isd-t360sb ETC-unknow, isd-t360sb Datasheet - Page 49

• Manufacturer Part Number: isd-t360sb
• Manufacturer: ETC-unknow

2—SOFTWARE
BUSY AND DIAL TONES
Busy and dial-tone detectors work with a band-
pass filter that limits the frequency range in which
tones can be detected to 0–1100Hz. Figure 2-2
shows the frequency response of this band-pass
filter.
The design of the busy-tone detector allows very
high flexibility in detecting busy tones with varying
cadences.
The tunable parameters are divided into four sets:
ISD
1. Busy Tone On-time and Off-time Range
2. Busy Tone Cadence Control Specification
Specification:
BUSY_DET_MIN_ON_TIME
BUSY_DET_MIN_OFF_TIME
BUSY_DET_MAX_ON_TIME
BUSY_DET_MAX_OFF_TIME
BUSY_DET_VERIFY_COUNT
BUSY_DET_DIFF_THRESHOLD
BUSY_DET_TONE_TYPE
BUSY_DET_VERIFY_COUNT determines the
number of On/Off cadences that detector
should detect before reporting busy tone
presence.
BUSY_DET_DIFF_THRESHOLD describes the
maximum allowed difference between
Figure 2-2: Busy-Tone Detector—Default Cadence Specification
[E
1
–
E
3
] < 100 ms [S
E
1
1
–
S
1
S
3
] < 100 ms 100 < E
E
2
3. Busy and Dial Tone Energy Thresholds
4. Busy Detection Time
two compared On or Off periods, as deter-
mined by the BUSY_DET_TONE_TYPE tunable
parameter.
BUSY_DET_TONE_TYPE specifies the type of
cadences that are supported.
Legal values are:
Two cadences only
Three cadences only
Both two and three cadences.
The acceptance criteria for two cadences:
[E1–E3] < BUSY_DET_DIFF_THRESHOLD
and
[S1–S3] < BUSY_DET_DIFF_THRESHOLD
The acceptance criteria for three cadenc-
es:
[E1–E4] < BUSY_DET_DIFF_THRESHOLD
and
[S1–S4] < BUSY_DET_DIFF_THRESHOLD
TONE_DET_ON_ENERGY THRESHOLD
TONE_DET_OFF_ENERGY THRESHOLD
BUSY_DET_MIN_TIME
i
< 1680 ms 70 < S
S
2
E
3
i
< 1220 ms
S
3
ISD-T360SB
2-13