US 6,675,003 B1 · L1/L2 GPS receiver

Abstract

In a system and method for simultaneously receiving or switching between dual frequency carrier signals in a GPS receiver is adapted to utilize different harmonics of a sub-harmonic frequency generator, which may include a lower frequency voltage controlled oscillator (VCO) to detect the L1 and L2 GPS carriers. A sub-harmonic mixer may be used to simultaneously down convert the L1 and L2 signals to a lower intermediate frequency (IF). A second mixer may be an image reject (IR) mixer used to separate the downconverted second L2 signals. This mixer may be configured to simultaneously monitor the L1 and L2 signals, or to switch between the L1 and L2 signals. High frequency switching is not required of the radio frequency (RF) input or local oscillator signals, and simultaneous L1 and L2 reception is enabled without a 3 dB image noise degradation. This method minimizes the RF components and power dissipation in a dual frequency GPS receiver, while optimizing the functionality and performance.

Claims30

Dependent claims

A system for simultaneously receiving or switching between dual frequency carrier signals, comprising:

a sub-harmonic frequency generator, for generating a sub-harmonic frequency so as to enable harmonics of the sub-harmonic frequency to generate local oscillator frequency signals for the dual frequency carrier signals, and for mixing the dual frequency carrier signals with the local oscillator frequency signals, to generate distinct intermediate frequency signals for each dual frequency carrier signal, wherein the local oscillator frequency signals are adapted to include I and Q phases;
and
an image reject mixer, for separating the dual frequency carrier signals, and for switching between the dual frequency carrier signals, responsive to exchanging the I and Q phases of the local oscillator frequency signals.

A method of simultaneously receiving or switching between dual frequency carrier signals, in a system which comprises a sub-harmonic frequency generator, for generating a sub-harmonic frequency so as to enable harmonics of the sub-harmonic frequency to generate local oscillator frequency signals for the dual frequency carrier signals, and for mixing the dual frequency carrier signals with the local oscillator frequency signals, to generate distinct intermediate frequency signals for each dual frequency carrier signal, wherein the local oscillator frequency signals are adapted to include I and Q phases, and an image reject mixer, for separating the dual frequency carrier signals, and for switching between the dual frequency carrier signals responsive to exchanging the I and Q phases of the local oscillator frequency signals, wherein the method comprises:

generating a sub-harmonic frequency so as to enable harmonics of the sub-harmonic frequency to generate local oscillator frequency signals for the dual frequency carrier signals, and mixing the dual frequency carrier signals with the local oscillator frequency signals, to generate distinct intermediate frequency signals for each dual frequency carrier signal;
and
separating the dual frequency carrier signals, and switching between the dual frequency carrier signals, responsive to exchanging I and Q phases of the local oscillator frequency signals.

Dependencies are inferred from the claim text.

L1/L2 GPS receiver

Life of this patent

L1/L2 GPS receiver

Life of this patent

Abstract

Claims30