The HD-3540 systems for remote-controlled cameras such as goal cams, surveillance/homeland security, distance learning, houses of worship, surgical video and specialty cameras. The HD-3540 gives the same uncompromised video quality and AES or analog audio for fixed camera positions such as weather or scoreboard cameras. As with the HD-3500, you have the capability of inputting either analog or digital AES audio signals and getting both analog and digital signals out at the control room. For fixed surveillance application, the HD-3540 is an extremely cost efficient and small package that will fit into most weatherproof enclosures and most budgets.