摘要:
An entire radio transceiver can be completely integrated into one IC chip. In order to integrate the IF filters on the chip, a heterodyne architecture with a low IF is used. A single, directly modulated VCO is used for both up-conversion during transmission, and down-conversion during reception. Bond-wires are used as resonators in the oscillator tank for the VCO. A TDD scheme is used in the air interface to eliminate cross-talk or leakage. A Gaussian-shaped binary FSK modulation scheme is used to provide a number of other implementation advantages.
摘要:
A proximity detector for use in a mobile telephone having at least a microphone and a loudspeaker operatively connected to a signal processor is presented. The proximity detector includes data processing and control modules having a module for controlling the signal processor for activating the loudspeaker to reproduce an acoustic control signal. A correlator correlates a control signal received directly by the microphone and a control signal being reflected from a user of the telephone and then received by the microphone to determine the distance between the telephone and the user. A signal level controller controls the signal processor to vary the signal level of an audible signal reproduced by the loudspeaker depending on the determined distance between the telephone and the user.
摘要:
An entire radio transceiver can be completely integrated into one IC chip. In order to integrate the IF filters on the chip, a heterodyne architecture with a low IF is used. A single, directly modulated VCO is used for both up-conversion during transmission, and down-conversion during reception. Bond-wires are used as resonators in the oscillator tank for the VCO. A TDD scheme is used in the air interface to eliminate cross-talk or leakage. A Gaussian-shaped binary FSK modulation scheme is used to provide a number of other implementation advantages.
摘要:
Methods and apparatus for performing synchronization and DC-offset compensation in FM transmission systems significantly reduce the overhead associated with transmitting a conventional digital preamble at the start of each of a succession of transmitted digital data packets. According to exemplary embodiments, a multi-part digital preamble includes a short, substantially DC-free leading part followed by a code-protected synchronization part which is not necessarily substantially DC-free. The leading part provides for coarse DC offset estimation and synchronization, while the coded synchronization part carries timing and/or other useful information which can be unique for each packet. One or more substantially DC-free trailing parts follow the synchronization part, or are included in the synchronization part itself, and provide for fine tuning of the DC-offset estimate. Since the substantially DC-free leading and trailing parts are extremely short, and since the synchronization part carries useful information, the overhead associated with a preamble according to the invention is significantly reduced as compared to a conventional, entirely DC-free, preamble.
摘要:
Transmission power in a frequency-hopping radio system that transmits packets from a sending radio unit to a receiving radio unit, wherein each packet includes an address designating the receiving radio unit, is controlled by measuring received signal strength of packets whose addresses were successfully received in the receiving radio unit, regardless of whether other portions of the respective packets were successfully received. An average signal strength value is generated from the received signal strength measurements. The mathematical difference between the average signal strength value and a target value associated with the receiving radio unit is then determined and used as a basis for deciding whether to send a power control message from the receiving radio unit to the sending radio unit. In order to provide a hysteresis in the power control process, a power control message is sent from the receiving radio unit to the sending radio unit if the mathematical difference is greater than a first decision boundary, or if the mathematical difference is less than a second decision boundary. The power control message may itself include the mathematical difference which, when received by the sending radio unit, is used as a basis for determining a transmission power level adjustment amount. The target value, against which the average signal strength value is compared, may be based on the receiver sensitivity adjusted to account for implementation losses and other inaccuracies.
摘要:
In a radio front-end circuit having at least two amplifier-mixer cascades, the amplifiers are switched on or off via the mixers. By switching between the amplifier-mixer cascades, the power consumption is lowered.
摘要:
A frequency modulated signal demodulator circuit includes a phase shift element and a time delay element which operate on an input signal (V_IF). The phase shift element and the time delay element are provided by a gyrator component (14, 16, 20).
摘要:
A radio communication system that utilizes an available frequency spectrum that is divided up into a plurality of channels to be used by the radio communication system is operated in accordance with a frequency hopping strategy that permits a user to simultaneously utilize more than one channel during each hop period, wherein it is permissible, but not mandatory, for at least one of the channels utilized by the user during a first hop period to again be used by the user during an immediately following second hop period, so long as at least one of the channels utilized by the user during the second hop period is different from all of the channels utilized by the user during the first hop period. In some embodiments, the number of channels simultaneously utilized by any one user need not be the same as the number of channels simultaneously utilized by any other user.
摘要:
Circuits and methods are disclosed for reducing interference from transmitter leakage in a radio transceiver. An exemplary method for reducing interference from transmitter leakage in a radio transceiver comprises downconverting, filtering, and sampling a radio frequency signal comprising a desired signal and a transmitter leakage signal to obtain a sampled signal of interest. The method further comprises generating a sampled distortion signal estimate that estimates one or more distortion products of the transmitter leakage signal, such as a squared amplitude obtained from a square-law device or corresponding digital function. Finally, the method comprises combining the sampled distortion signal estimate with the sampled signal of interest to obtain interference-reduced signal samples. In some embodiments, this may comprise correlating the sampled distortion signal estimate with the sampled signal of interest to determine a scaling factor, scaling the sampled distortion signal estimate with the scaling factor, and subtracting the scaled distortion signal estimate from the sampled signal of interest to obtain the interference-reduced signal samples.
摘要:
Decoding a received Orthogonal Frequency Division Multiplex (OFDM) signal that occupies a first set of subcarriers in a radio frequency spectrum includes ascertaining an interference model that represents interference occurring in the first set of subcarriers caused by a transmitted OFDM signal that occupies a second set of subcarriers in the radio frequency spectrum. A set of scaled soft values is produced that represents information conveyed by the received OFDM signal over the first set of subcarriers, wherein each scaled soft value in the set of scaled soft values corresponds to a respective one of the subcarriers in the first set of subcarriers, and wherein a scaling amount applied to each of the scaled soft values is based on a corresponding level of interference in said respective one of the subcarriers as indicated by the interference model. A decoding process is performed that generates detected data from the scaled soft values.