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------------------------------------------------------------------------ r8020 | k9an | 2017-08-10 03:51:25 +0100 (Thu, 10 Aug 2017) | 1 line Correct misspelling. Thanks Seb, W4AS. ------------------------------------------------------------------------ r8021 | bsomervi | 2017-08-10 19:07:53 +0100 (Thu, 10 Aug 2017) | 1 line Fix FT8 encoding description ------------------------------------------------------------------------ git-svn-id: svn+ssh://svn.code.sf.net/p/wsjt/wsjt/branches/wsjtx-1.8@8025 ab8295b8-cf94-4d9e-aec4-7959e3be5d79
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@ -1820,7 +1820,7 @@ for assessing propagation and system performance.</string>
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<item>
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<item>
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<widget class="QGroupBox" name="groupBox_3">
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<widget class="QGroupBox" name="groupBox_3">
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<property name="toolTip">
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<property name="toolTip">
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<string>See WSPR documentattion Appendix C for details of how to determine these factors for your radio.</string>
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<string>See WSPR documentation Appendix C for details of how to determine these factors for your radio.</string>
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</property>
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</property>
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<property name="title">
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<property name="title">
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<string>Frequency Calibration</string>
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<string>Frequency Calibration</string>
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@ -61,15 +61,15 @@ _WSJT-X_ modes have continuous phase and constant envelope.
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[[FT8PRO]]
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[[FT8PRO]]
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==== FT8
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==== FT8
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Forward error correction (FEC) in FT8 uses a low-density
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Forward error correction (FEC) in FT8 uses a low-density parity check
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parity check (LDPC) code with 75 information bits, a 12-bit cyclic
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(LDPC) code with 75 information bits, a 12-bit cyclic redundancy check
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redundancy check (CRC), and 174 channel symbols. It is thus called an
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(CRC), and 87 parity bits making a 174-bit codeword. It is thus
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LDPC (174,87) code. Synchronization uses 7×7 Costas arrays at the
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called an LDPC (174,87) code. Synchronization uses 7×7 Costas arrays
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beginning, middle, and end of each transmission. Modulation is 8-tone
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at the beginning, middle, and end of each transmission. Modulation is
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frequency-shift keying (8-FSK) at 12000/1920 = 6.25 baud. Each
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8-tone frequency-shift keying (8-FSK) at 12000/1920 = 6.25 baud. Each
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transmitted symbol carries three bits, so the total number of channel
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transmitted symbol carries three bits, so the total number of channel
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symbols is 174/3 + 21 = 79. The total occupied bandwidth is
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symbols is 174/3 + 21 = 79. The total occupied bandwidth is 8 × 6.25
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8 × 6.25 = 50 Hz.
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= 50 Hz.
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[[JT4PRO]]
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[[JT4PRO]]
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==== JT4
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==== JT4
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