Off-the-shelf jammer tests GPS receiver compliance
-- Test & Measurement World, 9/17/2003
Noise Com (Parsippany, NJ; www.noisecom.com) has announced the GPS7500 noise and interference generator, an expandable, easy-to-use platform for testing the susceptibility to interference of GPS receivers used in airborne, automotive, defense, mobile-location, and E911 applications.
The instrument, based on Noise Com's digital-noise, arbitrary-waveform, and proprietary switching technology, enables an on/off ratio of 164.5 dB. This translates to an order of magnitude improvement compared with competitive instruments, the company says.
Using the GPS7500, low-phase-noise, high-power, out-of-band interference can be generated without obscuring signals in the GPS band, thereby isolating the GPS receiver from their effects. This allows engineers to meet the requirements for the RTCA (www.rtca.org) DO-229, DO-235, and DO253 standards using a single off-the-shelf platform. This is easier, faster, and more cost-effective than approaches that require equipment to be located in separate, shielded rooms.
The GPS7500 is equipped with one or, optionally, two independent arbitrary waveform generators capable of 40-MHz bandwidth for interference generation over the L1 and L2 or L5 bands. The instrument features an integrated PC that allows user-defined arbitrary interference and jamming waveforms. Any waveform can be generated, including sine waves and noise, which can be pulsed at any duty cycle between 0 and 100% at 6.67 ns resolution. The two-channel, modular design enhances expandability, allowing engineers to simultaneously test GPS receiver operation in L1 and L2 or L5 frequencies.
The GPS7500 provides an off-the-shelf platform integrating 1- to 2-GHz synthesizers, power amplifiers, a Gaussian noise source, and a power meter. The Gaussian noise source provides a fixed low-level reference, which is used to calibrate the output power of the arbitrary waveform. The internal power meter ensures accurate measurements, assists in calibration, and sets output-power levels to +21 dBm after the built-in GPS-signal and interference combiners.
The new generator supports three modes of operation: continuous wave (CW), arbitrary interference (including broadband Gaussin noise), and pulse. It features access tables of pre-stored GPS testing parameters as well as optimal color display functionality.
