Le58083
Data Sheet
Figure 7. Discrimination Against Out-of-Band Signals
0
-10
-20
-28 dBm
-32 dB, -25 dBm0 < input , 0 dBm0
-30
Level (dB)
-40
-50
3.4
4.0
4.6
Frequency (kHz)
Note:
The attenuation of the waveform below amplitude A, between 3400 Hz and 4600 Hz, is given by the formula:
π(4000 – f)
----------------------------
1200
Attenuation (db) = 14 – 14sin
Discrimination Against 12- and 16-kHz Metering Signals
If the Le58083 Octal SLAC device is used in a metering application where 12 kHz or 16 kHz tone bursts are injected onto the
telephone line toward the subscriber, a portion of these tones also may appear at the VIN terminal. These out-of-band signals
may cause frequency components to appear below 4 kHz at the digital output. For a 12 kHz or 16 kHz tone, the frequency
components below 4 kHz are reduced from the input by at least 70 dB. The sum of the peak metering and signal voltages must
be within the analog input voltage range.
Spurious Out-of-Band Signals at the Analog Output
With PCM code words representing a sine wave signal in the range of 300 Hz to 3400 Hz at a level of 0 dBm0 applied to the
digital input, the level of the spurious out-of-band signals at the analog output is less than the limits shown below.
Frequency
Level
4.6 kHz to 40 kHz
40 kHz to 240 kHz
240 kHz to 1 MHz
–32 dBm0
–46 dBm0
–36 dBm0
With code words representing any sine wave signal in the range 3.4 kHz to 4.0 kHz at a level of 0 dBm0 applied to the digital
input, the level of the signals at the analog output are below the limits in Figure 8. The amplitude of the spurious out-of-band
signals between 3400 Hz and 4600 Hz is given by the formula:
π(f – 4000)
----------------------------
Level = – 14 – 14sin
dBm0
1200
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Zarlink Semiconductor Inc.
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