# How GPS Receivers See Weak Signals by Combining Data > A method for improving GPS sensitivity by mathematically combining multiple, weak signal samples to extract navigation data that would otherwise be lost in noise. - **Patent:** US 6816710 - **Original title:** Method and apparatus for signal processing in a satellite positioning system - **Owner:** SnapTrack Inc - **Granted:** 2004 - **Status:** Public domain (expired) - **Times cited:** 76 - **Field:** consumer_electronics, telecommunications, semiconductors ## What it does This patent describes a way to make GPS receivers work in difficult environments, such as indoors or in urban canyons where satellite signals are very faint. The receiver captures multiple versions of the same signal over time. Because these signals contain repetitive data, the receiver can mathematically combine or 'sum' these samples. To ensure the final result is as clear as possible, the system weights each sample based on its signal-to-noise ratio, effectively giving more importance to the cleaner data. This process allows the device to pull usable navigation information out of what would otherwise appear as random background noise. ## What it does NOT cover - Does not cover GPS signal processing that relies solely on a single, instantaneous signal capture. - Does not cover methods that do not involve weighting the samples based on the signal-to-noise ratio. - Does not cover hardware-agnostic software that does not interact with satellite positioning system signals. - Does not cover non-repetitive data streams that lack common information between signal samples. ## The clever bit The invention treats time-separated, weak signal samples as pieces of a puzzle that can be aligned and summed to boost the signal strength, rather than discarding them as interference. ## Real-world examples 1. Assisted GPS (A-GPS) in smartphones 2. Indoor positioning systems 3. Wearable fitness trackers with GPS ## Why it matters This technology was essential for the transition of GPS from specialized outdoor equipment to the standard feature found in every modern smartphone. By allowing devices to acquire a location fix in challenging conditions, it enabled the rise of mobile location-based services, ride-sharing apps, and personal navigation. ## Frequently asked questions ### What does How GPS Receivers See Weak Signals by Combining Data cover? A method for improving GPS sensitivity by mathematically combining multiple, weak signal samples to extract navigation data that would otherwise be lost in noise. ### Who owns patent US 6816710? SnapTrack Inc owns this patent, granted in 2004. ### When does this patent expire? This patent has expired and is now in the public domain — anyone can use the invention freely. ### What is patent US 6816710 cited by? This patent has been cited by 76 later patents that build on its ideas. ### What problem does this patent solve? This technology was essential for the transition of GPS from specialized outdoor equipment to the standard feature found in every modern smartphone. By allowing devices to acquire a location fix in challenging conditions, it enabled the rise of mobile location-based services, ride-sharing apps, and personal navigation. ### What does this patent NOT cover? Does not cover GPS signal processing that relies solely on a single, instantaneous signal capture. **Full plain-English explainer:** https://patentbrief.org/patent/us/6816710/reusable-launch-vehicle-falcon-9-booster-landing **Original patent:** https://patents.google.com/patent/US6816710 --- _Source: PatentBrief — https://patentbrief.org. Patent facts are from public records; the plain-English explanation is PatentBrief's._ ## Related patents Semantically similar inventions in the PatentBrief corpus: - [How to Check if GPS Signal Corrections are Working Right](https://patentbrief.org/patent/us/12736683/system-and-method-for-gnss-correction-monitoring) — This patent describes a system to generate, check, and combine corrections for satellite navigation signals, ensuring they are accurate for precise positioning applications. - [How Passive Satellite Navigation Works Without Sending Signals](https://patentbrief.org/patent/us/3789409/gps-satellite-navigation) — A 1970s system for finding your location on Earth by listening to satellite signals without ever having to transmit a signal yourself. - [How a Tiny Sensor Uses an Extra Weight to Detect Motion](https://patentbrief.org/patent/us/20110120221/mems-sensor-method-of-manufacturing-thereof-and-electronic-apparatus) — This patent describes a miniature sensor that detects movement or force by measuring changes in electrical signals between tiny plates, featuring a clever extra weight to make it more sensitive. - [Using Millimeter Waves to Map Your Surroundings for Better Location](https://patentbrief.org/patent/us/20230213647/system-method-and-computer-accessible-medium-for-real-time-imaging-using-a-porta) — This patent describes a way for a mobile device to use millimeter wave signals to understand its environment and pinpoint its location by analyzing how those signals bounce off surfaces. - [How Vehicles and Drones Find Their Way Using Many Sensors](https://patentbrief.org/patent/us/10107627/adaptive-navigation-for-airborne-ground-and-dismount-applications-anagda) — This patent describes a layered computer system that combines data from many different sensors and an Inertial Measurement Unit to precisely determine a mobile platform's position, velocity, and orientation, even in challenging environments.