Complex sentence: The AQS-13B system was upgraded to the AQS-13E beginning in the late-1970s and early-1980s with the addition of a sonar data computer, selectively utilized for processing acoustic sonar and sonobuoy signals while retaining the original analog processing capability.
Split into simpler sentences: The AQS-13B system was upgraded to the AQS-13E beginning in the late-1970s and early-1980s with the addition of a sonar data computer. This added the capability to digitally process acoustic sonar and sonobuoy signals while still retaining the original analog processing capability.