This Paper introduces a effective method of improving the analogue magnetic tape recorder MCD-3 and the demodulator CBY-2. As this instrument includes a hardware and software of IBM-PC/ XT computer, so it can carry out full-frequency range and multi-channel digital and data processing. 本文主要介绍模拟碰带记录地震仪MCD3及其解调器CBY2系列的一种行之有效的改进法。该方案配以IBMPC/XT计算机硬软件,能实现宽频多道数字采集与处理。