A communication system uses skywave propagation to transmit data between communication nodes over a data transmission path. An atmospheric sensor is configured to collect atmospheric data at the reflection point of the data transmission path where the transmission path is redirected from the atmosphere toward the surface of the Earth. Data collected by the atmospheric sensor may be used to predict future ionospheric conditions and determine optimum working frequencies for transmission of data between the communication nodes.

A communication system transmits a data signal between a transmitter and a receiver. A service provider operates the communication system for a client. When the data signal is received at the receiver, the data signal is decoded and the service provider decides whether the decoded data signal is accurate or whether the decoded data signal should be rejected. The service provider transmits the decoded data signal and its determination as to its accuracy to the client. Metadata including information about the transmission of the data signal is also provided to the client so that the client can make its own determination regarding whether to accept or reject the decoded data signal.

A communication system transmits a data signal between a transmitter and a receiver. A service provider operates the communication system for a client. When the data signal is received at the receiver, the data signal is decoded and the service provider decides whether the decoded data signal is accurate or whether the decoded data signal should be rejected. The service provider transmits the decoded data signal and its determination as to its accuracy to the client. Metadata including information about the transmission of the data signal is also provided to the client so that the client can make its own determination regarding whether to accept or reject the decoded data signal.

A communication system transmits data signals between communication nodes. A first data signal is transmitted as an electromagnetic wave along a first data transmission path to a receiver using skywave propagation. A second data signal, identical to the first data signal, is transmitted to the receiver along a second data transmission path. The two data signals are compared at the receiver to determine any distortion caused by the skywave propagation. Data regarding the distortion is sent back to the transmitter so that subsequent transmitted data signals may be preconditioned when sent by skywave propagation.

A communication system transmits data signals between communication nodes. A first data signal is transmitted as an electromagnetic wave along a first data transmission path to a receiver using skywave propagation. A second data signal, identical to the first data signal, is transmitted to the receiver along a second data transmission path. The two data signals are compared at the receiver to determine any distortion caused by the skywave propagation. Data regarding the distortion is sent back to the transmitter so that subsequent transmitted data signals may be preconditioned when sent by skywave propagation.

Systems and methods for clock synchronization are disclosed. A client synchronization system (CSS) may transmit RF pulses to a server CSS over micrometeorite ionization trail (MMIT) channels, and may receive RF pulses from the server CSS over MMIT channels, each received RF pulse following transmitted RF pulse. The client CSS may receive from the server CSS over MMIT channels measurement data including pulse arrival times at the server CSS. The measurement and transmission data may be correlated to identify RF-pulse pairs, each pairing a transmitted RF pulse received by the server CSS with a received RF pulse received from the server CSS, both over the same MMIT. TWTT analysis may be applied to timing data the pairs to compute time offsets between a client clock and a server clock. An analytical model of clock drift may be applied to the offsets to synchronize the client clock to the server clock.

A communication system allows for clock synchronization between a transmitter and a receiver when switching from transmission of an analog signal to transmission of a digital signal. The system uses clock synchronization during transmission of the digital signal, but the clock synchronization may be lost when switching to transmission of an analog signal. A digital clock synchronization is embedded in the analog signal so that the clock synchronization between the transmitter and the receiver may be reestablished upon switching to a digital signal without any delay in transmission of the digital signal.

A high-frequency beyond line of sight ad-hoc communication system is disclosed. In embodiments, the system includes an originating node. The originating node is configured to transmit a transmission. In, the system includes a destination node. The destination node is configured to receive the transmission using one or more antennas. In, the system includes one or more relay nodes, which are configured to relay the transmission from the operating mode to the destination mode in a time diverse manner. The relay nodes further comprise a controller, configured to facilitate high-frequency beyond line of sight communication between the originating node and the destination node, wherein the transmission is carried in accordance with a TDMA based waveform that supports frames and time slots. In embodiments, the one or more relay nodes are further configured to relay the transmission from the originating mode to the destination mode in a frequency diverse manner.

A high-frequency beyond line of sight ad-hoc communication system is disclosed. In embodiments, the system includes an originating node. The originating node is configured to transmit a transmission. In, the system includes a destination node. The destination node is configured to receive the transmission using one or more antennas. In, the system includes one or more relay nodes, which are configured to relay the transmission from the operating mode to the destination mode in a time diverse manner. The relay nodes further comprise a controller, configured to facilitate high-frequency beyond line of sight communication between the originating node and the destination node, wherein the transmission is carried in accordance with a TDMA based waveform that supports frames and time slots. In embodiments, the one or more relay nodes are further configured to relay the transmission from the originating mode to the destination mode in a frequency diverse manner.

A backscatter tag device includes, in part, a receiver configured to receive a packet conforming to a communication protocol defining a multitude of codewords, a codeword translator configured to translate at least a first subset of the multitude of codewords disposed in the packet to a second multitude of codewords defined by the protocol in response to a data the backscatter tag is invoked to transmit, and a transmitter configured to transmit the packet supplied by the codeword translator at a frequency different than the first frequency at which the packer is received. The communication protocol may optionally be the 802.11 g/n, ZigBee or the Bluetooth communication protocol.