论文部分内容阅读
本文叙述一种双环自适应增量调制(TLADM)系统。它由一个内环和一个外环组成。内环是线性增量调制(LDM);外环是数字压扩增量调制(DCDM),具有量化阶自适应的功能。这种TLADM是专为移动通信研制的,具有数码率低、电路简单、单一电源、功耗低等特点。对所研制的系统进行了性能测试,在数码率为9.6KbPS时,对于400HZ正弦信号,最大的信号量化噪声比(SNR)_m是18.5dB,SNR>16dB的动态范围>25dB,800HZ正弦信号时的(SNR)_m是17.8dB,SNR>15dB的动态范围>20dB,平均单词可懂度为90％。数码率为8KbPS,400HZ正弦信号时的(SNR)_m为17.7dB,SNR>16dB的动态范围大于22dB,话音可懂。文中进行了理论分析,介绍了测试结果。
This article describes a double loop adaptive delta modulation (TLADM) system. It consists of an inner ring and an outer ring. The inner loop is linear delta-sigma modulation (LDM); the outer loop is digital companding delta-sigma modulation (DCDM) with quantization-order adaptive capability. The TLADM is designed for mobile communications developed with a low digital rate, simple circuit, a single power supply, low power consumption and so on. The performance of the developed system was tested and the maximum signal-to-noise ratio (SNR) _m was 18.5dB for a 400HZ sinusoidal signal at a digital rate of 9.6KbPS. The dynamic range of SNR> 16dB was> 25dB. For 800HZ sinusoidal signal (SNR) _m is 17.8dB, the dynamic range of SNR> 15dB is> 20dB, and the average word readability is 90%. Digital rate of 8KbPS, 400HZ sinusoidal signal (SNR) _m is 17.7dB, SNR> 16dB dynamic range greater than 22dB, the voice is understandable. The article has carried on the theory analysis, introduced the test result.