Communication device and effective signal detection method

Abstract

The effective signal detection method comprises the following operations: calculating a delay-related function of a communication signal by using a first period to determine first delay-related information; calculating the delay-related function of the communication signal using a second period to determine second delay-related information, wherein the first period is greater than the second period; and judging whether the communication signal is interference or not according to the first delay related information and the second delay related information.

Description

Technical Field

[0001] The present invention relates to a communication device, and more particularly to a communication device and an effective signal detection method thereof that can utilize delay correlation to determine whether a received signal is interference. Background Art

[0002] In practical applications, the communication signal received by the communication system is usually a valid signal, interference, or a combination of the two. Since the valid signal usually contains periodic symbols, the communication system can detect whether the received communication signal is a valid signal based on delay correlation. However, if the interference in the environment is a DC signal or a periodic signal, it may affect the detection result of delay correlation and mistakenly judge the interference as a valid signal, resulting in reduced system performance. Summary of the invention

[0003] In some embodiments, one of the objectives of the present invention is (but not limited to) to provide a communication device and an effective signal detection method thereof that can use delay correlation to determine whether a received signal is interference, so as to improve the deficiencies of the background technology.

[0004] In some embodiments, the communication device includes a receiving circuit and a processing circuit. The receiving circuit is used to receive a communication signal. The processing circuit is used to calculate the delay correlation function of the communication signal using a first period to determine first delay related information, and calculate the delay correlation function of the communication signal using a second period to determine second delay related information, and determine whether the communication signal is interference based on the first delay related information and the second delay related information, wherein the first period is greater than the second period.

[0005] In some embodiments, the effective signal detection method includes the following operations: using a first period to calculate a delay correlation function of a communication signal to determine first delay related information; using a second period to calculate the delay correlation function of the communication signal to determine second delay related information, wherein the first period is greater than the second period; and determining whether the communication signal is interference based on the first delay related information and the second delay related information.

[0006] The features, implementation and effects of the present invention will be described in detail below with reference to the accompanying drawings for preferred embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 This is a schematic diagram of a communication device according to some embodiments of the present invention.

[0008] Figure 2 The flowchart is a method for effectively detecting a signal according to some embodiments of the present invention.

[0009] Figure 3 According to some embodiments of the present invention, Figure 1 Schematic diagram of simulation (or measurement) results of a communication device.

[0010] Figure 4A According to some embodiments of the present invention, Figure 2 Flowchart of the operations in .

[0011] Figure 4B According to some embodiments of the present invention, Figure 2 Flowchart of the operations in .

[0012] Figure 5 According to some embodiments of the present invention, Figure 2 Flowchart of the operations in . DETAILED DESCRIPTION

[0013] All words used herein have their ordinary meanings. The definitions of the above words in commonly used dictionaries and the use examples of any of the words discussed herein in the context of the present invention are merely illustrative and should not limit the scope and meaning of the present invention. Similarly, the present invention is not limited to the various embodiments shown in this specification.

[0014] As used herein, "coupled" or "connected" may refer to two or more elements making direct physical or electrical contact with each other, or making indirect physical or electrical contact with each other, or may refer to two or more elements operating or acting on each other. As used herein, the term "circuit" may refer to a device composed of at least one transistor and / or at least one active and passive element connected in a certain manner to process signals.

[0015] As used herein, the term "and / or" includes any combination of one or more of the listed associated items. In this article, the words first, second, and third are used to describe and distinguish each element. Therefore, the first element in this article can also be referred to as the second element without departing from the original intention of the present invention. For ease of understanding, similar elements in the drawings will be designated with the same reference numerals.

[0016] Figure 1 Schematic diagram of a communication device 100 drawn according to some embodiments of the present invention. In some embodiments, the communication device 100 may be, but not limited to, a wireless communication device. The communication device 100 includes a receiving circuit 110 and a processing circuit 120. In some embodiments, the receiving circuit 110 may be, but not limited to, a circuit for receiving signals in a transceiver (not shown) in the communication device 100. In some embodiments, the processing circuit 120 may be implemented by, but not limited to, at least one microcontroller circuit with computing capabilities and / or at least one digital signal processing circuit, but the present invention is not limited thereto.

[0017] The receiving circuit 110 can receive the communication signal SIN. The processing circuit 120 is coupled to the receiving circuit 110 to receive the communication signal SIN and perform the following operations according to the communication signal SIN. Figure 2 The processing circuit 120 can perform multiple operations in order to determine whether the communication signal SIN currently received by the receiving circuit 110 is interference. If the communication signal SIN is determined to be interference, the processing circuit 120 can discard the currently received communication signal SIN and will not perform subsequent signal processing on it. If the communication signal SIN is determined to be a valid signal (i.e., it is determined that the communication signal SIN is not interference), the processing circuit 120 can further determine whether the communication signal SIN is a data packet of a predetermined communication protocol, thereby selectively performing corresponding signal processing on the communication signal SIN.

[0018] Figure 2 FIG. 2 is a flow chart of a valid signal detection method 200 according to some embodiments of the present invention. In some embodiments, multiple operations of the valid signal detection method 200 may be performed by Figure 1 The processing circuit 120 in the embodiment is executed, but the present invention is not limited thereto.

[0019] In operation S210, a communication signal (eg, Figure 1 A delay correlation function of a communication signal SIN) is used to determine the first delay related information. In operation S220, the delay correlation function of the communication signal is calculated using a second cycle (for example, the second cycle L2 described later) to determine the second delay related information, wherein the first cycle is greater than the second cycle. In operation S230, the communication signal is determined to be interference based on the first delay related information and the second delay related information. If the communication signal is determined to be interference, operation S240 is performed. If the communication signal is determined not to be interference, operation S250 is performed. In operation S240, the communication signal is not processed. In operation S250, the communication signal is determined to be a valid signal of a predetermined communication protocol based on the first delay related information. In some embodiments, the detailed operation of operation S250 may refer to the algorithm of the existing delay correlation function. For example, as described later, in some embodiments, the first delay related information may include a first delay related output value and a first critical value. Under this condition, the processing circuit 120 may perform operation S250 to confirm whether the first delay related output value is greater than the product of the first critical value and the first cycle. If the first delay-related output value is greater than the product, the processing circuit 120 may determine that the communication signal SIN is a valid signal of the predetermined communication protocol, and perform subsequent data processing on the communication signal SIN accordingly.

[0020] The description of the multiple operations of the above-mentioned effective signal detection method 200 can refer to the above-mentioned multiple embodiments, so it will not be repeated here. The above-mentioned multiple operations are only examples and are not limited to being performed in the order in this example. Without violating the operation mode and scope of each embodiment of the present invention, the various operations under the effective signal detection method 200 can be appropriately increased, replaced, omitted or performed in a different order. Alternatively, one or more operations under the effective signal detection method 200 can be performed simultaneously or partially simultaneously.

[0021] To facilitate understanding of operations S210, S220, and S230 of the effective signal detection method 200, a mathematical model of a delay correlation function is described below (but the present invention is not limited thereto). In some embodiments, the delay correlation function can be expressed as the following formula (1):

[0022]

[0023] Among them, r i,n is the i-th antenna (not shown) of the communication device 100 Figure 1 ) is the communication signal SIN received at the nth time point, and τ is the period of a preamble sequence. In formula (1), the communication signal SIN is represented as a complex number with a real part and an imaginary part (i.e., r i,n ), which contains information about the signal amplitude and phase, which can be fully understood by ordinary technicians in this field, so it will not be repeated here. In addition, in formula (1) For r i,n-τ The complex conjugate of .

[0024] As mentioned above, the processing circuit 120 may use the first period to calculate the delay correlation function of the communication signal SIN to determine the first delay correlation information (ie Figure 2 Operation S210). In some embodiments, the first period may be the period of a symbol in a preamble defined in a predetermined communication protocol used by the communication device 100. For example, the predetermined communication protocol may be IEEE 802.15.4. In this protocol, the preamble in a data packet of a valid signal contains 8 identical symbols, and the period of each symbol is 16 microseconds (μs). Under this condition, the first period may be set to approximately 16 microseconds. In some embodiments, the first delay-related information may include a first delay-related output value and / or a first critical value. In detail, the processing circuit 120 may obtain an output value C(t) based on the delay-related function of formula (1), and accumulate the output value C(t) in a first period, and calculate the square of the accumulated result to generate a first delay-related output value. The above operation may be expressed as the following formula (2):

[0025]

[0026] Wherein, O1 is the first delay-related output value, and L1 is the first period.

[0027] In some embodiments, the processing circuit 120 may obtain an output value C(t) based on the delay correlation function of formula (1), and accumulate the square of the output value C(t) in a first period, and calculate the square of the accumulated result to generate a first critical value. The above operation can be expressed as the following formula (3):

[0028]

[0029] Wherein, TH1 is the first critical value.

[0030] Similarly, the second delay-related information may include a second delay-related output value and / or a second critical value. The processing circuit 120 may use the same operation and obtain the second delay-related output value and the second critical value in a second cycle, which may be expressed as equation (4) and equation (5) respectively:

[0031]

[0032]

[0033] Wherein, O2 is the second delay-related output value, TH2 is the second threshold value, and L2 is the second period. In some embodiments, the first period L1 is set to be greater than the second period L2. As described above, the first period L1 can be set to about 16 microseconds. In the example, the second period L2 can be set to, but not limited to, about 8 microseconds.

[0034] Figure 3 To draw a pair according to some embodiments of the present invention Figure 1 Schematic diagram of the result of simulation (or measurement) of the communication device 100. In some embodiments, the predetermined communication protocol is the aforementioned IEEE 802.15.4, the first period L1 is set to about 16 microseconds, the second period L2 is set to about 8 microseconds, and the power of the communication signal SIN is set to about -99 decibel milliwatts (dBm). According to the aforementioned parameter settings, the communication device 100 is simulated and / or measured, and the result is Figure 3 The relevant results are shown. Figure 3 , the horizontal axis is time (in microseconds), and the vertical axis is the ratio between the delay-related output value and a specific product, wherein the specific product may be the product of a corresponding threshold value and a corresponding period. For example, the value of line segment 300 is the ratio between the first delay-related output value O1 and the product of the first threshold value TH1 and the first period L1, which may be expressed as O1 / (TH1×L1), and the value of line segment 310 is the ratio between the second delay-related output value O2 and the product of the second threshold value TH2 and the second period L2, which may be expressed as O2 / (TH2×L2).

[0035] exist Figure 3 In the embodiment of FIG. 1 , the communication device 100 receives the communication signal SIN after approximately 32 microseconds. Figure 3 As shown, after 32 microseconds, the value of line segment 300 becomes larger and larger, while the value of line segment 310 continues to be in a lower value range. Since line segment 300 is generated based on the first delay-related information, and the first delay-related information is generated based on the first period L1 that is the same as the symbol period of the communication signal SIN, when the communication signal SIN with the same period begins to be received, the value of line segment 300 will begin to increase in response to the period correlation. In contrast, since line segment 310 is generated based on the second delay-related information, and the second delay-related information is generated based on the second period L2 that is smaller than the symbol period of the communication signal SIN, the value of line segment 310 will be maintained in a lower value range in response to the period difference. Accordingly, Figure 3 It can be seen that when the communication signal SIN is a valid signal defined in a predetermined communication protocol, the value of the line segment 300 obtained based on the first delay-related information (corresponding to the first period L1) will be significantly greater than the value of the line segment 310 obtained based on the second delay-related information (corresponding to the second period L2).

[0036] On the other hand, in the above-mentioned embodiment, if the communication signal SIN is replaced by additive white Gaussian noise, the result that the value of the line segment 300 is close to (or the same as) the value of the line segment 310 can be obtained. In other words, when the communication signal SIN received by the communication device 100 is mainly noise or when the communication signal SIN received by the communication device 100 is only interference caused by other devices, the value of the line segment 300 obtained based on the first delay-related information (corresponding to the first cycle L1) will be close to the value of the line segment 310 obtained based on the second delay-related information (corresponding to the second cycle L2). That is, when the communication signal SIN is a DC signal or noise, no matter how much the value of the calculation cycle used is, the delay-related information obtained will be quite close. Based on the above, the processing circuit 120 can confirm whether the communication signal SIN is interference according to the first delay-related information and the second delay-related information (i.e., operation S230).

[0037] Figure 4A According to some embodiments of the present invention, Figure 2In this embodiment, the processing circuit 120 is used to compare a first ratio between the first delay-related output value O1 and a first product and a second ratio between the second delay-related output value O2 and a second product to determine whether the communication signal SIN is interference, wherein the first product is a product of a first threshold value TH1 and a first period L1, and the second product is a product of a second threshold value TH2 and a second period L2.

[0038] In detail, in this embodiment, operation S230 includes steps S410, S420, S430 and S440. In step S410, a first ratio between the first delay-related output value and the first product and a second ratio between the second delay-related output value and the second product are compared, wherein the first product is the product of the first threshold value and the first period, and the second product is the product of the second threshold value and the second period (in Figure 4A In the example, the first ratio is greater than the second ratio, and the step S420 is performed. If the first ratio is not greater than the second ratio, the step S430 is performed. In the step S420, it is confirmed whether the difference between the first ratio and the second ratio is greater than a predetermined value. If the difference is greater than the predetermined value, the step S440 is performed. If the difference is not greater than the predetermined value, the step S430 is performed. In the step S430, it is determined that the communication signal is interference. In the step S440, it is determined that the communication signal is not interference.

[0039] It should be understood that the first ratio O1 / (TH1×L1) in step S410 is Figure 3 The value of line segment 300, and the second ratio O2 / (TH2×L2) in step S420 is Figure 3As mentioned above, after the communication signal SIN is initially received, if the first ratio O1 / (TH1×L1) is greater than the second ratio O2 / (TH2×L2) and the difference between the first ratio O1 / (TH1×L1) and the second ratio O2 / (TH2×L2) is larger (e.g., greater than a predetermined value), it indicates that the communication signal SIN may be a data packet defined under a predetermined communication protocol. Under this condition, the processing circuit 120 may determine that the communication signal SIN is not interference. Alternatively, if the first ratio O1 / (TH1×L1) is greater than the second ratio O2 / (TH2×L2) but the difference between the first ratio O1 / (TH1×L1) and the second ratio O2 / (TH2×L2) is lower (e.g., not greater than a predetermined value), or if the first ratio O1 / (TH1×L1) is not greater than the second ratio O2 / (TH2×L2), it indicates that the communication signal SIN is not a data packet defined under a predetermined communication protocol. Under this condition, the processing circuit 120 can determine that the communication signal SIN is interference. Accordingly, according to the above steps, the processing circuit 120 can use the first ratio O1 / (TH1×L1) and the second ratio O2 / (TH2×L2) generated based on the first delay related information and the second delay related information to determine whether the communication signal SIN is interference. In some embodiments, the aforementioned predetermined value can be based on simulation and / or measurement, and can be adjusted according to the relevant requirements of the predetermined communication protocol. In some embodiments, operation S230 may not include step S420.

[0040] Figure 4B According to some embodiments of the present invention, Figure 2 Flow chart of operation S230 in FIG. Figure 4A In this embodiment, operation S230 further includes step S433 and step S435. After executing step S420, if the difference is greater than a predetermined value, step S433 is executed. In step S433, it is determined whether the first delay-related output value has a second delay-related output value greater than a first predetermined multiple, wherein the first predetermined multiple is the square of the ratio between the first period and the second period (in Figure 4B It is expressed as O1>O2×(L1 / L2) 2 ). If the first delayed related output value is not greater than the first predetermined multiple (i.e. Figure 4B (L1 / L2) 2 ), execute step S430. Alternatively, if the first delay-related output value is greater than the second delay-related output value of the first predetermined multiple, execute step S435.

[0041] For example, as shown in equation (2) and equation (4), the processing circuit 120 generates the first delay-related output value O1 and the second delay-related output value O2 by accumulating the output value C(t) of the delay-related function in the first cycle and the second cycle respectively, and squaring the accumulated result. Therefore, if the communication signal SIN is a valid signal, the first delay-related output value O1 will be greater than the second delay-related output value O2 by a first predetermined multiple, wherein the first predetermined multiple is the square of the ratio between the first cycle L1 and the second cycle L2. For example, if the first cycle L1 is approximately 16 microseconds and the second cycle L2 is approximately 8 microseconds, the first predetermined multiple is approximately 4 (i.e., (16 / 8) 2 ). Therefore, step S433 can be expressed as O1>O2×4. If the first delay correlation output value O1 is not greater than the second delay correlation output value O2 by the first predetermined multiple, it means that the communication signal SIN may be interference (ie, step S430).

[0042] To explain it another way, in an ideal situation (i.e., the received communication signal SIN is a valid signal), the communication signal SIN of formula (1) will satisfy the following relationship:

[0043] r i,n =r i,n-L1

[0044] r i,n ≠r i,n-L2

[0045] Under this condition, it can be deduced from the previous equations (2) and (4) that the first delay-related output value O1 and the second delay-related output value O2 satisfy the following relationship:

[0046]

[0047]

[0048] From the above derivation, it can be known that if the communication signal SIN is a valid signal, the first delay-related output value O1 will be greater than the second delay-related output value O2 by a first predetermined multiple, wherein the first predetermined multiple is the square of the ratio between the first period L1 and the second period L2.

[0049] Continue to refer to Figure 4B In step S435, it is determined whether the first critical value has a second critical value greater than a second predetermined multiple, and the second predetermined multiple is the ratio between the first cycle and the second cycle (in Figure 4B TH1>TH2×(L1 / L2)). If the first critical value is not greater than the second predetermined multiple (i.e. Figure 4B If the first threshold value is greater than the second predetermined multiple of the second threshold value, step S440 is executed.

[0050] For example, as shown in equation (3) and equation (5), the processing circuit 120 accumulates the square of the output value C(t) of the delay correlation function with the first period L1 and the second period L2, respectively, and outputs the accumulated result as the first critical value TH1 and the second critical value TH2. Therefore, if the communication signal SIN is a valid signal, the first critical value TH1 will be greater than the second critical value TH2 of the second predetermined multiple, wherein the second predetermined multiple is the ratio between the first period L1 and the second period L2. For example, if the first period L1 is approximately 16 microseconds and the second period L2 is approximately 8 microseconds, the second predetermined multiple is approximately 4 (i.e., 16 / 8). Therefore, step S435 can be expressed as TH1>TH2×2. (If the first critical value TH1 is not greater than the second critical value TH2 of the second predetermined multiple, it means that the communication signal SIN may be interference (i.e., step S430).

[0051] To explain it in another way, as mentioned above, under ideal conditions (i.e., the received communication signal SIN is a valid signal), the communication signal SIN of formula (1) will satisfy the following relationship:

[0052] r i,n =r i,n-L1

[0053] r i,n ≠r i,n-L2

[0054] Under this condition, it can be deduced from the previous equations (3) and (5) that the first threshold value TH1 and the second threshold value TH2 satisfy the following relationship:

[0055]

[0056]

[0057] From the above deduction, it can be known that if the communication signal SIN is a valid signal, the first threshold TH1 will be greater than the second threshold TH2 by a second predetermined multiple, wherein the second predetermined multiple is the ratio between the first period L1 and the second period L2.

[0058] According to the above-mentioned steps S433 and S435, the processing circuit 120 may further check whether the correspondence between the first delay-related output value O1, the second delay-related output value O2, the first critical value TH1 and the second critical value TH2 is correct, so as to further improve the detection accuracy. In different embodiments, the processing circuit 120 may be configured to execute at least one of steps S410, S420, S433 and / or S435 to determine whether the communication signal SIN is interference. The more steps executed, the more reference information used to determine the communication signal SIN, and the higher the detection accuracy. In some embodiments, the number of steps executed can be adjusted according to actual needs (for example, including operating speed). Therefore, it should be understood that the scope covered by the present invention is not limited to Figure 4A and Figure 4B .

[0059] Figure 5 According to some embodiments of the present invention, Figure 2 Flow chart of operation S230 in FIG. Figure 4A In this embodiment, the processing circuit 120 further determines whether the communication signal SIN is interference according to the first period L1, the second period L2, the first delay-related information, and the second delay-related information. Specifically, the processing circuit 120 determines whether the communication signal SIN is interference according to the first product of the first delay-related output value O1, the second threshold value TH2, and the second period L2 and the second product of the second delay-related output value O2, the first threshold value TH1, and the first period L1.

[0060] For example, operation S230 includes steps S510, S520, and S530. In step S510, it is determined whether the first product of the first delay-related output value O1, the second threshold value TH2, and the second period L2 is greater than the second product of the second delay-related output value O2, the first threshold value TH1, and the first period L1 (in Figure 5 In the example, O1×TH2×L2>O2×TH1×L1). If the first product O1×TH2×L2 is greater than the second product O2×TH1×L1, step S520 is performed. Alternatively, if the first product O1×TH2×L2 is not greater than the second product O2×TH1×L1, step S530 is performed. In step S520, it is determined that the communication signal is not interference. In step S530, it is determined that the communication signal is interference. As described above, Figure 4AStep S410 in can be expressed as O1 / (TH1×L1)>O2 / (TH2×L2). According to simple deduction, step S410 can be re-expressed as O1×TH2×L2>O2×TH1×L1 (i.e., the judgment condition of step S510). Compared with step S410, the processing circuit 120 can only use multiplication operation to perform step S510, which is easy to implement in circuit. If the first product O1×TH2×L2 is greater than the second product O2×TH1×L1, it means that the communication signal SIN may not be interference. Alternatively, if the first product O1×TH2×L2 is not greater than the second product O2×TH1×L1, it means that the communication signal SIN is interference.

[0061] Similar to Figure 4B , the processing circuit 120 Figure 5 In the example above, you can also execute Figure 4B In various embodiments, the processing circuit 120 may be configured to execute at least one of step S510, step S420, step S433 and / or step S435 to determine whether the communication signal SIN is interference. Therefore, the scope of the present invention is not limited to Figure 4A , Figure 4B and Figure 4B .

[0062] Figure 4A , Figure 4B and Figure 5 The multiple steps in operation S230 are only examples and are not limited to being performed in the order in this example. Without violating the operation mode and scope of each embodiment of the present invention, the various steps in operation S230 can be appropriately increased, replaced, omitted or performed in a different order. Alternatively, one or more operations in the various steps in operation S230 can be performed simultaneously or partially simultaneously.

[0063] The delay correlation function, the first delay correlation output value O1, the second delay correlation output value O2, the first threshold value TH1, the second threshold value TH2, the mathematical model of the first period L1 and the second period L2 and / or the related definitions provided in the above embodiments are only used for examples, and the present invention is not limited thereto. In some embodiments, antenna weight parameters, threshold value correction parameters, etc. may be additionally added to the delay correlation function. Various delay correlation functions and delay related information that can be used for signal detection are all within the scope of the present invention.

[0064] On the other hand, the values ​​of the first period L1 and the second period L2 and the type of the predetermined communication protocol provided in the above embodiments are only examples, and the present invention is not limited thereto. The values ​​of the first period L1 and the second period L2 can be set according to the predetermined communication protocol, and various predetermined communication protocols that can be used for signal transmission are within the scope of the present invention.

[0065] In summary, the communication device and valid signal detection method provided by some embodiments of the present invention can use the delayed correlation function to determine whether the currently received communication signal is interference (even if the interference may be a periodic signal), thereby avoiding receiving invalid signals.

[0066] Although the embodiments of the present invention are described above, the embodiments are not intended to limit the present invention. Those skilled in the art may make changes to the technical features of the present invention according to the explicit or implicit contents of the present invention. All these changes may fall within the scope of patent protection sought by the present invention. In other words, the scope of patent protection of the present invention shall be subject to the definition of the claims of this specification.

[0067] Description of Reference Numerals

[0068] 100:Communication device

[0069] 110: receiving circuit

[0070] 120: Processing circuit

[0071] 200: Effective signal detection method

[0072] 300,310: line segment

[0073] L1: First cycle

[0074] L2: Second cycle

[0075] O1: first delay related output value

[0076] O2: Second delay related output value

[0077] S210, S220, S230, S240, S250: Operation

[0078] S410, S420, S430, S433, S435, S440: Steps

[0079] S510, S520, S530: Steps

[0080] SIN: communication signal

[0081] TH1: First critical value

[0082] TH2: Second critical value

Claims

1. A communication device, comprising: A receiving circuit for receiving a communication signal; and A processing circuit is used to use a first period to calculate the delay correlation function of the communication signal to determine first delay related information, and use a second period to calculate the delay correlation function of the communication signal to determine second delay related information, and determine whether the communication signal is interference based on the first delay related information and the second delay related information, wherein the first period is greater than the second period.

2. The communication device according to claim 1, wherein the first delay-related information includes a first delay-related output value and a first critical value, the second delay-related information includes a second delay-related output value and a second critical value, and the processing circuit is used to compare a first ratio between the first delay-related output value and a first product and a second ratio between the second delay-related output value and the second product to determine whether the communication signal is the interference, the first product being the product of the first critical value and the first period, and the second product being the product of the second critical value and the second period. 3 . The communication device according to claim 2 , wherein if the first ratio is not greater than the second ratio, the processing circuit determines that the communication signal is the interference. 4 . The communication device according to claim 2 , wherein if the first ratio is greater than the second ratio and the difference between the first ratio and the second ratio is not greater than a predetermined value, the processing circuit determines that the communication signal is the interference.

5. The communication device according to claim 1, wherein the first delay-related information includes a first delay-related output value and a first critical value, the second delay-related information includes a second delay-related output value and a second critical value, and the processing circuit is also used to determine whether the communication signal is the interference based on a first product of the first delay-related output value, the second critical value and the second period and a second product of the second delay-related output value, the first critical value and the first period. 6 . The communication device of claim 5 , wherein if the first product is not greater than the second product, the processing circuit determines that the communication signal is the interference.

7. A communication device according to claim 1, wherein the first delay-related information includes a first delay-related output value, the second delay-related information includes a second delay-related output value, and the processing circuit is also used to confirm whether the first delay-related output value is greater than a predetermined multiple of the second delay-related output value to determine whether the communication signal is the interference, and the predetermined multiple is the square of the ratio between the first period and the second period.

8. A communication device according to claim 1, wherein the first delay-related information includes a first critical value, the second delay-related information includes a second critical value, and the processing circuit is also used to confirm whether the first critical value is greater than a predetermined multiple of the second critical value to determine whether the communication signal is interference, and the predetermined multiple is the ratio between the first period and the second period.

9. The communication device according to claim 1, wherein the first period is one period of symbols in a preamble defined by a predetermined communication protocol.

10. An effective signal detection method, comprising: Calculating a delay correlation function of the communication signal using the first period to determine first delay correlation information; Calculating the delay correlation function of the communication signal using a second period to determine second delay correlation information, wherein the first period is greater than the second period; and It is determined whether the communication signal is interference according to the first delay related information and the second delay related information.

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