# $USTLC Target Location Message

{% hint style="info" %}
Note: From time to time, Cerulean adds features to the ROVL as requested by users, some of which require changes to this message. Cerulean undertakes to maintain backward compatibly on this message, so once a field is defined and published, we try not to not move it or change its behavior. We may add new fields to the end of the message, so we recommend you allow for extra fields that you can ignore if writing a parser for this message, rather than requiring a specific field count.
{% endhint %}

Example:

`$USTLC,1.3,MKIII,A,F,,,0.0,0.705793,0.046481,-0.026662,0.706388,100.0,-90.0,5.0,90.4,3.4,,,46,-1,,448500645,,*1E`

Format:  $USTLC,mv,di,ch,cc,lt,ln,hd,qw,qx,qy,qz,sr,rb,re,tb,te,ta,to,gn,sn,dtg,ot,vi\*hh

mv: version number of message format \[1.3]

di: device identifier {MkII, MkIII, MkV}

ch: channel {A, B}

cc: GNSS Compass connected {T, F}

lt: latitude where GNSS Compass is (blank if no position lock or no compass connected)

ln: longitude where GNSS Compass is (blank if no position lock or no compass connected)

hd: GNSS Compass heading (NED) (blank if no heading lock or no compass connected)

qw, qx, qy, qz: quaternion of ROVL receiver platform (ENU)

sr: slant range to ROV (blank if no ping detected)

rb: relative bearing to ROV (blank if no ping detected)

re: relative elevation to ROV, horizontal ==  0 (blank if no ping detected)

tb: true bearing to ROV (blank if no ping detected)

te: true elevation to ROV, horizontal ==  0  (blank if no ping detected)

ta: latitude of ROV (blank if can't be computed)

to:  longitude of ROV (blank if can't be computed)

gn: analog AGC gain, in decibels (range 16 – 82)

sn: Seconds since last autosync or distance sync command (valid Mk II only)

dtg: date/time group, UTC, format "ddmmyy hhmmss.ss" \[note 1]

ts: time since boot, milliseconds \[added v1.2]

vi: worst case voltage in (volts), blank if hardware does not support reading v-in \[added v1.3]

hh: NMEA-style hex checksum, always the last field and following the asterisk

**Note 1:** Only in -e version, only present if GNSS compass is attached and it has a fix (otherwise blank)


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