Apparatus and Method for Generating Weil Codes

Abstract

A Weil code generator and a method for generating a Weil code having a Weil code length (N) are provided. The Weil code generator includes a plurality of parallel channels (10) connected in series, a multi-channel read arbiter (20), and two parallel Legendre ROMs (30). One of the plurality of channels stores a current Weil code for demodulating a signal from a satellite. The multi-channel read arbiter (20) can determine a winning channel from the plurality of channels. The two Legendre ROMs (30) store a first Legendre sequence and a second Legendre sequence (LS1, LS2), respectively, and each Legendre sequence length (2N) is twice the Weil code length (N). The Weil code generator can efficiently generate a Weil code.

Description

Technical Field

[0001] The present application relates to apparatuses and methods for generating codes, and more particularly, to a generator and method for generating Weil codes. Background Art

[0002] In a global navigation satellite system (GNSS) such as Beidou III, a Weil code generator is typically used to generate local Weil codes for demodulating satellite signals received by a signal receiver. However, a typical Weil code generator may be very complex in hardware and software design, may require high throughput, and may result in high power consumption. Therefore, an improved Weil code generator capable of efficiently generating Weil codes is needed. Summary of the Invention

[0003] According to one embodiment, a Weil code generator for generating a Weil code having a Weil code length (N) includes: a plurality of parallel channels, one of the plurality of parallel channels storing a current Weil code for demodulating a signal from a satellite, and including a read address control unit and a processing and storage unit; a multi-channel read arbiter connected in parallel to the plurality of parallel channels for determining a winning channel from the plurality of parallel channels; and two Legendre ROMs connected in parallel to the read arbiter, the two Legendre ROMs storing a first Legendre sequence and a second Legendre sequence respectively, wherein the Legendre sequence length (2N) of each Legendre sequence is twice the Weil code length (N).

[0004] According to one embodiment, a method of generating a Weil code using a Weil code generator, the Weil code generator including a plurality of parallel channels connected in series, a multi-channel read arbiter, and two parallel ROMs, the method comprising: detecting a valid Weil code depth of a current Weil code stored in one of the plurality of parallel channels, the channel communicating with a satellite; comparing the valid Weil code depth with a Legendre read bit length of a first Legendre sequence and a second Legendre sequence respectively stored in the two Legendre ROMs; in response to detecting that the valid Weil code depth is less than the Legendre read bit length, sending a request and sequence address pair to the read arbiter through the channel, wherein a Legendre sequence length (2N) of each of the first Legendre sequence and the second Legendre sequence is twice the Weil code length (N); sending the sequence address pair to the first Legendre sequence and the second Legendre sequence respectively through the read arbiter; obtaining first S-bit data and second S-bit data from the first Legendre sequence and the second Legendre sequence respectively by the channel as a function of the sequence address pair; performing an exclusive OR operation on the first S-bit data and the second S-bit data by the channel to obtain an additional Weil code; and adding the additional Weil code to the end of the current Weil code to obtain an extended Weil code.

[0005] According to one embodiment, a system may include: a memory storing instructions; and one or more processors configured by the instructions to perform operations including: detecting a valid Weil code depth of a current Weil code stored in one of a plurality of parallel channels that communicate with a satellite; comparing the valid Weil code depth with a Legendre read bit length of a first Legendre sequence and a second Legendre sequence respectively stored in two Legendre ROMs; in response to detecting that the valid Weil code depth is less than the Legendre read bit length, sending a request and sequence address pair from the channel to a read arbiter, where a Legendre sequence length (2N) of each of the first Legendre sequence and the second Legendre sequence is twice the Weil code length (N); sending the sequence address pair to the first Legendre sequence and the second Legendre sequence respectively by the read arbiter; receiving, by the channel via the read arbiter, first S-bit data and second S-bit data obtained from the first Legendre sequence and the second Legendre sequence respectively as a function of the sequence address pair; performing an exclusive OR operation on the first S-bit data and the second S-bit data by the channel to obtain an additional Weil code; and adding the additional Weil code to the end of the current Weil code to obtain an extended Weil code. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] The non-limiting and non-exhaustive embodiments of the present application are described with reference to the following drawings, in which like reference numerals represent like components in the various views unless otherwise specified.

[0007] Figure 1 FIG. is a diagram showing a Weil code generator for generating a Weil code having a Weil code length N according to one embodiment.

[0008] Figure 2 FIG. is a diagram showing a first Legendre sequence and a second Legendre sequence respectively stored in two ROMs according to one embodiment.

[0009] Figure 3 FIG. is a diagram showing an example of reading S-bit data from a first Legendre sequence stored in a first ROM according to one embodiment.

[0010] Figure 4 FIG. is a diagram showing a current Weil code according to one embodiment.

[0011] Figure 5FIG. is a diagram showing an exclusive - OR operation on two S - bit data according to an embodiment.

[0012] Figure 6 FIG. is a flowchart of a method for generating a Weil code using a Weil code generator according to an embodiment.

[0013] Figure 7 FIG. is a block diagram showing a software architecture in which examples can be implemented. DETAILED DESCRIPTION

[0014] Aspects and examples of the present application will now be described. The following description provides specific details in order to provide a thorough understanding and description of these examples. However, those skilled in the art will understand that the present application can be practiced without many of these details.

[0015] In addition, for the purpose of brevity and to avoid unnecessarily obscuring the relevant description, some well - known structures or functions may not be shown or described in detail.

[0016] Although used in conjunction with a detailed description of certain specific examples of the present application, the terms used in the following description are intended to be interpreted in the broadest reasonable manner. The following may even emphasize certain terms. However, any term intended to be interpreted in a limiting manner will be disclosed and clearly defined in this section.

[0017] Without loss of generality, illustrative embodiments will be described by way of example with a generator and a method for generating a Weil code. Those of ordinary skill in the art will understand that this is merely for the purpose of clearly and fully describing the present application and not limiting the scope of the present application, which is defined by the appended claims.

[0018] Figure 1 FIG. shows a Weil code generator (100) for generating a Weil code with a Weil code length of N.

[0019] According to an embodiment, the Weil code generator (100) may include M parallel channels (10(0), 10(1), 10(2), 10(3)…10(M - 1)) connected in series, a multi - channel read arbiter (20), and two Legendre ROMs (30). The number M of channels (10) (e.g., 20) may depend on the number of satellites (not shown) intended to communicate with the Weil code generator (100).

[0020] One of the M channels (10) can store the current Weil code for demodulating the signal received from the satellite. The channel (10) may include a read address control unit (11) and a processing and storage unit (12). The read address control unit (11) may include an update unit (13) and a phase data memory (14). The processing and storage unit (12) may include an exclusive OR logic (15) (or exclusive OR operation unit), an exclusive OR memory (16) (or exclusive OR register bank), and a buffer register (17) (or buffer register bank) that can store the current Weil code.

[0021] The multi-channel read arbiter (20) is connected to the M parallel channels and can be used to determine the winning channel (e.g., 10(2)) from the M channels (10). In one embodiment, the read arbiter (20) can sequentially determine the winning channel from the M channels (10) using a polling arbitration method to ensure that the M channels have equal arbitration opportunities to access the two ROMs (ROM1, ROM2).

[0022] The two ROMs (30) respectively store the first Legendre sequence and the second Legendre sequence (LS1, LS2) as Figure 2 shown. The first Legendre sequence and the second Legendre sequence (LS1, LS2) are the same Legendre sequence (LS), and the Legendre sequence length 2N of each Legendre sequence is twice the Weil code length N. N can be, for example, 10243 bits.

[0023] Figure 2 is a diagram showing the first Legendre sequence and the second Legendre sequence (LS1, LS2) respectively stored in the two Legendre ROMs (ROM1, ROM2) according to one embodiment. The first Legendre sequence (LS1) sequentially has a first part and a second part. The data structures of the first part and the second part of the first Legendre sequence (LS1) are the same, and each has a length N that is half of the Legendre sequence length 2N. Similarly, the second Legendre sequence (LS2) sequentially has a first part and a second part, and the data structures of the first part and the second part of the second Legendre sequence (LS2) are the same, and each has a length N that is half of the Legendre sequence length 2N.

[0024] Figure 3FIG. is an example showing reading of S-bit data from a first Legendre sequence (LS1) stored in a first ROM (ROM1) according to an embodiment. In response to receiving an address index (IND) as an input, the first Legendre sequence (LS1) may provide S-bit data (including S bits, such as S0, S1, S2, S3, S4, S5, S6, S7) as an output. Here, for example, S = 8. Alternatively, S may be 16, 32, 64, or 128. If the received index (IND) is in the first part of the first Legendre sequence (LS1), the first Legendre sequence (LS1) will directly read the S-bit data (e.g., 8-bit data, S0 - S7) without a wrap-around operation. The wrap-around operation may be time-consuming and may affect the throughput of the Weil code generator (10).

[0025] Reading of S-bit data from a second Legendre sequence (LS2) stored in a second ROM (ROM2) works in the same way.

[0026] Figure 4 FIG. is a diagram showing the current Weil code stored in a channel (10) according to an embodiment. The current Weil code stored in the channel (10) is read bit by bit in a forward direction from the current position (as indicated by a pointer INT) to the end of the current Weil code. The effective Weil code depth (D) of the current Weil code is detected and monitored. The effective Weil code depth (D) of the current Weil code is defined as the remaining number of bits from the current position to the end of the current Weil code (e.g., as Figure 4 shown, D = 5).

[0027] The phase data memory (14) of the read address control unit (11) of the channel (10) may store the current phase pair (index1, index2) obtained from the observation signal received from a satellite. The phase data memory (14) may also store the initially set initial phase pair (init_index1, init_index2).

[0028] The sequence address pair (ADDR1, ADDR2) may be obtained from the current phase pair (index1, index2) and the effective Weil code depth (D) of the current Weil code. For example, the first sequence address (ADDR1) may be obtained as the first current phase (index1) plus the effective Weil code depth (D) of the current Weil code, and the second sequence address (ADDR2) may be obtained as the second current phase (index2) plus the effective Weil code depth (D) of the current Weil code. That is, ADDR1 = index1 + D, ADDR2 = index2 + D.

[0029] As shown Figures 1-3 in FIG. 1, the sequence address pairs (ADDR1, ADDR2) are respectively transmitted to two ROMs (30) to respectively access the first Legendre sequence and the second Legendre sequence (LS1, LS2). To avoid loopback operations, the sequence address pairs (ADDR1, ADDR2) are respectively transmitted to the first part of the first Legendre sequence (LS1) and the first part of the second Legendre sequence (LS2) to respectively start reading the first Legendre sequence and the second Legendre sequence (LS1, LS2) to avoid loopback operations. Here, for example, S = 8, N = 10243.

[0030] In response to receiving the sequence address pairs (ADDR1, ADDR2), the first Legendre sequence and the second Legendre sequence (LS1, LS2) respectively output the first S-bit data and the second S-bit data (Data1, Data2). Both the first S-bit data and the second S-bit data have the Legendre read bit length S (for example, S = 8). The first S-bit data and the second S-bit data (Data1, Data2) are transmitted to the winning channel (10) via the read arbiter (20). The exclusive OR memory (16) of the read address control unit (12) in the winning channel (10) can store the first S-bit data and the second S-bit data (Data1, Data2).

[0031] Figure 5 FIG. 2 is a diagram showing an exclusive OR operation on two S-bit data (Data1, Data2) according to an embodiment. The exclusive OR operation unit (15) of the read address control unit (12) in the winning channel (10) can perform an exclusive OR operation on the first S-bit data and the second S-bit data (Data1, Data2) to obtain an additional Weil code (as Figure 4 shown by the dashed line in FIG. 2). As Figure 5 shown in FIG. 2, the exclusive OR operation on the first S-bit data and the second S-bit data (Data1, Data2) is performed bit by bit starting from phase 2 (phase = 2) of the first S-bit data (Data1) and phase 3 (phase = 3) of the second S-bit data (Data2), and a 6-bit additional Weil code is obtained. Then, the winning channel (10) can add the additional Weil code to the end of the current Weil to form an extended Weil code with the current effective Weil code depth (D').

[0032] The winning channel (10) can continue to detect the current valid Weil code depth (D') of the extended Weil code to check whether another additional Weil code is needed. For example, in response to detecting that the current valid Weil code depth (D') of the extended Weil code is less than the Legendre read bit length (S), another sequence address pair (ADDR1' and ADDR2') will be sent to the first Legendre sequence and the second Legendre sequence (LS1, LS2) in the two ROMs respectively to obtain another additional Weil code, and this another additional Weil code will be added to the end of the extended Weil code. These processes will be repeated until it is detected that the current valid Weil code depth (D') of the extended Weil code is greater than or equal to the Legendre read bit length (S).

[0033] Figure 6 is a flowchart showing a method (600) of generating a Weil code using a Weil code generator (100) according to an embodiment. As Figure 1 shown, the Weil code generator (100) can include a plurality of parallel channels (10) connected in series, a multi-channel read arbiter (20), and two parallel ROMs (30). The method (600) of generating a Weil code using the Weil code generator (100) is described as follows.

[0034] In block 602, the effective Weil code depth (D) of the current Weil code stored in the current channel (e.g., 10(1)) among the plurality of parallel channels (10) is detected. As Figure 4 shown, D = 5.

[0035] In block 604, the effective Weil code depth (D) is compared with the previously defined Legendre read bit length (S). As Figure 3 shown, S = 8.

[0036] In block 608, in response to detecting that the effective Weil code depth (D) is less than the Legendre read bit length (S), the channel (10) sends a request and a sequence address pair (ADDR1, ADDR2) to the read arbiter (20). The Legendre sequence length (2N) of the first Legendre sequence and the second Legendre sequence is twice the Weil code length (N). As Figures 2-3 described, N = 10243.

[0037] In block 610, the read arbiter (20) sends the sequence address pair (ADDR1, ADDR2) to the first Legendre sequence and the second Legendre sequence (LS1, LS2) respectively.

[0038] In block 612, a first S-bit data and a second S-bit data (Data1, Data2) obtained from a first Legendre sequence and a second Legendre sequence (LS1, LS2) respectively based on a sequence address pair (ADDR1, ADDR2) are received by the current channel (10) via a read arbiter (20).

[0039] In block 614, the first S-bit data and the second S-bit data (Data1, Data2) are XORed by the current channel (10) to obtain an additional Weil code.

[0040] In block 616, the additional Weil code is added to the end of the current Weil code to obtain an extended Weil code.

[0041] In one embodiment, the method (600) of generating a Weil code using a Weil code generator (100) may further include: detecting an effective Weil code depth (D') of the extended Weil code for comparison with a Legendre read bit length (S).

[0042] In response to detecting that the effective Weil code depth (D') of the extended Weil code is less than the Legendre read bit length (S), the channel (10) sends another sequence address pair (ADDR1', ADDR2') to the first Legendre sequence and the second Legendre sequence (LS1, LS2) respectively via the read arbiter (20) to obtain another additional Weil code, and the another additional Weil code is added to the end of the extended Weil code so that the effective Weil code depth (D') of the extended Weil code reaches or exceeds the Legendre read bit length (S).

[0043] Thus, due to the improvement of the Weil code generator, there is no need to wrap around when reading the Legendre sequences stored in the ROM respectively, so the Weil code generator can efficiently generate Weil codes.

[0044] Figure 7FIG. 700 is a block diagram showing a software architecture 704 that can be installed on any one or more of the wireless smart devices (such as smart sockets) described herein. The software architecture 704 is supported by hardware such as a machine 702 that includes a processor 720, a memory 726, and an I / O component 738. In this example, the software architecture 704 can be conceptually thought of as a stack of layers, where each layer provides a specific function. The software architecture 704 includes layers such as an operating system 712, libraries 710, frameworks 708, and applications 706. In operation, the application 706 makes API calls 750 through the software stack and receives messages 752 in response to the API calls 750.

[0045] The operating system 712 manages hardware resources and provides common services. The operating system 712 includes, for example, a kernel 714, services 716, and drivers 722. The kernel 714 acts as an abstraction layer between the hardware and other software layers. For example, the kernel 714 provides memory management, processor management (such as scheduling), component management, networking, and security settings, as well as other functions. The services 716 can provide additional common services for other software layers. The drivers 722 are responsible for controlling or interfacing with the underlying hardware. For example, the drivers 722 can include a display driver, a camera driver, or a low-power driver, a flash driver, a serial communication driver (such as a USB driver), drivers, an audio driver, a power management driver, and so on.

[0046] The libraries 710 provide a common underlying infrastructure used by the applications 706. The libraries 710 can include system libraries 718 (such as the C standard library), which provide functions such as memory allocation functions, string manipulation functions, mathematical functions, and so on. Additionally, the libraries 710 can include API libraries 724, such as media libraries (for example, libraries that support the presentation and manipulation of various media formats, such as Moving Picture Experts Group - 4 (MPEG4), Advanced Video Coding (H.264 or AVC), Moving Picture Experts Group Layer - 3 (MP3), Advanced Audio Coding (AAC), Adaptive Multi-Rate (AMR) audio codec, Joint Photographic Experts Group (JPEG or JPG), or Portable Network Graphics (PNG)), graphics libraries (such as the OpenGL framework for presenting graphic content in two-dimensional (2D) and three-dimensional (3D) forms on a display), database libraries (such as SQLite that provides various relational database functions), network libraries (such as WebKit that provides web browsing functions), and so on. The libraries 710 can also include a variety of other libraries 728 to provide many other APIs to the applications 706.

[0047] The framework 708 provides a common high-level structure used by the application 706. For example, the framework 708 provides various graphical user interface (GUI) functions, advanced resource management, and advanced location services. The framework 708 can provide various other APIs that can be used by the application 706, some of which may be specific to a particular operating system or platform.

[0048] In one example, the application 706 can include a Home application 736, a Contacts application 730, a Browser application 732, a Book Reader application 734, a Location application 742, a Media application 744, a Messaging application 746, a Gaming application 748, and a wide variety of other applications such as third-party applications 740. The application 706 is a program that executes functions defined in the program. Various programming languages can be employed to create one or more applications 706 constructed in various ways, such as object-oriented programming languages (e.g., Objective-C, Java, or C++) or procedural programming languages (e.g., C or assembly language). In a particular example, a third-party application 740 (e.g., an application developed using an ANDROID TM or IOS TM software development kit (SDK) by an entity other than the vendor of a particular platform) can be mobile software that runs on an operating system such as iOS TM , Android TM , a cell phone, or other mobile operating systems. In this example, the third-party application 740 can call API calls 750 provided by the operating system 712 to facilitate the functions described herein.

[0049] The features and aspects of various embodiments can be integrated into other embodiments, and the embodiments shown in this specification can be implemented without all of the features or aspects shown or described.

[0050] Those skilled in the art will understand that, although specific examples and embodiments of systems and methods have been described for purposes of illustration, various modifications can be made without departing from the spirit and scope of the present application. Moreover, the features of one embodiment can be incorporated into other embodiments, even if those features are not described together in a single embodiment of this specification. Accordingly, the present application is defined by the appended claims.

Claims

1. A Weil code generator for generating Weil codes with Weil code lengths, characterized in that, Comprising: A plurality of parallel channels, one of the plurality of parallel channels storing a current Weil code for demodulating a signal from a satellite, and including a read address control unit and a processing and storage unit; A multi-channel read arbiter, the multi-channel read arbiter being connected in parallel to the plurality of parallel channels for determining a winning channel from the plurality of parallel channels; And Two Legendre ROMs, the two Legendre ROMs being connected in parallel to the read arbiter and respectively storing a first Legendre sequence and a second Legendre sequence, wherein the Legendre sequence length of each Legendre sequence is twice the Weil code length; The current Weil code is read bit by bit in the direction from the current position to the end of the current Weil code, wherein the effective Weil code depth of the current Weil code is the remaining number of bits from the current position to the end of the current Weil code; The read address control unit includes an update unit and a phase data memory, wherein the phase data memory stores a current phase pair obtained from an observation signal received from the satellite and an initial phase pair set initially; A sequence address pair is obtained from the current phase pair and the effective Weil code depth of the current Weil code.

2. The Weil code generator according to claim 1, wherein The first Legendre sequence sequentially has a first part and a second part, the first part and the second part of the first Legendre sequence having the same data structure and each having a length that is half of the Legendre sequence length, and wherein, the second Legendre sequence sequentially has a first part and a second part, the first part and the second part of the second Legendre sequence having the same data structure and each having a length that is half of the Legendre sequence length.

3. The Weil code generator according to claim 1, characterized in that, The first sequence address of the sequence address pair is obtained as the first current phase plus the effective Weil code depth of the current Weil code, and the second sequence address of the sequence address pair is obtained as the second current phase plus the effective Weil code depth of the current Weil code.

4. The Weil code generator according to claim 1, characterized in that, The processing and storage unit includes an exclusive OR operation unit, an exclusive OR memory, and a register for storing the current Weil code.

5. The Weil code generator according to claim 1, characterized in that, The read arbiter is configured to adopt a polling arbitration method to sequentially determine the winning channel from the plurality of parallel channels to ensure that the plurality of parallel channels have equal arbitration opportunities to access the two ROMs.

6. The Weil code generator according to claim 2, wherein, In response to detecting that the effective Weil code depth is less than the Legendre read bit length, the channel sends a request and a sequence address pair to the read arbiter, the Legendre read bit length being the number of bits read by the channel from the first Legendre sequence or the second Legendre sequence in one read operation, and the Legendre read bit length being 8, 16, 32, or 64.

7. The Weil code generator according to claim 6, wherein, The sequence address pairs are respectively sent to the first Legendre sequence and the second Legendre sequence.

8. The Weil code generator according to claim 7, characterized in that, The sequence address pairs respectively start to access the first part of the first Legendre sequence and the second Legendre sequence.

9. The Weil code generator according to claim 8, characterized in that, The first Legendre sequence and the second Legendre sequence respectively output first S-bit data and second S-bit data, where the first S-bit data and the second S-bit data respectively have the Legendre read bit length, and the first S-bit data and the second S-bit data are sent to the winning channel via the read arbiter.

10. The Weil code generator according to claim 9, characterized in that, The winning channel performs an exclusive OR operation on the first S-bit data and the second S-bit data to obtain an additional Weil code.

11. The Weil code generator according to claim 10, characterized in that, The winning channel adds the additional Weil code to the end of the current Weil code to form an extended Weil code.

12. The Weil code generator according to claim 11, wherein, The current valid Weil code depth of the extended Weil code is detected.

13. The Weil code generator according to claim 12, characterized in that, In response to detecting that the current valid Weil code depth of the extended Weil code is less than the Legendre read bit length, another sequence address pair is respectively sent to the first Legendre sequence and the second Legendre sequence to obtain another additional Weil code and add it to the end of the extended Weil code until the current valid Weil code depth of the extended Weil code reaches the Legendre read bit length.

14. A method of generating a Weil code having a Weil code length using a Weil code generator, the Weil code generator including a plurality of parallel channels connected in series, a multi-channel read arbiter, and two parallel ROMs; the method includes: Detecting the effective Weil code depth of the current Weil code stored in one of the plurality of parallel channels, which communicates with a satellite; Comparing the effective Weil code depth with the Legendre read bit lengths of the first Legendre sequence and the second Legendre sequence respectively stored in two Legendre ROMs; In response to detecting that the effective Weil code depth is less than the Legendre read bit length, sending a request and a sequence address pair from the channel to the read arbiter, and the Legendre sequence length of each of the first Legendre sequence and the second Legendre sequence is twice the Weil code length; Sending the sequence address pair respectively to the first Legendre sequence and the second Legendre sequence by the read arbiter; Receiving, by the channel via the read arbiter, first S-bit data and second S-bit data respectively obtained from the first Legendre sequence and the second Legendre sequence, where the first S-bit data and the second S-bit data are functions of the sequence address pair; The XOR operation is performed on the first S-bit data and the second S-bit data by the channel to obtain an additional Weil code; and The additional Weil code is added to the end of the current Weil code to obtain an extended Weil code.

15. The method according to claim 14, wherein It further includes: The read arbiter determines the winning channel from the multiple parallel channels in sequence by using a polling arbitration method, so that the multiple parallel channels have equal arbitration opportunities to access the Legendre ROM.

16. The method according to claim 14, wherein It further includes: Detect the effective Weil code depth of the extended Weil code to compare with the Legendre read bit length of the first Legendre sequence and the second Legendre sequence.

17. The method according to claim 16, further comprising: In response to detecting that the effective Weil code depth of the extended Weil code is less than the Legendre read bit length, the channel sends another sequence address pair to the first Legendre sequence and the second Legendre sequence respectively via the read arbiter to obtain another additional Weil code and add it to the end of the extended Weil code until the effective Weil code depth of the extended Weil code reaches or exceeds the Legendre read bit length.

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