International Report

BAE Systems C41SR Delivers First Skynet 5 Terminals

UK contractor BAE Systems Command, Control, Communications, Computing, Intelligence, Surveillance and Reconnaissance (C4ISR) has delivered the first batch of six Talon satellite communications terminals to Paradigm Secure Communications for eventual use in the UK's Skynet 5 military communications satellite system. In all, 15 such terminals will be acquired, with second and third tranches being scheduled for delivery during December 2002 and August 2003, respectively. Skynet 5 (scheduled for introduction by 2010) is being procured via the UK's Private Finance Initiative and will see (as a beginning) the transfer of the existing Skynet 4 from UK Ministry of Defence control to that of Paradigm. This transfer is scheduled to take place during mid-2003.

BAE Systems C4ISR describes Talon as being a lightweight, deployable terminal that is man-portable, makes use of carbon fibre in its construction and can be configured to operate in the C- (4 to 8 GHz), X- (8 to 12.5 GHz), Ku- (12.5 to 18 GHz) and Ka- (26.5 to 40 GHz) bands. Here, the necessary changes are described as being simple and involving the introduction of frequency specific feed arms and some key electronic components. Talon is further noted as being fitted with either a 1.2, 1.9 or 2.4 m antenna dish, with an X-band 1.9 m configuration noted as being able to deliver a G/T value of better than 21 dB/k. The standard terminal includes all the functionality needed to support the required communications link (including antenna control and tracking, frequency conversion and the requisite modem functions) and is packed in four modular cases that can include heaters and cooling elements as required. Again using the 1.9 m dish configuration as an example, the equipment can be set-up in wind speeds of up to 15 m/s, can be operated in winds of up to 16 m/s and will survive gusts of up to 27 m/s.

ESA Launches Most Sensitive Gamma Ray Observatory Ever Built

Billed as the most sensitive gamma ray observatory ever built, the European Space Agency's (ESA) INTErnational Gamma-Ray Astrophysics Laboratory (INTEGRAL) was launched into an eccentric, 72-hour, 9000 to 155,000 km orbit around the Earth on 17 October 2002. Designed to provide new insights into celestial objects such as black holes, neutron stars, active galactic nuclei and supernovae, the 2 tonne INTEGRAL vehicle is equipped with a payload that includes a spectrometer (known as the SPectrometer on INTEGRAL - SPI), an imager (the Imager on Board the INTEGRAL Satellite - IBIS), an X-Ray monitor (the Joint European X-ray Monitor - JEM-X), an Optical Monitoring Camera (OMC) and an Integral Radiation Environment Monitor (IREM).

Of these, the SPI is designed to perform spectral analysis of gamma-ray point sources and extended regions in the 20 keV to 8 MeV energy range, with a resolution of 2.2 keV at 1.33 MeV. As such, the SPI device incorporates an array of 19 hexagonal, high purity, germanium detectors that are cooled to an operating temperature of 85 K by a Stirling engine. A hexagonal coded aperture mask is located 1.7 m above the detection plane in order to image a 16° section of the sky with 2° angular resolution. In order to reduce background radiation, the detector assembly is shielded by an anti-coincidence system that includes limiting the aperture to approximately 30° and the provision of a plastic veto below the mask to further reduce the 511 keV background. For its part, the IBIS provides fine imaging, source identification and spectral sensitivity to both continuum and broad lines over the 15 keV to 10 MeV energy range. Within the device, a tungsten coded-aperture mask is located 3.2 m above its detection plane and is optimised for high angular resolution. The IBIS detector uses two planes, namely a 2600 cm2 front layer (made up of 4 x 4 x 2 mm pixels) and a 3100 cm2 back layer (9 x 9 x 30 mm pixels) that are 90 mm apart. The use of a two-layer detector allows photon paths to be tracked in 3-D as they scatter and interact with more than one element of the array. Events can be categorised and the device's signal-to-noise ratio is improved by rejecting those responses (usually towards the high end of the energy range) that are unlikely to correspond to real celestial photons. The IBIS aperture is restricted by a lead shielding tube and is shielded in all other directions by an active scintillation veto system.

The JEM-X X-ray monitor supplements the SPI and IBIS instruments and is used to detect and identify gamma-ray sources and in the analysis and interpretation of acquired gamma-ray data. Accordingly, JEM-X takes readings simultaneously with those of the SPI and IBIS devices and provides imagery with arcminute angular resolutions within the 3 to 35 keV prime energy band. Its baseline photon detection system consists of two identical high pressure imaging microstrip gas chambers (1.5 bar pressure and made up of 90 percent xenon and 10 percent methane), at a nominal gas gain of 1500. Each detector views the sky through a coded-aperture mask that is located approximately 3.2 m above the detection plane.

JEM-X itself is supported by the OMC which is used to observe optical emissions from INTEGRAL's prime targets at the same time as those targets are being observed by the SPI, IBIS and JEM-X. The remaining instrument - the IREM - is described as performing a wide range of in-orbit radiation monitoring functions and downloading the acquired data via the INTEGRAL vehicle's telemetry system. Overall, the satellite's orbit is designed in such a way as to keep it at an altitude of 40,000 km or above for as long as possible in order to minimise background radiation effects from the Earth's own radiation belts. INTEGRAL's unit cost is put at 330 million in year 2000 values.

Philips Launches TPMS Chip Solution

In order to meet upcoming US 2004 legislation and a wider perceived global market, Netherlands contractor Royal Philips Electronics has launched a chip-based Tire Pressure Monitoring System (TPMS) that provides the automobile driver with measurements of individual tire pressures and notification of pressure/inflation problems as they arise. TPMS applications have major safety and cost implications in terms of tire-related accidents, levels of tire wear and fuel consumption values. Goodyear calculates that at any given time, one in five vehicular tires is under-inflated by as much as 40 percent. Such irregularities lead to significant alterations in road-holding and braking characteristics, a significant shortening of tire life and an increase in fuel consumption of roughly one percent for every three pounds/in2 of under-inflation.

The Philips TPMS uses a direct monitoring approach and takes the form of a Tire Module (TM) that broadcasts RF data to a central receiver. Each TM typically comprises an analogue piezo-resistive pressure sensor, a pressure sensor signal conditioning chip and an RF transmitter unit. As applied to the tire, the TM has to withstand a temperature range of from as low as -40° to as high as +150°C and acceleration rates of up to 2000 G. Functionally, the signal from the pressure sensor is amplified and digitised and the full device calibrated and initialised. A P2SC signal processing chip picks up the signal from a sensor bridge, digitises it, measures chip temperature and performs all the required calibration and initialisation. The P2SC chip includes a field proven Reduced Instruction Set Computer (RISC) microcontroller core, minimum power consumption and a wheel identification feature to solve issues of auto-rotation.

After calibration and initialisation, each tire sends its pressure data to the automobile's dashboard and a controller recognises which tire the signal is coming from. A low frequency wake-up approach has been used for tire location and is described as providing immediate and reliable identification. Small, 125 kHz wheel arch antennas are used to send the wake-up signal to the specific TM, which responds via the RF link. Each tire is woken up each time the ignition is switched on. Thereafter, tire pressure is checked at regular intervals and in the event of a sudden pressure drop, a warning is relayed to the driver without the need to wake the system up. Looking to the future, Philips notes that Bluetooth™ technology could have a TPMS application, as could inductive coupling on passive GHz technologies to overcome the need for internal batteries.