Using the Smartphone as a Data Logger for Household Travel Survey
These days travel habits surveys are carried out using GPS-based technological tools to record the subject’s trips. At first, the most common technological tool was a simple data logger device, which was only able to save GPS data in its internal memory and in order to access the data, one had to manually connect the device to the computer and download it. In recent years, more sophisticated GPS devices have appeared, including the SIM card, which enables them to transmit the data at a distance to a server in real time, thus achieving two benefits – watching data in real time and receiving data without having to meet the subject. Furthermore, there are additional benefits such as getting a report on the battery status and the level of reception of the GPS in real time.
Using the Smartphone as a Data Logger
Recently, some surveys have been carried out, particularly household travel surveys, using smartphones as a replacement for the Data Logger device. In addition to the advantages already mentioned, smartphone users can enjoy accessible means of communication with the subject and moreover, can send the subject questions about his activities in real time.
In order to use the phone as a Data Logger, one must install a designated application that can collect the data and send it to a server from a distance. Pristo has an application for such purposes, that was intentionally built to gather data at a high frequency (3 second intervals) with as little battery use as possible.
Following are the advantages of using a smartphone as a data logger for a travel habits survey:
- √ Getting data in real time.
- √ Receiving additional data such as: battery status, GPS signal strength, movement status etc.
- √ Higher quality of data – the smartphone crosses data between a number of different antennae (Wifi, GPS and GSM), and therefore can provide more precise data than a simple GPS device. In addition, the device is able to approximate location even when there is no GPS reception, for instance in a dense urban area or inside buildings.
- √ The possibility of sending the subject questions in real time.
- √ Saving on equipment – the application can be installed on the subject’s personal device.
- √ Means of direct communication between the surveyor and the survey subject.
How to choose the most suitable smartphone for the purpose of a travel habits survey?
Choosing the device must be done in two stages – first, you must select a reduced number of devices that meet the preconditions that you have decided upon. Second, you must acquire a single device of each type and test it in the field, since sometimes the device’s technical data and capabilities are not represented accurately, for example: consumption rate of the battery, satellite coverage of the GPS antenna, etc.
Following are the initial parameters that must be examined:
- √ The existence of a GPS antenna.
- √ Screen size – one must choose a device without a large screen, since the screen consumes a lot of battery energy.
- √ Battery capacity – the larger the battery capacity, the more time the device can work without charging.
- √ Available in stock – one must check that the suppliers have a large enough inventory for the number of devices that you intend to acquire.
After you have compared a number of devices, choose two or three devices that will work best for you, and get one of each. Now, you must do checks and experiments that will determine which is the most suitable device for you. Following are a number of basic tests that we recommend doing:
- Remove all applications and services from the phone that are not useful, that could drain energy from the battery.
- Install the Data Logger application for gathering the GPS data.
- Charge all the phones so that the batteries will be full.
- Carry out a number of different trips, taking all the devices together with you. Each trip should be of a different nature, for example:
- A trip in a dense urban area.
- A trip that includes entering and exiting buildings and parking lots, such that the GPS antenna will lose reception for a while.
- A trip in open areas.
- A trip where the devices are inside of a bag.
- A trip when the devices are inside a car/train/bus.
- For each of the trips that you carry out, download the data to the computer and compare the following data between devices:
- Rate of battery usage.
- Quality of data, in terms of accuracy/precision.
- Amount of time it took for each device to begin to transmit data at the beginning of the trip.
- Amount of time that it took each device to return and to transmit data after being disconnected from reception (for example: after exiting a parking lot).
After executing the above checks, you can decide which device is the most suitable for your purposes, in terms of quality and price.
Pristo has a designated application for gathering GPS data which is suitable for Android and IOS. The application has served a number of large organizations for carrying out travel surveys for households and even a survey for tourists. The application has proven to be indispensable!
If you wish to receive more details about choosing a smartphone or dedicated application for GPS data logging, we would be thrilled to hear from you!