# US 8,787,432 B1 · HF communication system with decoding operations and related methods > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,787,432 B1 - Document ID: US8787432B1 - Status: Granted - Kind: B1 - Application number: 13/803,174 - Filed: 2013-03-14 - Granted: 2014-07-22 - Earliest claimed: 2013-03-14 - Assignees: Harris Corporation - Applicants: Harris Corporation - Inventors: William N. Furman; John W. Nieto; Eric N. Koski - Web page: https://patentgrep.com/patent/US8787432B1 ## CPC - H04L 1/08: by repeating transmission, e.g. Verdan system {(H04L1/1858 and H04L1/189 take precedence)} - H04L 1/0038: {Blind format detection (for detection of modulation format H04L27/0012)} - H04L 1/0084: {Formats for payload data} - H04L 1/0091: {arrangements specific to receivers, e.g. format detection (detection of data rate H04L25/0262; detection of coding rate H04L1/0046)} - H04L 1/0008: {by supplementing frame payload, e.g. with padding bits} - H04L 1/0061: {Error detection codes} - H04L 27/0014: {Carrier regulation (of chaotic carriers H04L27/001; for multicarrier receivers H04L27/2657)} - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) ## Abstract An HF communication system includes a first device, and a second device. The first device sends a message to the second device, the message including a preamble portion, a variable length data portion after the preamble portion having a given ending point selected from among potential ending points, and a check portion after the variable length data portion indicating an end of the message. The second device performs a decoding operation on the message at a potential ending point, and performs a check operation on a potential check portion of the decoded message, and when the check operation is successful, recovers the variable length data portion from the decoded message. Otherwise, the second device performs another decoding operation on the message at a next potential ending point, and performs another check operation on another potential check portion of the respective decoded message. ## Claims ### Claim 1 A high frequency (HF) communication system comprising: a first HF radio communications device comprising a first HF radio transceiver and a first controller coupled thereto; and a second HF radio communications device comprising a second HF radio transceiver and a second controller coupled thereto; said first controller being operable with said first HF radio transceiver and being configured to send a message to said second HF radio communications device, the message comprising: a preamble portion; a variable length data portion after the preamble portion and having a given ending point selected from among a plurality of potential ending points with each potential ending point being spaced apart from an adjacent potential ending point by a set quantity of digital data; and a check portion after the variable length data portion indicating an end of the message; said second controller being operable with said second HF radio transceiver and being configured to perform a decoding operation on the message at a potential ending point, and perform a check operation on a potential check portion of the decoded message, and when the check operation is successful, recover the variable length data portion from the decoded message, otherwise perform another decoding operation on the message at a next potential ending point, and perform another check operation on another potential check portion of the respective decoded message. ### Claim 2 (depends on 1) The HF communication system of claim 1 wherein the set quantity of digital data comprises one of a set number of characters, or a set number of bits. ### Claim 3 (depends on 1) The HF communication system of claim 1 wherein said second controller is configured to determine an estimated time alignment and estimated frequency offset of the message based upon the preamble portion. ### Claim 4 (depends on 1) The HF communication system of claim 1 wherein said second controller is configured to perform each decoding operation based upon a forward error correction (FEC) decoding. ### Claim 5 (depends on 1) The HF communication system of claim 1 wherein the check portion comprises a cyclic redundancy check (CRC) portion; and wherein said second controller is configured to perform the check operation comprising a CRC operation. ### Claim 6 (depends on 1) The HF communication system of claim 1 wherein the set quantity of digital data comprises a uniform set quantity of digital data. ### Claim 7 (depends on 1) The HF communication system of claim 1 wherein said first controller is configured to append null characters to an end of the variable length data portion so that the message reaches the given ending point. ### Claim 8 (depends on 1) The HF communication system of claim 1 wherein said first controller is configured to generate the variable length data portion comprising text based communications. ### Claim 9 (depends on 1) The HF communication system of claim 1 wherein said first controller is configured to generate the message with the variable length data and check portions sequentially repeated a set number of times. ### Claim 10 (depends on 9) The HF communication system of claim 9 wherein said first controller is configured to determine the set number of times based upon at least one communication channel characteristic. ### Claim 11 (depends on 9) The HF communication system of claim 9 wherein said second controller is configured to perform a plurality of decoding operations on the message, each decoding operation being performed based upon the variable length data and check portions being sequentially repeated a respective number of times. ### Claim 12 (depends on 3) The HF communication system of claim 3 wherein said second controller is configured to perform a plurality of decoding operations on the message at the potential ending point, the plurality of decoding operations being performed at a plurality of estimated frequency offsets for the message. ### Claim 13 (depends on 12) The HF communication system of claim 12 wherein said second controller is configured to perform a plurality of check operations on the potential check portion of the decoded message for the plurality of decoding operations. ### Claim 14 A high frequency (HF) radio communications device operable to communicate with a HF radio transmission device, the HF radio transmission device operable to send a message comprising a preamble portion, a variable length data portion after the preamble portion and having a given ending point selected from among a plurality of potential ending points with each potential ending point being spaced apart from an adjacent potential ending point by a set quantity of digital data, and a check portion after the variable length data portion indicating an end of the message, the HF radio communications device comprising: an HF radio receiver; and a controller being operable with said HF radio receiver and being configured to perform a decoding operation on the message at a potential ending point, and perform a check operation on a potential check portion of the decoded message, and when the check operation is successful, recover the variable length data portion from the decoded message, otherwise perform another decoding operation on the message at a next potential ending point, and perform another check operation on another potential check portion of the respective decoded message. ### Claim 15 (depends on 14) The HF radio communications device of claim 14 wherein the set quantity of digital data comprises one of a set number of characters, or a set number of bits. ### Claim 16 (depends on 14) The HF radio communications device of claim 14 wherein said controller is configured to determine an estimated time alignment and estimated frequency offset of the message based upon the preamble portion. ### Claim 17 (depends on 14) The HF radio communications device of claim 14 wherein said controller is configured to perform each decoding operation based upon a forward error correction (FEC) decoding. ### Claim 18 (depends on 14) The HF radio communications device of claim 14 wherein the check portion comprises a cyclic redundancy check (CRC) portion; and wherein said controller is configured to perform the check operation comprising a CRC operation. ### Claim 19 (depends on 14) The HF communications device of claim 14 wherein the HF radio transmission device is operable to generate the message with the variable length data and check portions sequentially repeated a set number of times. ### Claim 20 (depends on 16) The HF radio communications device of claim 16 wherein said controller is configured to perform a plurality of decoding operations on the message at the potential ending points, the plurality of decoding operations being performed at a plurality of estimated frequency offsets for the message. ### Claim 21 (depends on 19) The HF communications device of claim 19 wherein the HF radio transmission device is operable to determine the set number of message repeats based upon at least one communication channel characteristic. ### Claim 22 (depends on 19) The HF communications device of claim 19 wherein said controller is configured to perform a plurality of decoding operations on the message, each decoding operation being performed based upon the variable length data and check portions being sequentially repeated a respective number of times. ### Claim 23 (depends on 20) The HF radio communications device of claim 20 wherein said controller is configured to perform a plurality of check operations on the potential check portion of the decoded message for the plurality of decoding operations. ### Claim 24 A method of operating a high frequency (HF) radio communications device communicating with another HF radio communications device, the other HF radio communications device sending a message comprising a preamble portion, a variable length data portion after the preamble portion and having a given ending point selected from among a plurality of potential ending points with each potential ending point being spaced apart from an adjacent potential ending point by a set quantity of digital data, and a check portion after the variable length data portion indicating an end of the message, the method comprising: operating an HF radio transceiver and a controller in the HF radio communications device to perform a decoding operation on the message at a potential ending point, and perform a check operation on a potential check portion of the decoded message, and when the check operation is successful, recover the variable length data portion from the decoded message, otherwise perform another decoding operation on the message at a next potential ending point, and perform another check operation on another potential check portion of the respective decoded message. ### Claim 25 (depends on 24) The method of claim 24 wherein the set quantity of digital data comprises one of a set number of characters, or a set number of bits. ### Claim 26 (depends on 24) The method of claim 24 further comprising operating the HF radio transceiver and the controller to determine an estimated time alignment and estimated frequency offset of the message based upon the preamble portion. ### Claim 27 (depends on 24) The method of claim 24 further comprising operating the HF radio transceiver and the controller to perform each decoding operation based upon a forward error correction (FEC) decoding. ### Claim 28 (depends on 24) The method of claim 24 wherein the check portion comprises a cyclic redundancy check (CRC) portion; and further comprising operating the HF radio transceiver and the controller to perform the check operation comprising a CRC operation. ### Claim 29 (depends on 24) The method of claim 24 wherein the set quantity of digital data comprises a uniform set quantity of digital data. ### Claim 30 (depends on 24) The method of claim 24 wherein the other HF radio communications device appends null characters to an end of the variable length data portion so that the message reaches the given ending point. ### Claim 31 (depends on 24) The method of claim 24 wherein the other HF radio communications device generates the message with the variable length data and check portions sequentially repeated a set number of times. ### Claim 32 (depends on 26) The method of claim 26 further comprising operating the HF radio transceiver and the controller to perform a plurality of decoding operations on the message at the potential ending point, the plurality of decoding operations being performed at a plurality of estimated frequency offsets for the message. ### Claim 33 (depends on 31) The method of claim 31 wherein the other HF radio communications device determines the set number of times based upon at least one communication channel characteristic. ### Claim 34 (depends on 31) The method of claim 31 further comprising operating the HF radio transceiver and the controller to perform a plurality of decoding operations on the message, each decoding operation being performed based upon the variable length data and check portions being sequentially repeated a respective number of times. ### Claim 35 (depends on 32) The method of claim 32 further comprising operating the HF radio transceiver and the controller to perform a plurality of check operations on the potential check portion of the decoded message for the plurality of decoding operations.