In one aspect, a method includes: determining a power mode of a device; setting a first reference voltage level and a second reference voltage level based at least in part on the power mode; and using at least one of the first reference voltage level and the second reference voltage level for comparison against incoming data.

Disclosed herein is a method for transmitting, by a terminal, a sounding reference signal (SRS). The terminal receives a grant for uplink multiple subframes from a base station. The terminal determines a first subframe for an SRS transmission of the terminal among the uplink multiple subframes on the basis of SRS transmission position information received from the base station. Further, the terminal transmits the SRS in the first subframe.

In one implementation, a receiver has a module to calculate the cross-correlation between a portion of a digital representation of a received signal and a reference signal. The receiver also has a module to generate an estimate of a portion of a message potentially included in the digital representation of the received signal and a screening module to determine the likelihood that the received signal includes a message. For a received signal that is determined likely to include a message, the receiver includes a carrier refinement module to shift the frequency of carrier pulses in the digital representation of the received signal toward a desired frequency and to align the phase of carrier pulses in the digital representation of the received signal with a desired phase and a coherent matched filter to recover the message from the digital representation of the received signal.

In a system according to one embodiment of the present disclosure, the system comprises a first device, a second device, a communications link, and a memory. The memory stores instructions that when executed by the system perform a method of communications link training. This method comprises requesting a speed change to a second speed for the first device communicating with the second device at a first speed via the communications link. A saved set of parameters are accessed for at least one of the first device and the second device. A first training cycle is performed for the first device and the second device at the second speed using the saved set of parameters for the at least one of the first device and second device. The reuse of parameters from a previous successful equalization training cycle reduces the time required to perform equalization training.

Methods and apparatus for establishing a communication link between a first user equipment and at least one other user equipment in a radio communication cell using a radio frequency spectrum divided into a plurality of channels. The first user equipment comprises a tuner configured to tune a communication unit to channels of a channel sequence vector in order. The channel sequence vector comprises at least a partial vectorization of a symmetric Toeplitz matrix formed from a set of the plurality of channels. The communication unit is configured, at each channel, to receive link data for establishing a communication link with the at least one other user equipment. A link establisher is configured to establish a communication link with the at least one other user equipment over the tuned channel if the link data is received.

A digital radio receiver is adapted to receive radio signals modulated using continuous phase modulation. The receiver includes components for receiving analogue radio signals having various carrier frequencies and a plurality of correlators corresponding to different bit sequences. Each of the plurality of correlators share a common estimator for estimating a frequency offset between the radio signals carrier frequencies and nominal carrier frequencies. The receiver further includes components allowing the estimator to determine which of the correlators produce the most optimal output signal.

Systems, devices, and methods of the present invention facilitate secure communication by changing sets of symbol waveforms used transmit data in particular symbol times defined herein as Symbol Waveform Hopping. SWH may be enabled by selecting two or more modulation formats that have sufficiently comparable communication performance (e.g., occupied bandwidth and signal power efficiency) to enable successful sending of data between a transmitter and receiver employing SWH, but characterized by symbol waveform alphabet that include different symbol waveform, so that the overall transmission/communication performance of data stream in a signal transmission channel of the system is not significantly affected by switching between modulation formats, but one symbol waveform alphabet is not reliably able to receive signals sent using the other alphabets. Some or all of the symbol waveforms in each alphabet may not be present in other alphabets.

Methods and apparatus to monitor GPS/GNSS atomic clocks are disclosed. An example method includes establishing a measured difference between an atomic frequency standard (AFS) and a monitoring device. The method also includes modeling an estimated difference model between the AFS and the monitoring device, and computing a residual signal based on the measured difference and the estimated difference model. In addition, the method includes analyzing, by a first detector, the residual signal at multiple thresholds, each of the thresholds having a corresponding persistency defining the number of times a threshold is exceeded before one or more of a phase jump, a rate jump, or an acceleration error is indicated. Furthermore, the method includes analyzing, by a second detector, a parameter of the estimated difference model at multiple thresholds, each of the thresholds having a corresponding persistency defining the number of times a drift threshold is exceeded before a drift is indicated.

Methods and apparatus to monitor GPS/GNSS atomic clocks are disclosed. An example method includes establishing a measured difference between an atomic frequency standard (AFS) and a monitoring device. The method also includes modeling an estimated difference model between the AFS and the monitoring device, and computing a residual signal based on the measured difference and the estimated difference model. In addition, the method includes analyzing, by a first detector, the residual signal at multiple thresholds, each of the thresholds having a corresponding persistency defining the number of times a threshold is exceeded before one or more of a phase jump, a rate jump, or an acceleration error is indicated. Furthermore, the method includes analyzing, by a second detector, a parameter of the estimated difference model at multiple thresholds, each of the thresholds having a corresponding persistency defining the number of times a drift threshold is exceeded before a drift is indicated.

The invention relates to a method for serial data transmission, comprising the steps consisting in computing the running disparity (RD) of a bit stream that is being transmitted; when the running disparity reaches a threshold (T), computing a point disparity on a subsequent frame (S) of the stream; if the point disparity has the same sign as the threshold, inverting the states of the bits of the frame in the transmitted bit stream; and inserting into the transmitted bit stream a polarity bit having a state signalling the inversion.