sames

SA2531 A/B/C/E/G/U

9/24

Tone Ringer

The Tone Ringer of the SA2531 incorporates a Discriminator Circuit and adjustable Melody

Generator

Ring Frequency Discrimination

The Ring Frequency Discriminator assures that only signals with a frequency between

20Hz and 60Hz (option 13 Hz to 70 Hz) are regarded as valid ring signals.

When a valid ring signal is present for 73 ms continuously, the melody generator is

activated and remains active as long as the ring signal is present.

Once the melody generator has been started, the ring signal is continuously monitored

and the melody generator is instantly turned on or off according to the momentary

presence of a valid or unvalid ring signal respectively (until next POR of off-hook).

Melody Generator

When a Valid Ring Signal is detected the Melody generator is activated and creates a

ringing Signal comprising 3 frequencies F1 (800Hz), F2 (1067Hz) and F3 (1333Hz).

These frequencies are repeated in a sequence of 6 time slots constructed by the

frequencies

F1

F2

F3

F1

F2

F3

This seqeunce is repeated 1, 4, 7 or 10 times per second as indicated by the connection

of the RR Pin to one of the four rows of the keyboard.

KEYBORD ARRANGEMENT 2

4 Direct and 10 Indirect memories

(either VOL or +/- keys)

Figure 3