A method for generating private eLoran signals includes receiving, by a transmitter that is configured to transmit a transmission at a fixed time, a transmission key; determining, by the transmitter, a pseudo-random transmission time for transmitting the transmission, where the pseudo-random transmission time is determined using the transmission key; and initiating transmission, by the transmitter, of the transmission at the pseudo-random transmission time. A receiving device includes a processor that is configured to obtain a pseudo-random time for receiving a transmission from a transmitter; receive the transmission at the pseudo-random time; and use the transmission to determine at least one of a time, a longitude, or a latitude at the receiving device.

Provided herein is a method for separating Loran sky and ground waves based on a Levenberg-Marquart algorithm, including: (1) collecting a plurality of Loran sky-ground wave signals followed by normalization to obtain a normalized signal; (2) preprocessing the normalized signal by inverse Fourier transform method to obtain an initialization parameter; (3) establishing a mathematical model for the Loran sky-ground wave signals in time domain; and (4) solving parameters of the mathematical model using the Levenberg-Marquart algorithm to separate the Loran sky and ground waves.

A method for passively locating a non-movable transmitter on the ground implemented by a group of at least one receiving station, each of the receiving stations comprising a detector of radars and a time reference, the set of time references being mutually synchronized, the transmitter transmitting a set of periodic pulses, wherein a first estimation of the position of the transmitter is carried out by the Bancroft scheme on the basis of the mean arrival times of the pulses transmitted by the transmitter at the level of each station of the group of at least one receiving station, the result obtained being used thereafter as point for initializing a maximum likelihood scheme so as to converge toward the position of the transmitter.

An enhanced LOng RAnge Navigation (eLORAN) system may include a plurality of eLORAN transmitter stations, each configured to transmit respective eLORAN signals at different frequencies. An eLORAN receiver device may be configured to receive the respective eLORAN signals at different frequencies from each of the eLORAN transmitter stations, determine a correction factor based upon the received respective eLORAN signals, and apply the correction factor to determine a geographical position of the eLORAN receiver device.

A LORAN device may include a LORAN antenna, a LORAN receiver, an RF signal path extending between the LORAN antenna and the LORAN receiver and being subject to ambient RF interference, and an ambient RF interference canceller coupled in the RF signal path. The ambient RF interference canceller may include an ambient RF interference sensor configured to generate an estimated ambient RF interference signal based on the sensed ambient RF interference, and cancellation circuitry configured to cooperate with the ambient RF interference sensor to generate an ambient RF interference cancellation signal based upon the sensed ambient RF interference signal, and add the ambient RF interference cancellation signal to the RF signal path.

A LORAN device may include a housing, and an electrically short LORAN antenna carried by the housing. The LORAN device may have a LORAN receiver carried by the housing and coupled to the electrically short LORAN antenna, and an RF crystal resonator coupled to the electrically short LORAN antenna so that the electrically short LORAN antenna is forced to a resonant condition for a LORAN receive signal.

A transmitter includes a Loran pulse generator, a dispersion filter, an equalizer, a power amplifier, an antenna tuner, and an antenna. The Loran pulse generator is configured to generate a Loran pulse signal. The dispersion filter is coupled to the Loran pulse generator, and is configured to generate a dispersed signal responsive to the Loran pulse signal. The equalizer is coupled to the dispersion filter, and is configured to generate an equalized dispersed signal responsive to the dispersed signal. The power amplifier is coupled to the equalizer, and configured to generate an amplified signal responsive to the equalized dispersed signal. The antenna tuner is coupled to the power amplifier, and is configured to generate a tuned signal responsive to the amplified signal. The antenna is coupled to the antenna tuner, and is configured to radiate a transmitted signal responsive to the tuned signal.

A device is disclosed. The device may include an antenna, which antenna may receive a ranging signal encoding timing information for one or more of positioning, navigation, and timing. The ranging signal may include a first pulse of a pulse group, a second pulse of the pulse group, and an inter-pulse interval between a start of the first pulse and a start of the second pulse. The device may include a processor, which processor may identify a transmitter of the ranging signal at least partially responsive to the inter-pulse interval.

A device is disclosed. In one or more examples, the device may include an antenna to receive a signal comprising a ranging signal and a data signal. The signal may encode timing information for one or more of positioning, navigation, and timing. The signal may include a first pulse having a first start time and a second pulse having a second start time. The second start time may be an integer number of inter-pulse intervals plus an encoding delay after the first start time. The encoding delay may encode data. The device may include a processor to obtain the data responsive to the encoding delay.

A device is disclosed. In one or more examples, the device may include an antenna to receive a signal encoding timing information for one or more of positioning, navigation, and timing. The signal may include a pulse group comprising a number of ranging pulses and a number of data pulses subsequent to the number of ranging pulses. Respective ones of the number of data pulses may have a phase of either a positive-going phase or a negative-going phase. Data may be encoded using the either positive-going phases or negative-going phases of the data pulses. The device may include a processor to decode the data at least partially responsive to the phases of the respective ones of the number of data pulses.