Abstract: A radar transmits electromagnetic energy in pulse repetition intervals and receives reflections from objects in range gates including Doppler filters. The radar approves desirable ambiguous echoes and suppresses ambiguous echoes of no interest or that interfere with the radar's display. The radar frequency varies according to a staggered or wobbling pattern. The ambiguous echoes produce one pulse in the range gates within a predetermined number of periods. The Doppler filter works with an impulse function response that includes a small number of samples. The Doppler filter, during the predetermined number of periods, gives rise to independent samples from reflectors within the radar's unambiguous range. When the independent samples exceed the small number of samples, the radar approves the ambiguous echo. Otherwise, it is suppressed. In this way, ambiguous echoes are prevented from interfering with the reception or display of echoes. The suppression of asynchronous interferences can be made easier.

Abstract: A radar is arranged to transmit electromagnetic energy in pulse repetition intervals and to receive reflections or echoes from objects in range gates intended for the purpose, which range gates are provided with Doppler filters. The radar is arranged to approve ambiguous echoes that are desirable and to suppress ambiguous echoes that are of no interest or that interfere with the display function of the radar. The radar works with a frequency that varies according to a staggered or wobbling pattern. The respective ambiguous echoes produce only one pulse in the respective range gates concerned, within a predetermined number of periods. The respective Doppler filter concerned is arranged to work with an impulse function response that only consists of a small number of samples. The Doppler filter is also arranged, during the predetermined number of periods, to give rise to a number of independent samples from reflectors within the radar's unambiguous range.

Abstract: A method and system are disclosed for decorrelating background interference signals in a time-synchronized cellular system, in which a mobile station inserts a different training sequence in each successive transmitted burst. The constantly varying background interference signal environment that results can be decorrelated at base station receivers, which enhances the reception of multiple independent mobile station transmissions, and thus increases the sensitivity and precision of time-synchronization measurements, such as, for example, time-of-arrival or time-difference-of-arrival measurements made for mobile station positioning purposes.

Abstract: A method and system are disclosed for decorrelating background interference signals in a time-synchronized cellular system, in which a mobile station inserts a different training sequence in each successive transmitted burst. The constantly varying background interference signal environment that results can be decorrelated at base station receivers, which enhances the reception of multiple independent mobile station transmissions, and thus increases the sensitivity and precision of time-synchronization measurements, such as, for example, time-of-arrival or time-difference-of-arrival measurements made for mobile station positioning purposes.

Abstract: The present invention relates to a method of sending to an unknown switching centre that serves a given mobile station a command concerning said mobile station. The command is sent by using a previously known short message service, e.g. SMS in the GSM-system. The command may constitute a request for the switching centre to determine the position of the mobile station and is sent from a positioning node outside the mobile communications system. The invention also relates to a method of sending data from the switching centre to the positioning node. The invention also relates to a switching centre and also to a system for carrying out the method.

Abstract: A method and system are disclosed for determining the distance between a radio receiver (RX) and a radio transmitter (TX) by uplink time measurements, whereby uplink messages are transmitted by the transmitter (TX) and used primarily for position determination. In one embodiment, the uplink messages are intra-cell handover messages if the transmitter (TX) is a component of a mobile radio terminal which is operating in accordance with an existing TDMA standard. In a second embodiment, the uplink messages are a new type of message transmitted in time slots not used by the mobile radio terminal and preferably, also not used by other mobile radio terminals in the system, if the transmitter (TX) is a component of a mobile radio terminal which is operating in accordance with a new or emerging TDMA standard. The evolving GSM radio air-interface standard is an example of such a TDMA standard.