Possible bug/question about mbelib.

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IanWraith

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Hi Folks
I have just been looking at the mbelib code looking at the possibility of "borrowing" the Golay code in it for use in DMRDecode. However I have found an oddity if you look in ecc_const.h

https://github.com/szechyjs/mbelib/blob/d30b81603d9feda80c0466cba902c2b01f92b0f8/ecc_const.h

you see golayMatrix declared as an array consisting of 2048 ints.

const int golayMatrix[2048] = { numbers ...]

except there are only 1839 numbers then given. The problem is that the method mbe_checkGolayBlock() in ecc.c ..

https://github.com/szechyjs/mbelib/blob/d30b81603d9feda80c0466cba902c2b01f92b0f8/ecc.c

uses the golayMatrix trying to access all the elements right up to 2048. So should golayMatrix be larger or are we just using a "feature" of C to assume that all elements of golayMatrix above 1839 are set to zero ?

Thanks for your time.

Regards

Ian
 

slicerwizard

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It's a bug. I noticed it myself awhile back. Transmission errors that hit those missing entries don't get fixed or reported.

Also, the table is somewhat limiting as it only tells you which of the 12 payload bits were incorrectly received - it doesn't tell you if any of the 11 FEC bits are damaged, so you can't get a proper BER estimate from it. And it reduces the accuracy of DSD's error indicators (the "===" displays)
 
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woodpecker

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Hi Folks
I have just been looking at the mbelib code looking at the possibility of "borrowing" the Golay code in it for use in DMRDecode. However I have found an oddity if you look in ecc_const.h

https://github.com/szechyjs/mbelib/blob/d30b81603d9feda80c0466cba902c2b01f92b0f8/ecc_const.h

you see golayMatrix declared as an array consisting of 2048 ints.

const int golayMatrix[2048] = { numbers ...]

except there are only 1839 numbers then given. The problem is that the method mbe_checkGolayBlock() in ecc.c ..

https://github.com/szechyjs/mbelib/blob/d30b81603d9feda80c0466cba902c2b01f92b0f8/ecc.c

uses the golayMatrix trying to access all the elements right up to 2048. So should golayMatrix be larger or are we just using a "feature" of C to assume that all elements of golayMatrix above 1839 are set to zero ?

Thanks for your time.

Regards

Ian

Well spotted Ian, despite playing with DSD quite a bit I hadn't noticed that and it does make a difference on some transmisions I've tested it with. I've generated the correct decoding matrix with all entries:-

Code:
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 72, 0, 0, 0, 0, 0, 0, 0, 2084, 0, 0, 0, 769, 0, 1024, 144,
2, 0, 0, 0, 0, 0, 0, 0, 72, 0, 0, 0, 72, 0, 72, 72, 72, 0, 0, 0, 16, 0, 1, 1538, 384, 0, 134, 2048, 1056, 288,
2576, 5, 72, 0, 0, 0, 0, 0, 0, 0, 1280, 0, 0, 0, 4, 0, 546, 144, 2049, 0, 0, 0, 66, 0, 1, 144, 520, 0, 2056, 144,
1056, 144, 324, 144, 144, 0, 0, 0, 2688, 0, 1, 32, 22, 0, 272, 3, 1056, 3076, 128, 768, 72, 0, 1, 268, 1056, 1, 1, 2112, 1, 576,
1056, 1056, 1056, 10, 1, 144, 1056, 0, 0, 0, 0, 0, 0, 0, 1280, 0, 0, 0, 160, 0, 21, 2560, 2, 0, 0, 0, 16, 0, 704, 9,
2, 0, 2056, 1092, 2, 288, 2, 2, 2, 0, 0, 0, 16, 0, 2050, 132, 545, 0, 1536, 3, 2308, 288, 128, 1040, 72, 0, 16, 16, 16, 288,
1036, 2112, 16, 288, 65, 648, 16, 288, 288, 288, 2, 0, 0, 0, 1280, 0, 1280, 1280, 1280, 0, 2056, 3, 592, 64, 128, 44, 1280, 0, 2056, 544,
133, 6, 48, 2112, 1280, 2056, 2056, 256, 2056, 1537, 2056, 144, 2, 0, 100, 3, 8, 536, 128, 2112, 1280, 3, 128, 3, 3, 128, 128, 3, 128, 1152,
770, 2112, 16, 2112, 1, 2112, 2112, 20, 2056, 3, 1056, 288, 128, 2112, 516, 0, 0, 0, 0, 0, 0, 0, 131, 0, 0, 0, 4, 0, 1024, 2560,
304, 0, 0, 0, 16, 0, 1024, 320, 520, 0, 1024, 42, 2240, 1024, 1024, 5, 1024, 0, 0, 0, 16, 0, 772, 32, 3072, 0, 2081, 1408, 514, 18,
128, 5, 72, 0, 16, 16, 16, 2184, 98, 5, 16, 576, 264, 5, 16, 5, 1024, 5, 5, 0, 0, 0, 4, 0, 2128, 32, 520, 0, 4, 4,
4, 265, 128, 1090, 4, 0, 416, 3073, 520, 6, 520, 520, 520, 576, 19, 256, 4, 2080, 1024, 144, 520, 0, 1034, 32, 321, 32, 128, 32, 32, 576,
128, 2072, 4, 128, 128, 32, 128, 576, 2052, 130, 16, 1296, 1, 32, 520, 576, 576, 576, 1056, 576, 128, 5, 2306, 0, 0, 0, 16, 0, 40, 2560,
68, 0, 322, 2560, 1033, 2560, 128, 2560, 2560, 0, 16, 16, 16, 6, 2305, 1184, 16, 129, 548, 256, 16, 88, 1024, 2560, 2, 0, 16, 16, 16, 1089,
128, 266, 16, 12, 128, 96, 16, 128, 128, 2560, 128, 16, 16, 16, 16, 512, 16, 16, 16, 3074, 16, 16, 16, 288, 128, 5, 16, 0, 513, 200,
2082, 6, 128, 17, 1280, 1072, 128, 256, 4, 128, 128, 2560, 128, 6, 1088, 256, 16, 6, 6, 6, 520, 256, 2056, 256, 256, 6, 128, 256, 97, 2304,
128, 1540, 16, 128, 128, 32, 128, 128, 128, 3, 128, 128, 128, 128, 128, 41, 16, 16, 16, 6, 128, 2112, 16, 576, 128, 256, 16, 128, 128, 1032,
128, 0, 0, 0, 0, 0, 0, 0, 528, 0, 0, 0, 160, 0, 1024, 262, 2049, 0, 0, 0, 66, 0, 1024, 9, 384, 0, 1024, 2048, 28, 1024,
1024, 608, 1024, 0, 0, 0, 1029, 0, 2050, 32, 384, 0, 272, 2048, 514, 641, 36, 1040, 72, 0, 552, 2048, 384, 84, 384, 384, 384, 2048, 65, 2048,
2048, 10, 1024, 2048, 384, 0, 0, 0, 66, 0, 140, 32, 2049, 0, 272, 1544, 2049, 64, 2049, 2049, 2049, 0, 66, 66, 66, 2816, 48, 1028, 66, 37,
640, 256, 66, 10, 1024, 144, 2049, 0, 272, 32, 8, 32, 1600, 32, 32, 272, 272, 196, 272, 10, 272, 32, 2049, 1152, 2052, 529, 66, 10, 1, 32,
384, 10, 272, 2048, 1056, 10, 10, 10, 516, 0, 0, 0, 160, 0, 2050, 9, 68, 0, 160, 160, 160, 64, 776, 1040, 160, 0, 260, 9, 3584, 9,
48, 9, 9, 530, 65, 256, 160, 2180, 1024, 9, 2, 0, 2050, 832, 8, 2050, 2050, 1040, 2050, 12, 65, 1040, 160, 1040, 2050, 1040, 1040, 1152, 65, 38,
16, 512, 2050, 9, 384, 65, 65, 2048, 65, 288, 65, 1040, 516, 0, 513, 2068, 8, 64, 48, 642, 1280, 64, 1030, 256, 160, 64, 64, 64, 2049, 1152,
48, 256, 66, 48, 48, 9, 48, 256, 2056, 256, 256, 64, 48, 256, 516, 1152, 8, 8, 8, 261, 2050, 32, 8, 2592, 272, 3, 8, 64, 128, 1040,
516, 1152, 1152, 1152, 8, 1152, 48, 2112, 516, 1152, 65, 256, 516, 10, 516, 516, 516, 0, 0, 0, 2312, 0, 1024, 32, 68, 0, 1024, 81, 514, 1024,
1024, 136, 1024, 0, 1024, 644, 33, 1024, 1024, 2066, 1024, 1024, 1024, 256, 1024, 1024, 1024, 1024, 1024, 0, 192, 32, 514, 32, 25, 32, 32, 12, 514, 514,
514, 2368, 1024, 32, 514, 259, 2052, 1096, 16, 512, 1024, 32, 384, 176, 1024, 2048, 514, 1024, 1024, 5, 1024, 0, 513, 32, 1168, 32, 258, 32, 32, 2178,
104, 256, 4, 532, 1024, 32, 2049, 24, 2052, 256, 66, 193, 1024, 32, 520, 256, 1024, 256, 256, 1024, 1024, 256, 1024, 32, 2052, 32, 32, 32, 32, 32,
32, 1025, 272, 32, 514, 32, 128, 32, 32, 2052, 2052, 32, 2052, 32, 2052, 32, 32, 576, 2052, 256, 137, 10, 1024, 32, 80, 0, 513, 1026, 68, 400,
68, 68, 68, 12, 2064, 256, 160, 35, 1024, 2560, 68, 2144, 138, 256, 16, 512, 1024, 9, 68, 256, 1024, 256, 256, 1024, 1024, 256, 1024, 12, 1312, 2177,
16, 512, 2050, 32, 68, 12, 12, 12, 514, 12, 128, 1040, 257, 512, 16, 16, 16, 512, 512, 512, 16, 12, 65, 256, 16, 512, 1024, 194, 2088, 513,
513, 256, 513, 3080, 513, 32, 68, 256, 513, 256, 256, 64, 128, 256, 26, 256, 513, 256, 256, 6, 48, 256, 2176, 256, 256, 256, 256, 256, 1024, 256,
256, 82, 513, 32, 8, 32, 128, 32, 32, 12, 128, 256, 3136, 128, 128, 32, 128, 1152, 2052, 256, 16, 512, 328, 32, 1027, 256, 34, 256, 256, 2065,
128, 256, 516, 0, 0, 0, 0, 0, 0, 0, 528, 0, 0, 0, 4, 0, 2432, 1057, 2, 0, 0, 0, 1160, 0, 1, 320, 2, 0, 112, 2048,
2, 524, 2, 2, 2, 0, 0, 0, 290, 0, 1, 132, 3072, 0, 1536, 2048, 145, 18, 36, 768, 72, 0, 1, 2048, 580, 1, 1, 56, 1, 2048,
264, 2048, 2048, 1216, 1, 2048, 2, 0, 0, 0, 4, 0, 1, 2058, 224, 0, 4, 4, 4, 64, 1048, 768, 4, 0, 1, 544, 2320, 1, 1, 1028,
1, 1282, 640, 73, 4, 2080, 1, 144, 2, 0, 1, 1104, 8, 1, 1, 768, 1, 168, 2114, 768, 4, 768, 1, 768, 768, 1, 1, 130, 1, 1,
1, 1, 1, 20, 1, 2048, 1056, 1, 1, 768, 1, 0, 0, 0, 2113, 0, 40, 132, 2, 0, 1536, 280, 2, 64, 2, 2, 2, 0, 260, 544,
2, 3088, 2, 2, 2, 129, 2, 2, 2, 2, 2, 2, 2, 0, 1536, 132, 8, 132, 336, 132, 132, 1536, 1536, 96, 1536, 2057, 1536, 132, 2, 74,
2208, 1281, 16, 512, 1, 132, 2, 20, 1536, 2048, 2, 288, 2, 2, 2, 0, 146, 544, 8, 64, 2564, 17, 1280, 64, 289, 3200, 4, 64, 64, 64,
2, 544, 1088, 544, 544, 392, 1, 544, 2, 20, 2056, 544, 2, 64, 2, 2, 2, 2304, 8, 8, 8, 1058, 1, 132, 8, 20, 1536, 3, 8, 64,
128, 768, 2096, 20, 1, 544, 8, 1, 1, 2112, 1, 20, 20, 20, 448, 20, 1, 1032, 2, 0, 0, 0, 4, 0, 40, 320, 3072, 0, 4, 4,
4, 18, 577, 136, 4, 0, 2562, 320, 33, 320, 148, 320, 320, 129, 264, 1552, 4, 2080, 1024, 320, 2, 0, 192, 521, 3072, 18, 3072, 3072, 3072, 18,
264, 96, 4, 18, 18, 18, 3072, 1060, 264, 130, 16, 512, 1, 320, 3072, 264, 264, 2048, 264, 18, 264, 5, 672, 0, 4, 4, 4, 1664, 258, 17,
4, 4, 4, 4, 4, 2080, 4, 4, 4, 24, 1088, 130, 4, 2080, 1, 320, 520, 2080, 4, 4, 4, 2080, 2080, 2080, 4, 2304, 560, 130, 4, 76,
1, 32, 3072, 1025, 4, 4, 4, 18, 128, 768, 4, 130, 1, 130, 130, 1, 1, 130, 1, 576, 264, 130, 4, 2080, 1, 1032, 80, 0, 40, 1026,
896, 40, 40, 17, 40, 129, 2064, 96, 4, 1284, 40, 2560, 2, 129, 1088, 2060, 16, 512, 40, 320, 2, 129, 129, 129, 2, 129, 2, 2, 2, 2304,
7, 96, 16, 512, 40, 132, 3072, 96, 1536, 96, 96, 18, 128, 96, 257, 512, 16, 16, 16, 512, 512, 512, 16, 129, 264, 96, 16, 512, 2116, 1032,
2, 2304, 1088, 17, 4, 17, 40, 17, 17, 522, 4, 4, 4, 64, 128, 17, 4, 1088, 1088, 544, 1088, 6, 1088, 17, 2176, 129, 1088, 256, 4, 2080,
784, 1032, 2, 2304, 2304, 2304, 8, 2304, 128, 17, 578, 2304, 128, 96, 4, 128, 128, 1032, 128, 2304, 1088, 130, 16, 512, 1, 1032, 292, 20, 34, 1032,
2561, 1032, 128, 1032, 1032, 0, 0, 0, 528, 0, 528, 528, 528, 0, 11, 2048, 1344, 64, 36, 136, 528, 0, 260, 2048, 33, 162, 2120, 1028, 528, 2048,
640, 2048, 2048, 273, 1024, 2048, 2, 0, 192, 2048, 8, 1288, 36, 67, 528, 2048, 36, 2048, 2048, 36, 36, 2048, 36, 2048, 1042, 2048, 2048, 512, 1, 2048,
384, 2048, 2048, 2048, 2048, 2048, 36, 2048, 2048, 0, 3104, 385, 8, 64, 258, 1028, 528, 64, 640, 50, 4, 64, 64, 64, 2049, 24, 640, 1028, 66, 1028,
1, 1028, 1028, 640, 640, 2048, 640, 64, 640, 1028, 296, 518, 8, 8, 8, 2192, 1, 32, 8, 1025, 272, 2048, 8, 64, 36, 768, 1154, 352, 1, 2048,
8, 1, 1, 1028, 1, 2048, 640, 2048, 2048, 10, 1, 2048, 80, 0, 260, 1026, 8, 64, 1153, 2336, 528, 64, 2064, 517, 160, 64, 64, 64, 2, 260,
260, 208, 260, 512, 260, 9, 2, 1064, 260, 2048, 2, 64, 2, 2, 2, 49, 8, 8, 8, 512, 2050, 132, 8, 386, 1536, 2048, 8, 64, 36, 1040,
257, 512, 260, 2048, 8, 512, 512, 512, 1120, 2048, 65, 2048, 2048, 512, 152, 2048, 2, 64, 8, 8, 8, 64, 64, 64, 8, 64, 64, 64, 8, 64,
64, 64, 64, 2051, 260, 544, 8, 64, 48, 1028, 2176, 64, 640, 256, 1041, 64, 64, 64, 2, 8, 8, 8, 8, 64, 8, 8, 8, 64, 8, 8,
8, 64, 64, 64, 8, 1152, 8, 8, 8, 512, 1, 274, 8, 20, 34, 2048, 8, 64, 3328, 161, 516, 0, 192, 1026, 33, 2053, 258, 136, 528, 800,
2064, 136, 4, 136, 1024, 136, 136, 24, 33, 33, 33, 512, 1024, 320, 33, 70, 1024, 2048, 33, 1024, 1024, 136, 1024, 192, 192, 276, 192, 512, 192, 32,
3072, 1025, 192, 2048, 514, 18, 36, 136, 257, 512, 192, 2048, 33, 512, 512, 512, 14, 2048, 264, 2048, 2048, 512, 1024, 2048, 80, 24, 258, 2624, 4, 258,
258, 32, 258, 1025, 4, 4, 4, 64, 258, 136, 4, 24, 24, 24, 33, 24, 258, 1028, 2176, 24, 640, 256, 4, 2080, 1024, 515, 80, 1025, 192, 32,
8, 32, 258, 32, 32, 1025, 1025, 1025, 4, 1025, 2568, 32, 80, 24, 2052, 130, 1792, 512, 1, 32, 80, 1025, 34, 2048, 80, 388, 80, 80, 80, 1026,
2064, 1026, 1026, 512, 40, 1026, 68, 2064, 2064, 1026, 2064, 64, 2064, 136, 257, 512, 260, 1026, 33, 512, 512, 512, 2176, 129, 2064, 256, 584, 512, 1024, 52,
2, 512, 192, 1026, 8, 512, 512, 512, 257, 12, 2064, 96, 257, 512, 257, 257, 257, 512, 512, 512, 16, 512, 512, 512, 512, 512, 34, 2048, 1156, 512,
512, 512, 257, 164, 513, 1026, 8, 64, 258, 17, 2176, 64, 2064, 256, 4, 64, 64, 64, 1568, 24, 1088, 256, 2176, 512, 2176, 2176, 2176, 256, 34, 256,
256, 64, 13, 256, 2176, 2304, 8, 8, 8, 512, 1044, 32, 8, 1025, 34, 656, 8, 64, 128, 2054, 257, 512, 34, 69, 8, 512, 512, 512, 2176, 34,
34, 256, 34, 512, 34, 1032, 80
 

mtindor

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This all poses a problem unless somebody has access to / can update the github stuff to reflect that change. And then only those people who compile from scratch can benefit from it.

Everyone using the pre-compiled DSD (or DSD with DMR Filter) will not be able to avail themselves of it. Sure they could compile from scratch using an updated mbelib, but that would only help the standard DSD users. For me, DSD with DMR Filter is the only way to fly.

Mike
 

woodpecker

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Hi Mike,

I Already have it compiled into my DSD with filter but I need to tidy it up a bit before I release it, it doesn't make a staggering difference but after playing various recordings through it making comparisons I found it did correct some speach frames that dropped out, in one recording It made a big difference where the incorrect matrix decoded a speach frame as being in the incorrect DMR time slot.
 

mtindor

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Hi Mike,

I Already have it compiled into my DSD with filter but I need to tidy it up a bit before I release it, it doesn't make a staggering difference but after playing various recordings through it making comparisons I found it did correct some speach frames that dropped out, in one recording It made a big difference where the incorrect matrix decoded a speach frame as being in the incorrect DMR time slot.

Good deal. I'm not looking for a staggering difference. The current version w/filter does quite a fine job on its own. But if there is any bug that can be fixed and/or any performance gain to be had, I'm all about having it rofl.

Thanks!

Mike
 

racingfan360

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Hi Woodpecker...do you use PM on this group? If so, would you mind checking your inbox when you get a moment? Thanks,

Jim
 
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