Digital answering machine

• Main Authors: Tan, Andro, Tan, Winston Glenn O., Topacio, Wilfredo
• Format: text
• Language: English
• Published: Animo Repository 1994
• Subjects: Digital electronics; Electronic instruments, Digital; Signal processing > Digital techniques; Telephone, Automatic
• Online Access: https://animorepository.dlsu.edu.ph/etd_bachelors/16372
• Institution: De La Salle University

The Digital Answering Machine can be used as an interface card between a computer and telephone. The objectives of the thesis are to be able to convert voice messages received from the caller into a digital signal, to provide dual tone and pulse dialing, and to be able to initiate calls. It has several features namely: Speed Dialing, Do Not Disturb Mode, Automatic Reminder, Save Busy Number, Automatic Tracer and Call Timer. Recording is done by the ADC while the DAC is used for playback. Relays were used in dialing from the keyboard, switching from pulse to tone dialing, and for the do not disturb feature. The call timer and automatic reminder is implemented through software. A terminate-stay-resident program using either the keyboard or clock interrupt is used for loading the main program to memory after the ringing signal is detected by the ring detector. The system could be used in recording audio signals from other sources such as the radio. A dual tone multi-frequency decoder could be used to playback the messages from another location.