Section 7 AUDIO CODING PRINCIPLES
114
better than two of LII. And we’ve had customers who have used a pass, or two, of LIII
followed by SEDAT without evident problems.
CHOOSING THE CODING METHOD
MOST APPROPRIATE TO YOUR APPLICATION
The following chart describes and compares some of the important characteristics of
each method.
Audio Coding Comparison Chart
Layer III
Layer II
G.722
Algorithm
PerHuffman
Perceptual
ADPCM
Audio Freq. Response/mono
7 kHz
24 kHz sample rate
- -
8.6kHz
- -
32 kHz sample rate
15 kHz
- -
- -
48 kHz sample rate
20 kHz
7.8/9.8 kHz**
- -
Audio Freq. Response/stereo
15/20 kHz*
20 kHz
7 kHz
Delay at HALF/24 kHz
- -
990 ms
45 ms
Delay at 32 kHz/mono
275 ms
- -
45 ms-
Delay at 32 kHz/dual mono
275 ms
- -
45 ms-
Delay at 48 kHz/mono
225 ms
160 ms
45 ms-
Delay at 48 kHz/dual mono
225 ms
160 ms
45 ms-
Delay at 48 kHz/mono- 128
- -
220 ms
- -
Delay at 32 kHz/stereo/jstereo
390 ms
- -
45 ms-
Delay at 48 kHz/stereo/jstereo
270 ms
220 ms
45 ms-
Joint Stereo
MS Matrix
“Intensity Coding” - -
ISO Target Bit Rate
64kbps/channel
128kbps/channel
N/A
Coding “Power”
12:1
6- 8:1***
4:1
Bands
576
32
2
Frequency Resolution (48 kHz)
42 Hz
750 Hz
- -
* 15 kHz at 32 kHz sample rate; 20 kHz at 48 kHz sample rate.
** 7.8 kHz at a 56 kbps network rate; 9.8 kHz at 64 kbps.
*** 12:1 in Intensity Joint Stereo mode
- G.722 delay will vary. Spec is 35 ms +/- 10 msec for 45 ms maximum
Delay times may vary depending upon ISDN line delay and other factors.
Frequency response is given for swept sine test; response with program material may vary
owing to the
dynamic nature of the coding process.
Because the Zephyr includes all three popular coding methods, it is possible to choose
the most appropriate for each application.
Summary of Contents for Zephyr
Page 13: ...Table of Contents 13 SECTION 1 QUICK RESULTS ...
Page 26: ...Section 2 INTRODUCTION 26 This page intentially left blank ...
Page 27: ...Section 2 INTRODUCTION 27 SECTION 2 INTRODUCTION ...
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Page 39: ...39 SECTION 3 ZEPHYR AT A GLANCE ...
Page 52: ...Section 4 INSTALLATION BASIC OPERATION 52 This page intentionally left blank ...
Page 53: ...Section 4 INSTALLATION BASIC OP 53 SECTION 4 INSTALLATION BASIC OPERATION ...
Page 84: ...Section 4 INSTALLATION BASIC OPERATION 84 ...
Page 85: ...Section 5 ISDN 85 SECTION 5 ISDN ...
Page 105: ...Section 6 NON ISDN NETWORKS 105 SECTION 7 AUDIO CODING ...
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Page 119: ...Section 8 DETAILED MENU REFERENCE 119 SECTION 8 DETAILED MENU REFERENCE ...
Page 157: ...Section 9 REMOTE CONTROL 157 SECTION 9 REMOTE CONTROL ...
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Page 177: ...Section 10 ADVANCED PROBLEM SOLVING 177 SECTION 10 ADVANCED PROBLEM SOLVING ...
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Page 197: ...Section 11 TECHNICAL INFORMATION 197 SECTION 11 DETAILED TECHNICAL INFORMATION ...
Page 219: ...Section 12 SCHEMATICS 219 SECTION 12 SCHEMATICS ...
Page 221: ...Section 13 MANUFACTURER S DATA SHEETS 221 SECTION 13 MANUFACTURER S DATA SHEETS ...
Page 223: ...Section 14 SPECIFICATIONS WARRANTY 223 SECTION 14 SPECIFICATIONS AND WARRANTY ...
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Page 229: ...Section 15 APPENDICES 229 SECTION 15 APPENDICES ...