Munich, August 06, 2009 — New options from Rohde & Schwarz enable manufacturers and operators of aeronautical radio navigation systems to test distance measurement equipment (DME) with far greater flexibility and precision. The high-end R&S SMA100A analog signal generator makes it possible for the first time to generate and analyze DME signals in both the lab and in mobile applications. It also allows users to check the receive and transmit unit of a DME ground station as well as the DME unit aboard an aircraft. The compact R&S EVS300 ILS/VOR analyzer has been enhanced to include the ability to analyze DME signals, which makes it ideal for mobile maintenance of DME ground stations. Options for measurements on ILS and VOR services are already available for both instruments. As a result, users always have the right solution at their fingertips for checking the key functions of their systems in accordance with the specifications of the International Civil Aviation Organization (ICAO).
An aircraft uses DME to measure its slant distance to a ground station. To make this measurement, the aircraft's onboard radio unit (interrogator) transmits shaped RF double pulses to the ground station, which returns them after a defined delay (reply delay). Up to now, most of the parameters could be checked only with integrated test equipment. However, any fault in the equipment could lead to incorrect measurement results or even malfunctioning of the system. The use of external measuring equipment therefore increases air traffic safety.
The flexible R&S EVS300 level and modulation analyzer is already being used by air traffic control (ATC) authorities for mobile maintenance of ILS/VOR ground stations. The new R&S EVS-K5 option allows users to also perform power measurements on DME as well as ILS/VOR ground stations. The only user action required is to connect the power sensors of the R&S NRP or R&S NRT family to the analyzer. Using the new R&S EVS-K6 option, the R&S EVS300 can also check the envelope and timing of the double pulse transmitted to DME ground stations. The combination of the R&S NRP-Z81 broadband power sensor and the new option enables users to view the rise time, fall time and pulse spacing of the DME signal directly on the analyzer's display. Thanks to this compact solution, service technicians no longer have to carry a notebook or measuring instruments around with them.
For ATC authorities and for manufacturers of DME systems, Rohde & Schwarz provides a solution that can perform even more detailed measurements: When equipped with the R&S SMA-K26 option, the R&S SMA100A generates DME aircraft interrogator signals. It can also simulate a DME ground station including the squitter and identification pulses. Using a connected R&S NRP-Z81 broadband power sensor, the parameters specified by the ICAO can be analyzed directly on site at a ground station. This measurement solution is unique on the market because an additional signal analyzer is no longer required. The DME test parameters include, for example, reply delay, reply efficiency (ratio of reply pulses to interrogation pulses), pulse repetition rate of the ground station, pulse power of the transmit pulse as well as pulse shape. For test purposes, the parameters can be set so that they deviate from the ICAO specification.
The DME options (R&S EVS-K6 for the R&S EVS300 and R&S SMA-K26 for the R&S SMA100A) are now available from Rohde & Schwarz.
The Rohde & Schwarz application note "Test of DME/TACAN Transponders" describes the operating principle of DME and its military version (TACAN), as well as various test scenarios for ground station maintenance. It can be downloaded from the Rohde & Schwarz website athttp://www.rohde-schwarz.com/ad/dme/pr.
