ml7084-001 Oki Semiconductor, ml7084-001 Datasheet - Page 173

• Manufacturer Part Number: ml7084-001
• Description: 4ch Voip Codec
• Manufacturer: Oki Semiconductor

TONE Detector TX0 (TONE_TXDET0)
The tone detector TX0 is a 400 Hz tone detector mounted on the transmit side of CH0.
TONE_TXDET0 consists of a main signal detection section that detects signals having the applicable frequency, a
noise detection section that detects signals having other than the applicable frequency, a ON guard timer and a OFF
guard timer, and detects input 400 Hz single tone signals.
TONE_TXDET0 is enabled when the control register TONE_TXDET0EN is “1”. When a tone is detected (a main
signal is detected and in a state where no noise detected), the control register TONE_TXDET0 is set to “1”. When no
tone is detected or TONE_TXDET0EN is “0”, TONE_TXDET0 is set to “0”.
Also, it can adjust the detection time with the ON and OFF guard timers, as well as the noise detection level for main
signal detection and noise detection. The initial values of both guard timers are 5 ms. The initial value of the
detection level is –5.3 dBm0 for both main signal detection level and noise detection level. Figure 46 shows the tone
detection timing.
A. TONE_TXDET0 enable control register (TONE_TXDET0EN)
B. TONE_TXDET0 detection status register (TONE_TXDET0)
C. Internal data memory for TONE_TXDET0 main signal detection level control (TONE_TXDET0_S_TH)
OKI Semiconductor
0 : Stop (Initial value)
1 : Operate
0 : No tone detected (Initial value)
1 : Tone detected
Initial value : 1EBBh (–5.3 dBm0)
Compute the setting value using the following equation when changing the detection level X.
Equation: 10^((X–3.17)/20)*2/PI*32768
Example: Detect level of –5.3 dBm0
10^((–5.3 – 3.17)/20)*2/PI*32768 = 7867d = 1EBBh
Upper limit: 3.17 dBm0
Lower limit: –35 dBm0
Main signal detection
TONE_TXDET0_EN
: –5.3 dBm0
TONE_TXDET0
Noise detection
Tone detecting
internal signal
AIN input
Figure 46 Tone Detection Timing
ON guard timer
(data: 517Dh)
(data: 1EBBh)
(data: 0102h)
Voice
Tone signal
OFF guard timer
FEDL7224-001FULL-01
ML7224-001TC
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