Signal quality measurement device and signal quality measurement method

Abstract

The invention provides a signal quality measuring device and a signal quality measuring method. The signal quality measuring device comprises a processing circuit and a signal quality measuring circuit. The processing circuit receives a reference signal from a first circuit, receives a signal to be measured from a second circuit, and obtains a processed signal from the signal to be measured by referring to the reference signal, and the signal to be measured is obtained by processing a predetermined signal of the reference signal. The signal quality measuring circuit calculates a signal quality value according to the reference signal and the processed signal.

Description

Technical Field

[0001] The present invention relates to wireless communication, and more particularly to a method and apparatus for calculating a signal quality value based on a reference signal (e.g., a baseband modulation signal) and a signal under test obtained from a predetermined signal processing (e.g., frontend signal processing). Background Art

[0002] Due to its excellent low power consumption and low complexity in implementation, Gaussian frequency shift keying (GFSK) modulation signals have been applied to various wireless communication systems, such as Bluetooth (BT) systems. With the progress of wireless communication technology, more and more advanced GFSK modulators have been used. For example, advanced GFSK modulators can adopt direct polar-modulation, all digital phase-locked loop (ADPLL), one-point polar-modulation, or two-point polar-modulation. However, the common tools for verifying the modulation accuracy or signal quality of GFSK modulation signals are to check the frequency deviation (FD) of the opening of the eye pattern (also called eye diagram) displayed on the oscilloscope screen, or to compare the average FD values obtained when the input bits are "11110000" and "10101010" respectively. Therefore, an innovative signal quality measurement design is needed, which can calculate the signal quality value to quantify the signal quality or modulation accuracy of the output signal of the device under test (DUT) in a wireless communication device (e.g., a BT device or a ZigBee device) without using any test instrument. Summary of the Invention

[0003] One object of the present invention is to provide a method and apparatus for calculating a signal quality value based on a reference signal (e.g., a baseband modulation signal) and a signal under test obtained from a predetermined signal processing (e.g., frontend signal processing).

[0004] In an embodiment of the present invention, a signal quality measurement device is disclosed. The signal quality measurement device includes a processing circuit and a signal quality measurement circuit. The processing circuit is configured to receive a reference signal from a first circuit and a signal under test from a second circuit, and obtain a processed signal from the signal under test with reference to the reference signal, wherein the signal under test is obtained by processing a predetermined signal of the reference signal. The signal quality measurement circuit is configured to calculate a signal quality value based on the reference signal and the processed signal.

[0005] In an embodiment of the present invention, a signal quality measurement method is disclosed. The signal quality measurement method includes: receiving a reference signal from a first circuit and a signal under test from a second circuit, wherein the signal under test is obtained by processing a predetermined signal of the reference signal; obtaining a processed signal from the signal under test with reference to the reference signal; and calculating a signal quality value based on the reference signal and the processed signal.

[0006] The signal quality measurement device and method of the present invention can calculate a signal quality value to quantify the signal quality or modulation accuracy of the output signal of a device under test in a wireless communication device (e.g., a BT device or a ZigBee device) without using any test instruments. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 It is a schematic diagram of a signal quality measurement device according to an embodiment of the present invention.

[0008] Figure 2 It is a schematic diagram of a processing circuit according to an embodiment of the present invention.

[0009] Figure 3 It is a schematic diagram of a signal quality measurement circuit according to an embodiment of the present invention.

[0010] Figure 4 It is the Figure 1 schematic diagram of the first wireless communication device whose signal quality is measured by using the signal quality measurement device proposed by the present invention shown in the figure.

[0011] Figure 5 It is the Figure 1 schematic diagram of the second wireless communication device whose signal quality is measured by using the signal quality measurement device proposed by the present invention shown in the figure.

[0012]

SYMBOL DESCRIPTION

[0013] 10: First circuit

[0014] 12: Second circuit

[0015] 100: Signal quality measurement device

[0016] 102, 200: Processing circuit

[0017] 104, 300: Signal quality measurement circuit

[0018] 202: Sampling rate conversion circuit

[0019] 204: Subsequent processing circuit

[0020] 206: Cross - correlation circuit

[0021] 208: Selection circuit

[0022] 302: Matching gain estimation circuit

[0023] 304: Adjustment circuit

[0024] 306: Calculation circuit

[0025] 400, 500: Wireless communication device

[0026] 402, 502: Digital baseband circuit

[0027] 404: Digital phase - locked loop circuit

[0028] 504: Power amplifier

[0029] S_X: Reference signal

[0030] S_Y: Signal to be measured

[0031] S_Y’: Processed signal

[0032] S_Y”: Resampled signal to be measured

[0033] SQ: Signal quality value

[0034] Fs_X, Fs_Y: Sampling rate

[0035] #t0: Optimal starting sample position

[0036] g opt : Optimal matching gain

[0037] g opt xS_Y’: Adjusted processed signal Detailed implementation manner

[0038] In the specification and claims, certain terms are used to refer to specific elements. Those skilled in the art should understand that hardware manufacturers may use different terms to refer to the same element. The specification and claims do not use the difference in names as a way to distinguish elements, but rather use the difference in the functions of the elements as the criterion for distinction. The terms "comprising" and "including" mentioned throughout the specification and claims are open-ended terms and should be interpreted as "including but not limited to". In addition, the term "coupled" or "coupling" herein includes any direct and indirect electrical connection means. Therefore, if a first device is described as being coupled to a second device in the text, it means that the first device can be directly electrically connected to the second device, or indirectly electrically connected to the second device through other devices and connection means.

[0039] Figure 1 FIG. is a schematic diagram of a signal quality measurement device according to an embodiment of the present invention. The signal quality measurement device 100 includes a processing circuit 102 and a signal quality measurement circuit 104. The processing circuit 102 is configured to receive a reference signal S_X from a first circuit 10 and a signal under test S_Y from a second circuit 12, and obtain a processed signal S_Y' from the signal under test S_Y with reference to the reference signal S_X. For example, the second circuit 12 is a device under test in a wireless communication device. Therefore, the signal under test S_Y is obtained by processing a predetermined signal (e.g., front-end signal processing) of the reference signal S_X. That is to say, the reference signal S_X has not been processed / destroyed by the predetermined signal processing and can be regarded as an ideal signal of the output signal of the second circuit 12. For example, the reference signal S_X can be the modulation result of a known random sequence of 0 and 1. In other words, the reference signal S_X can be a baseband modulation signal output by a modulator, and the modulator is part of a modulator / demodulator (modem) module in a wireless communication device. The signal quality measurement circuit 104 is used to calculate a signal quality value SQ based on the reference signal S_X and the processed signal S_Y'.

[0040] Figure 2 FIG. is a schematic diagram of a processing circuit according to an embodiment of the present invention. Figure 1 The illustrated processing circuit 102 can use Figure 2It is implemented by the processing circuit 200 shown. In this embodiment, the processing circuit 200 includes a sampling rate conversion (hereinafter simply referred to as "SRC") circuit 202 and a subsequent processing circuit 204. The subsequent processing circuit 204 may include a cross-correlation circuit 206 and a selection circuit 208. The first circuit 10 can generate a reference signal S_X (which is a digital signal) at a sampling rate Fs_X. The second circuit 12 can generate a signal under test S_Y (which is a digital signal) at a different sampling rate Fs_Y (i.e., ), so the reference signal S_X can include a sample sequence composed of multiple samples x n {x n , n = 0, 1,..., N - 1}, and the signal under test S_Y can include a sample sequence composed of multiple samples y m {y m , m = 0, 1,..., M - 1}. The SRC circuit 202 is used to perform an SRC operation on the signal under test S_Y (in particular, the samples y m of the signal under test S_Y) to generate a re-sampled signal under test S_Y". The SRC circuit 202 can generate a re-sampled signal under test S_Y" at the sampling rate Fs_X, so that the re-sampled signal under test S_Y" and the reference signal S_X have the same sampling rate. Therefore, the re-sampled signal under test S_Y" can include a sample sequence composed of multiple samples y" k {y" k , k = 0, 1,..., K - 1}.

[0041] The sampling rate Fs_Y is different from (e.g., higher or lower than) the sampling rate Fs_X. In the case where the sampling rate Fs_Y is higher than the sampling rate Fs_X, the SRC circuit 202 is configured as a down-sampler for performing down-sampling. In another case where the sampling rate Fs_Y is lower than the sampling rate Fs_X, the SRC circuit 202 is configured as an up-sampler for performing up-sampling. In other words, based on the magnitude relationship between the sampling rate Fs_X and the sampling rate Fs_Y, the SRC circuit 202 can be a down-sampler or an up-sampler. For simplicity, it is assumed hereinafter that the sampling rate Fs_Y is higher than the sampling rate Fs_X. Therefore, the SRC operation performed by the SRC circuit 202 includes down-sampling applied to the signal under test S_Y. Specifically, the reference signal S_X may include a plurality of samples x output at the sampling rate Fs_X during the period T_X n {x n , n = 0, 1, …, N-1}, the signal under test S_Y may include a plurality of samples y output at the sampling rate Fs_Y during the period T_Y m {y m , m = 0, 1, …, M-1}, and the resampled signal under test S_Y” may include a plurality of samples y” output at the sampling rate Fs_X during the period T_Y k {y” k , k = 0, 1, …, K-1}, where , and . Additionally, the start time of the period T_Y is earlier than the start time of the period T_X, and the end time of the period T_Y is later than the end time of the period T_X

[0042] After obtaining the resampled signal under test (e.g., the down-sampled signal under test) S_Y”, the subsequent processing circuit 204 is used to obtain the processed signal S_Y’ from the resampled signal under test S_Y” based on the reference signal S_X. Since the reference signal S_X and the signal under test S_Y are generated by different circuits 10, 12, the cross-correlation circuit 206 is used to perform the cross-correlation between the resampled signal under test S_Y and the reference signal S_X to find the best starting sample position #t0 of the resampled signal under test S_Y” (i.e., selecting from the K samples y” k {y” k , k = 0, 1, …, K-1} the one that can best match the N samples x n {x n, the sample position of the first sample in the sample sequence composed of N consecutive samples of the sample sequence {y", k = 0, 1, …, K - 1}, that is, the cross - correlation circuit 206 is to find the resampled signal under test S_Y" (which contains a series of samples y" output at the sampling rate Fs_X) k {y" k , k = 0, 1, …, K - 1}) which is a subset of the resampled signal under test S_Y" (which contains a series of samples y" output at the sampling rate Fs_X), and this subset has consecutive samples from #t0 to #t0 + N - 1 and has the maximum correlation with the reference signal S_X (which contains a series of samples x n {x n , n = 0, 1, …, N - 1}).

[0043] After the cross - correlation circuit 206 finds the optimal starting sample position #t0, the selection circuit 208 is used to extract N consecutive samples from the multiple samples y" k {y" k , k = 0, 1, …, K - 1} and outputs these N consecutive samples (i.e., a subset of the resampled signal under test S_Y") as the processed signal S_Y', where the N consecutive samples start from the sample y" corresponding to the optimal starting sample position #t0. Specifically, the subset of the SRC output (i.e., the resampled signal under test S_Y") with consecutive samples y" from #t0 to #t0 + N - 1 #t0 will be extracted and output as the processed signal S_Y'. Therefore, the processed signal S_Y' will contain a sample sequence composed of multiple samples y' #t0 ~y" #t0+N-1 and is a subset {y" n {y' n , n = 0, 1, …, N - 1} of the multiple samples y" in the resampled signal under test S_Y" output by the SRC circuit 202, and this subset is {y" k {y" k , k = 0, 1, …, K - 1} and is {y" k , k = #t0, …, #t0 + N - 1}.

[0044] Figure 3 is a schematic diagram of a signal quality measurement circuit according to an embodiment of the present invention. Figure 1 The signal quality measurement circuit 104 shown can be used Figure 3It is implemented by the signal quality measurement circuit 300 shown. In this embodiment, the signal quality measurement circuit 300 includes a matching gain estimation circuit 302, an adjustment circuit 304, and a calculation circuit 306. The matching gain estimation circuit 302 is used to find the best matching gain g for the processed signal S_Y' based on the reference signal S_X (in particular, multiple samples x of the reference signal S_X n {x n , n = 0, 1, …, N-1}) and the processed signal S_Y' (in particular, multiple samples y' of the processed signal S_Y' n {y' n , n = 0, 1, …, N-1}). In this embodiment, the matching gain estimation circuit 302 is used to find the best matching gain g that can minimize opt . For example, the following formula can be used to calculate the best matching gain g For example, the best matching gain g that can minimize can be found opt . For example, the following formula can be used to calculate the best matching gain g opt .

[0045] (1)

[0046] The adjustment circuit 304 can be implemented by a multiplier and is used to apply the best matching gain g opt to the processed signal S_Y' (in particular, multiple samples y' of the processed signal S_Y' n {y' n , n = 0, 1, …, N-1}) to generate an adjusted processed signal g opt xS_Y', which contains a sample sequence composed of multiple gain-adjusted samples .

[0047] The calculation circuit 306 is used to calculate the signal quality value SQ based on the reference signal S_X (in particular, multiple samples x of the reference signal S_X n ) and the adjusted processed signal g opt xS_Y' (in particular, multiple gain-adjusted samples of the adjusted processed signal g opt xS_Y' ). For example, the following formula can be used to calculate the signal quality value SQ.

[0048] (2)

[0049] The signal quality measurement scheme proposed by the present invention can be used to quantify the signal quality of constant envelope (CE) modulation signals, or alternatively, the signal quality measurement scheme proposed by the present invention can also be used to quantify the signal quality of non-constant envelope (non-CE) modulation signals. In short, any wireless communication device using the signal quality measurement scheme proposed by the present invention falls within the scope of the present invention.

[0050] Figure 4 is Figure 1 a schematic diagram of a first wireless communication device that measures its signal quality using the signal quality measurement device 100 proposed by the present invention shown in. In this embodiment, Figure 1 the first circuit 10 shown in can be the digital baseband (hereinafter simply referred to as "DBB") circuit 402 of the wireless communication device 400, and Figure 1 the second circuit 12 shown in can be the digital phase-locked loop (hereinafter simply referred to as "DPLL") circuit 404 of the wireless communication device 400. For example, the DPLL circuit 404 can be an all-digital phase-locked loop (hereinafter simply referred to as "ADPLL") circuit, and the DBB circuit 402 can include a baseband modulator / demodulator (baseband modem) module. When the DPLL circuit 404 is an ADPLL circuit, the phase sample and frequency offset sample (FD sample) output from the DBB circuit 402 to the DPLL circuit 404 can be used as the input for polarization modulation.

[0051] In the case where the wireless communication device 400 is a BT device, the reference signal S_X can be a GFSK modulation signal, which is the output of the modulator in the modulator / demodulator module of the DBB circuit 402. In one example, multiple samples x n {x n , n = 0, 1,..., N-1} in the reference signal S_X can be multiple waveform samples (I&Q samples), and multiple samples y m {y m , m = 0, 1,..., M-1} in the signal under test S_Y can be multiple waveform samples (I&Q samples). In another example, multiple samples x n {x n , n = 0, 1,..., N-1} in the reference signal S_X can be multiple FD samples, and multiple samples y m{y m , m = 0, 1, …, M-1} can be multiple FD samples. In yet another example, multiple samples x n {x n , n = 0, 1, …, N-1} can be multiple phase samples, and multiple samples y m {y m , m = 0, 1, …, M-1} can be multiple phase samples.

[0052] In another case where the wireless communication device 400 is a ZigBee device, the reference signal S_X can be an offset-quadrature phase shift keying (O-QPSK) modulation signal, which is the output of the modulator in the modulator / demodulator module of the DBB circuit 402. In one example, multiple samples x n {x n , n = 0, 1, …, N-1} can be multiple waveform samples (I&Q samples), and multiple samples y m {y m , m = 0, 1, …, M-1} can be multiple waveform samples (I&Q samples). In another example, multiple samples x n {x n , n = 0, 1, …, N-1} can be multiple FD samples, and multiple samples y m {y m , m = 0, 1, …, M-1} can be multiple FD samples. In yet another example, multiple samples x n {x n , n = 0, 1, …, N-1} can be multiple phase samples, and multiple samples y m {y m , m = 0, 1, …, M-1} can be multiple phase samples.

[0053] The signal quality measurement device 100 provides a tool to verify the modulation accuracy of the output of the DPLL circuit 404, evaluate the performance of the radio frequency (RF) design at the output of the DPLL circuit 404 after each revision, debug the RF design at the output of the DPLL circuit 404, evaluate the trade-off of the RF design at the output of the DPLL circuit 404 after each revision, or evaluate the modulation accuracy without expensive test instruments. In addition, the wireless communication device 400 can determine whether to correct the DPLL circuit 404 and how to correct the DPLL circuit 404 by comparing the previous signal quality value and the current signal quality value provided by the signal quality measurement device 100.

[0054] Figure 5 employs Figure 1 FIG. is a schematic diagram of a second wireless communication device that measures its signal quality using the signal quality measurement device 100 proposed by the present invention. In this embodiment, Figure 1 the first circuit 10 shown in FIG. may be the DBB circuit 502 of the wireless communication device 500, and Figure 1 the second circuit 12 shown in FIG. may be the analog RF circuit of the wireless communication device 500 (e.g., power amplifier (PA) 504). The reference signal S_X may be a GFSK modulation signal or an O-QPSK modulation signal. In one example, multiple samples x n {x n , n = 0, 1, …, N-1} in the reference signal S_X may be multiple waveform samples (I&Q samples), and multiple samples y m {y m , m = 0, 1, …, M-1} in the signal under test S_Y may be multiple waveform samples (I&Q samples). In another example, multiple samples x n {x n , n = 0, 1, …, N-1} in the reference signal S_X may be multiple magnitude samples (i.e., ), and multiple samples y m {y m , m = 0, 1, …, M-1} in the signal under test S_Y may be multiple magnitude samples. In yet another example, multiple samples x n {x n , n = 0, 1, …, N-1} in the reference signal S_X may be multiple power samples (i.e., ), and multiple samples y in the signal S_Y to be measured m {y m , m = 0, 1, …, M-1} can be multiple power samples. The wireless communication device 500 can perform optimization of the power amplifier 504 according to one or more signal quality values SQ provided by the signal quality measurement device 100.

[0055] Please note that the above various applications are only for illustrative purposes and are not limitations of the present invention. In some embodiments, the signal quality measurement device 100 can monitor the signal quality for transmit / receive (TX / RX) loop-back adjustment. In some embodiments, the signal quality measurement device 100 can monitor the currently received data packet or the currently used channel to report the signal quality value to the upper layer for TX / RX optimization. For example, if a signal quality value indicating poor signal quality is generated, the radio frequency circuit of the wireless communication device 400 / 500 can be triggered to be recalibrated. Another example is that if a signal quality value indicating poor signal quality is generated, the upper layer will be informed of the interfered channel, and the wireless communication device 400 / 500 will be prevented from using the interfered channel next time. In short, the present invention has no limitation on the applications designed using the signal quality measurement proposed by the present invention.

[0056] In an exemplary implementation, the signal quality measurement device 100 can be used to provide on-line signal quality measurement and calibration for the wireless communication device 400 / 500. For example, the wireless communication device 400 / 500 and the signal quality measurement device 100 can be integrated on the same chip. In another exemplary implementation, the signal quality measurement device 100 can be used to provide off-line signal quality measurement and debugging for the wireless communication device 400 / 500. For example, the signal quality measurement device 100 can be implemented by a processor that loads and executes program code to implement the functions of the processing circuit 102 and the signal quality measurement circuit 104. In other words, the signal quality measurement circuit 104 can be implemented by a processor (which executes a software module), and the signal quality measurement circuit 104 can be implemented by a processor (which executes another software module). Therefore, the designer of the wireless communication device 400 / 500 can obtain off-line signal quality measurement results without using any test instruments and can refer to the off-line signal quality measurement results to optimize the circuit design of the wireless communication device.

[0057] The above are only the preferred embodiments of the present invention, and all equivalent changes and modifications made according to the claims of the present invention shall fall within the scope of the present invention.

Claims

1. A signal quality measurement device, comprising: A processing circuit for receiving a reference signal from a first circuit and a signal under test from a second circuit, and obtaining a processed signal from the signal under test with reference to the reference signal, wherein the signal under test is obtained by processing a predetermined signal of the reference signal; and A signal quality measurement circuit for calculating a signal quality value based on the reference signal and the processed signal.

2. The signal quality measurement device according to claim 1, wherein the reference signal includes a plurality of first samples output at a first sampling rate, the signal under test includes a plurality of second samples output at a second sampling rate different from the first sampling rate, and the processing circuit includes: A sampling rate conversion circuit for performing a sampling rate conversion operation on the signal under test to generate a resampled signal under test, wherein the resampled signal under test includes a plurality of third samples output at the first sampling rate; and A subsequent processing circuit for obtaining the processed signal from the resampled signal under test with reference to the reference signal.

3. The signal quality measurement device according to claim 2, wherein the second sampling rate is higher than the first sampling rate, and the sampling rate conversion operation includes downsampling; or the second sampling rate is lower than the first sampling rate, and the sampling rate conversion operation includes upsampling.

4. The signal quality measurement device according to claim 2, wherein the subsequent processing circuit includes: A cross-correlation circuit for performing cross-correlation between the resampled signal under test and the reference signal to find the best starting sample position of the resampled signal under test; and A selection circuit for extracting a plurality of consecutive samples from the plurality of third samples of the resampled signal under test and outputting the plurality of consecutive samples as the processed signal, wherein the plurality of consecutive samples start from the third sample corresponding to the best starting sample position in the resampled signal under test.

5. The signal quality measurement device according to claim 1, wherein the reference signal includes a plurality of first samples output at a sampling rate, the processed signal includes a plurality of second samples output at the sampling rate, and the signal quality measurement circuit includes: A matching gain estimation circuit for finding the best matching gain for the processed signal based on the plurality of first samples and the plurality of second samples; An adjustment circuit for applying the best matching gain to the plurality of second samples included in the processed signal to respectively generate a plurality of gain-adjusted samples; and A calculation circuit for calculating the signal quality value based on the plurality of first samples and the plurality of gain-adjusted samples.

6. The signal quality measurement device according to claim 1, wherein the reference signal is a baseband modulated signal.

7. The signal quality measurement device according to claim 6, wherein the baseband modulated signal is a constant envelope modulated signal.

8. The signal quality measurement device according to claim 7, wherein the constant envelope modulated signal is a Gaussian frequency shift keying modulated signal or a ZigBee signal.

9. The signal quality measurement device as claimed in claim 1, wherein both the reference signal and the signal under test comprise a plurality of waveform samples, a plurality of frequency offset samples, or a plurality of phase samples.

10. The signal quality measurement device as claimed in claim 1, wherein the signal under test is the output of a digital phase-locked loop circuit or the output of a power amplifier.

11. A signal quality measurement method, comprising: receiving a reference signal from a first circuit and receiving a signal under test from a second circuit, wherein the signal under test is obtained by performing predetermined signal processing on the reference signal; obtaining a processed signal from the signal under test with reference to the reference signal; and calculating a signal quality value based on the reference signal and the processed signal.

12. The signal quality measurement method as claimed in claim 11, wherein the reference signal comprises a plurality of first samples output at a first sampling rate, the signal under test comprises a plurality of second samples output at a second sampling rate different from the first sampling rate, and the step of obtaining the processed signal from the signal under test with reference to the reference signal comprises: performing a sampling rate conversion operation on the signal under test to generate a resampled signal under test, wherein the resampled signal under test comprises a plurality of third samples output at the first sampling rate; and obtaining the processed signal from the resampled signal under test with reference to the reference signal.

13. The signal quality measurement method as claimed in claim 12, wherein the second sampling rate is higher than the first sampling rate, and the sampling rate conversion operation comprises downsampling; or the second sampling rate is lower than the first sampling rate, and the sampling rate conversion operation comprises upsampling.

14. The signal quality measurement method as claimed in claim 12, wherein the step of obtaining the processed signal from the resampled signal under test with reference to the reference signal comprises: performing cross-correlation between the resampled signal under test and the reference signal to find the best starting sample position of the resampled signal under test; and extracting a plurality of consecutive samples from the plurality of third samples of the resampled signal under test and outputting the plurality of consecutive samples as the processed signal, wherein the plurality of consecutive samples start from the third sample in the resampled signal under test corresponding to the best starting sample position.

15. The signal quality measurement method as claimed in claim 11, wherein the reference signal comprises a plurality of first samples output at a sampling rate, the processed signal comprises a plurality of second samples output at the sampling rate, and the step of calculating the signal quality value based on the reference signal and the processed signal comprises: finding a best matching gain for the processed signal based on the plurality of first samples and the plurality of second samples; applying the best matching gain to the plurality of second samples comprised in the processed signal to respectively generate a plurality of gain-adjusted samples; and calculating the signal quality value based on the plurality of first samples and the plurality of gain-adjusted samples.

16. The signal quality measurement method as claimed in claim 11, wherein the reference signal is a baseband modulated signal.

17. The signal quality measurement method according to claim 16, wherein the baseband modulation signal is a constant envelope modulation signal.

18. The signal quality measurement method according to claim 17, wherein the constant envelope modulation signal is a Gaussian frequency shift keying modulation signal or a ZigBee signal.

19. The signal quality measurement method according to claim 11, wherein both the reference signal and the signal to be measured include a plurality of waveform samples, a plurality of frequency offset samples, or a plurality of phase samples.

20. The signal quality measurement method according to claim 11, wherein the signal to be measured is an output of a digital phase-locked loop circuit or an output of a power amplifier.

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