Abstract: A navigation system comprising at least one terminal configured to at least once transmit, to a communicant, e.g. via n>=1 satellite/s, a request for a reply transmission and wherein the communicant, responsively, at least once transmits a response transmission to the terminal. The terminal measures the response transmission's time of arrival and/or round-trip time and determines a round-trip time characterizing the terminal's own communication, via each of the satellite/s, with the communicant, and/or the terminal's own range (aka distance) from each of the satellite/s. The terminal is configured to derive self-orientation data from at least said round-trip time and from internal delay data characterizing the at least one satellite and/or the communicant.

Abstract: A method to disguise existence of a communication channel and/or type of communication method thereby to provide a discrete communication channel and/or protect communicated contents from malevolent manipulations, the method comprising: at a transmitter end, transforming a signal to be transmitted into a noise-like signal without changing the original communication parameters and protocol, and transmitting the noise-like signal; and/or at a receiver end, receiving a noise-like signal and de-spreading the noise-like signal thereby to reconstruct the signal to be transmitted.

Abstract: A communication system comprising at least one communication network node having a capacity for communicating with at least one additional communication network node at a given center frequency; and at least one external frequency converter, external to said node, operative to cause at least one communication network node, from outside said node, to communicate with at least one additional communication network node, at least on occasion, according to a given communication protocol, at at least one converted center frequency which differs from the given center frequency, and also comprising beacon functionality.

Abstract: Add-on apparatus dynamically enhancing frequency diversity of a main signal sent over an existing communication system, the system using a communication protocol to convey the main signal from a Tx end to an Rx end, the add-on apparatus comprising a Transmission Frequency Converter (TFC) at the Tx end operative while the system is transmitting the main signal, to at least once shift a given center frequency about which the system is transmitting, to at least one corresponding alternative center frequency, wherein the TFC and an Reception Frequency Converter at the Rx end share prior knowledge defining how each shift of the given center frequency is to be timed relative to at least one recognizable element within the known communication protocol and wherein the Transmission Frequency Converter is operative to use the prior knowledge to recognize the at least one recognizable element and to shift the center frequency accordingly.

Abstract: A system for receiving signals from an array antenna that includes a first number of antenna elements, including an orthogonal signals generator module configured to generate the first number of orthogonal signals. Plurality of multipliers configured to receive array antenna element analog signals and the first number of orthogonal signals and generate a corresponding multiplied analog signal, giving rise to a first number of multiplied analog signals. A second number of summation modules configured to receive the first number of multiplied analog signals from the multipliers and generate a second number of summed analog signals. A second number of analog to digital converters configured to receive the summed analog signals and generate the second number of summed digital signals. The summed digital signals are capable of being fed to a digital processor for generating a processed signal of the array antenna, wherein the second number falls in the range of 1 to less than the first number.

Abstract: A system for receiving signals from an array antenna that includes a first number of antenna elements, including an orthogonal signals generator module configured to generate the first number of orthogonal signals. Plurality of multipliers configured to receive array antenna element analog signals and the first number of orthogonal signals and generate a corresponding multiplied analog signal, giving rise to a first number of multiplied analog signals. A second number of summation modules configured to receive the first number of multiplied analog signals from the multipliers and generate a second number of summed analog signals. A second number of analog to digital converters configured to receive the summed analog signals and generate the second number of summed digital signals. The summed digital signals are capable of being fed to a digital processor for generating a processed signal of the array antenna, wherein the second number falls in the range of 1 to less than the first number.

Abstract: A communication system comprising at least one communication network node having a capacity for communicating with at least one additional communication network node at a given center frequency; and at least one external frequency converter, external to said node, operative to cause at least one communication network node, from outside said node, to communicate with at least one additional communication network node, at least on occasion, according to a given communication protocol, at at least one converted center frequency which differs from the given center frequency, and also comprising beacon functionality.

Abstract: Add-on apparatus dynamically enhancing frequency diversity of a main signal sent over an existing communication system, the system using a communication protocol to convey the main signal from a Tx end to an Rx end, the add-on apparatus comprising a Transmission Frequency Converter (TFC) at the Tx end operative while the system is transmitting the main signal, to at least once shift a given center frequency about which the system is transmitting, to at least one corresponding alternative center frequency, wherein the TFC and an Reception Frequency Converter at the Rx end share prior knowledge defining how each shift of the given center frequency is to be timed relative to at least one recognizable element within the known communication protocol and wherein the Transmission Frequency Converter is operative to use the prior knowledge to recognize the at least one recognizable element and to shift the center frequency accordingly.