One of the most frequent questions we hear from customers is what do we recommend for the ideal GPS tracking device and plan? Regardless of wether you are tracking a person, animal, vehicle, trailer or other asset, how should you decide what type of device to purchase and what your ideal tracking plan should look like?
To make this determination, its important to understand the different factors involved and their resulting effects. If there were no trade-off’s, then of course everyone would choose the plan with the most frequent GPS updates. As with any other aspect of our lives, there are always trade-off’s:)
- First, let’s review the basics. Basically, every GPS tracking device consists of 3 primary components:
- A GPS receiver that receives position information from the GPS satellite constellation as often as once every second.
- Once this information is received, internal logic processes the information, using algorithms to determine its location, speed, heading and altitude.
- A communications transceiver transmits the location information of the device to the tracking system via a cellular data network.
The first component -receiving the GPS signals from space does not cost anything, does not consume much power and does not use any cellular airtime -so no big trade-off’s here. Ditto the second component -determining position information uses very little power and has no direct cost. It’s the 3rd component where we see all the trade-off’s. It is when we transmit the position information to the tracking system that we use the most power and this is also where we incur cellular data airtime costs.
- These are the trade-off’s. The more often we transmit position information:
- The greater the amount of power we consume
- The greater the amount of data airtime we use
- The greater the amount of information we need to store in the tracking system
- The longer it takes to produce historical GPS vehicle tracking reports when needed
Ok, now let’s examine the affects each of these trade-off’s can have in different types of GPS tracking situations:
If we are tracking a self powered device, such as a Blackberry, or portable GPS unit or a self powered trailer or asset tracking device, the frequency of GPS transmission has a dramatic effect on battery life. Each time a self powered device sends a position, the device needs to establish a packet data session with the wireless network, whereupon it is assigned a temporary (dynamic) IP address, after which it transmits the information to the GPS mapping server. More frequent transmissions will have a directly proportional effect on battery life. For example, a Blackberry sending its position every 5 minutes will use about 5% of its battery life in a typical day. If we were to change that to 1 minute reporting, we could see battery life degrade to as much as 20% of its total capacity. Similarly, in the case of a self powered trailer tracking unit, we can easily turn 5 years of battery life into only a few months with excessive GPS transmissions.
When tracking commercial vehicles with an installed GPS unit, power consumption is not a major factor in daily operation, unless the vehicle has no power source, such as an un-tethered trailer or other un-powered asset. However, regardless of the vehicle type, we need to pay close attention to how the GPS device operates when the vehicle is in an idle state. Some GPS tracking units report on a timed basis (such as once per minute) and they may continue to report every minute ad infinitum, even when the vehicle has not moved. This can cause a vehicle dead battery situation if the vehicle sits for 3 or 4 days at a time. Even in situations where the installed GPS device is intelligent enough to cease reporting when stopped, its current consumption may be sufficiently high enough to kill the vehicle’s battery after a few days of sitting idle. In some applications, a provider may try to reduce costs by installing a GPS phone as an installed-in-vehicle device. This can have all sorts of implications: First, the phone will be under constant charge, which can cause its battery to bloat over time, requiring annual replacement and in some cases, an explosion. Second, when the vehicle sits idle for a few days, the vehicle battery will eventually die. After it is boosted, the phone will not power up automatically, rendering its GPS tracking device useless until manually started.
When choosing an installed GPS solution, ensure that these types of scenarios are considered: First, a well designed vehicle tracking unit, once stopped, should transmit its position to indicate the stop, then cease transmitting further until the vehicle is either moved, powered back up (engine started) or an event occurs. (Such as a vehicle alarm system) Avoid devices that report strictly on a timed basis and report duplicate positions when stopped. Secondly, ensure that the device will actually transmit intelligent stops. The majority of GPS devices on the market simply report on a timed basis, therefore, determining whether the vehicle is stopped must be done by the mapping application, which is not always as accurate. Thirdly, a state of the art GPS tracking device should also go into a sleep mode a few minutes after the vehicle is powered down, such that battery consumption becomes negligible.
There are two primary factors that affect data consumption. The first relates to the programmed GPS reporting parameters of the GPS unit, or what we call the GPS tracking plan. Each GPS tracking device, whether a GPS cellular phone, a vehicle tracking device or an asset or trailer tracking unit is typically programmed to send position information on a timed basis, such as once per minute or on a distance basis, such as once per mile. Generally speaking, distance based reporting is more efficient, as it is exception based. A key factor in keeping data consumption as low as possible is having the intelligence in the device to eliminate duplicate position reports. There is no point in telling me where you are every minute all night long when you have not moved.
The second primary factor has to do with the transmission protocol of the GPS tracking unit. The vast majority of GPS tracking products on the market transmit the GPS location information to the tracking system using the TCP/IP protocol. While TCP/IP works reliably, UDP is much more efficient, often using less than 1/2 the data bandwidth of TCP. Why do most GPS providers use TCP/IP then? Simply because it is easier to implement. This is because, in order to use UDP reliably, the system provider must engineer the tracking application with a two-way client/server architecture that provides guaranteed delivery. In the case of UDP, the GPS device sends its position via UDP, whereupon the tracking application receives this information and then sends an acknowledgment UDP message back to the device. If the GPS tracking unit does not receive the acknowledgement back, it assumes the device may be out of coverage, in which case it stores the information for re-transmission. A properly designed UDP transmission method with acknowledgement not only ensures 100% reliability, but also uses the least amount of data that the customer will need to pay for.
If your tracking application involves Smartphone tracking, chances are it will use TCP/IP. In this case, you likely do not need to worry about efficiency, because these Smartphones typically come with substantial data plans anyway. However, if you are tracking a commercial vehicle, an asset or a trailer, choose a device and provider that uses the UDP protocol with guaranteed delivery and store and forward. Store and forward implies that every GPS message is acknowledged and that there will never be a hole in an historical breadcrumb trail or position history report. Acknowledged position reports are also the key to receiving reliable vehicle alert messages, such as boundary, ignition on/off and speeding alerts.
When determining an optimal tracking plan, first decide your primary objectives or purpose for using GPS tracking. If you will be tracking a self-powered device, such as a cellphone or trailer tracking unit, then you will want to choose the minimum reporting interval required to achieve your objective in order to conserve battery life. For example, tracking your sales team via their Blackberries does not require knowing their whereabouts every 5 minutes. You just need to know they are actually out on the road working, rather than on the golf course. A 15 minute plan will likely suffice. If we use that same Blackberry to track photo copier techs or courier driver owner operators for customer service and job scheduling reasons, 5 minute updates probably makes more sense.
If you are tracking commercial vehicles to enhance productivity and customer service, your plan needs to first take your dispatch needs into account. If your operation dispatches ad hoc jobs at a high frequency throughout the day, such as a towing or taxi operation, then you will be looking to dispatch the closest vehicle and may require 1/2 mile or 1 minute GPS updates. For most service organizations with pre-scheduled jobs, GPS vehicle tracking is not required as much for dispatch efficiency as it is for productivity analysis, billable hours justification and customer service assurance. In this case, 1 mile reporting with accurate stop reporting is likely appropriate. In asset and trailer tracking situations, if are you primarily interested in theft prevention and inventory determination, then motion alerts with daily roll call reporting will be sufficient. If you wish to measure engine hours on construction equipment or tether alerts on a trailer, then a combination plan can give you alerts and position reports on these events, but otherwise revert to daily inventory reporting when the asset is inactive.
Smaller Is Better
A common misperception in the GPS tracking industry is that the more often a unit sends GPS, the better. However, there is such a thing as too much information. Unless your operation involves ambulance or police car tracking, 10, 20 and even 30 second GPS updates can not only waste data and involve exorbitant tracking fees, but simply provide too much information. Pulling up an historical written position report or a breadcrumb trail for your fleet or a particular vehicle for yesterday can be a lengthy process with excessive position reporting. Ask yourself if you really need to see where that truck is every few seconds. Generally, knowing where a vehicle is at a given second is not nearly as important as where they stopped, when they stopped and how long they were stopped for. When vehicles are moving, they are usually en-route to a job or an assigned destination. For most service organizations, when a vehicle is moving, knowing its location within 1 mile is sufficient. Choose a plan that provides accurate stop reporting and the minimum distance based reporting necessary to get the job done.