GNSS Satellite Identification Using CDMA

GNSS (Global Navigation Satellite System) constellations need a reliable method for receivers to distinguish signals from multiple satellites operating simultaneously. The primary technique used is Code Division Multiple Access (CDMA).

Why CDMA for GNSS?

• In CDMA, each GNSS satellite transmits its signal using a unique pseudo-random noise (PRN) code.
• GNSS receivers are designed to recognize and synchronize with these specific PRN codes.
• By matching the incoming signal's code to a known satellite's PRN code, the receiver can isolate and identify that specific satellite, even when multiple signals occupy the same frequency band.
• This allows the receiver to differentiate between signals from different satellites, which is crucial for calculating position.

Alternative Methods and GNSS

• Time Division Multiple Access (TDMA): Assigns different time slots to users/satellites. Not the primary method for GNSS satellite identification.
• Amplitude Division Multiple Access (ADMA) and Phase Division Multiple Access (PDMA): These are less common or not the standard methods employed by GNSS constellations for distinguishing satellites. CDMA is the established standard due to its efficiency and robustness in this application.

Therefore, Code Division Multiple Access (CDMA) is the widely used method.