontal shift & induces tearing on the top of the screen. These horizontal shifting does not roll over the screen. We thought it was a ground loop problem and installed ground loop isolator on RX side, TX side and both, but to no avail. Upon careful examination of the video, we found that the tearing only happens when we are looking at bright object (i.e. sky). When we move the PTZ to look at dark object (i.e. ground pavement), then the tearing artefact goes away. As such, at night time, we see the tearing artefact less than compared to day time. Any ideas? It could still be ground issue as we measured 6Vac between BNC shield and our DVR ground. After installing Ground loop isolator, this value went down to 0.5Vac, but as stated earlier video did not improve. Any help or guidance would be appreciated. What speed does that PTZ pan at? What display device are you using ? What frequency is your monitor set to - refresh rate? Share this post Link to post Share on other sites
meyerside 0 Posted July 12, 2011 The brand of camera is Pelco Spectra IV PTZ The display we are using is LCD monitor - refresh rate of 60Hz. Share this post Link to post Share on other sites
meyerside 0 Posted July 12, 2011 I don't know if this helps or not. We are also using Pelco IWM24-GY PTZ arm which has built in transformer and accepts 120VAC directly. Share this post Link to post Share on other sites
