• Turn the Instrument on
• Hit the AUX key and then use the up/down arrow keys to scroll to AUTOGRAV SETUP; hit ENTER
  • Scroll to TIDE CORRECT and make sure it is SELECTED (you have to start somewhere in this sub menu so this is where I start)
  • Scroll down to DEG. LAT; hit ENTER to change value (enter numbers, clear fixes mistakes, ENTER records value)
  • Scroll down to DEG. LONG (proceed as above. NOTE: WEST is POSITIVE for this meter, East is negative)
  • Keep scrolling through the following:
  • GMT. DIFF = 6 for MDT, 7 for MST
  • GREF = 0
  • DRIFT CORRECT = 0 (unless you measure it for 48 hours and are doing micro gravity – see manual)
  • INIT. CONT NEVER CHANGE THESE!!! (they are: TILTX = 256.6; TILTY = 302.9; GCAL.1 = 6295.685; GCAL 2 = 0.0; TEMPCO = -0.1278), DRIFT = 0.21 (Fall 2003).
  • MODE= FLD GRAV
  • AUTO REPEAT = Disabled
  • AUTO-RECORD = Disabled (if you enable this you won’t get to use the record button and you won’t get to compare the current and last measurements)
  • SEISMIC FILTER = DISABLED (near Yellowstone, ground popping? Read the manual)
  • READ TIME = 60 (the GPS takes a few minutes longer anyhow)
  • CAL. AFTER = 12
  • CONT. TILT CORR. = Disabled
  • AUTO REJECT = Selected (removes measurements outside of 4 standard deviations)
• TIDE CORR. - this is where we entered this submenu
• AUX takes you back up a menu level.

INITIALISE PARAMETERS – get here by scrolling past SETUP PARAMETERS to "initialise"

• AUTOSTART = Disabled (it has to be to use the instrument)
• SERIAL # = 858011 (do you think you should change this?)
• LANG. = English (could be hard to recover, or graduate, if you change this one)
• HEATER = Disabled unless you are going to be working at below 10^o F.
• TIME = now
• ERASE MEMORY – you can erase the memory if you think you need more room. However this is unlikely and I would prefer you check with me first. Percent of remaining memory shows to the right of the screen during measurement)
• JOB NO = if you want one…
• OPERATOR = 19 for S, etc; generally not a critical parameter
• GRID = 0; generally not a critical parameter
• LINE DIR = as above, obvious and convenient if you are collecting a grid of data
• AUTO STN INC. = Selected (automatically increments the station number after you press the RECORD key.
• AUX takes you back up to main level.

YOU ARE READY TO MEASURE

Do until end of survey:

HIT START and you are ready to take measurements. Level the gravity meter using the bulls eye bubble, then the dials.

ADJUST tilts to < 10

Hit START and the CG3 pauses to stabilize, then measures for the amount of time you set in READ TIME (probably 60 seconds).

Hear the Beep? Hit RECORD - the upper reading is the new value, the lower one the previous value.

END DO

General Considerations:

• Close loops in 4 hours or less
• Repeat GPS and gravity at some stations a few times so you can calculate your standard errors
• The battery never lasts more than 16 hours and it can be half of that. Take a spare and the manual so you know how to change it if necessary.
• ALWAYS PLUG THE GRAVIMETER BACK INTO THE CHARGER WHEN YOU ARE NOT TRANSPORTING OR MEASURING. Take the cover plate off when you leave the gravity meter on the charger - no sense in blowing up the battery housing...
• IF YOU TAKE A 15 MINUTE BREAK LEVEL IT AND PLUG IT IN IF YOU CAN (but don't get desperate and do it in a public place where it could get kicked or stolen).