摘要:
Aspects of a method and system for a radio data service (RDS) demodulator for a single chip integrated Bluetooth and frequency modulation (FM) transceiver and baseband processor are presented. Aspects of the system may include circuitry on a single chip that enables demodulation of an RDS signal, filtering of the RDS signal, and detection of binary bits in the filtered RDS signal. The filtered RDS signal may be generated by filtering the RDS signal based on a raised cosine filter, or a doublet filter. In general, the RDS signal may also be filtered by a filter that is a first, or greater derivative of a Gaussian filter in either the time or frequency domain. Aspects of the method may include demodulating the RDS signal, filtering the RDS signal, and detecting binary bits in the filtered RDS signal.
摘要:
Certain aspects of determining a signal quality metric in event of a CRC false positive may comprise measuring an amplitude and/or phase of at least a portion of a phase shift keyed section of a frame. The measured amplitude and/or phase may be checked to determine if it lies within a range of a reference amplitude and/or phase respectively. An amplitude and/or phase counter may be incremented if the measured amplitude and/or phase lies outside the range of the reference amplitude and/or phase respectively. A confidence level value of a cyclic redundancy check (CRC) for at least a portion of the phase shift keyed section of the frame may be determined based on a determined value of the incremented amplitude and/or phase counter.
摘要:
In RF transceivers, a method and system for using phase shift key (PSK) sync word for fine tuning frequency adjustment are provided. One aspect of the invention provides for adjusting a local oscillator frequency in a radio frequency (RF) receiver when a residual DC offset remains after a coarse frequency offset adjustment if performed. The fine adjustment may be necessary because of the synchronization required with a PSK-based modulated portion of a Bluetooth packet. A residual phase shift detected in a sync sequence portion of the Bluetooth packet may be utilized to determine a residual or fine frequency adjustment. This approach may allow an RF receiver to operate, in some instances, without the need for an equalizer. In this regard, the power consumed by the RF receiver may be minimized and/or the overall cost of the RF receiver may be reduced.
摘要:
A method and system for digital spur cancellation may include removing a spur in a left channel minus right channel (L−R) baseband signal generated from a FM signal. The L−R baseband signal may be generated by demodulating a sub-carrier, for example, by using CORDIC algorithm, in a signal demodulated from the FM signal. An orthogonal signal may also be generated by demodulating a sub-carrier, for example, by using CORDIC algorithm, in a signal demodulated from the FM signal. The phase of the orthogonal signal may be further adjusted to introduce a substantially −90° phase shift to spurs at a specific frequency. Accordingly, the spurs in the L−R baseband signal may be cancelled when the first L−R baseband signal is combined with the phase adjusted orthogonal signal.
摘要:
A method for calibrating a filter begins with the filter filtering a first signal having a first frequency to produce a first filtered signal, wherein the first frequency is in a known pass region of the filter. The processing continues by measuring signal strength of the first filtered signal to produce a first measured signal strength. The processing continues with the filter filtering a second signal having a second frequency to produce a second filtered signal, wherein the second frequency is at a desired corner frequency of the filter. The processing continues by measuring signal strength of the second filtered signal to produce a second measured signal strength. The processing continues by comparing the first measured signal strength with the second measured signal strength to determine whether the filter has attenuated the second signal by a desired attenuation value with respect to the first signal. The processing continues by adjusting filter response of the filter to produce an adjusted filter response when the filter has not attenuated the second signal by the desired attenuation value with respect to the first signal.
摘要:
A method for calibrating a phase locked loop (PLL) includes an open loop test and a closed loop test. The open loop test includes providing an optimal control input to a controlled oscillator (CO) of the PLL; determining rate of output oscillation of the CO based on the optimal control input; comparing the rate of the output oscillation with rate of an optimal output oscillation; and when the comparing the rate of the output oscillation with rate of the optimal output oscillation is unfavorable, adjusting an oscillation point of the CO until the comparing is favorable to produce an open-loop adjusted CO oscillation point. The close loop test includes determining a closed-loop input control level of the CO at the open-loop adjusted CO oscillation point; comparing the closed-loop input control level with the optimal control input; and when the comparing the closed-loop input control level with the optimal control input is not favorable, adjusting the open-loop adjusted CO oscillation point until the comparing is favorable.
摘要:
A method for determining attenuation of a transmit/receive switch for attenuating inbound RF signals begins by enabling the transmit/receive switch to provide a loop back configuration between a transmitter section and a receiver section of a radio frequency integrated circuit. When the transmit section provides a test RF signal to the receiver section the processing continues when the receiver section measures the signal strength of the test RF signal to produce a 1st signal strength. The processing continues by enabling receive attenuation mode of the transmit/receive switch. The processing continues when the transmit section provides another test RF signal to the receiver section via the transmit/receive switch in the receive attenuation mode to produce an attenuated test RF signal. The processing continues when the receive section measures the signal strength of the attenuated test RF signal to produce a 2nd signal strength. The processing continues when the 1st signal strength is compared with the 2nd signal strength to determine the attenuation of the transmit/receive switch.
摘要:
A method for adjusting a DC offset slice point in an RF receiver is provided and may comprise estimating DC offset using a combination of fast tracking of an input signal and slow tracking of an input signal. If both are used, the fast tracking may be executed prior to executing the slow tracking. The fast tracking may acquire synchronizing signals transmitted before a payload. Additionally, noise tolerance may be increased in the fast tracking and the slow tracking by using tracking envelopes. The fast tracking may average acquisition envelopes and tracking envelopes using a fast tracking weighting factor to a sum of the acquisition envelopes and a slow tracking weighting factor to a sum of the tracking envelopes. Additionally, the slow tracking may average the tracking envelopes.
摘要:
A method for calibrating a filter begins with the filter filtering a first signal having a first frequency to produce a first filtered signal, wherein the first frequency is in a known pass region of the filter. The processing continues by measuring signal strength of the first filtered signal to produce a first measured signal strength. The processing continues with the filter filtering a second signal having a second frequency to produce a second filtered signal, wherein the second frequency is at a desired corner frequency of the filter. The processing continues by measuring signal strength of the second filtered signal to produce a second measured signal strength. The processing continues by comparing the first measured signal strength with the second measured signal strength to determine whether the filter has attenuated the second signal by a desired attenuation value with respect to the first signal. The processing continues by adjusting filter response of the filter to produce an adjusted filter response when the filter has not attenuated the second signal by the desired attenuation value with respect to the first signal.
摘要:
A method and system for a single chip integrated Bluetooth and FM transceiver and baseband processor are provided. The single chip may comprise a Bluetooth radio, an FM radio, a processor system, and a peripheral transport unit (PTU). FM data may be received and/or transmitted via the FM radio and Bluetooth data may be received and/or transmitted via the Bluetooth radio. The FM radio may receive radio data system (RDS) data. The PTU may support digital and analog interfaces. A processor in the processor system may time-multiplex processing of FM data and processing of Bluetooth data. The single chip may operate in an FM-only, a Bluetooth-only, and an FM-Bluetooth mode. The single chip may reduce power consumption by disabling portions of the Bluetooth radio during FM-only mode and/or disabling analog circuitry when performing digital processing. Communication between Bluetooth and FM channels may be enabled via the single chip.