When your scheduled time for a GPS position attempt arrives the GPS will turn on. And it will remain on for some number of seconds that it needs in order to produce that GPS position but it won’t go past the GPS timeout which was 60 seconds. The estimated battery life calculated by the user software before you deployed will have made the assumption that each time the GPS turns on it uses those entire 60 seconds. But in fact that’s not going to happen, many times the GPS will turn off well before 60 seconds and you will still have a GPS position. Therefore the estimated battery life is based on using the entire GPS timeout each and every time the GPS comes on.
Stay with me, we’re almost there. Let’s talk about how precision and time to fix are related. When the GPS turns on and off in a short period of time, let’s say 15 seconds... that GPS location will be good but not as precise as it could be. But sometimes 15 seconds are all that is needed to obtain a GPS location. When this happens the GPS turns off and just does not use that other 45 seconds that were available according to your 60 second GPS timeout setting. But if you use our ‘GPS additional time’ feature and set it to 45 seconds, for example, then when the GPS would still have acquired that position within those 15 seconds rather than turn off, the GPS will remain on for an additional 45 seconds. That position is going to be far more precise than the position that was acquired and written to memory after 15 seconds. But the GPS will not remain on for longer than your GPS timeout and therefore your estimated battery life calculation is still valid! This costs nothing; it is included in the user software. We call this GPS additional time. Click here to watch video.
The basic function can be described as a 3-axis accelerometer informing the microprocessor about movement levels and using that information to determine whether or not to attempt the next scheduled GPS attempt or to save the battery usage and just skip it.
There are 4 parts to Smart GPS
A minimum activity level that must be exceeded in order for the next GPS to take place. In this way you are in control over what constitutes a resting animal.
A counter which keeps track of instances of this minimum activity level being exceeded. In conjunction with the minimum activity level above this gives you more control over what constitutes a resting animal.
A function that enables you to choose when the "instances of exceeded activity level" counter resets back to 0. This helps you to protect your data set from just being totally empty in the case that you set either the minimum activity level too high or the counter too high.
A function that temporarily disables Smart GPS based upon movement information. This function protects you in the case that you set the activity level and counter too high.
To elaborate, before deployment you will set all of these parameters. Setting the minimum activity level is done simply by inputting an arbitrary number into the software. This number represents an activity level that must be exceeded so that Smart GPS won’t take effect. The user software enables you to see what this number represents in terms of movement because you move the collar while looking at the user software and you can see that number change as movement intensity changes (GPS device connected to PC by USB cable at the time you do this).
The counter needs to know the minimum number of instances (x) that the movement intensity described above must be exceeded in order to disable the Smart GPS the next time the GPS should turn on. In other words, since the counter started counting the minimum activity intensity must be exceeded X number of times or else the next scheduled GPS position attempt will be skipped.
Another setting allows you to control the way in which the counter resets itself. The counter will always reset after a scheduled GPS location takes place. Other than that your counter works in one of two ways. The first is that it will always reset to 0 at the time of a GPS location that was skipped because the minimum activity level was not exceeded enough times to warrant a GPS location. But what if you set that counter number much higher than you should have? You will be missing out on a lot of GPS data.
To protect yourself from this you can choose to have the counter to continue accumulating instances of the minimum intensity occurrences even if the time for the next scheduled GPS instance has arrived and been skipped.
Finally, yet another way to protect your data set from the mistake of setting either the minimum activity intensity too high or setting the counter too high. This last feature allows you to force the GPS to totally ignore the Smart GPS feature after X number of consecutive skipped GPS attempts. In other words, the animal has not moved enough to override Smart GPS skip. This can be because the animal really isn’t moving much or it could be because your settings are too high. Choose a number from 1 to 99 and use that to program this feature and then the GPS will always turn on after that number of skipped GPS positions regardless of movement. Click here to watch video.
If you know where your study animals are going to be you can set up this base station to perform the above task without your physical presence. Understandably this is not practical for every application but for those that it practical for all you have to do to get the GPS data is make a trip out to the base station. Extract the data from the laptop that is running the base station... just plug a flash drive into it, wait for the beep and you are done.
Sampling rates: There are 6 activity sampling rate choices. 4 times per second, 2 times per second, 1 time per second, once every 2 seconds, once every 3 seconds or once every 4 seconds.
Delta Time: You choose how many of these samples are compiled into one line of data in the output. In other words, if you have the accelerometer set to sample activity levels 4 times per second and then you choose to have one line of data represent 60 seconds worth of sampling then in fact that one line of activity data represents 240 instances of activity sampling. Conversely you may choose that 1 line of data is representative of 1 second worth of sampling with in this case would be 4 samples. That allows you either fine scale activity monitoring or coarse scale monitoring.
The user software empowers you to set a level of activity below which activity data will not be recorded even when it occurs. In the case that you are not interested in small movements this allows you to eliminate from your data set those small movements. If you are interested in small movements then you can set this feature to 1 and everything will be logged.
After you have set the activity detection parameters described above you then schedule the times in the day that the activity data will be detected and stored.