GNSSSignals.jl

A Julia package for generating GNSS (Global Navigation Satellite System) spreading codes and signals.

Features

Supported GNSS Systems

Modulation Types

• LOC - Legacy/BPSK modulation (GPS L1, GPS L5)
• BOCsin - Sine-phased Binary Offset Carrier
• BOCcos - Cosine-phased Binary Offset Carrier
• CBOC - Composite Binary Offset Carrier (Galileo E1B)

Installation

using Pkg
Pkg.add("GNSSSignals")

Or from the Julia REPL:

julia> ]
pkg> add GNSSSignals

Quick Start

For most applications, use gen_code or gen_code! to generate sampled codes. These functions are highly optimized and significantly faster than calling get_code in a loop.

using GNSSSignals
using Unitful: MHz

gpsl1 = GPSL1()
prn = 1

# Generate 1 ms of sampled code at 4 MHz (recommended approach)
sampled_code = gen_code(4000, gpsl1, prn, 4MHz)

# For repeated calls, use the in-place version with a pre-allocated buffer
buffer = zeros(Int16, 4000)
gen_code!(buffer, gpsl1, prn, 4MHz)

For accessing individual code values at specific phases, use get_code:

# Get a single code value
code_value = get_code(gpsl1, 0.0, prn)  # Returns 1 or -1

# Get a full code period (slower than gen_code for large arrays)
code_phases = 0:1022
full_code = get_code.(gpsl1, code_phases, prn)

For more detailed examples, see the Usage guide.

Package Overview

GNSSSignals.jl provides functionality to:

• Generate spreading codes for GPS L1, GPS L5, and Galileo E1B
• Sample codes at arbitrary frequencies with gen_code and gen_code!
• Access code values at specific phases with get_code
• Query system parameters (code length, frequencies, modulation type)
• Compute signal spectra for analysis

The gen_code and gen_code! functions are highly optimized for real-time GNSS signal processing, using fixed-point arithmetic and minimizing memory access by exploiting the fact that consecutive samples often map to the same code chip.

The package is designed to be used as a building block for GNSS receiver implementations and signal processing research.