Abstract: A first transceiver (4, 30) can position itself by forming an ad hoc network (20) of transceivers which assist the first transceiver in acquiring its position. A dedicated infrastructure such as GPS satellites is not required. The first transceiver (4, 30), once it has acquired its position, can be involved in a network (20) by another transceiver (32, 34, 36, 38, 40) to assist in the positioning of that transceiver. The acquisition of the position may involve factors such as the trustworthiness of the transceivers in the network and/or the positions of transceivers with which the first transceiver cannot directly communicate.

Abstract: A first transceiver (4, 30) can position itself by forming an ad hoc network (20) of transceivers which assist the first transceiver in acquiring its position. A dedicated infrastructure such as GPS satellites is not required. The first transceiver (4, 30), once it has acquired its position, can be involved in a network (20) by another transceiver (32, 34, 36, 38, 40) to assist in the positioning of that transceiver. The acquisition of the position may involve factors such as the trustworthiness of the transceivers in the network and/or the positions of transceivers with which the first transceiver cannot directly communicate.

Abstract: A first transceiver can position itself by forming an ad hoc network of transceivers which assist the first transceiver in acquiring its position. A dedicated infrastructure such as GPS satellites is not required. The first transceiver, once it has acquired its position, can be involved in a network by another transceiver to assist in the positioning of that transceiver. The acquisition of the position may involve factors such as the trustworthiness of the transceivers in the network and/or the positions of transceivers with which the first transceiver cannot directly communicate.

Abstract: An animal electronic data collecting device is disclosed which includes a radio transmitter and a radio receiver, a processor for controlling operation of the device, and memory for storing information including a first identifier associated with the device. The processor is arranged to transmit a signal, by means of the radio transmitter, and to receive, by means of the radio receiver, one or more signals, each representing a second identifier from other devices, and the processor is arranged to store in the memory each second identifier. The default operating condition of the device is for the radio receiver to be in a receive condition and, upon receipt of a wakeup call, the processor is arranged to place the radio transmitter into a transmit condition.

Abstract: A first transceiver (4, 30) can position itself by forming an ad hoc network (20) of transceivers which assist the first transceiver in acquiring its position. A dedicated infrastructure such as GPS satellites is not required. The first transceiver (4, 30), once it has acquired its position, can be involved in a network (20) by another transceiver (32, 34, 36, 38, 40) to assist in the positioning of that transceiver. The acquisition of the position may involve factors such as the trustworthiness of the transceivers in the network and/or the positions of transceivers with which the first transceiver cannot directly communicate.

Abstract: A receiver for calculating its position according to a first transmitter, having a processor arranged to convolve: the probability density function representing the position of the first transmitter, sent by the first transmitter to the receiver; with the probability density function representing the likelihood that a transmission from the first transmitter will be successfully received at the receiver.

Abstract: A noise cancelling system comprises two conventional noise cancelling microphones (1,2) spaced apart by a distance of one of up to 10 cms with use of the microphones (1) being arranged to be close to the mouth of a user for reception of speech and the other microphone (2) spaced therefrom and used as a reference microphone. The signals from the microphones are processed by means (7) which use a batch of signals derived from the reference microphone (2) to modify a signal derived from the speech microphone in accordance with the Widrow algorithm known in the art. This system enables effective noise cancellation to be achieved with a delay of only 0.1 sec.