Abstract: A video encoder (2) is disclosed for sending video data to a server (4) over a channel. A video compressor (16) can compress video data using an adjustable compression factor. A multiplexer/pack constructor (18) can receive compressed video from the compressor, together with non-video data, and can queue data for transmission. A bandwidth monitor (20) is provided for monitoring the performance of the channel based on the behaviour of transmitted data packets, including their round-trip travel time to and from the server (4). The compressor (16) can modify the adjustable compression factor based on the performance of the channel, as determined by the bandwidth monitor, and the amount of non-video data received by the packet constructor. This can permit transmission of non-video data without disrupting the live video feed or introducing any delay.

Abstract: A video encoder (2) is disclosed for sending video data to a server (4) over a channel. A video compressor (16) can compress video data using an adjustable compression factor. A multiplexer/pack constructor (18) can receive compressed video from the compressor, together with non-video data, and can queue data for transmission. A bandwidth monitor (20) is provided for monitoring the performance of the channel based on the behaviour of transmitted data packets, including their round-trip travel time to and from the server (4). The compressor (16) can modify the adjustable compression factor based on the performance of the channel, as determined by the bandwidth monitor, and the amount of non-video data received by the packet constructor Specifically, the compression factor can be changed so that video data can be transmitted promptly but with reduced quality if there is less bandwidth available and if space is required in the channel for non-video data.

Abstract: An unattended ground sensor unit (30) is disclosed comprising an antenna (2) which is accommodated mainly in a head portion (5) of the unit. The antenna (2) comprises a base conductor (100) and a top conductor (102), both of which are circular plates arranged in a horizontal plane. An antenna rod (204) is electrically connected to the top conductor (102). A hole is provided in the base conductor (100) and the antenna rod (204) extends through the hole to be connected to antenna control circuitry on a printed circuit board (104) on the reverse side of the base conductor (100). An insulating ring (106) is provided around the antenna rod (204) where it extends through the base conductor (100) so that the antenna (rod 204) is electrically insulated from the base conductor (100). Two shorting pins (205) are provided between the top conductor (102) and the base conductor (100). The shorting pins (20) are provided on diametrically opposite sides of the antenna rod (204).

Abstract: An unattended ground sensor unit (30) is disclosed comprising an antenna (2) which is accommodated mainly in a head portion (5) of the unit. The antenna (2) comprises a base conductor (100) and a top conductor (102), both of which are circular plates arranged in a horizontal plane. An antenna rod (204) is electrically connected to the top conductor (102). A hole is provided in the base conductor (100) and the antenna rod (204) extends through the hole to be connected to antenna control circuitry on a printed circuit board (104) on the reverse side of the base conductor (100). An insulating ring (106) is provided around the antenna rod (204) where it extends through the base conductor (100) so that the antenna (rod 204) is electrically insulated from the base conductor (100). Two shorting pins (205) are provided between the top conductor (102) and the base conductor (100). The shorting pins (20) are provided on diametrically opposite sides of the antenna rod (204).