Implementation method for DTMF code transmission of airborne telephone

Abstract

The invention provides an implementation method for DTMF code transmission of an airborne telephone, which comprises the following steps of: loading data for generating sine waves into a DMA (direct memory access) module of a single chip microcomputer module, adjusting the conversion rate of two channels of a DAC (digital-to-analog conversion) module by using a timer (TIM) module so as to generate eight sine waves with different frequencies, and outputting the signals from two DAC module ports of the single chip microcomputer; connecting an adder module built based on an operational amplifier, synthesizing two sine waves into a DTMF signal of a fixed frequency group, sending the DTMF signal through the output end of the DAC module, connecting an access selection module, controlling the on-off of the access selection module through the single chip microcomputer, then connecting a signal coupling module, couplingly connecting the signal coupling module to an external power supply line after direct current filtering, impedance matching and capacitance matching, and sending the DTMF signal to a broadcast interphone system. The problem that an existing telephone depends on a DTMF coding chip is solved, power consumption of a system is reduced, and cost is saved.

Description

technical field [0001] The invention belongs to the technical field of airborne broadcast intercom, in particular relates to a method for realizing DTMF coded transmission of an airborne phone, in particular to a design of a DTMF dial coded communication circuit without a DTMF code chip. Background technique [0002] The airborne intercom intercom system is a communication system used in civil airliners for pilots and flight attendants, between flight attendants and flight attendants to call each other and cabin broadcast. boom microphone. The flight attendants use the buttons on the on-board phone to complete functions such as cabin broadcasting, in-flight calls, and emergency calls. [0003] The keys and functions of the onboard phone include: [0004] 1) "PA ALL" key: trigger the PA function in all cabins; [0005] 2) "PA FWD" key: trigger the forward cabin broadcast function; [0006] 3) "PA AFT" key: trigger the rear cabin broadcast function; [0007] 4) "EMER CALL...

AI Technical Summary

Problems solved by technology

[0020] The technical problem solved by the present invention: provide a kind of realization method that is used for the DTMF code transmission of airborne telephone set, the present invention solves the problem of existing airborne telephone set through the design of single-chip microcomputer module, adder module, path selection module, signal coupling module Due to the dependence on imported encoding chips and the system’s requirements for reducing power consumption of dialogue phones, it is suitable for handheld microphone terminals in airborne broadcast intercom systems of civil aviation airliners. It has the advantages of low power consumption, simple implementation, high precision, and high flexibility.

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