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US 10,931,294 B2Granted
Apparatus and method for measuring frequency of signal
AssigneeAgency for Defense Development
InventorsSang Won Kim, Dong Keun Lee, Jeung Min Joo, Jung Hoon Kim, Sung Jin Jo, Un Seob Jeong
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Abstract
Provided are an apparatus and a method for measuring a frequency of a broadband signal by using low-speed ADCs having sub-Nyquist sampling rates. A plurality of channels each including a low-speed ADC having a sub-Nyquist sampling rate (e.g. sampling frequency from several MHz to hundreds of MHz) are provided, and the frequency of an input signal corresponding to a combination of frequencies calculated through the respective channels is estimated. Therefore, as the number of channels increases, the range of measurable frequencies may be extended.
Claims10
A frequency measuring apparatus comprising:
- a coupler configured to generate an I component and a Q component from an input signal;
- a distributor configured to distribute the I component and the Q component to a plurality of channels;
- the plurality of channels each comprising an analog digital convertor (ADC), which is configured to sample an I component and a Q component input thereto and quantize a sampled I component and a sampled Q component, and a frequency measuring unit configured to calculate a frequency from a quantized I component and a quantized Q component;
- and
- a frequency estimator configured to detect a signal frequency corresponding to a combination of frequency values respectively calculated in the plurality of channels based on frequency combination information including different signal frequencies and a combination of frequency values respectively corresponding to the signal frequencies,
- wherein respective ADCs included in the plurality of channels have different sampling speeds for sampling the I component and the Q component,
- wherein the frequency measuring unit
- generates trajectories corresponding to frequency values calculated in the plurality of channels according to a change of an input signal in a multi-dimensional space according to the number of channels, and
- when the trajectories overlap at least partially, changes a sampling frequency of each channel to satisfy a pre-set minimum distance between the trajectories.
6 more elements
A frequency measuring apparatus comprising:
- a coupler configured to generate an I component and a Q component from an input signal;
- a distributor configured to distribute the I component and the Q component to a plurality of channels;
- the plurality of channels each comprising an analog digital convertor (ADC), which is configured to sample an I component and a Q component input thereto and quantize a sampled I component and a sampled Q component, and a frequency measuring unit configured to calculate a frequency from a quantized I component and a quantized Q component;
- and
- a frequency estimator configured to detect a signal frequency corresponding to a combination of frequency values respectively calculated in the plurality of channels based on frequency combination information including different signal frequencies and a combination of frequency values respectively corresponding to the signal frequencies,
- wherein respective ADCs included in the plurality of channels have different sampling speeds for sampling the I component and the Q component,
- wherein the frequency measuring unit comprises:
- a delay correlator configured to perform a correlation operation with values obtained by 1-clock delaying a quantized I component and a quantized Q component;
- a cumulator configured to accumulate I component values and Q component values correlated by the delay correlator on an I and Q coordinate plane;
- and
- a frequency calculator configured to calculate average values for each of accumulated I component values and accumulated Q component values that are accumulated on the I and Q coordinate plane, calculate a phase change range based on calculated average values of the accumulated I component values and the accumulated Q component values, and calculate a frequency value corresponding to a calculated phase change rate.
8 more elements
A frequency measuring method comprising:
- a first step for generating an I component and a Q component from an input signal;
- a second step for distributing the I component and the Q component to a plurality of channels;
- a third step for sampling the I component and the Q component in each channel;
- a fourth step for quantizing a sampled I component and a sampled Q component in each channel;
- a fifth step for calculating a frequency value based on a quantized I component and a quantized Q component in each channel;
- a sixth step for generating a combination of frequency values calculated in respective channels;
- and
- a seventh step for estimating a signal frequency corresponding to generated combinations of frequency values based on frequency combination information including different signal frequencies and a combination of frequency values respectively corresponding to the signal frequencies,
- wherein the third step is a step for sampling the I component and the Q component input to the respective channels at different sampling speeds from one channel to another,
- wherein the seventh step comprises:
- a step 7-1 for generating trajectories corresponding to frequency values calculated in the plurality of channels according to a change of an input signal in a multi-dimensional space according to the number of channels;
- and
- a step 7-2 for, when the trajectories overlap at least partially, changing a sampling frequency of each channel to satisfy a pre-set minimum distance between the trajectories.
10 more elements
A frequency measuring method comprising:
- a first step for generating an I component and a Q component from an input signal;
- a second step for distributing the I component and the Q component to a plurality of channels;
- a third step for sampling the I component and the Q component in each channel;
- a fourth step for quantizing a sampled I component and a sampled Q component in each channel;
- a fifth step for calculating a frequency value based on a quantized I component and a quantized Q component in each channel;
- a sixth step for generating a combination of frequency values calculated in respective channels;
- and
- a seventh step for estimating a signal frequency corresponding to generated combinations of frequency values based on frequency combination information including different signal frequencies and a combination of frequency values respectively corresponding to the signal frequencies,
- wherein the third step is a step for sampling the I component and the Q component input to the respective channels at different sampling speeds from one channel to another,
- wherein the fifth step includes a step for calculating a frequency value according to Equation 4 below,
- f
- avg
- m
-
- (
- n
- )
- =
-
- Δϕ
- avg
- m
-
- (
- n
- )
- 2
-
- πΔ
-
-
- t
- =
- 1
- 2
-
- π
-
-
- t
- s
-
- atan
-
- (
- Q
- avg
- m
- ′
-
- (
- n
- )
- I
- avg
- m
- ′
-
- (
- n
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- =
-
- 1
- 2
-
- π
-
-
- t
- s
-
- atan
-
- (
- ∑
- k
- =
- n
- -
- m
- +
- 1
- n
-
-
- Q
- ′
-
- (
- k
- )
- m
- ∑
- k
- =
- n
- -
- m
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- 1
- n
-
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- I
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- (
- k
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- m
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- [
- Equation
-
-
- 4
- ]
- where favgn(n) denotes a frequency value measured with the last m samples, Δϕavgm(n) denotes an average phase angle change rate of the last m samples, Δt denotes a time for the last m samples, ts denotes 1/sampling frequency (fs), Q′avgm(n) denotes an average of Q component correlation values Q′ of the last m samples, I′avgm(n) denotes an average of I component correlation values I′ of the last m samples, and m denotes the number of samples-used for averaging.
117 more elements
Dependencies are inferred from the claim text.