Digital Wireless Camera Technology Fundamentals
Len Mann · SMPTE Motion Imaging Journal · 2003
Analog wireless camera systems have been available to the broadcast industry for decades and are in common use at sporting events for sideline coverage of football, pit-lane coverage of car racing, etcetera. Analog systems are essentially line-of-sight systems, meaning that the frequency modulation (FM) used requires an uninterrupted path between the transmitter and receiver. In situations such as transmission in built-up areas where the transmitted signal can be reflected by a number of routes back to the receiver (multipath interference), analog systems can suffer from picture-quality impairments such as ghosting, noise, chroma flutter, or complete loss. Viewers have become used to these impairments, which can occur when watching in-car cameras or marathon coverage, typically when the transmitter passes under a bridge or behind an obstacle. Traditional analog systems, therefore, have never offered true roaming freedom to cameramen. Analog wireless cameras need labor-intensive manual targeting of transmit and receive antennas to ensure a reasonable quality of link.