TSD Navigator

Table of Contents

1.  Purpose. 2

2.  Overview.. 2

3.  Requirements and device options. 2

4.  Images of the app. 3

5.  Running the rally. 3

A. At the starting line. 3

B.  At the end of the odometer calibration section. 5

C.  Staying on time. 7

D. Speed changes. 8

E.  Pauses & Time Allowances. 8

F.  Correcting your odometer during a leg. 9

G. Reverse. 10

H. Park. 10

I.   Arrival at a checkpoint (control) 10

J.   Starting a new leg. 11

6.  Settings screen. 12

7.  Data storage. 12

8.  GPS information. 12

A. GPS drift 12

B.  GPS accuracy. 14

C.  Installation and use of an external GPS receiver 15

9.  Other helpful thoughts. 16

1.  Purpose 

The Mojo TSD Navigator app is designed to be used by the navigator on a time-speed-distance car rally.  The app will report the amount of time that the rally car is either ahead of schedule (early) or behind schedule (late).  It reports this value once per second.

2.   Overview 

The app receives location updates from your device’s GPS once a second (or more frequently if you’re using an external GPS).  It uses this information to calculate the distance you’ve traveled and displays this value in miles in the Odometer.  It then calculates how long it should take you to travel that distance at the assigned average speed (the CAST) and determines the exact time of day that you should be at the point along the rally course where you currently are.  This time of day is displayed in the Calc Time (short for Calculated Time).  The difference between the Calc Time and the actual time (shown in Clock) is the Deviation – the amount of time that you are early or late.  The Deviation is shown in the upper left corner of the app.  The heading above it tells whether you are early or late. 

3.   Requirements and device options 

This app will run on either an Android phone or an Android tablet.  You will find that running it on a tablet is easier because the screen is larger, the buttons are larger, and the text is easier to read.  Trying to press tiny buttons on a phone while the car is bouncing down the road is a challenge.  We recommend using a tablet if possible.  A Samsung Tab A7 10” tablet in a case is a very good option.  Just make sure that your phone or tablet has a GPS receiver unless you’re always going to use an external GPS receiver.  This app does not work without access to a GPS.

You can use either the device’s own internal GPS receiver (most Android devices have one) or you can use an external GPS receiver such as the Dual Skypro DGPS 160.  All GPS apps consume more power than other apps, so we recommend that you keep your phone or tablet plugged into a power source during the rally.

4.   Images of the app

                See images above.

5.   Running the rally

A.   At the starting line 

1. Most rallies begin with an odometer calibration section that allows you to adjust your odometer to match the rallymaster’s odometer.  Make sure the ‘Split’ button in the upper right corner is yellow.  If it’s not, press it once and it will turn yellow.  When your car is stopped at the starting line, press the red ‘Zero Odometer’ button in the lower left corner of the screen.  A window will pop up asking if you are sure you want to zero Odometer.  Touch “YES”. The Odometer should now read 0.000. 

2. Press the purple ‘Zero Auxiliary’ button. Press the ‘Forward’ button and confirm that it is green.

3. Press the ‘Set Next CAST’ button and confirm that it is green.  Using the blue and yellow numeric buttons (+10, +1, +0.1, etc.) change the value of the Next CAST to whatever speed (in miles per hour) is in effect at the starting line.  Press the orange ‘Change CAST’ button to move the Next CAST to the CAST.  Confirm that the CAST is whatever speed is in effect at the starting line. (Most rallies begin with a Transit Zone where you do not have to drive at a specific speed, rather you have a specified amount of time to get to the end of the Transit Zone.  Whenever you begin a Transit Zone, you set the CAST to zero.)

4. Press the blue ‘Go To Settings’ button.  This takes you to a different screen.  Press the ‘Reset Odo Factor 1.0000’ button. Confirm that the displayed Odo factor is 1.0000.  Press the ‘Return to Main Screen’ button.  You will see the Odo factor of 1.0000 displayed in the Odo factor box.  (The Odo factor is multiplied to the distance derived from your GPS.  An Odo factor of larger than 1.000 will increase the reported distance traveled. An Odo factor of less than 1.000 will decrease the reported distance traveled.  In this way, you can adjust your odometer to better match the Rallymaster’s odometer.  Typically, your Odo factor would be somewhere between 1.0200 and 0.9800.  If would be odd for the Rallymaster’s odometer to be off more than 2% from the GPS distance.  Be sure to reset the Odo factor to 1.0000 at the start of every new rally.)

5. Press the ‘Set Calc Time’ button and confirm that it turns green.  Using the blue and yellow numeric buttons, adjust the Calc Time to your assigned starting time.  If your assigned starting time is 8:00 plus your car number in minutes, and your car number is 12, you would set the Calc Time to 08:12:00.  If your assigned starting time is 2:00 pm plus your car number in minutes, and your car number is 25, you would set the Calc Time to 14:25:00.  (This app uses the 24 hour clock system, so 3:00 pm is 15:00.)  (The +0.001 and -0.001 buttons do not do anything when Set Calc Time is selected.)

6. The Deviation box in the upper left corner now displays the amount of time that remains before your assigned starting time.

7. Press the ‘Set Next CAST’ button and confirm that it turns green.

8. Press the purple ‘Zero Auxiliary’ button.

9. Double check and confirm:

      Odometer = 0.000

      Calc Time = your assigned starting time

      CAST = 0

            ‘Forward’ button is green

            ‘Set Next CAST’ button is green

            Odo factor = 1.0

                Auxiliary box is blank

The app is now properly set and ready to go.  You will see the Deviation box in the upper left corner counting down to your assigned starting time (the Calc Time).  A couple of seconds before the Deviation reaches zero, you should start.

B.   At the end of the odometer calibration section

Stop your car precisely at the sign that ends the odometer calibration section.  Write down the app’s odometer reading on your route instructions.  Use a calculator to divide the rallymaster’s odometer value at that point by your app’s Odometer value.  This number is your new odometer correction factor.

Odo factor = Rallymaster’s odometer ÷ Mojo TSD Navigator odometer

Press the blue ‘Go To Settings’ button.  Use the blue and yellow numeric buttons to change the Odo factor to the number on your calculator.  Confirm that the Odo factor is correct and press the blue ‘Return to Main Screen’ button.  (Do not press the red ‘Reset Odo Factor 1.0000’ by mistake.)

If the route instructions tell you to zero your odometer here, press the ‘Zero Odometer’ button.  Answer ‘YES’ to the ‘Are you sure’ question. Confirm that the Odometer now reads 0.000.  If the route instructions do not tell you to zero your odometer here (rare), press the ‘Adjust only Odo’ button and use the blue and yellow numeric buttons to change your odometer to match the rallymaster’s official mileage.

Press the ‘Set Next CAST’ button and confirm that it is green.  Use the blue and yellow numeric buttons to set the next CAST to the speed (miles per hour) that will be in effect going forward from this point.  Then press the orange ‘Change CAST’ button to move that number into the CAST field.  Look ahead in the route instructions to find what the next assigned average speed will be and enter it in the Next CAST field using the blue and yellow numeric buttons.

Press the ‘Set Calc Time’ button (confirm that it turns green) and use the numeric buttons to change to Calc Time to the time of day that you should restart at this point.  Then press the ‘Set Next CAST’ button.  The Deviation field shows that amount of time that remains before you should restart from this point.

Confirm that the ‘Forward’ button is green and the ‘Split’ button is yellow.

As the deviation box approaches zero, get ready to go.  When the deviation box displays a couple of seconds before zero, go.

C.   Staying on time 

As you drive, you will see your speed in the Speed box (in miles per hour). 

You will see the Odometer increasing as you drive and displaying the distance you have traveled (in miles) since the point that you zeroed the Odometer. 

You will see the Calc Time increasing.  The Calc Time is showing the time of day that you should be at the point you are along the rally course based on the assigned average speed (the CAST). 

For example:  Let’s say you started at 9:00 am (Calc Time) with a zeroed odometer and a CAST of 30 (mph).  When you have traveled exactly one mile, the Odometer will read 1.000 and the Calc Time will read 9:02:00.  This is because it should take you exactly 2 minutes to travel 1 mile at 30 mph.  This is the time that you should be at that point.  The app compares this Calc Time to the Clock once per second.  If you are exactly on time, the Clock will match the Calc Time. 

The Deviation box in the upper left corner displays the difference between the Clock and the Calc Time.  This is the amount of time that you are either ahead of schedule (early) or behind schedule (late).  If you are early, the deviation box shows the amount of time that you are early with a plus sign (+) and the header “UP/EARLY”.  If you are late, the deviation box shows the amount of time that you are late with a minus sign and the header “DOWN/LATE”.  If you are late, both the amount of time and the header are shown in red letters and numbers to better alert you to the fact that you are late.

If you are precisely on time, the Deviation box will display “0.0” and the header “ON TIME”.  Both letters and numbers will be in black font with a green background.  The green background provides a more obvious signal that you are precisely on time.  Your goal is to arrive at each timing checkpoint with the Deviation box displaying “ON TIME 0.0”.

D.   Speed changes

Look ahead in the route instructions to find the next speed change.  Confirm that the ‘Set Next CAST’ button is green and use the numeric buttons to enter the next speed in the Next CAST field.  At the exact moment when you are instructed to change your average speed to this new speed, press the orange Change CAST button.  Confirm that the CAST field now shows the new, correct speed.

E.    Pauses & Time Allowances 

To execute an instructed Pause, press the Set Calc Time button and confirm that it is green.  Use the numeric buttons to enter the amount of the Pause.  Here are the values that are added with the blue numeric buttons:

+10 adds 10 minutes

+1 adds 1 minute

+0.1 adds 10 seconds  (not 0.1 minute)

+0.01 adds 1 second (not 0.01 minute)

+0.001 does nothing

The yellow numeric buttons subtract these amounts.  You would use these yellow numeric buttons to execute a Gain instruction (very rarely used).

Most rallies now offer no-penalty Time Allowances.  If you are delayed during a rally, rather than speeding to try to make up lost time, claiming a Time Allowance will deduct that amount of time from your arrival time at the next checkpoint.  This is a marvelous safety feature that is now standard on most TSD rallies.  On Mojo TSD Navigator you treat a Time Allowance exactly like a Pause.  If you claim a 3:30 Time Allowance, you simply enter a 3:30 Pause.  If you are delayed further and need to increase your Time Allowance by one minute to 4:30, you would just add a 1:00 Pause for a total Pause of 4:30. 

Whenever the Set Calc Time button is selected (is green), the Auxiliary field displays the total amount of time that you have added and subtracted with the numeric buttons since the point that it was last reset using the Zero Auxiliary button.  This is a handy way to keep track of the total amount of Pause time that you’ve adding during the leg.

F.     Correcting your odometer during a leg

Many rallies will provide some official mileages during a leg.  Some even provide the official mileage at every route instruction. These mileages provide an opportunity for you to confirm that your Odometer is matching the rallymaster’s official mileage and to make a correction if it’s not. 

As you pass the sign where an official mileage is given, press the yellow Split button.  This freezes the display of the Odometer, Calc Time, Clock, Speed, and Deviation.  (These values continue to update in the background while the display is frozen.)  You can now compare your Odometer reading with the official mileage.  If the route instructions give the mileage with three decimal places, you can determine exactly the thousandths of a mile difference between your odometer and the official mileage. 

There are two ways to make an adjustment to your odometer – the ‘Adjust only Odo’ button and the ‘Adjust Odo & Time’ button.  The ‘Adjust only Odo button’ does just that – it changes just the Odometer.  The ‘Adjust Odo & Time’ button does what the Adjust only Odo button does PLUS it adjusts the Calc Time as well.  If you are in a timed section where you are running on an average speed, you would want to adjust both distance and time.  You would use the ‘Adjust Odo & Time’ button.  If you were running in a Transit Zone, you would adjust only the mileage with the ‘Adjust only Odo’ button.

In both cases, the Auxiliary box will display the total mileage that you have adjusted with the numeric buttons since the Auxiliary box was reset (zeroed) with the ‘Zero Auxiliary’ button.

G.  Reverse

When you go off course, you’ll either backup or turn around to go back.  In both of those cases, you’ll want to deduct the distance that you travel from the Odometer as you return to the point where you went off course.  If you touch the ‘Reverse’ button it turns red, and any distance travelled will be deducted from the Odometer.  Once you reach the point where you are back on course, touch the ‘Forward’ button (make sure it turns green) to resume adding distance to the Odometer.

H.  Park

When you touch the ‘Park’ button and it turns orange, any distance travelled is ignored, whether you’re still moving or stopped.   You can still add or subtract mileage using the ‘Adjust only Odo’ and the ‘Adjust Time & Odo’, but any distance derived from the GPS will be ignored.

If you are going to be stopped for more than a couple of minutes (like for a break or for lunch), we recommend putting the app in ‘Park’ while you’re stopped.  Don’t forget to press ‘Forward’ when you return and before you start to move. (See section on GPS drift for explanation)

I.  Arrival at a checkpoint (control)

You do not have to do anything as you pass a checkpoint.  However, you may wish to press the Split button as you pass the checkpoint in order to freeze the display.  In this way, you can make a note of what your Odometer and the Deviation were reading at the checkpoint (if you care – most users won’t bother with this).

J. Starting a new leg

When you are stopped at the restart point/sign, first compare your Odometer to the official mileage at that point.  This allows you to get a sense of how well your Odo Factor is working.  If you find that your Odometer is deviating from official mileage in a consistent direction (either too high or too low), you can adjust your Odo Factor in the manner described in Section B.

Once you’ve either adjusted your Odo Factor (typically only done once at the end of the odometer calibration section) or decided to leave it as is, next adjust your Odometer to match the official mileage at the restart. 

Typically, the official mileage will rezero at each restart, so you would simply press the Zero Odometer button, answer “YES” to the question of “Are you sure?”, and confirm that the Odometer now reads 0.000. 

Next press the ‘Set Next CAST’ button (make sure it’s green) and enter the CAST that you will use to begin this new leg.  Then press the orange ‘Change CAST’ button to move this value from Next CAST to CAST. 

Finally, press the ‘Set Calc Time’ button and confirm that it turns green.  Use the numeric buttons to set the Calc Time to the time of day that you will start the next leg. 

Finally, press the ‘Zero Auxiliary’ button to clear out that data.  This is not critical.  If you forget to do it, don’t worry.  But it’s best to start each leg with a zeroed Auxiliary box because it does allow you to see how much time and distance you have added or subtracted during the leg.

Double check and confirm:

Odometer is set to official mileage, typically 0.000

CAST is set to the proper assigned speed

Calc Time is set to your restart time of day

‘Forward’ button is green

‘Set Next CAST’ button is green

The Deviation field now shows the amount of time before you are due to start the leg.  You are ready to go.  

6. Settings screen

The settings screen has two settings:  Odo factor and Minimum Speed.

Important note: The Odometer will be paused any time that you are in the Settings screen.  For this reason, you should only use the Settings screen while you are stopped.

7.   Data storage

Whenever this app is minimized or closed, the following data is automatically saved:  Odometer, Calc Time, CAST, Next CAST, Odo factor, and Minimum speed.

8.   GPS information

A.   GPS drift

An unfortunate aspect of GPS receivers is that they don’t know when you’re stopped.  They continue to compute and update your location (latitude and longitude) and send this data to the app.  If you examined this data, you would see that the GPS is reporting that you are continuing to move a small distance every second.  The amount of this erroneous distance is a function of the quality of your GPS.  (The better your GPS, the smaller is this erroneous distance.) This small distance typically would imply a speed of less than 1 mile per hour. 

If we didn’t detect this and adjust for it, your odometer would (erroneously) add distance while you’re stopped (that’s bad). 

If you touch the ‘Go To Setting’ button, you’ll see “Enter minimum speed”.  When you open this app for the very first time, this value is set to 3 (mph).  The app will reject any distance that the GPS reports where the reported speed is 3 mph or less.  If you are using your device’s internal GPS (most uses will be doing this), the 3 mph setting may be appropriate. If you are using an external GPS receiver like the Dual Skypro 160, you can probably reduce this setting to 1 mph. 

You should test the app on your device by going outside and waiting for the Accuracy value to stabilize.  Typically, the Accuracy on an Android device will stabilize somewhere between 3.0 and 3.8 (meters).  (The lower the value, the better the accuracy.)  Once your device has stabilized Accuracy outside, zero your odometer.  (Don’t perform this test indoors.  GPS is very inaccurate indoors.)  Without moving, observe the Odometer.  If you can stand still for 1 minute and the Odometer still reads zero, you’re good to go.  If the Odometer adds distance while you’re standing still, you should increase the Minimum speed value and repeat the test.  We recommend against setting the Minimum speed higher than 5 mph.  As you set this value higher, you risk missing some mileage whenever you slow to a stop and then resume speed on the rally. 

If you find that at even 5 mph minimum speed your device adds mileage while you’re stopped, the best way to compensate for this is to press the ‘Park’ button when stopped for more than a few seconds.  ‘Park’ tells to app to not change to odometer.  But don’t forget to press ‘Forward’ before you start moving again!

B.   GPS accuracy

The app displays the estimated GPS accuracy in small numbers just below the ‘Change CAST’ button.  This number is in units of meters and is an estimate of how far off the GPS reported location could be from the true location.  The smaller the number, the more accurate is the GPS data. 

Android devices will typically report an accuracy between 3.0 meters and 3.8 meters as long as they have a good view of the sky. 

Most navigators will choose to hold their phone or tablet in their hands during the rally in order to use this app. This is not ideal for GPS accuracy as the view of the sky is better up on the dash.  For that reason, some users will choose to buy an external GPS receiver (such as the Dual Skypro 160 or Garmin Glo).  Those external receivers will sit comfortably on your car’s dash and will communicate with your phone/tablet via Bluetooth. 

Using a Dual Skypro or Garmin Glo will typically provide an accuracy of 1.8 meters.  They also send location updates 10 times per second instead of the once per second of your phone/tablet’s internal GPS.

Using an external GPS receiver will provide more accurate information to your Mojo TSD Navigator app.  For most competitors though, an external GPS receiver is not necessary. 

C.   Installation and use of an external GPS receiver

The operating system of Android devices (both phones and tablets) will not automatically connect to a Dual Skypro 160 or other external Bluetooth GPS receivers.  You need to install a “helper app” that will connect to the external GPS receiver. 

Go to the Google Play Store and search for “Bluetooth GPS”.  If you see an app by that exact name, download it and install it on your device.  If you don’t see it, that means that it is not compatible with the Android version on your device.  In that case, choose “Bluetooth GNSS” and install it on your device.

Go to Setting on your device.  In the search field, search for “Build number”.  Tap on the result that appears to go to the Build Number in your Settings.  Tap on the words “Build number” seven times quickly.  A window should then appear announcing that you are now a Developer. 

Now search for “mock” in the search field.  You should see a result titled “Select mock location app”.  Touch this result to go there.  Now touch “Select mock location”.  You should see a list of possible choices.  The helper app that you just downloaded should be in this list (it might be the only one in the list).  Touch it to select it.  You’ve now specified that your device can use that helper app to connect to an external GPS receiver.

In order to use your external GPS receiver, you need to do the following:

-        Turn on your external GPS receiver.

-        Open your helper app (Bluetooth GPS, Bluetooth GNSS)

-        Allow your external GPS receiver a minute to get a fix on the satellites.

-        In your helper app, choose “Connect”.

-        In a few moments, you should see data in the helper app indicating that it has connected with the GPS receiver.

-        In the case of the Dual Skypro, you’ll see a solid blue light indicating that it has established a Bluetooth connection with a device.

-        Now you can open Mojo TSD Navigator.

-        You should see an accuracy of less than (better than) 3 meters, typically just under 2 meters.  Make sure the GPS receiver is situated on your car’s dash, as far forward as possible to get the best view of the sky.

-        If you take your device away from your car (like at a break or at lunch), you’re likely to break the Bluetooth connection as Bluetooth has a maximum range of 30 feet.  We recommend leaving your device in the car at breaks to avoid breaking this Bluetooth connection and having to go through the connecting process again.

9.   Other helpful thoughts

a. A common mistake in using the app is to not have the ‘Set Next CAST’ button selected (green) when you press the numeric buttons intending to set the Next CAST.  This will­­ cause you to inadvertently change either the Calc Time or the Odometer, depending on which button other than ‘Set Next CAST’ is green.  There is no ‘Undo’ button so be very careful that you have the proper button selected before pressing the numeric buttons.

b.   Cross off each route instruction as soon as you complete it.

c. Almost all rallies now permit no penalty time allowances.  Use them.  They are a critical aspect of safe rallying.

d.   Drive safely and legally – don’t let the route instructions distract the driver from paying attention to the road.