Abstract: A bidirectional amplifier includes first and second ports, with a first summing node connected to the first port and a second summing node connected to the second port. First and second gain stages are connected between the first and second summing nodes, respectively, and a first node. First and second feedback stages are also connected between the first and second summing nodes, respectively, and the first node. The amplifier operates in a first mode in which an amplified version of a signal applied to the first port is provided at the second port, or a second mode in which an amplified version of a signal applied to the second port is provided at the first port. The first and second gain stages are preferably first and second common emitter cascode arrangements, and the first and second feedback stages are preferably first and second emitter followers.

Abstract: The invention relates to a security barrier apparatus 10, 70, 100 comprising a support 12 having at least three upright posts 14, 16, 18, 72 thereon. Two of the posts 14, 18 being fixed to the support 12 and at least one post 16, 72 being translatably movable relative to the two fixed posts 14, 18. The two fixed posts 14, 18 being spaced apart from one another and comprise a first plane 19 therebetween. The movable post 16, 72 being mounted to a slide device 24 of the support 12 for providing said translatable movement. The slide device 24 to operate the apparatus 10, 70 between an open position and a closed position such that in the closed position the movable post 16, 72 is between the fixed posts 14, 18 for inhibiting the passage of a vehicle, and in the open position the movable post 16, 72 is out of alignment with the first plane 19 and adjacent to one of the fixed posts 14, 18 for allowing the passage of a vehicle therebetween.

Abstract: A bidirectional amplifier includes first and second ports, with a first summing node connected to the first port and a second summing node connected to the second port. First and second gain stages are connected between the first and second summing nodes, respectively, and a first node. First and second feedback stages are also connected between the first and second summing nodes, respectively, and the first node. The amplifier operates in a first mode in which an amplified version of a signal applied to the first port is provided at the second port, or a second mode in which an amplified version of a signal applied to the second port is provided at the first port. The first and second gain stages are preferably first and second common emitter cascode arrangements, and the first and second feedback stages are preferably first and second emitter followers.

Abstract: The invention relates to a security barrier apparatus 10, 70, 100 comprising a support 12 having at least three upright posts 14, 16, 18, 72 thereon. Two of the posts 14, 18 being fixed to the support 12 and at least one post 16, 72 being translatably movable relative to the two fixed posts 14, 18. The two fixed posts 14, 18 being spaced apart from one another and comprise a first plane 19 therebetween. The movable post 16, 72 being mounted to a slide device 24 of the support 12 for providing said translatable movement. The slide device 24 to operate the apparatus 10, 70 between an open position and a closed position such that in the closed position the movable post 16, 72 is between the fixed posts 14, 18 for inhibiting the passage of a vehicle, and in the open position the movable post 16, 72 is out of alignment with the first plane 19 and adjacent to one of the fixed posts 14, 18 for allowing the passage of a vehicle therebetween.

Abstract: The invention relates to a security barrier apparatus (10, 70, 100) comprising a support (12) having at least three upright posts (14, 16, 18, 72) thereon. Two of the posts (14, 18) being fixed to the support (12) and at least one post (16, 72) being translatably movable relative to the two fixed posts (14, 18). The two fixed posts (14, 18) being spaced apart from one another and comprise a first plane (19) therebetween. The movable post (16, 72) being mounted to a slide device (24) of the support (12) for providing said translatable movement. The slide device (24) to operate the apparatus (10, 70) between an open position and a closed position such that in the closed position the movable post (16, 72) is between the fixed posts (14, 18) for inhibiting the passage of a vehicle, and in the open position the movable post (16, 72) is out of alignment with the first plane (19) and adjacent to one of the fixed posts (14, 18) for allowing the passage of a vehicle therebetween.

Abstract: The invention relates to a security barrier apparatus (10, 70, 100) comprising a support (12) having at least three upright posts (14, 16, 18, 72) thereon. Two of the posts (14, 18) being fixed to the support (12) and at least one post (16, 72) being translatably movable relative to the two fixed posts (14, 18). The two fixed posts (14, 18) being spaced apart from one another and comprise a first plane (19) therebetween. The movable post (16, 72) being mounted to a slide device (24) of the support (12) for providing said translatable movement. The slide device (24) to operate the apparatus (10, 70) between an open position and a closed position such that in the closed position the movable post (16, 72) is between the fixed posts (14, 18) for inhibiting the passage of a vehicle, and in the open position the movable post (16, 72) is out of alignment with the first plane (19) and adjacent to one of the fixed posts (14, 18) for allowing the passage of a vehicle therebetween.