Sirius Stratus 6 commercial radio receiver, used to test antenna.

Project Overview

What is SDARS?


                 SDARS stands for the Satellite Digital Audio Radio Service.  It is a satellite-based direct-broadcast radio service which transmits digital audio signals from space to receivers on Earth. SDARS should not be confused with traditional FM or AM radio, because the frequency of their transmissions is different. While AM transmits from 535 – 1705 kHz and FM from 88 – 108 MHz, the SDARS transmits from 2320 – 2345 MHz.  From figure 1, proper reception is accomplished through an antenna with a clear view of the sky (direct reception from a satellite), or through terrestrial repeaters in case the view is blocked, such as when passing through a tunnel or by tall buildings. Most modern vehicles and receivers come equipped to receive and play satellite entertainment audio, requiring a subscription to either broadcast company: Sirius Radio or XM Radio. Combined, both Sirius and XM radio provide 200 different channels, with each channel 125 KHz wide.




Though putting satellites in space is more costly than building a few radio towers, the SDARS boasts several advantages over the long incumbent FM and AM radio.  The Higher transmission frequency allows the signal to be less attenuated by Earth’s atmosphere than FM or AM radio waves.  This, along with the fact that transmissions originate from space, allow for reception over an area thousands of miles wide.  Figure one approximates this area. Since users pay for a subscription to the service, there are few or no commercials.


Project Focus

                 This project focuses on the front-end receiver design for the Satellite Digital Audio Radio Service (SDARS).  The SDARS is used primarily for entertainment broadcasting from orbital satellites and received by modules commonly found on modern automobiles.  In particular, this project will focus primarily on the antenna design and its paired low noise amplifier (LNA), which largely affects the signal-to-noise ratio (SNR) and hence the sensitivity of the receiver.  The SNR determines the quality of the signal received to produce quality audio.  The active antenna (passive antenna + LNA) will be designed to minimize physical size while producing the best quality of signal.  In short, the main goal of this project is to design an active antenna that will receive SDARS wireless transmissions.