Mini Audio Directional System Power Consumption Optimization Method And Implementation

Micro audio directional loudspeaker is kind of new type of audio device used in mobile multimedia for portable communication equipments. The purpose of this paper is to optimize the system from both hardware and software and then design smaller power consumption, lower cost system for portable applications.The fundamental reason why micro audio directional loudspeaker has high power consumption is the low efficiency of the power amplifier and low electro-acoustic conversion efficiency of the transducers. According to these, proposed and designed two different audio directional systems to improve the efficiency of the power amplifier and transducers. On the one hand try to find the reason why the DSB (Double Side Band) and SSB (Single Side Band) algorithm are high power consumption in theoretically based on the algorithm which commonly used at this stage. The theoretical analysis shows that due to the constant amplitude carrier modulation, most of the power is wasted in the carrier signal when using the traditional DSB, SSB algorithm. For the problem above a dynamic algorithm based on the SSB carrier modulation algorithm was designed and optimized to improve the average power consumption of the traditional system. On the other hand in order to improve the efficiency of power amplifier and ruduce the power consumption a hardware modulation system is designed. The system is very different from traditional one. The entire power amplifier used in the system is Class D ampilifer. For the high efficiency of Class D amplifier system power consumption can effectively reduced. In order to optimize the system and compensate the transducer response, impedance matching circuit is designed. The hardware modulation system save the cost and acquire higher electro-acoustic conversion efficiency, more importantly reduce the system power consumption.With the purpose of testing the performance of system, a hardware test platform was built and a series of experiments are performed. Before the experiments power supplies, storage devices, digital to analog conversion circuit, analog-digital conversion circuit, power amplifier and impedance matching circuit were checked. The SPL (Sound Pressure Level), THD (Total Harmonic Distortion), average power consumption of the system are tested and the test data show that the SSB algorithm modulation and DSB algorithms are similar in power consumption, dynamic carrier SSB algorithm is better than SSB and DSB. The hardware modulation improved the system power consumption greatly.