Calling Line Identifier

FX602

© 1998 Consumer Microcircuits Limited

10

D/602/7

td = Internal FX602 delay; max. 1

µS

tclo = RXCK low time; min 1

µS

tchi = RXCK high time; min 1

µS

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.