Abstract: 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.

Abstract: A wireless communication system includes a first wireless communication node for transmitting a data signal that is sent to a second wireless communication node by skywave propagation over at least two different data transmission paths. The first data transmission path includes at least one reflection point where the data signal is reflected by the atmosphere and the second data transmission path includes more reflection points than the first data transmission path. The data signal that travelled along the first data transmission path is decoded before the data signal that travelled along the second data transmission path.

Abstract: A communication system uses multiple communications links, preferably links that use different communications media. The multiple communications links may include a high latency/high bandwidth link using a fiber-optic cable configured to carry large volumes of data but having a high latency. The communications links may also include a low latency/low bandwidth link implemented using skywave propagation of radio waves and configured to carry smaller volumes of data with a lower latency across a substantial portion of the earth's surface. The two communications links may be used together to coordinate various activities such as the buying and selling of financial instruments.

Abstract: 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.

Abstract: A communication system uses multiple communications links, preferably links that use different communications media. The multiple communications links may include a high latency/high bandwidth link using a fiber-optic cable configured to carry large volumes of data but having a high latency. The communications links may also include a low latency/low bandwidth link implemented using skywave propagation of radio waves and configured to carry smaller volumes of triggering data with a lower latency across a substantial portion of the earth's surface. The triggering data may be sent in a data stream as data frames without headers, security information, or error checking codes. The two communications links may be used together to coordinate various activities such as the buying and selling of financial instruments.

Abstract: 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.

Abstract: A method for equalizing a wireless communication channel includes transmitting a data signal over a primary channel. During transmission of the data signal, a corresponding data signal is sent over a secondary channel. The information received from the secondary channel is compared to the information received from the primary channel and differences between the information received from each of the channels are observed. These differences are used as inputs to an equalizer algorithm that may be used to reduce distortion of the data signal sent over the primary channel.

Abstract: A communication system transmits data between communication nodes over a data transmission path. The system collects data from at least two different sources to create a fused data stream that is used as the input to a model for determining a frequency at which to transmit the data by skywave propagation. The data is transmitted between the communication nodes at the frequency determined by the model.

Abstract: 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.

Abstract: Wireless communication is provided over an extended distance using a line or a series of drones traveling along a transmission path between a transmitter and a receiver. The transmitter sends a data signal to a first drone that is within range of the transmitter. The first drone sends the data signal to an adjacent drone in the line of drones which retransmits the data signal to the next drone in line. The data signal is transmitted between drones until it reaches a final drone within range of the receiver. The final drone transmits the data signal to the receiver. As the drones travel along the transmission path, new drones are launched from a location within range of the transmitter to replace drones that land after transmitting a data signal to the receiver.

Abstract: A wireless communication system includes a first wireless communication node for transmitting a data signal that is sent to a second wireless communication node by skywave propagation over at least two different data transmission paths. The first data transmission path includes at least one reflection point where the data signal is reflected by the atmosphere and the second data transmission path includes more reflection points than the first data transmission path. The data signal that travelled along the first data transmission path is decoded before the data signal that travelled along the second data transmission path.

Abstract: 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.

Abstract: A communication system uses multiple communications links that may include a high latency/high bandwidth link using a fiber-optic cable configured to carry large volumes of data but having a high latency. The communications links may include a low latency/low bandwidth link using skywave propagation of radio waves and configured to carry smaller volumes of data with a lower latency. The low latency/low bandwidth link employs a transmitting antenna system where aspects such as antenna height, type of ground, and typography of the surrounding area at the transmitting site are adjusted to optimize the direction and angle of propagation. Controlling these and other aspects increases the predictability and reliability of the wireless link by managing the number of hops and skip distance between the transmitting and receiving antennas. The two communications links may be used together to coordinate various activities such as the buying and selling of financial instruments.

Abstract: A communication method is configured to increase speed of messages reception over a bandwidth limited channel such as high frequency (HF) radio. User data arriving from a high-speed network is transformed into a format suitable for transmission over the radio channel. Message packets that will take longer to reach a destination via the radio channel as compared to alternative channels, such as a fiber optic network, are rejected for radio transmission. When the packet is received, the receiver deduces message length by using information from various error handling techniques, such as forward error correction (FEC) and cyclic redundancy check (CRC) techniques. Fill data is transmitted between message packets when no data is available. The FEC and CRC information for the fill data is modified so that the fill data will fail FEC and CRC checks at the receiving station.

Abstract: A method and communication system has been developed to increase the number of messages sent over a bandwidth limited channel and/or under noisy conditions by using a variable message length encoding and decoding scheme. With this technique, the messages having a higher probability of being sent are shorter as compared to the messages that are less likely to be sent under the current conditions. With this technique, a higher number of transactions per unit of time can be communicated and/or executed over a given bandwidth limited channel. When the transmitted message is received, the receiver does not know the message length, but the receiver deduces the length by using information from various error detection and correction techniques, such as forward error correction (FEC) and cyclic redundancy check (CRC) techniques.

Abstract: A gear shifting technique has been developed in which modulation and equalization are shifted to achieve optional performance. In one form, two or more equalizers, each associated with a demodulator and message decoder, determine if the modulation being used can be increased in complexity in order to increase the channel throughput or determine if the modulation method should be reduced in complexity in order to improve the receiver error performance. The quality metrics can based on which equalizer-demodulator-decoder is set to first detect a valid message. Other factors can be considered with this technique such as a packet-error ratio and a signal-to-noise ratio. In a financial trading system, message erasures can be favored over errored messages by limiting the number of bit or symbol corrections permitted per message to less than the maximum possible for the selected decoding schemes.

Abstract: An equalization method has been developed for low latency, low bandwidth wireless communication channel environments. With this method, an exact copy, nearly exact copy, or some facsimile of a message (or associated information), which was transmitted via a low latency, low bandwidth wireless communication channel, is also sent via a backend communication channel such as a fiber optic network. Equalization is generally performed by comparing the originally received message to the copy sent via the backend channel. The original message can incorporate an added channel delay to compensate for the time delay between the primary wireless channel and the backend channel.

Abstract: 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.