A shortwave radio fax communication module and a method for implementing shortwave radio fax communication
By designing the short-wave radio fax communication module, the dedicated or external connection with the G3 fax machine is realized, and multiple fax encoding methods are supported, and encryption processing and state machine scheduling are adopted, which solves the problems of low transmission rate and insufficient security, and is suitable for emergency communication, maritime communication and military communication.
Patent Information
- Application Number
- CN202510737966.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-04
- Publication Date
- 2025-08-22
- Estimated Expiration
- 2045-06-04
AI Technical Summary
The existing short-wave radio fax communications have problems such as low transmission rate, insufficient security, and difficulty in compatibility with various types of G3 fax machines.
A short-wave radio station fax communication module is designed, including a central control unit, storage unit, user line interface circuit, initialization module, fax communication state machine module, G3 fax communication module, fax data encryption and decryption module and waveform protocol processing module. The fax communication between G3 fax machine and short-wave radio station is realized through the LwIP protocol and waveform module protocol, supports multiple fax encoding methods, and uses the Blowfish algorithm to encrypt and decrypt data, and uses the state machine to realize real-time service scheduling.
It improves the security and compatibility of fax communication, ensures reliable transmission and efficient operation of fax data, and is suitable for emergency communication, maritime communication and military communication fields.
Smart Images
Figure CN120263909B_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of shortwave communication, in particular to a shortwave radio fax communication module and a method for realizing shortwave radio fax communication. Background Art
[0002] Shortwave radio communication systems are crucial in emergency, maritime, and military communications due to their long range, compact size, and strong anti-interference capabilities. Fax communication, a recording method for transmitting still images, boasts real-time recording and authentic transmission capabilities, making it widely used in various fields and particularly valuable in military communications. However, existing shortwave radio fax communication systems suffer from low transmission rates, insufficient security, and difficulty in compatibility with various G3 fax machines. A shortwave radio fax communication module and method are urgently needed to address these issues. Summary of the Invention
[0003] The present invention aims to solve the problems of low transmission rate, insufficient security and compatibility difficulties in existing shortwave radio fax communications, and provides a shortwave radio fax communication module and a method for implementing shortwave radio fax communications.
[0004] The specific technical solutions are as follows:
[0005] A shortwave radio fax communication module comprises: a central control unit, a storage unit, a user line interface circuit, an initialization module, a configuration module, a log module, a fax communication state machine module, a G3 fax machine fax communication module, a fax data encryption and decryption module, and a waveform protocol processing module; the central control unit is electrically connected to the storage unit, the user line interface circuit, and the embedded modem respectively; the initialization module, configuration module, log module, fax communication state machine module, G3 fax machine fax communication module, fax data encryption and decryption module, and waveform protocol processing module are stored in a Flash memory within the central control unit in the form of software binary code; the module is connected to the G3 fax machine via a second-line telephone line in a dedicated or external line mode to implement fax communication between the G3 fax machine and the shortwave radio; fax data is communicated with the waveform module according to a protocol; the module implements the LwIP protocol and the waveform module protocol; the waveform module and the fax communication module adopt UDP transmission.
[0006] The above-mentioned shortwave radio fax communication module, wherein the storage unit includes a 1MB SRAM memory CY62157 and a 1MB Flash memory W25X80, which are used to store fax data, fax capability analysis information and buffer data after encryption and decryption processing, and support on-demand dynamic allocation of up to 10 pages of fax data.
[0007] The above-mentioned shortwave radio fax communication module, wherein the user line interface circuit is a SLIC circuit Ag1170, which is used for picking up and hanging up signal detection, line power feeding and ringing signal generation, supports dedicated line or external line connection mode of two-line telephone line, and is compatible with information security laser dedicated fax machine and ship-use confidential fax machine type G3 fax machine.
[0008] The above-mentioned shortwave radio fax communication module, wherein the fax communication state machine module implements real-time scheduling of services such as PSTN fax communication, waveform protocol processing, on-hook and off-hook detection, dual-tone multi-frequency (DTMF) signal recognition, and ring signal generation through a state machine. After power-on, the system sequentially undergoes the Initial state and the Idle monitoring state. State transitions comply with specific conditions and routes, and network reception is achieved through interrupt callback.
[0009] The shortwave radio fax communication module mentioned above includes a G3 fax machine fax communication module that includes an embedded MT9234 modem. It communicates with the modem via the UART within the central control unit, implementing fax transmission and reception in accordance with the T.30 fax communication protocol. A stop-and-wait flow control mechanism is used in Phase C of the T.30 fax protocol to ensure the complete and reliable transmission of the entire fax data frame. Stop-and-wait flow control is implemented by monitoring the (XON / XOFF) characters on the modem line via software. The UART baud rate is set to 19200bps, and line rates support 9600bps or 11400bps. When receiving faxes, the UART baud rate is set to 57600bps, and a large buffer is provided, eliminating the need for flow control. This module implements multiple time-limited response processes for G3 fax machine call establishment, pre-message preparation, and post-message release, ensuring the reliable and complete reception and transmission of fax-encoded data frames in messages. Fax-encoded data supports MH, MHR, and MMR encoding.
[0010] The above-mentioned shortwave radio fax communication module, wherein the fax data encryption and decryption module encrypts and decrypts fax image data, and uses the Blowfish variable key length symmetric block cipher algorithm to encrypt and decrypt fax page encoded data to ensure that the fax data transmitted by the radio cannot be deciphered, thereby improving communication security.
[0011] The above-mentioned shortwave radio fax communication module, wherein the waveform protocol processing module implements protocol communication with the shortwave radio waveform module, the data packet format definition includes version, length, source module code, target module code, type, checksum, message payload, adopts UDP protocol transmission, has data confirmation mechanism and communication mechanism, and stipulates the waiting time and retransmission of data packets.
[0012] The hardware of the shortwave radio fax communication module mentioned above also includes the main controller LM3S9B96 with ARMCortex-M3 core, embedded modem MT9234, latch 7416373, DTMF signal recognition circuit HT9172 and power supply circuit. These hardware components work together to realize the hardware function support of the fax communication module.
[0013] The above-mentioned shortwave radio fax communication module, wherein the software system includes a HAL hardware abstraction layer based on the circuit layer, an OS operating system layer, and a logical function application layer; the HAL hardware abstraction layer includes a UART, a timer, a GPIO, an SRAM, a FLASH, a SLIC, and a modem driver; the logical function application layer includes an initialization module, a state machine, a fax data encryption and decryption module, a configuration module, a log module, a PSTN caller sending module, a PSTN called receiving module, and a waveform protocol transceiver processing module.
[0014] The above-mentioned shortwave radio fax communication module, wherein the simulation debugging software supports waveform protocol transceiver communication, can conveniently receive and send fax data through the network, and can browse fax image data in the form of Tiff files, and the data display window displays the communication data in real time.
[0015] The above-mentioned shortwave radio fax communication module, wherein the initialization module performs power-on detection and initialization on system resources; the configuration module configures network parameters and line connection methods; the log module records system activity status in real time and generates communication reports.
[0016] In the above-mentioned shortwave radio fax communication module, the PSTN caller sending module adopts a stop-and-wait flow control method in the T.30 fax communication protocol C phase, and the waveform protocol processing module uses a request-acknowledgement protocol flow control and retransmission error control method.
[0017] In the above-mentioned shortwave radio fax communication module, the waveform protocol processing module implements the LwIP protocol, and the waveform protocol is implemented by programming in the Raw / CallbackAPI callback mode.
[0018] The present invention also provides a method for implementing shortwave radio fax communication, which uses the shortwave radio fax communication module described above and includes sending and receiving faxes. When sending a fax, the fax communication module receives a fax sent by a G3 fax machine, communicates and stores the data through the T.30 fax communication protocol, encrypts the data, transmits it to a business unit via a network, and is then transmitted by the shortwave radio. When receiving a fax, the shortwave radio sends the encrypted fax data to the fax communication module, decrypts the data, and initiates a fax sending process, communicating with the G3 receiving fax machine according to the T.30 fax communication protocol.
[0019] The above-mentioned method for implementing shortwave radio fax communication includes the following steps: when sending a fax, when configured in external line mode, the calling G3 fax machine goes off-hook and dials *# to initiate the receiving process, and presses the start button to send according to the T.30 fax communication protocol call establishment phase A; when configured in dedicated line mode, the G3 fax machine directly connects and receives fax messages after pressing the start button; when receiving a fax, in external line mode, the line's on-hook and off-hook status is detected, and a ringing signal is sent to notify the recipient to go off-hook. In dedicated line mode, the line remains off-hook and a phase A connection is directly attempted. After the connection is successful, communication is carried out according to the T.30 fax communication protocol.
[0020] The present invention has the following beneficial effects:
[0021] The shortwave radio fax communication module of the present invention achieves dedicated or external line connection with a G3 fax machine through the coordinated operation of various modules. It supports multiple fax encoding methods and encrypts and decrypts fax data, improving communication security. A state machine enables real-time service scheduling, ensuring efficient and reliable system operation. The method for implementing shortwave radio fax communication details the fax sending and receiving processes, is compatible with different configurations, and resolves existing technical issues. It is suitable for emergency communications, maritime communications, military communications, and other fields. BRIEF DESCRIPTION OF THE DRAWINGS
[0022] Figure 1 A schematic diagram of a shortwave radio fax communication principle provided by an embodiment of the present invention;
[0023] Figure 2 A system hardware schematic diagram of a shortwave radio fax communication module provided by an embodiment of the present invention;
[0024] Figure 3 A system architecture diagram of a shortwave radio fax communication module provided by an embodiment of the present invention;
[0025] Figure 4 A schematic diagram of a fax communication module provided in an embodiment of the present invention as a called receiver;
[0026] Figure 5 A schematic diagram of the external line connection and external line setting operations provided in an embodiment of the present invention;
[0027] Figure 6 A schematic diagram of dedicated line connection and dedicated line setting operations provided in an embodiment of the present invention;
[0028] Figure 7 A flowchart of a fax communication module receiving a fax from a G3 fax machine provided by an embodiment of the present invention;
[0029] Figure 8 A flowchart of a fax data encryption process provided by an embodiment of the present invention;
[0030] Figure 9 A flowchart of sending fax data over a network provided by an embodiment of the present invention;
[0031] Figure 10 A schematic diagram of a fax communication module provided in an embodiment of the present invention as a caller transmitter;
[0032] Figure 11 A flowchart of a fax data network reception provided by an embodiment of the present invention;
[0033] Figure 12 Flowchart of the fax data network receiving, decrypting, processing and sending by a G3 fax machine provided by an embodiment of the present invention;
[0034] Figure 13 A fax communication flow chart showing the fax communication module provided in an embodiment of the present invention sending a fax to a G3 fax machine;
[0035] Figure 14 A schematic diagram of the protocol data packet format of the fax communication module and shortwave waveform module provided in an embodiment of the present invention;
[0036] Figure 15 Modem rate diagram of the T.30 fax communication process provided by an embodiment of the present invention;
[0037] Figure 16 A schematic diagram of the fax data format definition provided by an embodiment of the present invention;
[0038] Figure 17 A state transition diagram of the fax communication module system software provided by an embodiment of the present invention;
[0039] Figure 18 Blowfish encryption flow chart for fax data provided by an embodiment of the present invention;
[0040] Figure 19 Flowchart of Blowfish decryption of fax data provided by an embodiment of the present invention;
[0041] Figure 20 A schematic diagram of the internal implementation process of the network socket initialization function of the waveform protocol processing module provided in an embodiment of the present invention;
[0042] Figure 21 A schematic diagram of stop-and-wait flow control for fax data provided by an embodiment of the present invention;
[0043] Figure 22 A flowchart of sending fax data with stop-and-wait flow control provided in an embodiment of the present invention;
[0044] Figure 23A schematic diagram of protocol flow control for a waveform protocol processing module according to an embodiment of the present invention;
[0045] Figure 24 A network diagram showing a simulated commissioning of a fax communication module according to an embodiment of the present invention;
[0046] Figure 25 This is a diagram of the interface of the fax communication module waveform protocol simulation debugging software provided by an embodiment of the present invention. DETAILED DESCRIPTION
[0047] The technical solution of the present invention will be further described below with reference to the accompanying drawings and through specific implementation methods.
[0048] Among them, the accompanying drawings are only used for illustrative purposes and represent only schematic diagrams rather than actual pictures, and should not be understood as limiting the present application; in order to better illustrate the embodiments of the present invention, some parts of the accompanying drawings may be omitted, enlarged or reduced, and do not represent the size of the actual product.
[0049] The same or similar numbers in the drawings of the embodiments of the present invention correspond to the same or similar parts; in the description of the present invention, it should be understood that if the terms "upper", "lower", "left", "right", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, the terms describing the positional relationship in the drawings are only used for illustrative purposes and cannot be understood as limiting the present application. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.
[0050] In the description of the present invention, unless otherwise expressly specified or limited, when the term "connection" or the like appears to indicate a connection relationship between components, such term should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be internal communication between two components or an interaction between two components. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood in specific circumstances.
[0051] Example 1: This example provides a shortwave radio fax communication module, such as Figure 1-Figure 25As shown, it includes: a central control unit, a storage unit, a user line interface circuit, an initialization module, a configuration module, a log module, a fax communication state machine module, a G3 fax machine fax communication module, a fax data encryption and decryption module, and a waveform protocol processing module; the central control unit is electrically connected to the storage unit, the user line interface circuit, and the embedded modem respectively; the initialization module, the configuration module, the log module, the fax communication state machine module, the G3 fax machine fax communication module, the fax data encryption and decryption module, and the waveform protocol processing module are stored in the Flash memory inside the central control unit in the form of software binary code; the module is connected to the G3 fax machine via a second-line telephone line in a dedicated line or external line mode to realize fax communication between the G3 fax machine and the shortwave radio station; the fax data is communicated with the waveform module according to the protocol; the module implements the LwIP protocol and the waveform module protocol, and the waveform module and the fax communication module use UDP for transmission.
[0052] The shortwave radio fax communication module, utilizing the aforementioned technical solution, connects each module through a central control unit, enabling collaborative operation and building a complete shortwave radio fax communication system. Using a two-wire telephone line to connect to a G3 fax machine, fax communication between the G3 machine and the shortwave radio is possible. Communication utilizes the LwIP protocol and the Wave Module protocol, ensuring reliable and stable data transmission and providing a foundational architecture for fax communication.
[0053] Specifically, in this embodiment, the storage unit includes a 1MB SRAM memory CY62157 and a 1MB Flash memory W25X80, which are used to store fax data, fax capability analysis information, and encrypted and decrypted buffer data, and support on-demand dynamic allocation of up to 10 pages of fax data.
[0054] Using this technical solution, the storage unit, equipped with a certain capacity of SRAM and Flash memory, can effectively store fax data, fax capability analysis information, and encrypted and decrypted buffer data. Dynamic allocation is supported on demand to meet storage requirements for varying amounts of fax data, ensuring flexible and efficient data storage.
[0055] Specifically, in this embodiment, the user line interface is a SLIC circuit Ag1170, which is used for on-hook and off-hook signal detection, line power feeding, and ringing signal generation. It supports dedicated or external line connection of a two-line telephone line and is compatible with information security laser dedicated fax machines and ship-mounted confidential fax machine type G3 fax machines.
[0056] Using this technical solution, the subscriber line interface utilizes the SLIC circuit Ag1170, which accurately detects on-hook and off-hook signals, feeds line power, and generates ringing signals. It supports multiple connection methods and is compatible with various G3 fax machines, enhancing the module's versatility and adaptability to meet the needs of different users and fax machines.
[0057] Specifically, in this embodiment, the fax communication state machine module implements real-time scheduling of services such as PSTN fax communication, waveform protocol processing, on-hook and off-hook detection, dual-tone multi-frequency (DTMF) signal recognition, and ring signal generation through a state machine. After the system is powered on, it sequentially undergoes the Initial state and the Idle monitoring state. State transitions comply with specific conditions and routes, and network reception is implemented through interrupt callbacks.
[0058] Using this technical solution, the fax communication state machine module implements real-time scheduling of multiple services through a state machine, enabling the system to systematically handle tasks such as PSTN fax communication, waveform protocol processing, and on / off detection. After power-on, the system operates according to specific state transition rules, and network reception is implemented through interrupt callbacks, improving system efficiency and responsiveness, ensuring the smooth operation of various services.
[0059] Specifically, in this embodiment, the G3 fax machine's fax communication module includes an embedded MT9234 modem, communicating with the modem via the central control unit's internal UART. Fax transmission and reception are implemented according to the T.30 fax communication protocol. During Phase C of the T.30 fax protocol, software monitors the (XON / XOFF) characters on the modem line to implement stop-and-wait flow control. The UART baud rate is set to 19200bps, and line rates of 9600bps and 11400bps are supported. When receiving faxes, the UART baud rate is set to 57600bps, and a large buffer is provided, eliminating the need for flow control. This implements multiple timed response processes for the G3 fax machine, including call establishment, pre-message preparation, and post-message release, ensuring reliable and complete reception and transmission of fax-encoded data frames in messages. Fax-encoded data supports MH, MHR, and MMR encoding.
[0060] By adopting the above technical solution, the data throughput balance between the modem and UART is maintained through stop-and-wait flow control, and the complete and reliable sending and receiving of fax data messages are achieved. Fax data messages support multiple encoding methods. Selecting an encoding method with a higher compression rate is conducive to shortening the fax message data transmission time on the shortwave channel.
[0061] Specifically, in this embodiment, the fax data encryption and decryption module encrypts and decrypts the fax image data, and uses the Blowfish variable key length symmetric block cipher algorithm to encrypt and decrypt the fax page encoded data to ensure that the fax data transmitted by the radio station cannot be deciphered, thereby improving communication security.
[0062] Using the above technical solution, the fax data encryption and decryption module encrypts and decrypts fax image data, and uses the Blowfish symmetric block cipher algorithm with a variable key length to encrypt and decrypt fax page encoded data. This can ensure that the fax data transmitted by the radio station cannot be easily deciphered, greatly improving the security of communications and preventing fax information from being stolen or tampered with during transmission.
[0063] Specifically, in this embodiment, the waveform protocol processing module implements protocol communication with the shortwave radio waveform module. The data packet format definition includes version, length, source module code, target module code, type, checksum, and message payload. It uses UDP protocol for transmission and has a data confirmation mechanism and a communication mechanism. It stipulates the waiting time and retransmission of the data packet.
[0064] By adopting the above technical solution, the waveform protocol processing module realizes the protocol communication with the waveform module of the shortwave radio. By clearly defining the data packet format, adopting the UDP protocol for transmission and having a data confirmation mechanism and a communication mechanism, the waiting time and retransmission of the data packet are stipulated, thereby ensuring the accuracy and reliability of the fax data in the process of communicating with the shortwave radio, and reducing data loss and transmission errors.
[0065] Specifically, in this embodiment, the hardware part also includes the main controller ARMCortex-M3 core LM3S9B96, the embedded modem MT9234, the latch 7416373, the DTMF signal recognition circuit HT9172 and the power supply circuit. The hardware components work together to realize the hardware function support of the fax communication module.
[0066] With the above technical solution, the various hardware components work together, with the main controller acting as the core for coordination, the embedded modem implementing signal modulation and demodulation, the storage unit providing data storage functions for fax data storage and encryption and decryption processing of cached data, and auxiliary components such as the user line interface circuit, DTMF signal recognition circuit, and power supply circuit providing support, which together provide stable hardware functional support for the fax communication module and ensure the normal operation of the entire module.
[0067] Specifically, in this embodiment, the software system includes a HAL hardware abstraction layer based on the circuit layer, an OS operating system layer, and a logical function application layer; the HAL hardware abstraction layer includes UART, Timer, GPIO, SRAM, FLASH, SLIC, and Modem driver; the logical function application layer includes PSTN caller sending, PSTN callee receiving, a state machine, a waveform protocol transceiver processing module, an initialization module, and a fax data encryption and decryption module.
[0068] Specifically, in this embodiment, the initialization module performs power-on detection and initialization on system resources; the configuration module configures network parameters and line connection methods; and the log module records system activity status in real time and generates communication reports.
[0069] Specifically, in this embodiment, the PSTN caller sending module adopts a stop-and-wait flow control method in the T.30 fax communication protocol C phase, and the waveform protocol processing module uses a request-acknowledgement protocol flow control and retransmission error control method, so that the communication is efficient, reliable and complete.
[0070] Specifically, in this embodiment, the waveform protocol processing module implements the LwIP protocol, and the waveform protocol is implemented by programming in a Raw / Callback API callback manner, thereby improving the performance of the system.
[0071] Using this technical solution, the software system adopts a layered architecture with clear division of labor at each layer. The HAL hardware abstraction layer provides hardware drivers, enabling upper-layer software to easily operate the hardware. The logical function application layer contains multiple functional modules that implement various business logic for fax communications, improving the software's maintainability and scalability and facilitating system upgrades and optimization.
[0072] Example 2: This example provides a method for implementing shortwave radio fax communication, applying the shortwave radio fax communication module in Example 1, including fax sending and fax receiving. When sending a fax, the fax communication module receives a fax sent by a G3 fax machine, communicates and stores the data via the T.30 fax communication protocol, encrypts the data, transmits it to a business unit via a network, and is then transmitted by the shortwave radio. When receiving a fax, the shortwave radio sends the encrypted fax data to the fax communication module, decrypts the data, initiates the fax sending process, and communicates with the G3 receiving fax machine according to the T.30 fax communication protocol.
[0073] This method specifies in detail the process of sending and receiving faxes, realizes fax communication between G3 fax machines and shortwave radio stations, ensures that fax data can be transmitted accurately and securely between different devices, and solves the problems existing in existing shortwave radio fax communications.
[0074] When sending a fax, if configured in external line mode, the calling G3 fax machine goes off-hook and dials *# to initiate the receiving process. Then, according to the T.30 fax communication protocol, press the start button to send the call during Phase A. When configured in dedicated line mode, the G3 fax machine directly connects and receives fax messages after pressing the start button. When receiving a fax, in external line mode, the line detects whether the call is on or off-hook and sends a ringing signal to notify the recipient to go off-hook. In dedicated line mode, the line remains off-hook and directly attempts a Phase A connection. After a successful connection, communication follows the T.30 fax communication protocol. Specific fax sending and receiving procedures are provided for different configuration modes (external line mode and dedicated line mode), enabling the module to better adapt to different usage scenarios, improving system flexibility and compatibility, and meeting diverse user needs.
[0075] In summary, the shortwave radio fax communication module provided in this embodiment has the following advantages:
[0076] The shortwave radio fax communication module of this embodiment achieves dedicated or external line connection to a G3 fax machine through the coordinated operation of various modules. It supports multiple fax encoding methods and encrypts and decrypts fax data, improving communication security. A state machine enables real-time service scheduling, ensuring efficient and reliable system operation. The method for implementing shortwave radio fax communication details the fax sending and receiving process, is compatible with various configurations, and resolves existing technical issues. It is suitable for emergency communications, maritime communications, military communications, and other fields.
[0077] The shortwave radio fax communication module provided in this embodiment mainly consists of module hardware and software systems, including:
[0078] Module hardware composition
[0079] The LM3S9B96, a main controller based on the ARM Cortex-M3 core, serves as the central control unit, coordinating the operations of various hardware components. The embedded MT9234 modem performs signal modulation and demodulation. The SLIC circuit Ag1170, serving as the subscriber line interface, detects on-hook and off-hook signals, supplies line power, and generates ringing signals. The HT9172 DTMF signal recognition circuit recognizes dual-tone multi-frequency signals. The storage system, comprised of the CY62157 SRAM memory, the W25X80 Flash memory, and the 7416373 latch, stores fax message data. Auxiliary components, such as the power supply circuit, ensure stable hardware system operation.
[0080] Software system operation
[0081] After the system is powered on, it completes initialization in the Initial state. If initialization is successful, it enters the Idle monitoring state. In the Idle state, it monitors for off-hook signals or network data reception. When a fax machine is detected as off-hook, the dialed number is identified by the DTMF signal recognition circuit to determine whether the system is in a voice call state or PSTN fax reception state. In the PSTN fax reception state, fax data is received according to the T.30 fax communication protocol, stored, and encrypted, and the network transmission process is initiated. After the network transmission is completed, the status is reported and the system returns to the Idle state. When receiving a fax, data is received from the waveform module, decrypted, and sent to the G3 fax machine according to the T.30 fax communication protocol. The entire process is scheduled in real time by the fax communication state machine module.
[0082] Working principle process: The overall working principle process of this shortwave radio fax communication module is divided into two main processes: sending fax and receiving fax:
[0083] Send a Fax
[0084] 1. Connection and Data Reception: The G3 fax machine and the fax communication module are connected via a dedicated or external line via a second-line telephone line. If configured as an external line, the calling G3 fax machine goes off-hook and dials *# to initiate the receiving process. During Phase A of the T.30 fax communication protocol call setup, the caller presses the start button to send the fax message. If configured as a dedicated line, the G3 fax machine connects directly and receives the fax message after pressing the start button. The fax communication module receives fax data sent by the G3 fax machine through the subscriber line interface.
[0085] 2. Data Storage and Processing: Received fax data is stored in the storage system, while the fax communication state machine module analyzes the fax capabilities. The fax data encryption and decryption module encrypts the data to ensure data security.
[0086] 3. Data transmission: The encrypted fax data is processed by the waveform protocol processing module and, in accordance with the protocol communication rules with the shortwave radio waveform module, uses the UDP protocol for network transmission and is sent to the business unit, and is finally transmitted by the shortwave radio.
[0087] Receiving Faxes
[0088] 1. Data reception: The shortwave radio sends the received encrypted fax data to the fax communication module, and the waveform protocol processing module receives the data.
[0089] 2. Data decryption: The fax data encryption and decryption module decrypts the encrypted fax data and restores the original fax data.
[0090] 3. Data Transmission and Communication: After fax data decryption is complete, the fax transmission process begins. The fax communication module communicates with the G3 receiving fax machine according to the T.30 fax communication protocol. In external line mode, the module detects whether the line is on or off-hook and sends a ringing signal to notify the receiving party. In dedicated line mode, the line remains off-hook and a Phase A connection is attempted. Upon successful connection, the fax data is sent to the G3 receiving fax machine.
[0091] During the entire process, the central control unit coordinates the work of each module, and the fax communication state machine module dispatches various services in real time through the state machine to ensure the efficiency, accuracy and security of fax communication.
[0092] Condition 1: If an off-hook signal is detected and *# is received via the DTMF signal recognition circuit, the circuit is blocked, indicating that the line is busy. If a fax machine is off-hook at this time, a busy tone is displayed and a busy tone signal is returned. If condition 1 is met, the system enters the PSTN fax receiving state and completes the PSTN fax receiving process. If the receiving process terminates abnormally or an error occurs, the system enters the Idle state.
[0093] Condition 2: Network fax transmission can be initiated if the PSTN reception process completes successfully. This condition requires the PSTN reception process to complete successfully (i.e., PSTN reception OK), and then enter the Network Fax Transmit state. If the Network Fax Transmit process is completed, terminated abnormally, or successfully completed, the system will enter the Idle monitoring state.
[0094] Condition 3: The network fax sending process terminates abnormally or completes successfully and enters the Idle monitoring state.
[0095] Condition 4: The off-hook signal is detected, and the DTMF signal recognition circuit receives the digital number. A voice link is established to the incoming service unit (shortwave module), establishing a physical connection. The voice channel is provided by the shortwave module. If condition 4 is met, the voice call state is established.
[0096] Condition 5: Data reception is detected on the network port, and the message content is a request to send (valid) and line configuration, a handshake message, indicating that subsequent data will be sent, that is, a connection is established. After a successful handshake, the network can receive large amounts of data.
[0097] Condition 6: If initialization is OK, the system enters the Idle monitoring state. If initialization fails, the system enters the FAIL state.
[0098] Condition 7: If the receiving process is abnormally terminated or an error occurs, the state of receiving faxes from the PSTN switches to the Idle monitoring state.
[0099] Condition 8: PSTN fax sending ends normally or abnormally, and the system enters the Idle monitoring state.
[0100] Condition 9: Error or exception handling is complete, that is, the exception or error is repaired and the system enters the Idle monitoring state. Severe exceptions will automatically restart the system through the watchdog circuit.
[0101] Condition 10: A hardware or software error or problem occurs in the Idle monitoring state, causing the system to enter an abnormal error state.
[0102] Condition 11: If the network fax reception is OK (normal completion), the PSTN fax sending process (flow) will be automatically started. The condition is that the network reception is OK.
[0103] Condition 12: After the voice call is completed, the system enters the Idle monitoring state.
[0104] Condition 13: Network reception terminates abnormally or an error occurs. The state switches from the network fax reception state to the idle monitoring state.
[0105] The above are only preferred embodiments of the present invention and do not limit the implementation mode and protection scope of the present invention. For those skilled in the art, it should be aware that all solutions obtained by equivalent substitutions and obvious changes made using the description and illustrations of the present invention should be included in the protection scope of the present invention.
Claims
1. A shortwave radio fax communication module, characterized in that: include: A central control unit, a storage unit, a user line interface circuit, an initialization module, a configuration module, a log module, a fax communication state machine module, a G3 fax machine fax communication module, a fax data encryption and decryption module, and a waveform protocol processing module; the central control unit is electrically connected to the storage unit, the user line interface circuit, and the embedded modem MT9234, respectively; the initialization module, configuration module, log module, fax communication state machine module, the G3 fax machine fax communication module, the fax data encryption and decryption module, and the waveform protocol processing module are stored in the form of software binary code in a Flash memory within the central control unit; the shortwave radio fax communication module is connected to the G3 fax machine via a second-line telephone line in a dedicated line or external line mode to implement fax communication between the G3 fax machine and the shortwave radio; UDP transmission is used between the shortwave radio fax communication module and the waveform module; the waveform protocol processing module implements an interface protocol between the shortwave radio fax communication module and the waveform module, and completes fax data communication between the shortwave radio fax communication module and the waveform module; The G3 fax machine's fax communication module includes an embedded MT9234 modem, which communicates with the modem via the central control unit's internal UART. Fax transmission and reception are implemented according to the T.30 fax communication protocol. During Phase C of the T.30 fax protocol, PSTN caller transmission tasks utilize software non-blocking reception to read the XON / XOFF characters on the UART receive line for stop-and-wait flow control. The UART baud rate for PSTN caller transmission tasks is set to 19200bps, with line rates supporting 9600bps or 11400bps. When receiving faxes, the UART baud rate is set to 57600bps, and a large buffer is configured, eliminating the need for flow control. The G3 fax machine's fax communication module implements multiple timed response processes, including call establishment, pre-message preparation, and post-message release. It also ensures the reliable and complete reception and transmission of fax-encoded data frames within messages, supporting MH, MHR, and MMR encoding. The waveform protocol processing module uses a request-acknowledgement protocol-based flow control and retransmission error control method; the waveform protocol processing module implements the LwIP protocol, and the interface protocol between the waveform module and the shortwave radio fax communication module is implemented using Raw / CallbackAPI callback programming; The fax communication state machine module improves the real-time performance of the system through real-time scheduling of on-hook and off-hook detection, G3 fax machine fax communication module PSTN caller sending tasks, G3 fax machine fax communication module PSTN called reception tasks, waveform protocol processing module network sending, waveform protocol processing module network receiving services, and the implementation of interrupt callbacks.
2. The shortwave radio fax communication module according to claim 1, characterized in that: The storage unit includes a 1MB SRAM memory CY62157 and a 1MB Flash memory W25X80, which are used to store fax data, fax capability analysis information and buffer data after encryption and decryption processing, and support on-demand dynamic allocation of up to 10 pages of fax data.
3. The shortwave radio fax communication module according to claim 1, characterized in that: The user line interface circuit is a SLIC circuit Ag1170, which is used for on-hook and off-hook signal detection, line power feeding, and ringing signal generation. It supports dedicated or external line connection of a two-line telephone line and is compatible with information security laser dedicated fax machines and ship-use confidential fax machine type G3 fax machines.
4. The shortwave radio fax communication module according to claim 1, characterized in that: The fax communication state machine module implements real-time scheduling of PSTN fax communication, waveform protocol processing, on-hook detection, dual-tone multi-frequency DTMF signal recognition, and ringing signal generation services through a state machine. After the system is powered on, it goes through the Initial state and the Idle monitoring state in sequence. The state transitions comply with specific conditions and routes, and network reception is achieved through interrupt callback.
5. The shortwave radio fax communication module according to claim 1, characterized in that: The fax data encryption and decryption module encrypts and decrypts the fax image data and uses the Blowfish variable key length symmetric block cipher algorithm to encrypt and decrypt the fax page encoded data to ensure that the fax data transmitted by the radio station cannot be deciphered, thereby improving communication security.
6. The shortwave radio fax communication module according to claim 1, characterized in that: The waveform protocol processing module realizes protocol communication with the shortwave radio waveform module. The data packet format definition includes version, length, source module code, target module code, type, checksum, and message payload. It adopts UDP protocol transmission, has data confirmation mechanism and communication mechanism, and stipulates the waiting time and retransmission of data packets.
7. The shortwave radio fax communication module according to claim 1, characterized in that: The hardware part also includes the main controller ARMCortex-M3 core LM3S9B96, latches, DTMF signal recognition circuit HT9172 and power supply circuit. These hardware components work together to realize the hardware function support of the fax communication module.
8. The shortwave radio fax communication module according to claim 1, characterized in that: The software system includes a HAL hardware abstraction layer based on the circuit layer, an OS operating system layer, and a logic function application layer; the HAL hardware abstraction layer includes UART, Timer, GPIO, SRAM, FLASH, SLIC, and Modem driver; the logic function application layer includes an initialization module, a state machine, a fax data encryption and decryption module, a configuration module, a log module, a PSTN caller sending module, a PSTN called receiving module, and a waveform protocol transceiver processing module.
9. The shortwave radio fax communication module according to claim 1, characterized in that: The simulation debugging software supports waveform protocol transceiver communication. It can easily receive and send fax data through the network, and can browse fax image data in the form of Tiff files. The data display window displays communication data in real time.
10. The shortwave radio fax communication module according to claim 1, characterized in that: The initialization module performs power-on detection and initialization on system resources; the configuration module configures network parameters and line connection methods; and the log module records system activity status in real time and generates a communication report.
11. A method for implementing shortwave radio fax communication, using the shortwave radio fax communication module according to any one of claims 1 to 10, characterized in that: It includes sending and receiving faxes. When sending a fax, the fax communication module receives the fax sent by the G3 fax machine, communicates and stores the fax page encoding data through the T.30 fax communication protocol, encrypts it and transmits it to the business unit through the network and is transmitted by the shortwave radio. When receiving a fax, the shortwave radio sends the encrypted fax data to the fax communication module, decrypts it and starts the fax sending process, and communicates with the G3 receiving fax machine according to the T.30 fax communication protocol.
12. The method for realizing shortwave radio fax communication according to claim 11, characterized in that: When sending a fax, if configured in external line mode, the calling G3 fax machine goes off-hook and dials *# to start the receiving process. According to the T.30 fax communication protocol, the call is established in Phase A and the start button is pressed to send. When configured in dedicated line mode, the G3 fax machine directly connects and receives fax messages after pressing the start button. When receiving a fax, in external line mode, the line's on-hook and off-hook status is detected, and a ringing signal is sent to notify the recipient to go off-hook. In dedicated line mode, the line remains off-hook and the connection in Phase A is directly attempted. After the connection is successful, communication is carried out according to the T.30 fax communication protocol.