Question: In the Adaptive Multi-Rate (AMR) speech codec's RX radio subsystem, if a received frame contains all information bits set to "1" in a SID_UPDATE marker and has a bad CRC, how is the frame passed to the RX DTX handler?
Option 1: As a SID_BAD frame with comfort noise parameters.
Option 2: As a SPEECH_DEGRADED frame for potential speech recovery.
Option 3: As a NO_DATA frame, indicating no usable speech content.
Option 4: As a SID_UPDATE frame for further processing despite the bad CRC.
Explanation: According to the AMR speech codec's operation principles, if all information bits of a SID_UPDATE frame are set to "1" and the CRC is bad, this specific condition leads to the frame being treated as if it contains no usable data. Thus, it is passed on as a NO_DATA frame to the RX DTX handler, ensuring that the system does not attempt to process potentially corrupted speech data. This approach prioritizes maintaining voice call quality by not introducing distorted or erroneous audio.