Abstract: A diversity receiver includes a first RF front end module for receiving a first RF signal, and frequency converting the first RF signal and outputting a first diversity signal, a second RF front end module for receiving a second RF signal, frequency converting the second RF signal and outputting a second diversity signal, a first converter for converting the first diversity signal to a first time-domain signal, a second converter for converting the second diversity signal to a second time-domain signal, a first transformer for translating the first time-domain signal to a first frequency-domain signal, a second transformer for translating the second time-domain signal to a second frequency-domain signal, a first pre-equalizer for equalizing the first frequency-domain signal, a second pre-equalizer for equalizing the second frequency-domain signal, and a combiner for combining the first and second pre-equalized frequency-domain signals.

Abstract: A method and apparatus for extending the coverage of geolocation to indoor locations through cooperative geolocation. The method includes establishing an ad-hoc wireless network comprising a plurality of devices including a first device. The method includes receiving, at the first device, position information from the plurality of devices and determining a physical location of the first device based on the received position information. In an embodiment, the position information is transmitted in response to a request by the first device. In an embodiment, the position information may include a time of arrival of the request received by each of the plurality of devices; and the time of arrival may be associated with a GNSS time. In an embodiment, the ad-hoc wireless network may be a Wi-Fi network, which is associated with one of the IEEE 802.11 standards.

Abstract: A circuit includes, an attenuator responsive to an input signal and a feedback signal, a variable gain low-noise amplifier responsive to the attenuator and to the feedback signal, a tracking filter, a frequency converter, and an RSSI responsive to the variable gain amplifier to generate an output signal to which the feedback signal is responsive. The frequency converter may be a mixer having a single-ended input and a differential output. The circuit may further include an analog baseband block responsive to the mixer to filter out high frequency signals. The tracking tuner performs bandpass filtering operation on the output signals of the variable gain low-noise amplifier.

Abstract: A filter for processing a digital TV composite signal having a video component and an audio component includes a digital video filter and a digital audio filter. The digital video filter includes a lowpass finite impulse response (FIR) filter, an up-mixer, an asymmetric filter for compensating a Nyquist slope of the video component, and a down-mixer connected in this order. The digital audio filter includes an audio down-mixer, a decimated FIR filter, an enhancing FIR filter, an interpolated FIR filter, and an audio up-mixer. These components are connected in series. Optionally, the decimating FIR filter is decimated by an integer decimation factor M, and the interpolated FIR filter is interpolated by an integer factor N. The integer M and N may have the same value.

Abstract: A clock generator includes, in part, a buffer, a peak detector and a control logic. The buffer generates a clock output signal in response to receiving a clock signal and a feedback signal that controls the gain of the buffer. If the peak detector detects that the amplitude of the output signal is higher than the upper bound of the predefined range, the gain value applied to the variable buffer is decreased. If the peak detector detects that the amplitude of the output signal is lower than the lower bound of the predefined range, the gain value applied to the variable buffer to increased. If the peak detector detects that the amplitude of the output signal is within the predefined range, no change is made to the gain value applied to the variable buffer. The control logic generates the feedback signal in response to the peak detector's output signal.

Abstract: A transmitting/receiving circuit includes, in part, at least one transceiver, and at least two receiving channels forming a diversity receiver. One of the receiving channels includes, in part, a saw filter, an amplifier, and a frequency converter. The other receiving channel includes, in part, an amplifier, a frequency converter, and a received signal strength indicator (RSSI) adapted to detect signals transmitted by the transceiver. The RSSI is optionally coupled to an input terminal of its associated amplifier. The receiver further includes, in part, at least one processor operative to combine signals processed through the first and second receiving channels using a weight the processor assigns to the signal received by the second receiving channel in accordance with a strength of the blocker signal that the RSSI detects. The second receiving channel optionally includes an RSSI.

Abstract: A circuit includes, in part, a receiver, a received signal strength indicator (RSSI), and an oscillator. The receiver receives an incoming signal and an oscillating signal. The RSSI is responsive to the receiver and generates an output signal representative of the strength of the incoming signal. The oscillator receives different biasing conditions in response to different outputs of the RSSI. The oscillator generates the oscillating signal received by the receiver. The oscillator receives a first biasing condition when the incoming signal is detected as having a strength lower than or equal to a predetermined threshold value and a second biasing condition when the incoming signal is detected as having a strength higher than the predetermined threshold value. The first biasing condition may be defined by a first current, and the second biasing condition may be defined by a sum of the first current and a second current.

Abstract: A receiver, in accordance with one embodiment of the present invention, includes a mixer, a filter, a received signal strength indicator, and a control loop. The mixer is adapted to convert the frequency of a received signal. The filter is adapted to filter out undesired noise that may be present in the output signal of the mixer. The received signal strength indicator is adapted to detect blocker (also known as jammer) signals that may be present in the output signal of the low-pass filter and generate a feedback signal in response. The control loop is adapted to vary its bandwidth in response to an output signal of the received signal strength indicator. The control loop supplies an oscillating signal to the mixer.

Abstract: A QRD processor for computing input signals in a receiver for wireless communication relies upon a combination of multi-dimensional Givens Rotations, Householder Reflections and conventional two-dimensional (2D) Givens Rotations, for computing the QRD of matrices. The proposed technique integrates the benefits of multi-dimensional annihilation capability of Householder reflections plus the low-complexity nature of the conventional 2D Givens rotations. Such integration increases throughput and reduces the hardware complexity, by first decreasing the number of rotation operations required and then by enabling their parallel execution. A pipelined architecture is presented (290) that uses un-rolled pipelined CORDIC processors (245a to 245d) iteratively to improve throughput and resource utilization, while reducing the gate count.

Abstract: A method for performing channel estimation of an OFDM channel includes, in part, interpolating pilots for sub-channels positioned within a first range of an OFDM symbol, and estimating frequency response of sub-channels positioned within a second range of the OFDM symbol. The first range is defined by subchannels positioned substantially away from channel edges and the second range is defined by subchannels positioned substantially near channel edges. The method optionally includes transforming the pilots from frequency domain into the time-domain, time-domain windowing to obtain a channel impulse response having a multitude of discrete values, estimating the discrete values within the channel impulse response; and transforming the channel impulse response to the frequency domain.

Abstract: To determine the level of frequency drift of a crystal oscillator as a result of a change in the its temperature, the temperature of the crystal oscillator is sensed and used together with previously stored data that includes a multitude of drift values of the frequency of the crystal oscillator each associated with a temperature of the crystal oscillator. Optionally, upon initialization of a GPS receiver in which the crystal oscillator is disposed, an initial temperature of the crystal oscillator is measured and a PLL is set to an initial frequency in association with the initial temperature. When acquisition fails in a region, the ppm region is changed. The temperature of the crystal oscillator is periodically measured and compared with the initial temperature, and the acquisition process is reset if there is a significant change in temperature. The GPS processor enters the tracking phase when acquisition is successful.

Abstract: A circuit for down-converting an RF signal to a baseband signal includes a trans-admittance amplifier adapted to receive the RF signal and generate in response a pair of differential current signals. The circuit further includes a trans-impedance amplifier having at least four mixers and at least four linear amplifiers. The four mixers frequency down-convert the pair of differential current signals to generate four pairs of differential baseband current signals, wherein each pair of the differential baseband current signals has a different phase and is associated with each of the linear amplifiers. Additionally, the circuit includes a summing block that generates an in-phase signal using a first weighted sum of the four different baseband current signals and a quadrature signal using a second weighted sum of the four different baseband current signals. The circuit further includes an analog-to-digital converter for converting the in-phase and quadrature signals to respective digital representations.

Abstract: A wireless diversity receiver includes, in part, N signal processing paths, a bin-wise combiner, and an inverse transformation module. Each signal processing path includes, in part, a mixer adapted to downconvert a frequency of an RF signal received by that path, an analog-to-digital converter adapted to convert the downconverted signal from an analog signal to a digital signal, and a transformation block adapted to transform the digital signal represented in time domain to an associated frequency domain signal having M subband signals. The bin-wise combiner is configured to combine the corresponding subband signals of the N paths. The inverse transformation block is configured to transform the output of the bin-wise combiner to an associated time-domain signal.

Abstract: To compensate for roll-off while estimating a communication channel, an estimate of the channel is provided using a signal transmitted via the communication channel. The pilot tones positioned along the edges of the estimated channel are divided by the corresponding pilot tones of the received signal to generate a first number of ratios. An algorithm is thereafter applied to the first number of ratios to generate a second number of ratios associated with the non-pilot tones positioned along the edges of the estimated channel. Next, numbers that are inverse of the first and second number of ratios are applied to the pilot and non-pilot tones positioned along the edges of the estimated channel to compensate for the roll-offs in the estimated channel.

Abstract: A mobile communication device includes, in part, a first wireless receiver adapted to determine, as it travels along a path, a multitude of positions of the mobile communication device using signals received from a primary positioning source, a second wireless receiver adapted to receive signals from one or more ambient wireless sources as the mobile communication device travels along the path, and a positioning module. An internal or external memory stores estimated positions and corresponding time references of the signals of the one or more ambient sources. The positioning module uses the data stored in the database to estimate the position of the mobile communication device when no primary positioning source signal is available. The positioning module optionally uses the data stored in the database to improve estimates of the position of the mobile communication device when primary positioning signal is available.

Abstract: A receiver system and method for determining the location of a device in a wireless network having a plurality of transmitters is provided. The method includes receiving a signal at the device, transforming the received signal into a time-domain signal having a characteristic, and computing a range of the device from each of the plurality of transmitters based on the characteristic. Additionally, the method includes determining the location of the device based on the computed ranges. In certain embodiments, the characteristic may be a time of arrival, time difference of arrival, or a signal strength, and the wireless network is a DTV broadcasting network.

Abstract: A wideband receiver system is provided to concurrently receive multiple RF channels including a number of desired channels that are located in non-contiguous portions of a radio frequency spectrum and to group the number of desired channels into a contiguous frequency band. The system includes a wideband receiver having a complex mixer for down-shifting the multiple RF channels and transforming them to an in-phase signal and a quadrature signal in the baseband. The system further includes a wideband analog-to-digital converter module that digitizes the in-phase and quadrature signals and a digital frontend module that transforms the digital in-phase and quadrature signals to baseband signals that contains only the number of desired RF channels. that are now located in a contiguous frequency band. An up-converter module up-shifts the baseband signals to a contiguous band in an IF spectrum so that the system can directly interface with commercially available demodulators.

Abstract: A GPS receiver includes an RF front end for acquiring and tracking a satellite signal and a baseband processor configured to preserve power. The baseband processor includes a GPS engine configured to process the satellite signal and generate a PVT fix, a power supervisory module for receiving the PVT fix, and a user state module that determines an environmental state, wherein the power supervisory module may power down the GPS receiver for a period of time based on a result of the determined environment state. The baseband processor also includes a time-based management module that adjusts the TCXO in response to the determined environmental state. The GPS receiver includes a plurality of operation modes, each of which is associated with a plurality of tracking profiles.

Abstract: Methods and apparatuses for concurrently recording multiple radio channels. A recorder includes a wideband tuner having a complex mixer for converting a received wideband RF signal to a complex signal that is then digitized. A digital front end module applies a number of complex down-mixers to the digital complex signal to generate the multiple radio channels in the baseband. Each one of the multiple radio channels in the baseband is further filtered, decimated and demodulated. A digital signal processing unit encodes each demodulated channel according to an audio compression format and stores the then encoded audio content to a storage unit. An RBDS decoder parses radio data service information associated with the stored audio content. The radio data service information is stored in a first section of the storage unit while the encoded audio content is stored in a second section of the storage unit.

Abstract: A device includes an analog front end for receiving a radio frequency (RF) signal. The analog front end contains a local oscillator that is tuned to a local oscillation frequency for down-converting the received RF signal to a first intermediate frequency (IF) signal. An analog-to-digital converter module converts the first IF signal to a digital baseband signal. The device also includes a digital processing unit for processing the baseband signal. The digital processing unit generates multiple clock signals from a reference oscillator having digitally adjustable reference frequency. The reference frequency and the multiple clock signals may interfere with the local oscillator and generate several frequency spurs that may fall within the bandwidth of the received RF signal. In a preferred embodiment, the digital processing unit adjusts the reference frequency by a certain amount so that the spurs do not fall within the RF signal bandwidth.