Raw GPS data viewer

Android application for real-time acquisition and visualization of GNSS receiver data. Provides access to raw GNSS measurements, satellite status, and fused location output. Available for Android phones (API 28+) and Wear OS devices (API 26+).

Supported GNSS constellations: GPS, GLONASS, Galileo, BeiDou, QZSS, SBAS, NavIC.

Three operating modes:

1. Sky Plot & Signal Bars
Polar plot showing satellite positions by azimuth (0-360°) and elevation (0-90°). Each satellite rendered with constellation-specific color coding. CN0 signal quality indicated by ring color thresholds: green (≥40 dB-Hz), yellow (≥30 dB-Hz), orange (≥20 dB-Hz), red (<20 dB-Hz). Satellites used in current fix distinguished by border marker. Adjacent bar chart displays per-satellite CN0 levels with reference lines at 20, 30, 40 dB-Hz, sorted by constellation and SVID.

2. Fused Location
Displays output from Google Play Services FusedLocationProviderClient configured with PRIORITY_HIGH_ACCURACY at 1-second intervals (minimum 500 ms). Reported parameters: latitude, longitude, altitude, horizontal accuracy, speed, bearing, speed accuracy, bearing accuracy, vertical accuracy. MSL altitude and MSL accuracy displayed on API 33+. Mock location flag indicated when applicable. Includes update frequency statistics: average, minimum, and maximum intervals between location callbacks.

3. Raw GNSS Measurements
Displays GnssMeasurementsEvent data from the device GNSS chipset. Per-satellite measurement fields:
— Pseudorange: computed from receivedSvTimeNanos and timeOffsetNanos
— Accumulated Delta Range (carrier phase) in meters with ADR state flags (VALID, RESET, CYCLE_SLIP)
— CN0 in dB-Hz
— Carrier frequency in MHz (when reported by hardware)
— Baseband CN0 in dB-Hz (API 30+)
— Measurement state bitmask: CODE_LOCK, BIT_SYNC, SUBFRAME_SYNC, TOW_DECODED, MSEC_AMBIGUOUS, SYMBOL_SYNC, GLO_STRING_SYNC, GLO_TOD_DECODED, BDS_D2_BIT_SYNC, BDS_D2_SUBFRAME_SYNC, GAL_E1BC_CODE_LOCK, GAL_E1C_2ND_CODE_LOCK, GAL_E1B_PAGE_SYNC
— Full Inter-Signal Bias and Satellite Inter-Signal Bias in nanoseconds (API 31+)
— Multipath indicator status
— Automatic Gain Control level in dB (API 27+)
— SNR in dB (when available)

GNSS Navigation Messages reported with message type, SVID, status, and payload size.

Data is displayed in real time and is not persisted to storage. No network access required beyond location services. No background services. No data collection or telemetry.