GPS Signal Tap is a L1 frequency GPS Receiver front end which serves as a programmable real time source of digitized GPS signal for a variety of desktop research and development related to signal processing. The Signal Tap consists of a two stage RF down converter whose second IF can be sampled and stored for analysis by the user at a programmable frequency. The Signal Tap allows the user to acquire samples for predefined intervals of time or continuously in real time. The GPS Signal Tap has two main blocks: the RF Down converter and the Signal Buffer. The RF down converter gets the input GPS satellite signal from an antenna-cable assembly. It uses mixers, local oscillators and band pass filters to down convert the carrier to a low IF. The IF is then sampled by a chosen sampling frequency to generate digitized IF signal of the satellites. The Signal Buffer collects the digitized GPS signal samples and temporarily stores them in the on-board RAM before sending them to the host computer through the USB interface. A powerful 32 bit floating DSP with 198 MFLOPS forms the heart of the signal buffer which has the capacity to store 64 Mbits of sampled data before downloading into the PC. The user can configure the GPS Signal Tap from the PC based software and start/stop acquisition for either predefined time interval or continuously, at the pre configured sampling rate. The data acquired by the software is stored in the PC hard disk and can be used with the software developed by the user or with popular mathematical programs such as MATLAB.

APPLICATIONS :The GPS Signal Tap can be used for a variety of purposes by engineers, scientists and researchers involved in the processing and analysis of the GPS Signal. Not only can it be used to realize or experiment with individual functional building blocks of GPS receiver but also to build a complete software intensive Receiver integrated with the engineer's chosen software development environment.New algorithms under development can be tested with real time GPS signal acquired from the Signal Tap. Receiver designers working on new architectures for emerging applications such as the E911 can try out their ideas on their desktop PC equipped with the Signal Tap. With its 8 MHz second IF bandwidth and a provision for higher sampling frequencies, the Signal Tap is ideally suited for research and development in real time kinematics and multi path mitigation. GPS Signal Tap can also be used by those scientists who require sampled GPS signal on an uninterrupted basis for their study of the ionospheric errors in the GPS L1 signal.Engineers involved in development related to SBAS signals can also use the Signal Tap. The signal tap can be used with active or passive gps antenna, antenna reradiation system or with single or multichannel GPS simulators. The GPS signal Tap can be accessed in real time from user's own software development environment, by interfacing with the USB device driver.