US 6,784,827 B2 · Determining a time of arrival of a sent signal

Abstract

The present invention provides an apparatus, method, and system for determining a time of arrival (TOA) and time differences of arrival (TDOA) of a transmitted signal {S} receivable at different locations of known spatial coordinates. The system comprises a first transmitter 10 with a respective antenna feed point positioned at an a priori unknown location P and emitting a first signal {S}. The system includes furthermore a set of transceivers or transponder units 20, 30 comprising first receivers 22, 32 for receiving first signals {S} by means of respective antennas with feed points located at known locations Ln. Such system also comprises second transmitters 26, 36 emitting respective derived second signals {{tilde over (S)}n} after known and scheduled respective time intervals δn as measurable between the feed points of said respective first receiving antennas located at known locations Ln and respective second transmitting antenna located at locations L′n. A set of second receivers 42, 52 receives respective second signals {{tilde over (S)}n} after known respective time intervals τn measured between the feed points of the second transmitting antennas and feed points of second receiving antennas. A controller 46 terminates the measurement cycle for each first transmitter 10 to define total signal transfer times and then sends to a processing unit 48 an ensemble of derived third signals {Ŝn}, after some known respective delay times ΔTn. Said delay times ΔTn are measured between the time one third signal {Ŝ} passes the feed point of the respective second receiving antenna and the time instant where the respective single time reference T0 issued by the controller 46 terminates the measurement cycle. The set of third signals {Ŝn} received by the processing unit 48 contains sufficient information for determining the time of arrival (TOA) and time differences of arrival (TDOA) and to compute {circumflex over (P)}, an estimate of the a priori unknown location P of a mobile radio terminal or radio tag emitting the first signal {S}.

Claims10

Dependent claims

Apparatus for determining a time of arrival (tn) of a transmitted signal ({S}), the apparatus comprising:

at least two transponder units, each comprising
a first receiver for receiving the transmitted signal ({S}),
a time-processing unit coupled to the first receiver for generating, in response to receipt of the transmitted signal ({S}) by the first receiver, a first time-count value (δn), and for scheduling transmission of a time-processed signal ({{tilde over (S)}n})), which is based on the transmitted signal ({S}), in dependence on the time-count value (δn), and
a transmitter for transmitting the time-processed signal ({{tilde over (S)}n}) from a transmission location (L′n);
and,
an evaluation unit comprising
a second receiver for receiving the time-processed signal ({{tilde over (S)}n}) after a determinable time-delay value (τn),
a timer unit coupled to the second receiver for generating, in response to receipt of the time-processed signal ({{tilde over (S)}n}) by the second receiver, a second time-count value (ΔTn),
a controller for generating a time reference (T0) for the timer unit, and
a processing unit for deriving the time of arrival (tn) based on the time reference (T0) from the first time-count value (δn), the time-delay value (τn), and the second time-count value (ΔTn).

7 more elements

Dependencies are inferred from the claim text.

Determining a time of arrival of a sent signal

Life of this patent

Determining a time of arrival of a sent signal

Life of this patent

Abstract

Claims10