Sources of Location Data
Mobile location data is collected and passed through apps through iOS and Android Location Services.
Apple and Google collect and send Location signals through Assisted GPS, which can be broken down into the following:
Assisted GPS (aGPS): Augments traditional GPS by using cell tower and Wi-Fi data to enhance speed, quality, and precision of satellite signals.
- GPS: Using the GPS chip in a device to trilaterate at least 3 satellite signals is the most accurate way to collect lat/longs. If a device can pick up at least 3 GPS satellite signals, this is the only method necessary. However, in dense areas or in certain weather conditions, a GPS signal might be blocked. When that happens, wi-fi and cell towers kick in.
- Wi-fi: Uses a database of wi-fi networks around the world to triangulate a signal. Note: A device does not need to be connected to wifi to pick up a hot spot.
- Cell Tower: Cell tower triangulation is the least accurate, but can help assist GPS and Wifi to speed the pick-up and pinpoint the location of a signal.
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Assisted GPS in Suburban vs. Urban areas |
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In less dense areas, GPS satellites have fewer barriers, so signals are generally more accurate. Wi-fi and cell towers can speed up the process of picking up a signal. In dense cities or difficult weather conditions, GPS satellites might not always be able to get through, so cell towers and wi-fi triangulation help inform location and speed signal detection.
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Ensuring quality data
Once a lat/long is determined, we collect location data from apps and through bid-stream, but not all signals are created equal.
In order to ensure we are passed quality location data, we:
- Choose which fields are passed. When we partner with apps and data aggregators to receive data, we make sure that certain fields are included so we can understand as much as possible about the signal being passed.
- Ensure that the majority of our data comes from pings from apps and not just ad requests. This data is often more consistent and accurate than using ad requests lat / long.
- Data Quality and Location Verification: Once we have the signals, we run our data through rigorous data quality tests to bucket them into groups based on accuracy. We do not use signals deemed inaccurate in advertising.
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