mirror of
https://git.vladimir.cc/vladimir/ewsdr.git
synced 2026-08-25 20:37:33 +00:00
feat(dmr): decode CACH and slot type
This commit is contained in:
@@ -8,3 +8,9 @@ lazbuild -B --ws=cocoa ewsdr.lpr
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# Optional DMR AMBE+2 adapter (requires mbelib development files)
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cmake -S native/dmr -B build/dmr -DCMAKE_BUILD_TYPE=Release
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cmake --build build/dmr
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# DMR receive/protocol tests
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fpc -Fu. -FE/tmp tests/dmr_protocol_test.pas
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/tmp/dmr_protocol_test
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fpc -Fu. -FE/tmp tests/dmr_frontend_test.pas
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/tmp/dmr_frontend_test
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+28
-3
@@ -18,7 +18,7 @@ unit DMRDecoder;
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interface
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uses
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Classes, SysUtils, SyncObjs, Math, DMRBindings;
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Classes, SysUtils, SyncObjs, Math, DMRBindings, DMRProtocol;
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const
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DMR_INPUT_RATE = 48000;
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@@ -49,6 +49,13 @@ type
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SignalRMS: Single;
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LastSyncAgeMs: QWord;
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VocoderAvailable: Boolean;
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CACHValid: Boolean;
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Slot: Integer;
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LCSS: Integer;
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SlotTypeValid: Boolean;
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ColorCode: Integer;
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DataType: Integer;
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SlotTypeCorrectedBits: Integer;
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end;
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TDMRDecoder = class;
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@@ -90,9 +97,10 @@ type
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FMagSum: array[0..DMR_SAMPLES_PER_SYM - 1] of Double;
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FBestSyncQuality: Double;
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FTrackPhase: Integer;
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FCurrentBurst: array[0..DMR_BURST_DIBITS - 1] of Byte;
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FCurrentBurst: TDMRDibitBurst;
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FCurrentBurstPos: Integer;
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FLastBurst: array[0..DMR_BURST_DIBITS - 1] of Byte;
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FLastBurst: TDMRDibitBurst;
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FLastBurstInfo: TDMRBurstInfo;
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FBurstCount: QWord;
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FRMSSq: Double;
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@@ -250,6 +258,7 @@ begin
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FBestSyncQuality := 0;
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FillChar(FCurrentBurst, SizeOf(FCurrentBurst), 0);
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FillChar(FLastBurst, SizeOf(FLastBurst), 0);
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FillChar(FLastBurstInfo, SizeOf(FLastBurstInfo), 0);
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FTrackPhase := -1;
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FCurrentBurstPos := 0;
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FBurstCount := 0;
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@@ -435,6 +444,7 @@ end;
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procedure TDMRDecoder.CompleteBurst;
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begin
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Move(FCurrentBurst[0], FLastBurst[0], SizeOf(FLastBurst));
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DMRParseBurst(FLastBurst, FLastBurstInfo);
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Inc(FBurstCount);
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FCurrentBurstPos := 0;
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end;
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@@ -494,6 +504,21 @@ begin
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(S.LastSyncAgeMs <= DMR_SYNC_HOLD_MS);
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S.SignalRMS := Sqrt(FRMSSq);
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S.VocoderAvailable := FMbe <> nil;
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// CACH exists on base-station bursts. On MS/direct bursts the same
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// positions are payload/guard symbols and can accidentally form a
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// syntactically valid Hamming word.
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S.CACHValid := FLastBurstInfo.CACH.Valid and
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(FSyncKind in [dskBSData, dskBSVoice]);
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S.Slot := FLastBurstInfo.CACH.Slot;
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S.LCSS := FLastBurstInfo.CACH.LCSS;
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// Voice sync replaces the centre Slot Type field. Do not expose a
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// chance Golay match from AMBE bits as a real colour/data type.
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S.SlotTypeValid := FLastBurstInfo.SlotType.Valid and
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(FSyncKind in [dskBSData, dskMSData,
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dskDirectTS1Data, dskDirectTS2Data]);
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S.ColorCode := FLastBurstInfo.SlotType.ColorCode;
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S.DataType := FLastBurstInfo.SlotType.DataType;
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S.SlotTypeCorrectedBits := FLastBurstInfo.SlotType.CorrectedBits;
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finally
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FStatusLock.Leave;
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end;
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+231
@@ -0,0 +1,231 @@
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unit DMRProtocol;
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{
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Small, allocation-free DMR burst protocol layer.
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The CACH interleave and Hamming/Golay generator matrices are derived from
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dsd-fme (src/dmr_bs.c and src/fec.c). The original code is distributed
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under the ISC licence; see the dsd-fme source tree for its full notice.
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}
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{$IFDEF FPC}
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{$MODE Delphi}
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{$ENDIF}
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interface
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uses
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SysUtils;
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const
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DMR_PROTOCOL_BURST_DIBITS = 144;
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type
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TDMRDibitBurst = array[0..DMR_PROTOCOL_BURST_DIBITS - 1] of Byte;
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TDMRBit7 = array[0..6] of Byte;
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TDMRBit20 = array[0..19] of Byte;
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TDMRCACH = record
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Valid: Boolean;
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CorrectedBits: Integer;
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AccessType: Boolean;
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Slot: Integer;
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LCSS: Integer;
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end;
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TDMRSlotType = record
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Valid: Boolean;
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CorrectedBits: Integer;
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ColorCode: Integer;
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DataType: Integer;
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end;
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TDMRBurstInfo = record
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CACH: TDMRCACH;
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SlotType: TDMRSlotType;
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end;
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function DMRHamming74Encode(Value: Byte): TDMRBit7;
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function DMRGolay208Encode(Value: Byte): TDMRBit20;
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function DMRDecodeCACH(const Burst: TDMRDibitBurst; out CACH: TDMRCACH): Boolean;
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function DMRDecodeSlotType(const Burst: TDMRDibitBurst;
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out SlotType: TDMRSlotType): Boolean;
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procedure DMRParseBurst(const Burst: TDMRDibitBurst; out Info: TDMRBurstInfo);
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function DMRDataTypeName(DataType: Integer): string;
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implementation
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const
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CACH_INTERLEAVE: array[0..23] of Byte = (
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0, 7, 8, 9, 1, 10,
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11, 12, 2, 13, 14, 15,
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3, 16, 4, 17, 18, 19,
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5, 20, 21, 22, 6, 23
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);
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HAMMING_7_4_G: array[0..3, 0..6] of Byte = (
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(1, 0, 0, 0, 1, 0, 1),
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(0, 1, 0, 0, 1, 1, 1),
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(0, 0, 1, 0, 1, 1, 0),
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(0, 0, 0, 1, 0, 1, 1)
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);
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GOLAY_20_8_G: array[0..7, 0..19] of Byte = (
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(1,0,0,0,0,0,0,0, 0,0,1,1,1,1,0,1,1,0,1,0),
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(0,1,0,0,0,0,0,0, 1,1,0,1,1,0,0,1,1,0,0,1),
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(0,0,1,0,0,0,0,0, 0,1,1,0,1,1,0,0,1,1,0,1),
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(0,0,0,1,0,0,0,0, 0,0,1,1,0,1,1,0,0,1,1,1),
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(0,0,0,0,1,0,0,0, 1,1,0,1,1,1,0,0,0,1,1,0),
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(0,0,0,0,0,1,0,0, 1,0,1,0,1,0,0,1,0,1,1,1),
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(0,0,0,0,0,0,1,0, 1,0,0,1,0,0,1,1,1,1,1,0),
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(0,0,0,0,0,0,0,1, 1,0,0,0,1,1,1,0,1,0,1,1)
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);
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function DMRHamming74Encode(Value: Byte): TDMRBit7;
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var
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i, j: Integer;
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begin
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FillChar(Result, SizeOf(Result), 0);
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for i := 0 to 3 do
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if ((Value shr (3 - i)) and 1) <> 0 then
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for j := 0 to 6 do Result[j] := Result[j] xor HAMMING_7_4_G[i, j];
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end;
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function DMRGolay208Encode(Value: Byte): TDMRBit20;
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var
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i, j: Integer;
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begin
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FillChar(Result, SizeOf(Result), 0);
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for i := 0 to 7 do
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if ((Value shr (7 - i)) and 1) <> 0 then
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for j := 0 to 19 do Result[j] := Result[j] xor GOLAY_20_8_G[i, j];
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end;
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function DecodeHamming74(const Received: TDMRBit7; out Value: Byte;
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out Corrected: Integer): Boolean;
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var
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Candidate: TDMRBit7;
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V, i, Distance, BestDistance: Integer;
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begin
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Value := 0;
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BestDistance := 8;
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for V := 0 to 15 do
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begin
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Candidate := DMRHamming74Encode(V);
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Distance := 0;
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for i := 0 to 6 do Inc(Distance, Candidate[i] xor (Received[i] and 1));
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if Distance < BestDistance then
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begin
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BestDistance := Distance;
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Value := V;
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end;
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end;
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Corrected := BestDistance;
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Result := BestDistance <= 1;
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end;
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function DecodeGolay208(const Received: TDMRBit20; out Value: Byte;
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out Corrected: Integer): Boolean;
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var
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Candidate: TDMRBit20;
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V, i, Distance, BestDistance: Integer;
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begin
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Value := 0;
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BestDistance := 21;
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for V := 0 to 255 do
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begin
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Candidate := DMRGolay208Encode(V);
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Distance := 0;
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for i := 0 to 19 do Inc(Distance, Candidate[i] xor (Received[i] and 1));
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if Distance < BestDistance then
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begin
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BestDistance := Distance;
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Value := V;
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if Distance = 0 then Break;
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end;
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end;
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Corrected := BestDistance;
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Result := BestDistance <= 2;
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end;
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function DMRDecodeCACH(const Burst: TDMRDibitBurst; out CACH: TDMRCACH): Boolean;
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var
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Deinterleaved: array[0..23] of Byte;
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TACT: TDMRBit7;
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Value: Byte;
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i: Integer;
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begin
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FillChar(CACH, SizeOf(CACH), 0);
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FillChar(Deinterleaved, SizeOf(Deinterleaved), 0);
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for i := 0 to 11 do
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begin
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Deinterleaved[CACH_INTERLEAVE[2 * i]] := (Burst[i] shr 1) and 1;
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Deinterleaved[CACH_INTERLEAVE[2 * i + 1]] := Burst[i] and 1;
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end;
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for i := 0 to 6 do TACT[i] := Deinterleaved[i];
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CACH.Valid := DecodeHamming74(TACT, Value, CACH.CorrectedBits);
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if CACH.Valid then
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begin
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CACH.AccessType := (Value and 8) <> 0;
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CACH.Slot := (Value shr 2) and 1;
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CACH.LCSS := Value and 3;
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end;
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Result := CACH.Valid;
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end;
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function DMRDecodeSlotType(const Burst: TDMRDibitBurst;
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out SlotType: TDMRSlotType): Boolean;
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var
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Bits: TDMRBit20;
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Value: Byte;
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i, k: Integer;
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begin
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FillChar(SlotType, SizeOf(SlotType), 0);
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k := 0;
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for i := 61 to 65 do
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begin
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Bits[k] := (Burst[i] shr 1) and 1; Inc(k);
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Bits[k] := Burst[i] and 1; Inc(k);
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end;
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for i := 90 to 94 do
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begin
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Bits[k] := (Burst[i] shr 1) and 1; Inc(k);
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Bits[k] := Burst[i] and 1; Inc(k);
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end;
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SlotType.Valid := DecodeGolay208(Bits, Value, SlotType.CorrectedBits);
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if SlotType.Valid then
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begin
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SlotType.ColorCode := (Value shr 4) and $0F;
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SlotType.DataType := Value and $0F;
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end;
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Result := SlotType.Valid;
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end;
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procedure DMRParseBurst(const Burst: TDMRDibitBurst; out Info: TDMRBurstInfo);
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begin
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FillChar(Info, SizeOf(Info), 0);
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DMRDecodeCACH(Burst, Info.CACH);
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DMRDecodeSlotType(Burst, Info.SlotType);
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end;
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function DMRDataTypeName(DataType: Integer): string;
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begin
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case DataType of
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0: Result := 'PI header';
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1: Result := 'voice LC';
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2: Result := 'terminator LC';
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3: Result := 'CSBK';
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4: Result := 'MBC header';
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5: Result := 'MBC continuation';
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6: Result := 'data header';
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7: Result := 'rate 1/2 data';
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8: Result := 'rate 3/4 data';
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9: Result := 'idle';
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10: Result := 'rate 1 data';
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11: Result := 'unified single block';
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else
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Result := 'reserved ' + IntToStr(DataType);
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end;
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end;
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end.
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+8
-3
@@ -3587,14 +3587,19 @@ end;
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function TMainForm.DMRStatusText: string;
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var
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S: TDMRStatus;
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Inv: string;
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Inv, Details: string;
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begin
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if not FController.GetDMRStatus(S) then Exit('DMR unavailable');
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if not S.Enabled then Exit('DMR off');
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if not S.Synced then Exit(Format('DMR sync... %.3f', [S.SignalRMS]));
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if S.Inverted then Inv := ' INV' else Inv := '';
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Result := Format('DMR %s%s #%d',
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[TDMRDecoder.SyncKindName(S.SyncKind), Inv, S.SyncCount]);
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Details := '';
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if S.CACHValid then Details := Format(' TS%d', [S.Slot + 1]);
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if S.SlotTypeValid then
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Details := Details + Format(' CC%d/DT%d', [S.ColorCode, S.DataType]);
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Result := Format('DMR %s%s%s #%d',
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[TDMRDecoder.SyncKindName(S.SyncKind), Details, Inv,
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S.SyncCount]);
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end;
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procedure TMainForm.UpdateStatusField7;
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@@ -0,0 +1,94 @@
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program dmr_protocol_test;
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{$MODE Delphi}
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uses
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SysUtils, DMRProtocol;
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const
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CACH_INTERLEAVE: array[0..23] of Byte = (
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0, 7, 8, 9, 1, 10,
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11, 12, 2, 13, 14, 15,
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3, 16, 4, 17, 18, 19,
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5, 20, 21, 22, 6, 23
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);
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procedure PutCACH(var Burst: TDMRDibitBurst; Value: Byte);
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var
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Code: TDMRBit7;
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Deinterleaved, Transmitted: array[0..23] of Byte;
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i: Integer;
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begin
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FillChar(Deinterleaved, SizeOf(Deinterleaved), 0);
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Code := DMRHamming74Encode(Value);
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for i := 0 to 6 do Deinterleaved[i] := Code[i];
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for i := 0 to 23 do Transmitted[i] := Deinterleaved[CACH_INTERLEAVE[i]];
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for i := 0 to 11 do
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Burst[i] := (Transmitted[2 * i] shl 1) or Transmitted[2 * i + 1];
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end;
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procedure PutSlotType(var Burst: TDMRDibitBurst; Value: Byte);
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var
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Code: TDMRBit20;
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i, k: Integer;
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begin
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Code := DMRGolay208Encode(Value);
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k := 0;
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for i := 61 to 65 do
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begin
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Burst[i] := (Code[k] shl 1) or Code[k + 1];
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Inc(k, 2);
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end;
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for i := 90 to 94 do
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begin
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Burst[i] := (Code[k] shl 1) or Code[k + 1];
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Inc(k, 2);
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end;
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end;
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procedure Check(Condition: Boolean; const Message_: string);
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begin
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if not Condition then
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begin
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WriteLn(Message_);
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Halt(1);
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end;
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end;
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var
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Burst: TDMRDibitBurst;
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Info: TDMRBurstInfo;
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begin
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FillChar(Burst, SizeOf(Burst), 0);
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// TACT: AT=1, slot=1 (TS2), LCSS=2. Slot Type: CC=9, data header=6.
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PutCACH(Burst, $0E);
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PutSlotType(Burst, $96);
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DMRParseBurst(Burst, Info);
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Check(Info.CACH.Valid, 'valid CACH rejected');
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Check(Info.CACH.AccessType and (Info.CACH.Slot = 1) and
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(Info.CACH.LCSS = 2), 'TACT fields decoded incorrectly');
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Check(Info.SlotType.Valid, 'valid Slot Type rejected');
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Check((Info.SlotType.ColorCode = 9) and (Info.SlotType.DataType = 6),
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'Slot Type fields decoded incorrectly');
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// Hamming(7,4) corrects one bit and Golay(20,8) corrects two.
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Burst[0] := Burst[0] xor 2;
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Burst[61] := Burst[61] xor 2;
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Burst[92] := Burst[92] xor 1;
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DMRParseBurst(Burst, Info);
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Check(Info.CACH.Valid and (Info.CACH.CorrectedBits = 1),
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'CACH one-bit correction failed');
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Check(Info.CACH.AccessType and (Info.CACH.Slot = 1) and
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(Info.CACH.LCSS = 2), 'corrected TACT fields are wrong');
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Check(Info.SlotType.Valid and (Info.SlotType.CorrectedBits = 2),
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'Slot Type two-bit correction failed');
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Check((Info.SlotType.ColorCode = 9) and (Info.SlotType.DataType = 6),
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'corrected Slot Type fields are wrong');
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// A third Slot Type error exceeds the guaranteed correction radius.
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Burst[94] := Burst[94] xor 1;
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DMRParseBurst(Burst, Info);
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Check(not Info.SlotType.Valid, 'uncorrectable Slot Type accepted');
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WriteLn('DMR CACH and Slot Type tests passed');
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end.
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