Calling Line Identifier
FX602
td = Internal FX602 delay; max. 1mS
tclo = RXCK low time; min 1mS
tchi = RXCK high time; min 1mS
Figure 5a : FSK Operation With Data Retiming
Note that, if enabled, the Data Retiming block will interpret the FSK Channel Seizure signal (a sequence of
alternating mark and space bits) as valid received characters, with values of 55 (hex). Similarly it may interpret
speech or other signals as random characters.
If the Data Retiming facility is not required, the RXCK input to the FX602 should be kept high. The
asynchronous data from the FSK Demodulator will then be connected directly to the RXD output pin, and the
IRQN output will not be activated by the FSK signal. This case is illustrated in Figure 5b.
Figure 5b : FSK Operation Without Data Retiming (RXCK always high)
1.5.7 Tone Alert Detector
This block is enabled when the FX602 is set to Tone Alert Detector operating mode. It will then monitor the
received signal for the presence of simultaneous 2130 and 2750Hz tones of sufficient level and duration.
The FX602 DET output will be set high while a valid Tone Alert signal is detected. At the end of the Tone Alert
signal the DET output will go low and the IRQN output will be pulled low until the FX602 is switched out of Tone
Alert Detector mode.
ã 1998 Consumer Microcircuits Limited
10
D/602/7
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