![]() ![]() When the receiver sees a tone difference in the range 0 – 29, followed by another in the range 0 – 29, it recognises a single-tone character (lower case etc). These are characterized by an initial difference, describing the character, and a continuation difference, defining the code table. The extra characters are allocated to three additional code tables, which are sent as two sequential tone differences. The total alphabet includes upper case and a reasonable range of symbols, yielding a total alphabet of 104 ASCII characters. The three ‘spare’ differences are used to define further code tables. These characters are all lower case, a-z, plus the most common punctuation symbols: space, full stop (period), and new line (CR/LF). NOTE: fldigi function keys are inoperative in the FSQ mode!įSQ is designed to use 32 tone differences between 33 equally spaced tones so it is possible to allocate 29 different individual differences directly to the most frequently used characters. The "Heard" list displays the callsign, s/n, and time of reception of all correctly decoded transmissions. This FSQ help content borrows shamelessly from Murray Greenman's (ZL1BPU) "FSQ Explained" document. Both Murray and Con were very supportive during the development and testing of fldigi's FSQ implementation.įldigi-fsq supports the undirected, directed and image modes of FSQCALL. FSQ is an invention of Murray Greenman, ZL1BPU. The offset rotation of the IFKP sequence offers improved performance under NVIS conditions, because the rotation significantly reduces the risk of adjacent symbols causing inter-symbol interference.įldigi can operate on the following FSQ modes without special setup by the operator:Īt the time of this release there is only one other amateur modem application that supports FSQ, FSQCALL, written by Con Wassilieff, ZL2AFP. FSQ uses 33 tones spaced by 3 times the 3 baud symbol rate or 8.8 Hz. It is a unique mode for fldigi users in that it is a line by line transmission rather than character by character. FSQ, Fast Simple QSO, is an Incremental-Frequency-Keyed mode using an offset differential modulation scheme similar to DominoEX, and Thor.
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