Receiver Losses when using Quadrature Bandpass Sampling

Use of Quadrature Bandpass Sampling (QBPS) in GNSS receivers gives several advantages over quadrature-sampled superheterodyne architectures. The sampling process has the important secondary function of providing frequency down-conversion (exploiting aliasing) that avoids the use of frontend RF mixers and oscillators. However, the process is not perfect and does incur some losses. This paper examines the use of naïve reconstruction of the QBPS quadrature samples and a simple compensation scheme such as a constant delay of the in-phase channel, and the losses that these methods incur. The paper concludes that for satellite navigation systems, losses incurred due to the use of these simple methods are small enough not to degrade receiver performance.