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Dla tego produktu nie napisano jeszcze recenzji!
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jedyne do czego mogę mieć zastrzeżenie to jakość zdjęć zawartych w przesłanej instrukcji serwisowej ponieważ są fatalnej jakości, praktycznie nieczytelne. tak poza tym jestem zadowolony to jest to czego szukałem.
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Wszystko w porządku.
Instrukcja czytelna i kompletna.
Dziękuję.
all right!
thank you.
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Bardzo dobra instrukcja. Zawiera wszystko co potrzeba, polecam!
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Instrukcja jest OK. Schematy czytelne, opisane niektóre procedury.
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Instrukcja bardzo czytelna. zawiera co potrzeba. Polecam
Level 3 Service Manual GALAXY ASTRAL GEO GEO WAP
4.
Speech coder.
Audio is sampled at 8 kHz rate, and divided into 20 ms blocks of 160 samples per block. Each 20 ms block is characterised by 260 bits i.e. 13 kbits/sec. The resulting signal is processed by a regular pulse excitation - long term predictor (RPE - LTP) codec. This yields a digital representation of vocal chord vibrations, together with the filter characteristics which must be applied to them to make voice sounds. The most significant 182 bits will go through error correction and become 378 bits. The less critical group of 78 bits will not go through error correction and will just be summed with the 378 bits which will yield 456 bits.
Voice SPEECH CODER 160 voice samples = 20 ms
182 bits
78 bits
260 bits (20 ms)
error correction block coding 378 bits 378 bits 78 bits 8 blocks of 57 bits 57 57 57 57 57 57 57 57 57 57 456 bits next speech block 57
57
57
57
57
time slot
time slot
These 456 bits are then separated in 8 blocks of 57 data bits. These blocks are interleaved with adjacent blocks to guard against burst errors and broken up into blocks of 114 bits for transmission. This block of 114 bits are the data bits of the timeslot. Timing data is added, and the resulting bit stream is fed to the Gaussian Minimum Shift Keying (GMSK) modulator, where the bits are taken two at a time and used to smoothly change the phase of an RF carrier according to bit combination.
4.1
Full rate / Half rate / Enhanced full rate.
The data rate of 13 kbit/sec ( full rate ) is considerably lower than for direct speech digitising as in PCM. Now more advanced voice coders cut this to 5.6 kbit/sec ( half rate coding ). The enhanced full rate, is just a full rate with a different speech coder which improves the transmission quality. Mitsubishi Electric Telecom Europe SA ZA le Piquet, 35370 Etrelles Phone: +33 2 99 75 71 00 Fax: + 33 2 99 75 71 47 Version E Date: 04/00
17/29
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