Inter-Range Instrumentation Group Research Articles

Bandwidth Efficient Frame Structure Algorithm and Analysis: An Extension to Telemetry Standard

An onboard telemetry system has access to a limited wireless bandwidth due to a high-speed airborne vehicle and large channel changing characteristics. The inefficiency of data placement happens at the transmission end if there is a large deviation between the packet rate and the frame rate for serial channels. For one of the current examples, the data rate of the transmitted signal can be decreased from 22 Mbps by straightforward placement in the major frame and to 3 Mbps using the novel algorithm introduced in this paper. The mathematical model in the subject is termed the bandwidth-efficient frame structure algorithm. A Xilinx Spartan 3E series has been used to frame the acquired data at the transmitting end and to deframe at the receiving end. The Inter-Range Instrumentation Group 106 standard has been used for the frame structure.

High-precision two-way optic-fiber time transfer using an improved time code.

We present a novel high-precision two-way optic-fiber time transfer scheme. The Inter-Range Instrumentation Group (IRIG-B) time code is modified by increasing bit rate and defining new fields. The modified time code can be transmitted directly using commercial optical transceivers and is able to efficiently suppress the effect of the Rayleigh backscattering in the optical fiber. A dedicated codec (encoder and decoder) with low delay fluctuation is developed. The synchronization issue is addressed by adopting a mask technique and combinational logic circuit. Its delay fluctuation is less than 27 ps in terms of the standard deviation. The two-way optic-fiber time transfer using the improved codec scheme is verified experimentally over 2 m to100 km fiber links. The results show that the stability over 100 km fiber link is always less than 35 ps with the minimum value of about 2 ps at the averaging time around 1000 s. The uncertainty of time difference induced by the chromatic dispersion over 100 km is less than 22 ps.

Fly-over aircraft noise measurement campaign at Montreal-Trudeau airport using a microphone array

Engines being quieter due to high by-pass ratios, the airframe noise, produced for instance by landing gears or high-lift devices, has become a significant contributor to the total noise radiated by aircraft during approach and landing. As part of the investigations carried out to understand noise generation mechanisms, the beamforming techniques developed over the last decade and applied to microphone array measurements have shown to be effective tools for localization and quantification of these aerodynamic noise sources. In order to validate their in-house beamforming softwares, Bombardier Aerospace and the Groupe d’Acoustique de l’Université de Sherbrooke have conducted a 5-day measurement campaign in June 2012. The 95-microphone array was located on the roof of a building next to the Montreal-Trudeau airport. Aircraft position was determined by two high-definition cameras, both synchronized with the microphone array by inter-range instrumentation group time codes generators. This paper summarizes the measurement campaign. The aircraft tracking tool and the beamforming algorithms used to characterize the noise sources are presented. Several Bombardier CRJ fly-overs were recorded during this test. Beamforming results obtained for different airlines are compared in order to evaluate the repeatability of the method.

Control and data acquisition ATCA/AXIe board designed for high system availability and reliability of nuclear fusion experiments

This paper describes the implementation and test of a control and data acquisition board designed to be integrated on systems demanding high availability and reliability, foreseen for future experiments like ITER or other long operation fusion devices. The Advanced Telecommunications Computing Architecture (ATCA) standard (PICMG 3.0 and 3.4) was selected for board implementation, which has support for the desired system robustness and performance. Some board features such as rear Input/Output (IO) signals connectivity (passive, copper tracks only), cable-less hot-swap maintenance, Intelligent Platform Management Controller (IPMC) and redundancy on timing signals, communications links and power supplies are significant board improvements, relatively to previous control and data acquisition boards, allowing the development of more reliable system architectures. Moreover, the developed board is also compatible with the emerging ATCA eXtensions for Instrumentation (AXIe) specifications, which provides additional timing and synchronization signals on the backplane. ATCA full-mesh, multi-gigabit, full-duplex, point-to-point communication links between Field Programmable Gate Arrays (FPGA), of peer boards inside the shelf, allow the implementation of distributed algorithms and development of Multi-Input Multi-Output (MIMO) systems. Up to 48 analog input channels, simultaneously digitized (2 MSPS @ 18-bits), are filtered/decimated by the board FPGA and sent to the ATCA/AXIe host through Peripheral Component Interconnect express (PCIe) using Direct Memory Access (DMA). In real-time, the host can update up to 48 analog output channels (1 MSPS @ 18-bits), per board, through PCIe. Further board characteristics comprise analog IO channels with galvanic isolation and an optional signal chopper mode, for offset compensation over time on digital integration of magnetic signals. Board time synchronization is attained by means of the Inter-Range Instrumentation Group (IRIG) time-code.

Near Optimal Common Detection Techniques for Shaped Offset QPSK and Feher's QPSK

A detector architecture capable of detecting both shaped offset quadrature phase shift keying (SOQPSK-TG) and Feher's quadrature phase shift keying (FQPSK-JR) is developed and analyzed. Both modulations are embodied as fully interoperable modulations in the Interrange Instrumentation Group (IRIG) standard IRIG-106. It is shown that the common detector achieves near optimal bit error rate performance without knowledge of which modulation is used by the transmitter. The detection techniques are based on a common trellis-coded modulation representation and a common continuous phase modulation (CPM) representation for these two modulations. In addition the common pulse amplitude modulation (PAM) decomposition of the common CPM representation is developed. The common PAM-based detector offers the best performance- complexity trade-off among the detectors considered.

Computer Optimization of FM/FM Telemetry Systems

In this correspondence, the threshold carrier power of FM/FM systems and the receiver IF bandwidth are optimized through a computer program. For a typical set of IRIG (inter-range instrumentation group) channels, it is demonstrated that the required carrier signal-to-noise ratio can be as low as 5 dB (much less than the conventional 12 dB value) in order to maintain the subcarrier signal-to-noise ratio at 12 dB, the threshold level. comparison of the optimized and the conventional taper analysis is tabulated.

Multiplex Telemetry Modulation and Demodulation Methods

There are a wide variety of modulation methods among the recently used telemetry systems. Characteristics and capabilities of some of these methods are briefly described. There is no generally accepted "best" method. Requirements for conservation of radio spectrum have a strong influence on the choice of modulation parameters. New Inter-Range Instrumentation Group (IRIG) modulation standards have been adopted. Some parameter variations within the new FM-FM standards are presented. The spectrum and data capacity of IRIG PCM-FM are discussed. Various forms of phase-shift keying (PSK) are described. Needs for increased data bandwidth have led to the development of single-sideband subcarriers, used as SSB-FM. Coded transmission with coherent demodulation can provide better carrier signal energy efficiency, but has been rarely used. Noncoherent orthogonal codes appear worthy of further exploitation, being almost as efficient as coherent orthogonal but simpler to produce and detect. Literature references are included for further study.

Experimental 600-ft Electrosonic Delay Line

For many types of data-transfer systems, it is desirable that the data be delayed long enough so that the system is ready for the data. In the present Space Surveillance system, it is desirable to delay data until the recorder is up to speed. The requirement for delaying the composite Inter-Range Instrumentation Group (IRIG) FM telemetering signals from a space surveillance site by 12 sec was fulfilled by converting the phone line frequencies into sound, which is then transmitted through a pipe long enough to provide the desired delay and then reconverted into electrical signals. The delayed output is essentially distortionless.

An experimental 600-foot electrosonic delay line for the navy space surveillance system

For many types of data transfer systems it is desirable that the data be delayed long enough so that the system is ready for the data. In the present Space Surveillance system it is desirable to delay data until the recorder is up to speed. The requirement for delaying the composite Inter-Range Instrumentation Group (IRIG) FM telemetering signals from a Space Surveillance site by one-half second was fulfilled by converting the phone-line frequencies into sound, which is then transmitted through a pipe long enough to provide the desired delay and then reconverted into electrical signals. The delayed output is essentially distortionless.

Inter-Range Instrumentation Group—Meteorological Working Group's 14th Semi-Annual Conference

Inter-Range Instrumentation Group—Meteorological Working Group's 14th Semi-Annual Conference

I R I G, Inter-Range Instrumentation Group----History, Functions and Status, 1959

The Inter-Range Instrumentation Group (IRIG) was established in 1952 by the commanders of the United States guided missile test ranges, principally for the purpose of facilitating the interchange of information on range instrumentation. Today, the IRIG consists of a Steering Committee and ten Technical Working Groups. Among other activities, the IRIG prepares and disseminates recommended standards and other documents (such as glossaries of terms and catalogs of range instruments) to advance the range instrumentation art.

Telemetry Working Group (TWG) of the Inter-Range Instrumentation Group (IRIG)

One of the ten Technical Working Groups of the IRIG (Inter-Range Instrumentation Group, established by the commanders of the United States guided missile test range), is the Telemetry Working Group (TWG). Among other activities, the TWG has prepared several System Standards that have been published as IRIG Recommendations.