Version: 1.18
PRELIMINARY/CONFIDENTIAL
TrueSpeech® Co-Processor
8 Test Modes
The CT8022 supports special modes of operation to facilitate both in-system testing of the device itself, and as an aid
to external system testing.
8.1
Test Mode 1: Count Mode
In this test mode, data received from the external A-law/µ-law CODEC by the record channel is discarded and
replaced by an incrementing count. This test mode is intended for use in A-law/µ-law speech mode where the
CODEC receive data is passed directly to the Host (without compression, and with record volume set to nominal).
8.2
Test Mode 2: Digital Milliwatt
In this test mode, data received from the external µ-law CODEC by the record channel is discarded and replaced by
the CCITT G.711 A-law/µ-law digital milliwatt (0 dBm0) code sequence. This is a sequence of 8 repeating bytes
(A-law µu-law samples) representing a 1 KHz sinewave at 0 dBm0. Selection between A-law and µ-law is made
using the CODEC configuration command. Digital milliwatt operation is not supported for use with a 16-bit linear
CODEC.
8.3
Test Mode 3: Internal Loopback
In this test mode, data received from the external A-law/µ-law CODEC by the record channel is discarded and
replaced by the output data from the transmit (playback) channel. This mode of operation does not affect the
playback channel. The playback speech data is transmitted to the output CODEC.
The Host can perform receive CODEC-to-transmit CODEC loopback with the CT8022 operating in normal mode.
To do this, the Host simply copies frames from the record (receive) channel back to the playback (transmit) channel
using A-law, µ-law, or 16-bit linear modes as appropriate.
8.4
CODEC Loopback and Monitoring
The CT8022 also supports CODEC loop-back and monitoring configurations.
CT8022A11AQC FW Revision 0118 DSP GROUP, INC., 3120 SCOTT BOULEVARD
SANTA CLARA, CA 95054 PH: 408 986 – 4300 FAX: 408 986 – 4490
49
All specifications are subject to change without prior notice.
ETC [ ETC ]
