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comparison tfo-ut/README @ 100:a1868d31ce7f default tip
tfo-ut: add README
| author | Mychaela Falconia <falcon@freecalypso.org> |
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| date | Wed, 19 Mar 2025 01:39:57 +0000 |
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| 99:f8b501c8bfce | 100:a1868d31ce7f |
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| 1 Each of the 3 tfo-*.bin files in this directory is an extract from an MSC-side | |
| 2 E1 timeslot recording in a Nokia TCSM2 TFO session involving a cross-connect | |
| 3 between two TRAU channels. The extracts have been chosen to begin at the point | |
| 4 where the TRAU starts emitting TFO frames, thereby beginning with a series of | |
| 5 TFO frames that contain an embedded TFO_TRANS message. In each experiment, one | |
| 6 of the two cross-connected TRAU channels emitted two "plain" TFO frames (not | |
| 7 containing embedded TFO messages) in between the initial embedded TFO_TRANS and | |
| 8 the subsequent embedded TFO_REQ_L; this channel was chosen for the present | |
| 9 extracts. Each extract is thus 2560 PCM samples, containing 16 aligned TFO | |
| 10 frames: 5 carrying TFO_TRANS, 2 plain, 9 carrying TFO_REQ_L. | |
| 11 | |
| 12 In each of the three TCSM2 sessions from which these TFO frame extracts were | |
| 13 taken, the Ater UL input was fed with a stream of good DHFs (decoder homing | |
| 14 frames) for the respective codec, hence the TFO frame content is nothing but | |
| 15 these DHFs. In the case of FR and EFR captures, one of the 16 consecutive | |
| 16 frames also exhibits TAF=1. OTOH, the same does not hold for HR: the TRAU-8k | |
| 17 frame format used in TFO and in most Abis implementations carries TAF only for | |
| 18 BFIs and invalid SID, but not for good speech or valid SID frames. | |
| 19 | |
| 20 The tfo-*.hex files that are generated from tfo-*.bin by the Makefile in this | |
| 21 directory are intended to serve as unit tests for TFO frame extraction functions | |
| 22 that are currently being implemented in libosmotrau. The lack of frame content | |
| 23 diversity (nothing but DHF) is not seen as a problem: the objective here is to | |
| 24 test TFO frame extraction functions; the higher-level logic of TRAU frame | |
| 25 decoding has its own unit tests. |