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SeaTrac Serial Command Interface Reference
Page 101
7.6.8. CID_XCVR_USBL
The CID_XCVR_USBL status message is generated when the acoustic transceiver has received
a message that contains a USBL signal, from which incoming signal angle information can be
computed. The message contents are design to assist with diagnosing the validity of acoustic
signals, and debug causes of reception/decoding failure.
This message is a status message that may be sent by the beacon at any time (not in
response to a command message) depending on acoustic activity triggering a
transceiver event.
This message is generated only when the XCVR_USBL_MSGS flag is specified in the
acoustic transceiver
SETTINGS_T structure – see CID_SETTINGS_SET .
The CID_XCVR_USBL message is large in size (typically 461 bytes) so suitable memory
buffering should be allocated when decoding.
Sending this message over a slow serial communications link may degrade the
performance of the beacon.
Status Message Parameters
Parameter Type Description
MSG_ID CID_E Command identification code (CID_XCVR_USBL)
XCOR_SIG_PEAK FLOAT The magnitude of the peak signal observer while
correlating the USBL signal.
XCOR_THRESHOLD FLOAT The magnitude of the detection threshold being
used to detect the first peak in the correlated USBL
signal.
XCOR_CROSS_POINT UINT16 The correlation sample number where the USBL
signal passes the detection threshold.
XCOR_CROSS_MAG FLOAT The actual magnitude of the correlated signal when
the USBL signal passed the detection threshold.
XCOR_DETECT UINT16 The correlation sample number where the first peak
of USBL signal was found.
XCOR_LENGTH UINT16 The number of correlation samples computed for
the received signal. Typically this value is 100.
XCOR_DATA FLOAT[x] Array of floating point data containing the
correlated received signal, where “x” is equal to the
value defined in XCOR_LENGTH.
CHANNELS UINT8 The number of USBL receiver channels being used
to compute the signal angle. Typically this value is
either 3 or 4.