Abstract:
A system and method for detecting the presence of a Bluetooth or Zigbee signal within a short period of time is disclosed. The signal identification circuit has two stages, a first stage that processes windows to determine whether noise is present, and a second stage that processes long windows to determine whether the signal is a particular lower-power network protocol. The signal identification circuit can be configured to detect Bluetooth at 1 Mbps, Bluetooth at 2 Mbps or Zigbee. The signal identification signal may be used to allow a lower-power network controller to coexist with a high duty cycle WiFi controller. The signal identification circuit may also be used for other functions, such as powering on a lower-power network controller, determining CCA, or determining which channel a packet is being transmitted on.
Abstract:
A method for communicating between a first radio frequency communications device including a first local oscillator and a second radio frequency communications device including a second local oscillator includes generating phase values based on samples of a received signal. Each of the phase values indicates an instantaneous phase of the received signal. The method includes unwrapping the phase values to generate unwrapped phase values. The method includes generating frequency offset estimates based on the unwrapped phase values. The method includes generating an average frequency offset estimate based on the unwrapped phase values. The method includes wrapping the average frequency offset estimate to generate a residual frequency offset estimate. The method includes adjusting the first local oscillator based on the residual frequency offset estimate, thereby reducing a frequency offset between the first local oscillator and the second local oscillator.
Abstract:
A method for communicating between a first radio frequency communications device including a first local oscillator and a second radio frequency communications device including a second local oscillator includes receiving a packet using a receiver of the first radio frequency communications device. The method includes detecting an average frequency offset based on sequential samples of the packet. The method includes applying a first adjustment to the first local oscillator to reduce a frequency offset between the first local oscillator and the second local oscillator. The first adjustment is based on the average frequency offset. The method includes, after adjusting the first local oscillator, transmitting a second packet to the second radio frequency communications device by the first radio frequency communications device using the first adjustment and the first local oscillator.
Abstract:
A method for operating a radio frequency communications system includes, while operating a first radio frequency communications device in a calibration mode, for each setting of a plurality of settings of a programmable gain amplifier in a receiver of the first radio frequency communications device configured in a zero-intermediate frequency mode of operation, generating an estimate of a DC offset in each of a plurality of digital samples received from an analog circuit path including the programmable gain amplifier, and storing in a corresponding storage element, a compensation value based on the estimate.
Abstract:
A system and method of minimizing interference and retries in an environment where two or more network protocols utilize the same frequency spectrum is disclosed. A lower-power network controller is co-located with a WIFI controller. The lower-power network controller listens for a signature that may indicate the presence of a low power protocol packet, such as BLE or Zigbee. The lower-power controller checks for a waveform that is representative of a Zigbee packet prior to generating a request signal to the WIFI controller. This maximizes the likelihood that no WIFI traffic will occur while the incoming packet is being received.
Abstract:
An apparatus includes a radio frequency (RF) receiver, which includes a digital signal arrival (DSA) detector to detect arrival of a transmitted signal. The DSA detector includes a signal correlator and at least one of (a) an absolute received signal strength indication (RSSI) detector; (b) a relative RSSI detector; and (c) a frequency offset detector). The RF receiver further includes a demodulator coupled to the DSA detector to demodulate a received signal and to provide a demodulated signal, and a synchronization word detector (SWD) coupled to the demodulator to receive the demodulated signal.
Abstract:
An apparatus includes a radio frequency (RF) receiver, which includes a digital signal arrival (DSA) detector to detect arrival of a transmitted signal. The DSA detector includes a signal correlator and at least one of (a) an absolute received signal strength indication (RSSI) detector; (b) a relative RSSI detector; and (c) a frequency offset detector). The RF receiver further includes a demodulator coupled to the DSA detector to demodulate a received signal and to provide a demodulated signal, and a synchronization word detector (SWD) coupled to the demodulator to receive the demodulated signal.
Abstract:
A system and method for one-way ranging is disclosed. The system comprises a transmitter, also referred to as tag, transmitting a packet having a first frequency. The receiver, also referred to as the locator, receives the first frequency and measures the phase at a specific point in time. At a predetermined time, the transmitter switches to a second frequency. This is performed while maintaining phase continuity. The receiver also switches to the second frequency at nearly the same time. The receiver then measures the phase of the second frequency at a second point in time. Based on these two phase measurements, the distance between the transmitter and the receiver may be calculated.
Abstract:
An apparatus includes a radio-frequency (RF) receiver for receiving an RF signal using a plurality of antennas. The RF receiver includes a demodulator to provide a switch signal to cause the RF receiver to use an antenna in the plurality of antennas. The RF receiver further includes a carrier frequency offset (CFO) correction circuit that uses an estimation of the carrier frequency offset and an estimation of phase differences to remove the carrier frequency offset.
Abstract:
An apparatus includes a radio-frequency (RF) receiver for receiving an RF signal using a plurality of antennas. The RF receiver includes a demodulator to provide a switch signal to cause the RF receiver to use an antenna in the plurality of antennas. The RF receiver further includes a carrier frequency offset (CFO) correction circuit that estimates and removes a carrier frequency offset.