Which minimum Video Frame Rate is needed in a Remote Tower Optical System

Abstract

Bandwidth, often limited and costly, plays a crucial role in cost-efficient Remote Tower system. Reducing the Video Frame Rate (in the following referred to Frame Rate (FR), expressed in fps, also referred to video update rate (European Organisation for Civil Aviation Equipment. EUROCAE: Minimum aviation system performance specification for remote tower optical systems, ED-240A change 1, EUROCAE, Saint-Denis: 2021)) of the relayed video stream is one parameter to save bandwidth, but at the cost of video quality. Therefore, the present article evaluates how much FR can be reduced without compromising operational performance and human factor issues. In our study, seven Air Traffic Control Officers (ATCOs) watched real air traffic videos, recorded by the Remote Tower field test platform at the German Aerospace Center (DLR e.V.) at Braunschweig-Wolfsburg Airport (BWE). In a passive shadow mode, they executed ATS relevant tasks in four different FR conditions (2, 5, 10 and 15 fps) to objectively measure their visual detection performance and subjectively assess their current physiological state and their perceived video quality and system operability. Study results have shown that by reducing the FR, neither the visual detection performance nor physiological state is impaired. Only the perceived video quality and the perceived system operability dropped by reducing FR down to 2 fps. The findings of the study presented in this chapter will help to better adjust video parameters in bandwidth limited applications in general, and in particular to alleviate large scale deployment of Remote Towers in a safe and cost-efficient way.