73M1822/73M1922 Data Sheet
DS_1x22_017
Freq Response of IPMF, AZ=01
10
10
9
8
7
6
5
4
3
2
1
0
F1db(f⋅1000)
0
0
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
5
f
kHz
Figure 34: Magnitude Response of IPMF, ACZ=01 (ETSI ES 203 021-2)
11.4 Billing Tone Rejection
Some countries use a large amplitude out-of-band tone to measure call duration to allow remote central
offices to determine the duration of a call for billing purposes. To avoid saturation and distortion of the input
caused by these tones, it is important to be able to reject them. Typical values of frequency are
12 kHz or16 kHz.
The 73M1x22 has an integrated notch filter that attenuates either of these tones. By enabling this filter and
selecting the position of the notch frequency such tones will be attenuated.
Figure 35 shows the magnitude response of the filter with a notch at either 12 kHz or 16 kHz.
10
10
0
10
F1db(f⋅1000)
20
F2db(f⋅1000)
30
40
− 50
50
0
0
2
4
6
8
10
12
14
16
18
20
20
f
Spans 20kHz
Figure 35: Magnitude Response of Billing Tone Notch Filter
In addition to the notch filter, the 73M1x22 can indicate the presence of an overload condition when a line’s
AC voltage exceeds 3.5 Vpk.
64
Rev. 1.6
TERIDIAN [ TERIDIAN SEMICONDUCTOR CORPORATION ]
