- 1). Replace DC-powered cameras with AC-powered cameras. DC-powered cameras cannot be line-locked, while AC-powered cameras have a line-locking feature. Line-locking refers to the ability to lock cameras together. The Line-Lock feature times the Vertical Interval Pulses based on the AC's 60-cycle frequency. Adjust the Phase control on each camera to match the Vertical Interval Pulses and remove vertical line interference.
- 2). Reinstall the camera if it and the UPS is also grounded. An induced ground loop can occur when UPS energy is transferred from the coax cable to the cameras -- especially DC-powered cameras. This is because the negative power supply wire at the camera and the coax shield are the same. An induced ground loop causes vertical line interference.
- 3). Replace square-wave UPS types with quasi-sine wave, semi-sine wave or sine-wave USP types. Square wave UPS power supplies have frequencies that go into the Kilo-Hertz, or 1000 Hz, and Mega-Hertz, or 1000,000 Hz, regions. This extends way beyond the video frequency range, and therefore causes video interference.
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