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BACKGROUND INFORMATION 

STU Operation  
The STU is designed to be outside on a trailer, railcar or locomotive in a vertical orientation 
either on the end of the asset or horizontal on the top.  The STU has an internal GPS antenna 
that must have a clear view of the sky.  Both the GPS and data communications antennas are 
in the apex of the enclosure and must be positioned to optimize the signal outward away 
from the asset and have access to as much sky as possible. 
 
The unit gets its power to operate from the sun.  Solar power is used to keep the internal 
batteries and power system charged.  The ideal position is one that optimizes the chance of 
getting direct sunlight sometime during the day.  Indirect sunlight provides enough power to 
run the unit, but does not significantly charge the batteries. 
 
Once the unit is installed (or put outside in the sun) it should start reporting within an hour 
or two. It will report up to every 10 minutes while moving (Moving Timed) and every 2 
hours while stopped (Timed). The Moving Timed reports are over the air programmable but 
can never be set lower than every 10 minutes while moving. The Timed Reports are in 
intervals of 2 hours. This means that it will start reporting every 2 hours from the 
hour/minute that it wakes up. If the unit can not get out a message, then the unit will store 
the message and try to send it out at the next report time.  The two possible reasons that a 
message will not be sent immediately are: 

1.

 

The unit can not communicate with a cell tower 

2.

 

The power of the unit has dropped below its normal operation threshold  

 

Communication requires sufficient proximity to a cell tower for adequate signal strength and 
the ability of the unit to reach the Lat-Lon web-site (via the internet) for validation that the 
message was received. 

 
 

STU Power 
During shipping, the STU internal battery rapidly drains because the unit tries to get a GPS 
fix and cannot, and tries to establish cellular communications and cannot.  Therefore, the 
STU will most likely have a depleted battery when you receive it.  To initialize the unit’s 
power, place the unit outdoors where it can get a GPS fix with a good sky view.  Placing the 
STU where direct sun is hitting the solar panels is the quickest way to charge the internal 
battery.   
 
The power level of the STU is reported in each message as bus voltage.  The user can see 
how much power the STU has as it operates from day to day by building a voltage history 
report or by adding the bus voltage field to other reports.  Some critical voltages are listed in 
the table below: 
 
Minimum voltage to power GPS (to build a message) 

 

6.8V 

Minimum voltage to power the GSM radio to transmit a report 

7.0V 

Max voltage – charging batteries with 100mA 

 

 

12.5V 

Charging batteries with at least 60mA  

 

 

 

12.0V 

Minimal battery charging 

 

 

 

 

 

10.0V 

 

 

 

 

 

 

 

 

Summary of Contents for Solar Tracking Unit

Page 1: ...ing Unit STU With Sensor Options User s Guide and Installation Instructions Version 1 1 A X13000 May 28 2009 LAT LON LLC 4251 S Natches Court Unit C Sheridan CO 80110 877 300 6566 Phone 303 531 5754 F...

Page 2: ...S This product contains commodities technology or software that fall within the Export Administration regulations Diversion contrary to U S law is prohibited FCC NOTICE This equipment has been tested...

Page 3: ...unshielded cables is likely to result in interference to radio and TV reception The user is cautioned that changes and modifications made to the equipment without the approval of manufacturer could v...

Page 4: ...TU ELECTRICAL SPECIFICATIONS 10 MECHANICAL SPECIFICATIONS 10 STU FUNCTIONAL SPECIFICATIONS 10 OPTIONAL SENSORS 11 STU IMPACT DETECTION 11 STU I MOUNTING INSTRUCTIONS 13 STU RF WIRELESS SENSORS 14 RF W...

Page 5: ...eivers such as the STU use the GPS satellite system to get their latitude and longitude position as well as exact time GPS satellites transmit data to GPS receivers on earth GPS satellites do not rece...

Page 6: ...5 is a self contained unit that includes everything that is required to track an asset The unit contains an internal GPS and data communication antenna a GPS receiver a data communications radio a rec...

Page 7: ...then the unit will store the message and try to send it out at the next report time The two possible reasons that a message will not be sent immediately are 1 The unit can not communicate with a cell...

Page 8: ...pdate the location of the STU and asset to which it is attached when stationary Move Begin Reports A message to update the location of the STU and to report that the STU has started moving Move End Re...

Page 9: ...nough power to run the unit 3 Determine mounting location on asset A suitable mounting location has the following A Provides exposure to the sun B Provides a relatively flat surface for attaching syst...

Page 10: ...energy storage Dual 0 9 Watt 24 cell solar panels MECHANICAL SPECIFICATIONS STU Size 9 2 x 6 8 x 4 25 Weight 2 lbs Screw Mounting 4 10 x self drilling screws STU FUNCTIONAL SPECIFICATIONS Reporting fr...

Page 11: ...ge during this type of impact Delta Velocity or DV is the sum of the accelerations during the impact event More technically it is the integral of the acceleration over time The DV measures the net cha...

Page 12: ...The ALARM event will give you the following information Time of the event GPS coordinates including nearest town X axis G force and DV in 10Hz and 100Hz filtering Y axis G force and DV in 10Hz and 100...

Page 13: ...not always possible therefore a good rule of thumb would be to have at least 6 feet of clearance in front of the STU in order to avoid reception problems J Is a structurally rigged and solid part of t...

Page 14: ...STU The STU can be set to send out a report on the receipt of each RF message over the air configurable The STU can also be set to take a picture on the receipt of a digital change of state RF message...

Page 15: ...ible to the STU RF The maximum range is about 60 feet RF sensors have a serial number and are keyed to a STU RF Make sure you mount the correct RF sensors with the correct STU RF RF sensors and the ST...

Page 16: ...digital change of state example door open Camera STU Infrared LED info The STU can illuminate a night shot up to about 20 feet away Cannot be seen by a human when on Only come on during the process o...

Page 17: ...ot installing right away If the internal batteries are completely dead then the STU will require at least 1 to 3 hours in the sun to start reporting and 24 to 48 hours of sun to charge its internal ba...

Page 18: ...eet of clearance in front of the STU in order to avoid reception problems Q It is important to have the camera lens pointing in the correct direction as well as the correct level to insure a good pict...

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