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Battery Comparison for GPS Tracking Device

Overview

Many different types of batteries may be used with Raveon’s M7 series of GPS transponders.  This Technical Brief describes how well some common battery types will work with the M7 radios.

Actual battery life will vary based upon how often the M7 GPS transponder transmits, but the data in this Technical Brief may be used to predict the battery life of most configurations.

Test Setup

For the tests in this brief, a UHF GPS transponder, model RV-M7-UC-GX was configured in GPS mode 2 to transmit its position every 10 seconds.  In GPS mode 2, the radio’s receiver is on 100% of the time, and the current draw of the M7 was an average of 90mA.  The peak current draw was 2.1 amps for 68mS each time the M7 transmitted its GPS position.

Summary Data

Brand Type Recharge-able mAh Life
(RX on)		 Life
(RX off)
Duracell Alkaline NO 1600 18 hours 36
Energizer Lithium NO 2500 28 hours 56
Lenmar NiMH Yes 1500 17 hours 34

Duracell Alkaline

These batteries are the common Duracel batteries found at most department stores.

Test Result Summary

Initial Voltage:                                   12.57 volts

Voltage at ½ discharge:                   10.2 volts

Usable life (hours)                           18 hours

Voltage drop when transmitting       2.4V  (1.1 ohm resistance)

Approximate mAh capacity             1600mAh

Discharge Curve

Transmit Transient

The plot below shows the dip in voltage as the transmitter turns on and off.


Summary

The Duracell is an OK battery to power the M7 transponder.  But its high internal resistance will reduce the RF power output after the first few hours of operation.  The DC to the radio should stay above 9V while transmitting for full power, above 8V for 3-4 watts.


Energizer Lithium

These batteries are the common Energizer Lithium batteries for cameras and digital electronics found at many department stores.

Test Result Summary

Initial Voltage:                                      12.1 volts  (14V for a few moments)

Voltage at ½ discharge:                      12.0 volts

Usable life (hours)                              28 hours

Voltage drop when transmitting          3.5V  (1.6 ohm resistance)

Approximate mAh capacity                2520mAh

Discharge Curve

Transmit Transient

The plot below shows the dip in voltage as the transmitter turns on and off.

Summary

Even though the internal resistance of the cell is higher than the alkaline, the Energizer Lithium is a good battery to power the M7 transponder.  Its high internal resistance will not reduce the RF power output because its voltage is fundamentally fairly high.  The DC to the radio should stay above 9V while transmitting for full power, above 8V for 3-4 watts, so the 3.5V dip means the radio will have full power at 12.5V, and 3-4 watts out at 11V DC at the battery pack.


Lenmar R2G NiMH pack, 2150mAh cells

These batteries are Nickel Metal Hydride rechargeable batteries.  They were fully charged before the test.

Test Result Summary

Initial Voltage:                                      11.0 volts

Voltage at ½ discharge:                      10.3volts

Usable life (hours)                              17 hours

Voltage drop when transmitting          2.0V  (.95 ohm resistance)

Approximate mAh capacity                1500mAh

Discharge Curve

Summary

These batteries should be a good power source for the M7 GX transponder.

The internal cell resistance is low, but the voltage is also low. The RF power output stayed at full power for most of the life of the battery, dropping to about 4 watts at the end of the battery life.  The double dip at end of live was due to the fact the radio keep working down to 6 volts (albeit with almost no RF output because the RF PA is off), and the batteries keep putting our very low voltage for another couple hours.


Raveon Technologies Corporation

990 Park Center Drive, C

Vista, CA 92081

sales@raveontech.com

760-727-8004

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TDMA Transmission Overview

TDMA, or Time-Division-Multiple-Access is a very effective way of allowing a lot of radios to share one radio channel.  Used extensively in GSM cellular and APCO public-safety systems, TDMA excels at allowing quick and reliable access to radio channels.  It allows 2-10 times more radios to share a radio channel than conventional carrier-sense methods.  This allows 2-10 times more tracking radios on one channel, as compared to radios that do not have TDMA capability.

The following diagram illustrates how it works.

When a RV-M7 GX wants to report its position and status, it waits until its assigned time-slot, and then transmits its data.  By default, TDMA time slot positions are assigned by unit-ID, so RV-M7 GX with ID 1 uses the first slot, and ID 2 uses the second slot, and so on.  This default slot assignment can be overriden by the SLOTNUM command or by using Raveon’s Radio Manager software, allowing each GX to have an ID that is different than the slot assignment.

A TDMA “Frame” time is the time it takes all units to transmit once.  This is configured with the TDMATIME xx command.  The factory default is 10 seconds, so every 10 seconds, each RV-M7 GX may transmit.  The TDMA frame must be set long enough for all units to transmit.  For example, if you have 50 RV-M7s, and use 200mS TDMA slots, then the TDMATIME should be set to 10 seconds.  The simplest way to set it the TDMATIME is to make it equal to the TXRATE, the rate you wish to report position

The duration of a TDMA time slot is programmed into the RV-M7 GX with the SLOTTIME command. If SLOTTIME is set to 200 milliseconds (factory default), then every 10 seconds, the RV-M7 will have a 200mS window to report its position in.

All TDMA frames are synchronized automatically in all RV-M7 GX Transponders to the top of the minute.  Slot 0, frame 0 is at the top of each minute. They use the internal GPS receiver to determine the current time, and calculate when their are supposed to transmit their position and status information.

A unit may be allocated additional time slots.  The SLOTQTY command sets the number of slots each unit receives.  It is normally set to 1.

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Criterion International

After searching for and testing several UHF radios to upgrade a municipal water department’s wireless SCADA system, RAVEON’s Fireline modem was chosen as the best performance/value solution. The simple and versatile ability of the Fireline to be quickly configured easily beat out the other radios on the market. Thirty + radios have been installed and in service continuously operating with no problems for over two years.

Regards.

Chris Carda

President

Criterion Industrial

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Setting Up VPN access to a Windows XP Computer

If you are running your GPS tracking system using RavTrack PC on a Windows XP computer, you may want remote users to be able to access the tracked objects database from a remote computer that is not on your local netwrok.  You may be able to do this using a Virtual Private Network (VPN) connection.

This article describes how to setup VPN access to a Windows XP computer.   VPN access will allows you to network two computers together, even if they are not on the same local network.  It will work across the Internet, while still maintaining security and privacy.

You will need Windows XP Professional with SP2 or SP3 installed.

How to Configure VPN host on a Windows XP computer

  1. From the Start menu, open the Windows Control Panel.
  2. Double-click the Network Connections item in Control Panel. A list of existing network connections will appear.
  3. Choose the ‘Create a new connection‘ item from the left-hand side of the window. The Windows XP New Connection Wizard will appear on the screen.
  4. First click Next to begin the new connection wizard.
  5. Select Setup Advanced Connection‘ item from the list and click Next.
  6. Choose the ‘Accept Incoming Connections‘ option and click Next.
  7. On the ‘Devices for Incoming Connections’, click Next.
  8. Choose an option on the “Allow Incoming Connections“and click Next.
  9. On the ‘Users Permissions’page, select all of the users you would like to allow VPN access to this computer.  Important: Every user that you wish to give VPN access, must have a Windows Login on both computers with the SAME login name and password.
  10. Click on the Next button.
  11. On the Network Software page, select TCP/IP and click on Properties.
  12. On the Incoming TCP/IP Properties page, select Allow Callers to Access my Local Area if you want remote users to also access the LAN.
  13. Click on the option that determines how the remote computer will get its IP address for this VPN connection.   Make sure the IP scheme is the same as on your server.
  14. Click OK.
  15. If the VPN server is behind a router, Port Mapping will need to be done on the router. Standard port usage is port number 1723 for PPTP.  You might also have to configure your router for ‘PPTP Passthrough’.  Port usage for IPSec is 500, 50-51.  These ports will have to be forwarded to the VPN server’s IP.

Microsoft has excellent technical articles about setting up VPN networks <here> and <here>.

Once you have VPN access configured to your RavTrack PC, you will need to connect to it from the remote client computer.  The remote client computer will need to have a VPN connection created on it.  Follow the steps below to create an VPN connection on the client computer.

Configure a VPN connection from a client computer

To set up a VPN connection on the client computer, follow these steps:

  1. On the computer that is running Windows XP, confirm that the connection to the Internet is correctly configured.
  2. Click Start, and then click Control Panel.
  3. In Control Panel, double-click on the Network Connections.
  4. Click Create a new connection.
  5. On the Network Connection Wizard, click Next.
  6. Click Connect to the network at my workplace, and then click Next.
  7. Click Virtual Private Network connection, and then click Next.
  8. If you are prompted to, do one of the following:
    • If you use a dial-up connection to connect to the Internet, click Automatically dial this initial connection, and then click your dial-up Internet connection from the list.
    • If you use a full-time connection such as a cable modem, click Do not dial the initial connection.
  9. Click Next.
  10. Give the connection a descriptive name, and then click Next.
  11. Enter the host name or the Internet Protocol (IP) address of the computer that you wish to connect to, then click Next.
  12. Click Anyone’s use if you want the connection to be available to anyone who logs on to the computer, or click My use only to make it available only when you log on to the computer, and then click Next.
  13. Click Finish.
  14. If you are prompted to ‘connect’, click No.
  15. In the Network Connections window, right-click the new connection you created.
  16. Click Properties, and then configure more options for the connection:
    • If you are connecting to a Windows domain, click the Options tab, and click to select the Include Windows logon domain check box to specify whether to request Windows logon domain information before trying to connect.

To use the new connection, follow these steps:

  1. Use one of the following two methods:
    • Click Start, point to Connect To, and then click the new connection.
    • If you added a network connection shortcut to the desktop, double-click the shortcut on the desktop.
  2. If you are not currently connected to the Internet, Windows offers to connect to the Internet.
  3. After your computer connects to the Internet, the VPN server prompts you for your user name and password. Type your user name and password, and then click Connect.
  4. Your network resources should be available to you in just like they are when you connect directly to the network.
  5. To disconnect from the VPN, right-click on the icon for the connection, and click Disconnect.
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Identifying Digital Input States in a $PRAVE message

The $PRAVE message has the status of each input as represented by a single digit hexadecimal number in field 12. For example, the the $PRAVE message below, the last 3 represents the digital inputs from transponder 0001.

$PRAVE,0001,0001,3308.9051,-11713.1164,195348,1,10,168,31,13.3,3,-83,0,0,,*66

In this example field 12 has value 3.  The field 12 value is the hexadecimal binary representation of the bits.  Refer to the following table:

IN 2
(TXD)

IN 1
(RTS)

IN 0
(DTR)

Hexadecimal Representation

0

0

0

0

0

0

1

1

0

1

0

2

0

1

1

3

1

0

0

4

1

0

1

5

1

1

0

6

1

1

1

7

The stock RV-M7 GX has up to 3 digital inputs, using the input pins of the RS-232 serial port.  An open circuit or ground is a 0, and if they are connected to a positive voltage greater than 3V, they are a digital 1. If all 3 pins are allowed to float (nothing connected – same as ground) the value should be 0.  If positive voltage is applied to a pin the pin value will be 1.  The field 12 value will be 1 or 2 or 4, depending on which pin had the voltage applied.

RS-232 Pin

Function

4 – DTR

Input 0

7 – RTS

Input 1

3 – TXD

Input 2

5 – Ground

GND

Connect to vehicle chassis or other ground point.

Note that the weatherproofed (-WX) model has less RS-232 pins and only 2 digital inputs.  Inputs 1 and 2 are valid, but input 0 is indeterminate (state can float).

In the RavTrack PC software it is easy to not monitor this missing pin, so any change of state or change of value of this pin would not matter to the software.  Simply configure this input as unused.

1aa

RS-232 Pin

Function

4 – RTS

Input 1

3 – TXD

Input 2

5 – Ground

GND

Connect to vehicle chassis or other ground point.

On the M7 series of transponders, if an input is left floating/unconnected, the transponder will read it as a digital 0 (low), and report it this way.

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Microsoft SQL Server User Logins

When you choose to use Microsoft SQL Server for your RavTrack PC database, all of the location information of the GPS tracked vehicles will be stored in the SQL database called “RavTrack“.   You must create this database manually using Micrtosoft’s Management Studio software program, and then assign the user login rights to the database.  RavTrack PC will create the tables within the database. 

The steps to take to setup the RavTrack SQL database in SQL Server 2005 or 2008 are as follows:

  1. Using the Management studio, create a database with the name “RavTrack”. You do not need to create any tables in the database, as RavTrack PC will create them the first time it connects to this database.
  2. Using Management Studio, create security login accounts for the users that will be using RavTrack PC on the network.  Right click on Databases > Security > Logins > New Login…  to create a new login account for each user. Set the Server Role to “serveradmin”. 
    S1
  3. Using Management Studio, assign the new user login to the RavTrack database.  Right click on Databases > RavTrack > Security > Users . Add User…  to add the new user to the database.  Set the Role Members” to db_datawriter and db_datareader. S2

Management Studiois a very good tool to use not only for configuring SQL Server, but also to verify that connections to the RavTrack database are OK.   On any workstation that you feel there is a login problem with the database, login to that workstation with the user name and password, run Management Studio, and try to access the RavTrack database.  If you can access it and list the tables, then the user name and password has the proper rights configured on the server. 

There is a verion of Microsoft SQL Management Studio for every version of their SQL Server program.

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Crystal Reports Installation Issues

Integrated into RavTrack PC GPS Tracking software is a powerful report generating software program called Crystal Reports from SAP.

As part of the RavTrack PC installation, a run-time redistribution module is installed on the computer along with RavTrack PC. The Crystal Reports run-time module allows crystal reports to be generated by RavTrack PC, and viewed by the user.  But, it does not include the report editor.  To customize your own Crystal Reports, you will need to by a full-version of Crystal Reports 10.   The run-time module included with RavTrack PC will give you the ability to view the Crystal Reports you generate with RavTrack PC’s report generator.

Installation Problems

There is often an installation error with the Crystal Reports run-time on certain Windows Vista machines.   If during the installation of RavTrack PC you get an error message about Crystal Reports, you can ignore it because there is a simple solution that can be performed after the installation of RavTrack PC is complete.

If, after RavTrack PC is installed and operating, you get an error when trying to open the report generator in RavTrack PC  (View > Reports), then you should manually install the Crystal Reports 10 run-time module.  To do this, perform the following steps:

  1. Close RavTrack PC.
  2. Install the 32 bit version of the Crystal Reports Runtime for Visual Studio if you are using for Windows XP or a 32 bit version of Vista, 7, and 8.  Install the 64 bit version if you are using the 64 bit versions of Windows OS.
  3. Download the Crystal Report run-time module from Raveon’s server at:
    32bit: http://ravtrack.com/downloads/CR_install_32bit_13_0_5.zip
    64bit: http://ravtrack.com/downloads/CR_install_64bit_13_0.zip
  4. Unzip the file to your local disk.
  5. Open Explorer, and go to the directory where the .zip file was stored to.
  6. Double click on the  CR_install_xxxxxx.msi file to run the installation program.
  7. Follow the instructions in the installer, and let it install.
  8. Once the Crystal Reports installer has finished, start RavTrack PC, and verify the report features are working.
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Configuring a Microsoft SQL Server Installation

With release of RavTrack PC vesion 3.1, RavTrack PC supports Microsoft’s SQL Server 2005 and 2008.  By default, RavTrack PC uses Microsoft Access databases and tables to store its inforamtion.  Access is a very good choice for a database when RavTrack PC software is ging to be run on a single workstation, in a vehicle, or when the number of concurrent users is small. 

But, when the number of users running RavTrack PC increases, or when the size of the Log table is large, Microsoft’s SQL Server is a superior product, albeit a bit more complex to install and manage. 

You can download RavTrack PC evaluation copy free as well as the technical manual from Ravoen’s web site at: http://ravtrack.com/RavTrack-PC-Software.html 

If you are going to use a Microsoft SQL Server 2005 or SQL Server 2008 database with RavTrack PC, then you will need to prepare the SQL Server first, before running RavTrack PC.  Perform the following steps:

SQL Server Installation

  1. Install Microsoft SQL Server or SQL Server Express.  SQL Server Express is available from Microsoft at no charge. It may be downloaded at: http://www.microsoft.com/Sqlserver/2005/en/us/express.aspx
  2. Use the “SQL Server Configuration Manager” software program that is installed with MS SQL Server to configure the server.
  3. Using the SQL Server Configuration Manager, enable the TCP/IP Client Protocol (SQL Server Configuration Manager > SQL Natice Client Configuration > Client Protocols > TCP/IP).
  4. Also download and install the “Management Studio” for SQL Server.  The Express version may be downloaded at the same website as the SQL Server Express is downloaded from.
  5. Set the default transaction time-out of Management Studio to 1000 seconds (Tools> Options> Designers> Transaction Timeout)
  6. Using the Management studio, create a database with the name “RavTrack”. You do not need to create any tables in the database, as RavTrack PC will create them the first time it connects to this database.
  7. Using Management Studio, create Login accouts for all users what will be accessing the SQL database using RavTrack PC. 

Troubleshooting:

If you are having trouble connecting RavTrack PC to your SQL server installation, check the following items:

  1. Shut down RavTrack PC using FIle > Exit, and restart it.  Whenever the database type is changed in RavTrack PC, you should restart the application.
  2. Install Microsoft’s Management Studio applicationon the computer running RavTrack PC.  Use Management Studio to connect to the server to verify that the SQL Server is running properly and accessible from the workstation.
  3. Make sure the the TCP/IP Client Protocol is enabled on the SQL Server.
  4. Make sure you are logged into RavTrack PC as an administrator with the ADMIN account.
  5. Make sure you have purchased and installed an “Unlimited” license on RavTrack PC. The “Limited” version will not connect to an SQL Server.
  6. Make sure you created a database on the SQL server named “RavTrack”.  The RavTrack database needs to be on the server before running the RavTrack PC program.  Yse the Management Studio to create the “RavTrack” database on the server.
  7. You should have an account on the SQL Server computer with the same name and password as the name/password that you used to log onto Windows on the RavTrack PC computer. If you have not done this, create a Windows user account and password on the SQL Server computer to match the Windows user/password on the RavTrack PC Windows login account.
  8. Make sure the rights assigned to the login account are at least db_reader, db_writer, and db_admin. 
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Verifying Communications with RavTrack PC

RavTrack PC receives $PRAVE messages from a Raveon GPS tracking transponder, and uses the information in the $PRAVE message to plot the position and display the status of tracked vehicles and personnel.

The $PRAVE messages come out of the M7 GX transponder, when it is configured in GPS mode 2.  The serial port of the M7 GX transponder must be connected to the PC running RavTrack PC.   This connection may be a direct RS232 connection, or it may use a terminal server to convert the RS232 from the M7 GX transponder to Ethernet. The Ethernet connection is then made to a LAN or WAN so that RavTrack PC can receive the GPS positions via the nework connection.

To verify that RavTrack PC is receiving $PRAVE messages, you can look at the communications statistics window within RavTrack PC, and see if $PRAVE messages are comming out.

commstats

In the “Messages In” column, there are two numbers (xxx/yyy)  The first number xxx is the total number of messages, and the second number, yyy, is the total number of $PRAVE messages that RavTrack PC has received.

If the communications with the M7 GX transponder is OK, the second number will increment each time a $PRAVE message is received, which is each time a transponder reports in. In the above example, RavTrack PC has received 311 position reports using its network connection.

If the second number is 0, but the first number is not zero (ie  123/0)  then the connection to the M7 GX is probably OK, because some messages are coming in.  These are usually the $GPGGA/RMC type messages output from the local GPS in the M7.  They are not over-the-air position reports.  Because the first number is incrementing, the connection to the M7 is OK. But, because the second number is 0, there are not $PRAVE messages coming in.  The most likely reasons that there are not $PRAVE messages are:

1.  All transponders are turned off.

2.  The UHF or VHF antenna to the M7 GX used with RavTrack PC is not connected.

3. The encryption keyphrase is not set corectly, and the My GX cannot receive the position reports.

4. All transponders are out of range of the M7 GX used with RavTrack PC.

5. The transponders are configured on a different RF frequency.

Hopefully you find this information helpfull.  Monitoring the communication statistics is an excellent way to verify the performance of your RavTrack GPS tracking system.  RavTrac PC automatically monitors the statistics, and will turn the communication status button on the bottom of the screen red if no messages are received for a long period of time, indicating that the communications with the transponder used to receive $PRAVE messages has failed.

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Who’s Tracking You? GPS Tracking Security

GPS vehicle tracking is a powerful technology that can speed emergency response, improve efficiency, and provide a safety link to support personnel.  Raveon Technologies sells real real-time tracking system so business, agencies, and commanders, can track their personnel, assets and vehicles.

Raven’s private tracking system uses a very secure AES encryption algorithm, so that only authorized radios can track the GPS transponders.  It would be bad, and maybe even disastrous if GPS tracking were not secure.  Law enforcement, military, and security forces use GPS tracking to do their job and GPS tracking provides extra security for their operations.  And if the bad guys were able to track them, their operations and their lives could be in jeopardy.

This is why Raveon takes GPS tracking security very seriously, and tracking systems based upon less-secure communication methods should be carefully considered.  Most all other GPS tracking systems us cellular radio technology, such as GSM networks to send their data.  Anyone using a public GSM system must carefully assess all aspects of the system’s security.

In 2009, a German computer engineer announced that he’s deciphered the 21-year old 64-bit encryption algorithm that protects the GSM standard.  According to the New York Times, the German encryption expert “aimed to question the effectiveness of the 21-year-old G.S.M. algorithm” and its use to protect the world’s GSM based GPS Tracking communications.  Having the code itself isn’t enough to eavesdrop, but it certainly helps people along the path. The GSM Association responded by calling the publication “theoretically possible but practically unlikely.”

OpenLock

It may be only a matter of time before the technology is readily available to eavesdrop on GSM communications.   Right now, it is believed that only the US military and certain foreign governments have the ability to eavesdrop on GSM communications.  Technology marches on, and the security of GPS tracking using GSM networks may be left behind.

See www.ravtrack.com for mor information about secure, private GPS tracking.