CMX869 View Datasheet(PDF) - CML Microsystems Plc
Part Name
Description
MFG CO.
'CMX869' PDF : 46 Pages View PDF
Low Power V.32 bis Modem
CMX869
Receive Tone Pair Programming
The Programmable Tone Pair Detector is implemented as shown in Figure 10a. The filters are 4th order
IIR sections. The frequency detectors measure the time taken for a programmable number of complete
input signal cycles and compare this time against programmable upper and lower limits.
Figure 10a Programmable Tone Pair Detector
Figure 10b Filter Implementation
Programming is done by writing a sequence of twenty-seven 16-bit words to the Programming Register.
The first word should be 32769 (8001 hex), the following twenty-six 16-bit words set the frequencies and
levels and are in the range 0 to 32767 (0000-7FFF hex).
Word
1
2
3
4
5
6
7
8
9
10
Value written
32769
Filter #1 coefficient b21
Filter #1 coefficient b11
Filter #1 coefficient b01
Filter #1 coefficient a21
Filter #1 coefficient a11
Filter #1 coefficient b22
Filter #1 coefficient b12
Filter #1 coefficient b02
Filter #1 coefficient a22
Word Value written
15 Filter #2 coefficient b21
16 Filter #2 coefficient b11
17 Filter #2 coefficient b01
18 Filter #2 coefficient a21
19 Filter #2 coefficient a11
20 Filter #2 coefficient b22
21 Filter #2 coefficient b12
22 Filter #2 coefficient b02
23 Filter #2 coefficient a22
© 2003 CML Microsystems Plc
36
D/869/1
Share Link: 
