A Ku-band Starlink downlink signal detection method

Abstract

The present invention discloses a Ku-band Starlink downlink signal detection method, comprising the following steps: step 1, a broadband receiver collects signal IQ data, the sampling rate is fs, and the length of the collected sample is L; step 2, the collected complex signal sample is recorded as X(n), n=0, 1, ..., L-2, L-1, and a cyclic correlation algorithm is used to detect the frame period of the signal; step 3, a spectrum peak search is performed on #imgabs0#, wherein the n=10, 11, ..., L / 2-1 part is searched, and the searched maximum spectrum peak position index is recorded as I max ; Step 4, according to I max Calculate the frame period T of the signal in ms. Step 5. Determine whether T satisfies the following formula: #imgabs1#, where #imgabs2# is the frame length of the Starlink downlink signal, #imgabs3# is the redundancy set to avoid multipath interference, and #imgabs4# should satisfy: #imgabs5#; Step 6. Detect the symbol period. For #imgabs6#, detect whether there is a spectral peak near #imgabs7#. If it is satisfied, go to the next step.

Description

Technical Field

[0001] The present invention relates to the field of radio monitoring technology, and more specifically to a Ku-band Starlink downlink signal detection method. Background Art

[0002] In recent years, satellite Internet services have experienced explosive growth around the world, but there is no regulatory plan. Since it is a broadband burst signal and low-orbit satellites only appear in the field of vision for a short time, only a few minutes, signal detection and identification must be fast and effective to meet monitoring requirements. Summary of the invention

[0003] The purpose of the present invention is to provide a Ku-band Starlink downlink signal detection method to solve the problem of Ku-band Starlink downlink signal detection.

[0004] In order to achieve the above object, the present invention adopts the following technical solutions:

[0005] A Ku-band Starlink downlink signal detection method comprises the following steps:

[0006] Step 1: The broadband receiver collects signal IQ data with a sampling rate of fs and a sample length of L;

[0007] Step 2: Let the collected complex signal samples be X(n), n = 0, 1, ..., L-2, L-1, and use the cyclic autocorrelation algorithm to detect the frame period of the signal. The cyclic autocorrelation detection formula is as follows:

[0008]

[0009] Step 3: Perform peak search, taking into account It is symmetrical and has a DC component. Only the part n = 10, 11, ..., L / 2-1 is searched, and the index of the maximum spectrum peak position found is recorded as I max ;

[0010] Step 4: According to I max Calculate the frame period T of the signal in ms using the following formula:

[0011]

[0012] Step 5: Determine whether T satisfies the following formula:

[0013]

[0014] in, is the frame length of the Starlink downlink signal, The redundancy is set to avoid multipath interference. Should meet:

[0015]

[0016] If T meets the conditions, go to the next step; if not, exit this test;

[0017] Step 6: Detect symbol period, , detect its Whether there is a spectrum peak nearby, that is, whether the following formula is satisfied:

[0018]

[0019] in, ( is the effective symbol length of the Starlink downlink signal), is the detection window length, is the detection threshold (the empirical value is 3),

[0020] If satisfied, go to the next step; if not satisfied, exit this test;

[0021] Step 7: Symbol length estimation, let Ng = round( ),N = , calculate the peak factor H(i) according to the following formula:

[0022] *

[0023] Through peak search, detection The average spacing between the peaks is calculated as Ns. If Ns = N +Ng, it is considered that the Starlink downlink signal is detected. If not, the detection is exited.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] The present invention uses the prior knowledge of the known Starlink downlink signal and the parameter estimation method to detect whether the parameters meet the characteristics of the Starlink downlink signal, which is of great significance for the rapid detection of the Starlink downlink signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is a flow chart of an embodiment of the present invention.

[0027] Figure 2 is the cyclic autocorrelation curve of the Starlink downlink signal, and its maximum spectrum peak position is the frame period.

[0028] Figure 3 Estimation of the effective symbol length of the Starlink downlink signal.

[0029] Figure 4 It is a joint estimate of the symbol period and cyclic prefix length of the Starlink downlink signal. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solutions and advantages of the present application clearer, the technical solutions in the embodiments of the present application will be described in more detail below in conjunction with the drawings in the preferred embodiments of the present application. In the drawings, the same or similar reference numerals throughout represent the same or similar parts or parts with the same or similar functions. The described embodiments are part of the embodiments of the present application, not all of the embodiments. The embodiments described below with reference to the drawings are exemplary and are intended to be used to explain the present application, and should not be construed as limitations on the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present application.

[0031] The embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0032] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, or it can be an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0033] In the description of the present application, it should be understood that the terms "upper", "lower", "front", "back", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are orientations or positional relationships based on the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0034] In addition, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, for example, a process, method, system, product, or display that includes a series of steps or elements is not necessarily limited to those steps or elements explicitly listed but may include other steps or elements not explicitly listed or inherent to such process, method, product, or display.

[0035] The following will be combined Figure 1-4 , a Ku-band Starlink downlink signal detection method involved in the embodiment of the present application is described in detail. It is worth noting that the following embodiments are only used to explain the present application and do not constitute a limitation on the present application.

[0036] Embodiment 1:

[0037] like Figure 1 As shown, a Ku-band Starlink downlink signal detection method includes the following steps:

[0038] Step 1: The broadband receiver collects signal IQ data with a sampling rate of fs=500MHz and a sample length of L=fs*0.01, i.e., a sampling duration of 10ms.

[0039] Step 2: Let the collected complex signal samples be X(n), n = 0, 1, ..., L-2, L-1, and use the cyclic autocorrelation algorithm to detect the frame period of the signal. The cyclic autocorrelation detection formula is as follows:

[0040]

[0041] Step 3: Perform peak search, taking into account Symmetrical, see Figure 2 , and has a DC component, only the part n = 10, 11, ..., L / 2-1 is searched, and the index of the maximum spectrum peak position searched is recorded as I max ;

[0042] Step 4: According to I max Calculate the frame period T of the signal in ms using the following formula:

[0043]

[0044] Step 5: Determine whether T satisfies the following formula:

[0045]

[0046] in, is the frame length of the Starlink downlink signal, The redundancy is set to avoid multipath interference. =0.0006;

[0047] If T meets the conditions, go to the next step; if not, exit this test;

[0048] Step 6: Detect symbol period, , detect its Whether there is a spectrum peak nearby, that is, whether the following formula is satisfied:

[0049]

[0050] in, ( is the effective symbol length of the Starlink downlink signal), =50 is the detection window length, is the detection threshold (the empirical value is 3), as follows Figure 3 As shown, =2133 (matlab index starts from 1, so you need to subtract 1)

[0051] If satisfied, go to the next step; if not satisfied, exit this test;

[0052] Step 7: Symbol length estimation, let Ng = round( )=67,N = , calculate the peak factor H(i) according to the following formula:

[0053] *

[0054] Through peak search, detection The average spacing between the peaks is calculated as Ns. If Ns = N +Ng is satisfied, it is considered that the Starlink downlink signal is detected. If not, the detection is exited. Figure 4 As shown, the average spacing is 2200, satisfying 2200 = 67+2133.

[0055] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A Ku-band Starlink downlink signal detection method, characterized in that: The following steps are involved: Step 1: The broadband receiver collects signal IQ data with a sampling rate of fs and a sample length of L; Step 2: Let the collected complex signal samples be X(n), n = 0, 1, ..., L-2, L-1, and use the cyclic autocorrelation algorithm to detect the frame period of the signal. The detection formula of the cyclic correlation algorithm is as follows: ； Step 3: Perform a spectrum peak search, where the part n = 10, 11, ..., L / 2-1 is searched, avoiding the DC component, and the index of the searched maximum spectrum peak position is recorded as I max ; Step 4: According to I max Calculate the frame period T of the signal in ms using the following formula: ； Step 5: Determine whether T satisfies the following formula: ； in, is the frame length of the Starlink downlink signal, The redundancy is set to avoid multipath interference. Should meet: ； If T meets the conditions, go to the next step; if not, exit this test; Step 6: Detect symbol period, , detect its Whether there is a spectrum peak nearby, that is, whether the following formula is satisfied: ； in, ,in, is the effective symbol length of the Starlink downlink signal, is the detection window length, is the detection threshold; If satisfied, go to the next step; if not satisfied, exit this test; Step 7: Symbol length estimation, let Ng = round( ),N = , calculate the peak factor H(i) according to the following formula: * ； Through peak search, detection The average spacing between the peaks is calculated as Ns. If Ns = N + Ng is satisfied, it is considered that the Starlink downlink signal is detected. If not, the detection is exited.

2. A Ku-band Starlink downlink signal detection method according to claim 1, characterized in that: In step 6, The experience value is 3.

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