Datasheet

Functional description ST7540
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6 Functional description
6.1 Carrier frequencies
ST7540 is a multi frequency device: eight programmable Carrier Frequencies are available
(see Ta b l e 6).
Only one Carrier can be used a time. The communication channel could be varied during
the normal working Mode to realize a multi frequency communication.
Selecting the desired frequency in the Control Register the Transmission and Reception
filters are accordingly tuned.
6.2 Baud rates
ST7540 is a multi Baud rate device: four Baud Rate are available (See Tab l e 8 ).
Table 6. Channels List
FCarrier F (KHz)
F0 60
F1 66
F2 72
F3 76
F4 82.05
F5 86
F6 110
F7
(1)
1. Default value
132.5
Table 7. ST7540 mark and space tones frequency distance Vs. baud rate and deviation
Baud Rate [Baud]
∆F
(1)
(Hz)
1. Frequency deviation
Deviation
(2)
2. Deviation = ∆F / (Baud Rate)
600 600
1
(3)
3. Deviation 0.5 not allowed
1200
600
1200
0.5
1
2400
(4)
1200
(4)
2400
4. Default value
0.5
1
4800
2400
4800
0.5
1