op25-dev July 2013

op25-dev@lists.osmocom.org

3 participants
5 discussions

grc/op25 [1 Attachment]
by Matt D 23 Jul '13

23 Jul '13

hey, i am having major problems here. i was testing some code i put into the ldu1 files to get the unit ids. after many installations of the revised ldu1 files my work was halted. first my grc got stuck on start up. now it starts and dies in a flash and prints out like a thousand errors that essentially, i think, say that op25 is not installed; or that it is installed incorrectly. i have been trying to remedy this all weekend. i uninstalled and reinstalled op25 and gr-baz and grc3.6.3. multiple times. i am fresh out of ideas. i attached the traceback stuff, if you can, please take a peek. any guidance would be much appreciated. -- Matt D ------------

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OP25 CAI reference
by Matt D 15 Jul '13

15 Jul '13

Hi, I have been unable to find the OP25 CAI reference. Can somebody point me to it? Thanks! -- Matt D ------------

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rs decoder in hdu.cc
by Matt D 15 Jul '13

15 Jul '13

Hey, In the hdu.cc file there is a function 'apply_rs_correction'. I am interested in finding out how this works. What is confusing me is that I know it works. But I have been looking at this code and to me it seems to do essentially nothing??? // apply a different kind of correction void hdu::apply_rs_correction(bit_vector& frame) { // pre-processor if statement that is *always false* (0 == false) #if 0 *// so this code is not included in the final compiled program static itpp::Reed_Solomon rs(6, 8, true); const size_t rs_codeword[][6] = { }; const size_t nof_codeword_bits = sizeof(codeword_bits) / sizeof(codeword_bits[0]); // the end of the pre-processor if statement #endif // and that's it for this function? -- so this function is actually empty in the compiled program??? } I am putting comments in the code trying to understand it. What am i missing here? -- Matt D ------------

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LCWs: hamming, rs, serialization
by Matt D 13 Jul '13

13 Jul '13

Hey, I am trying to get a handle on the data in the Link Control Word. The LCW is 72 bits right? On transmission the 72 bit LCW is serialized into 12 hex bits. And then it is encoded with a (24,12,13) RS code to yield 24 hex bits. The 24 hex bits are then encoded with a (10,6,3) shortened Hamming code to yield 240 bits total. Is it known how the bits are serialized? Or better yet is there an existing function for unserializing/serializing that will work here? And the Hamming and RS codes: does anyone have functions for decoding (10,6,3) Hamming and (24,12,13) RS code? If these decoders do not exist already, where should I start? Thanks! -- Matt D ------------

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Link Control Format
by Matt D 12 Jul '13

12 Jul '13

Hey, Does anyone know whats up with the LCFs??? There are only 2 examples in the Daniels manual. I have been unable to find out anything about the remaining LCFs. Thanks -- Matt D ------------

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op25-dev July 2013