System and method for real-time spectrum analysis in a communication device

A system for synchronizing to a communication signal, comprising:

• a. a clock module comprising:
• i. at least N registers, each of which stores a programmable duration value associated with one of two states of a pulse of the communication signal, where N is equal to 2 times the number of pulses in a cycle of the communication signal;
• ii. a down counter driven by a clock signal that counts down with each clock pulse from a value corresponding to the content of one of the N registers;
• iii. a mod(N) counter coupled to the down counter that counts up to N−1 by one in response to the down counter reaching zero and when reaching N−1, causing content of the next of the N registers to be loaded into the down counter;
• b. a pulse detector circuit that detects a signal pulse in the communication signal;
• and
• c. a processor coupled to the clock module and to the signal detector circuit, wherein the processor examines the count values of the down counter and the mod(N) counter to measure a phase error between the clock signal used to drive the down counter and the pulse of the communication signal.

In a radio device that operates in a frequency band, a method for analyzing activity in the frequency band based on signals received by the radio device, comprising steps of:

• a. computing Fast Fourier Transform (FFT) values at a plurality of frequency bins from a digital signal representing activity in a frequency band during a time interval;
• b. computing the power at each frequency bin;
• c. adding the power at each frequency bin for a current time interval with the power at the corresponding frequency bin for a previous time interval to obtain a running sum of the power at each frequency bin;
• d. comparing the power at each frequency bin with a power threshold to obtain a duty count of the number of times that the power at each frequency bin exceeds the power threshold over time intervals;
• and
• e. comparing the power at each frequency bin for a current time interval with the power at the corresponding frequency bin for a previous time interval to track the maximum power in each frequency binover time intervals.

A processor readable medium encoded with instructions that, when executed by a processor, cause the processor to perform steps of:

• a. computing Fast Fourier Transform (FFT) values at a plurality of frequency bins from a digital signal representing activity in a frequency band during a time interval;
• b. computing the power at each frequency bin;
• c. adding the power at each frequency bin for a current time interval with the power at the corresponding frequency bin for a previous time interval to obtain a running sum of the power at each frequency bin;
• d. comparing the power at each frequency bin with a power threshold to obtain a duty count of the number of times that the power at each frequency bin exceeds the power threshold over time intervals;
• and
• e. comparing the power at each frequency bin for a current time interval with the power at the corresponding frequency bin for a previous time interval to track the maximum power in each frequency bin over time intervals.

A spectrum analysis device for use in a radio device that operates in a frequency band, comprising:

• a. a Fast Fourier Transform (FFT) block that receives as input a digital signal representing activity in the frequency band for a time interval, wherein the FFT block computes FFT values for each of a plurality of frequency bins from the digital signal;
• b. a power calculation block that computes the power at each frequency bin and outputs a power data field comprising power values for the plurality of frequency bins;
• c. a signal detector circuit comprising:
• i. a peak detector that receives as input the power data field for successive time intervals of activity in a frequency band, and detects one or more peaks in the spectral information, the peak detector outputting information identifying peaks for each time interval;
• and
• ii. at least one pulse detector coupled to the peak detector that detects signal pulses that satisfy characteristics based on the output of the peak detector;
• d. a memory that stores one or more of:
• a running sum of the power at each frequency bin over time intervals;
• a duty count comprising a running sum at each time interval of the number of times the power at each frequency bin exceeds the power threshold;
• a maximum power for each frequency bin for the current and prior time intervals;
• and a running count of the number of time intervals in which a certain number of peaks have been detected.

A method for detecting radio signals in a frequency band comprising steps of:

• a. operating a radio receiver in a wideband mode so as to generate a downconverted signal representing activity in the entire frequency band;
• b. performing spectral analysis on the downconverted signal to generate spectral information of the frequency band;
• and
• c. detecting signal pulses of signals expected to be present in the frequency band from the downconverted signal by examining, from the spectral information, one or more of a bandwidth, center frequency and duration of peaks in the spectral information and determining whether it is within a corresponding range of one or more of those parameters.

A processor readable medium encoded with instructions that, when executed by a processor, cause the processor to perform steps of:

• a. computing Fast Fourier Transform (FFT) values for each of a plurality of frequency bins from a digital signal representing activity in a frequency band for a time interval;
• b. computing the power at each frequency bin from the FFT values;
• c. detecting one or more peaks from the FFT values;
• and
• d. detecting signal pulses that meet one or more characteristics from the detected one or more peaks;
• e. computing one or more of a running sum of the power at each frequency bin over time intervals, a duty count comprising a running sum at each time interval of the number of times the power at each frequency bin exceeds a power threshold, a maximum power for each frequency bin for the current and prior time intervals, and a running count of the number of time intervals in which a certain number of peaks have been detected.

A processor readable medium encoded with instructions that, when executed by a processor, cause the processor to perform steps of:

• a. computing Fast Fourier Transform (FFT) values for each of a plurality of frequency bins from a digital signal representing activity in a frequency band for a time interval;
• b. computing the power at each frequency bin from the FFT values;
• c. detecting one or more peaks from the FFT values;
• and
• d. detecting signal pulses that meet one or more characteristics from the detected one or more peaks;
• e. comparing the occurrence of the pulse with a local clock signal;
• f. determining a phase error between the occurrence of the pulse and a state of the local clock signal;
• and
• g. delaying or advancing the local clock signal by an amount corresponding to the phase error.

A system comprising:

• a. a Fast Fourier Transform (FFT) block that receives as input a digital signal representing activity in the frequency band and computes FFT values for a plurality of frequency bins for a time interval;
• and
• b. a power calculation block coupled to the FFT block that computes the power at each frequency bin at each time interval;
• c. a peak detector that receives as input an output of the power calculation block for successive time intervals of activity in a frequency band, detects one or more peaks in the spectral information and outputs information identifying peaks for each time interval;
• d. at least one pulse detector coupled to the peak detector, the pulse detector detects signal pulses that satisfy one or more characteristics based on the output of the peak detector;
• and
• e. a memory that stores one or more of a running sum of the power at each frequency bin over time intervals;
• a duty count comprising a running sum at each time interval of the number of times the power at each frequency bin exceeds the power threshold;
• a maximum power for each frequency bin for the current and prior time intervals;
• and a running count of the number of time intervals in which a certain number of peaks have been detected.