ISD-T360SB Datasheet, PDF (100/109 Pages) List of Unclassifed Manufacturers – VoiceDSP Digital Speech Processor with Master/Slave, Full-Duplex Speakerphone, Multiple Flash and ARAM/DRAM Support

ISD-T360SB
2—SOFTWARE
Table 2-9: TUNABLE PARAMETERS: Speakerphone
Index
Parameter Name
Description
Default
38
Electric Echo Canceler Specifies the positive peak value at which the analog circuit 16000
(EEC):
of the speaker saturates. Codec analog full scale
SP_EEC_CLIP_POS
corresponds to µLAW full scale values after expansion. The
value of SP_EEC_CLIP_POS is set as shown for
SP_AEC_CLIP_POS, above.
Legal values: 0 to 32767.
39
Electric Echo Canceler Specifies the negative peak value at which the analog circuit –16000
(EEC):
of the line-out saturates. Codec analog full scale corresponds
SP_EEC_CLIP_NEG
to µLAW full scale values after expansion. The value of
SP_EEC_CLIP_NEG is set as shown for SP_AEC_CLIP_POS,
above.
Legal values: –32768 to 0.
41
Electric Echo Canceler Enables/disables the electrical echo controller.
1
(EEC):
Legal values: 0 (disable), 1 (enable).
SP_EEC_ENABLE
44
Electric Echo Canceler Controls the hysteresis in far-talker detection. (The
10
(EEC):
speakerphone state machine has a built-in hysteresis
SP_EEC_VOX_HYST
mechanism to prevent fluctuations in the talker identification
process i.e., identifying the active side.) The value of this
parameter is a dimensionless number, which should be
evaluated during the tuning process for specific hardware.
Larger values for the parameter correspond to a wider
hysteresis loop. Negative values increase the probability that
the state machine remains in the last state.
Legal values: –127 to 127.
46
Electric Echo Canceler Controls the sensitivity of the system. Low values correspond to 82
(EEC):
high sensitivity, with a greater false alarm probability (i.e., an
SP_EEC_DTD_TH
echo is considered a real talker).
High values correspond to low sensitivity, with slower switching.
This parameter is affected by the loop gain and the specific
hardware characteristics.
Legal values: 0 to 127.
33
Attenuation:
SP_BLOCK_LEVEL
Controls the maximum attenuation level of the speakerphone
suppressors. It affects the speakerphone stability and its
subjective quality. The maximum attenuation is calculated
according to:
SP_BLOCK_LEVEL/2²⁸
Legal values: 550 to 32000.
10922
42
Tone Generation:
SP_TONE_GEN_
LEVEL
Controls the energy level at which DTMF, and other tones, are 6
generated to the line (codec 0) while the speakerphone is
active. Each unit represents 3 dB.
Legal values: 0 ≤ SP_TONE_GEN_LEVEL ≤ 10.
Note: the energy level at which the tones are generated to
the speaker (codec 1) while the speakerphone is active, is
controlled by the TONE_GEN_LEVEL tunable parameter and
the vol_level.
2-60
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