Systematic Error Correction for Geo-Location of Airborne Optoelectronic Platforms

In order to improve the geo-location accuracy of the airborne optoelectronic platform and eliminate the influence of assembly systematic error on the accuracy, a systematic geo-location error correction method is proposed. First, based on the kinematic characteristics of the airborne optoelectronic platform, the geo-location model was established. Then, the error items that affect the geo-location accuracy were analyzed. The installation error between the platform and the POS was considered, and the installation error of platform’s pitch and azimuth was introduced. After ignoring higher-order infinitesimals, the least square form of systematic error is obtained. Therefore, the systematic error can be obtained through a series of measurements. Both Monte Carlo simulation analysis and in-flight experiment results show that this method can effectively obtain the systematic error. Through correction, the root-mean-square value of the geo-location error have reduced from 45.65 m to 12.62 m, and the mean error from 16.60 m to 1.24 m. This method can be widely used in systematic error correction of relevant photoelectric equipment.

Research on Photoelectric Equipment Fault Diagnosis System Based on RS and Networks

Rough Sets (RS) networks and expert system theory were applied to the photoelectric equipment fault diagnosis, and the intelligent diagnosis expert system was built. The accuracy and efficiency of photoelectric equipment fault diagnosis were significantly improved by using of the RS and networks. With combined RS theory with networks, photoelectric equipment fault implementation was optimized and simplified during the training of sample set.

Design of Test System for one Type of Airborne Photoelectric Equipment Based on PC104 Bus

A certain type of airborne photoelectric equipment is the key device for aiming and distance measuring. On the basis of analyzing the test requirement of the equipment, a test system is designed with PC104 embedded computer as the core control system. The function of the test system is suggested. Hardware programs of power, bus board, signal conditioning circuit and anti-jamming measure are designed. The multithreading technology and measures to prevent wrong data communicating are applied to develop software of the test system. The test system can be applied to test and debug the photoelectric equipment. The data handling technology used in the test equipment has advantages as high speed, high efficiency and high reliability.

How Colossus was Built and Operated—One of its Engineers Reveals its Secrets

Flowers’ team, which included me, became involved with the design of the logic units of Newman’s proposed machine after Morrell’s Telegraph Group, which had been assigned the job, got into difficulties. For modulo-2 addition (‘exclusive-or’, or XOR) Morrell was proposing to use a type of frequency-modulator employed for voice-frequency telegraph signals. This might have been all right for adding only two signals, but it was useless for adding many signals, because the device was analogue in nature (i.e. not digital or discrete, but using continuously variable voltages). The small variations added up, with the result that the device often produced a wrong answer. After some clever work by Gil Hayward, it just about worked for the number of additions that were required. The Heath Robinson’s ‘bedstead’, containing the tape drive and the photoelectric tape-reader, was designed and built at Dollis Hill. Our people Eric Speight and Arnold Lynch had very recently used photoelectric cells to do what was required. Fighter Command had asked Dollis Hill for a fast means of recording the telegraphic signals from their aircraft observers. Speight and Lynch, working together with Morrell’s group, had designed some photoelectric equipment that would record these signals directly from the telegraphic punched tape. The device they built, called the ‘Auto-Teller’, was never in fact used, but this photoelectric technology formed the basis for the bedstead. When we finished our part of Newman’s machine at Dollis Hill I moved to Bletchley Park, and Alan Bruce from TRE accompanied their part of the machine, the counter and display rack. The Heath Robinson was installed in the wooden Hut 11—the Newmanry. I was privileged to be one of those present at the Heath’s inauguration before the VIPs—and I can confirm that smoke did rise from it at switch-on. I was able to deal with this. A large resistor had overloaded, which I bypassed, and we carried on. (The machine never did catch fire, on this or any other occasion, but as mentioned in Chapter 13, we had a benzene fire in our workshop, at a much later date, and this may have contributed to the erroneous stories of Heath Robinson catching fire.)

Asteroid and Cometary Occultations

Occultations of stars by minor planets and comets can be used to determine the diameter of the occulting body. With photoelectric equipment, it might also be possible to measure the diameter of the occulted star or to resolve close binary systems at the same time.On 1983 May 29, (2) Pallas occulted the 4.7-mag. star 1 Vulpeculae. A star this bright is occulted by one of the four largest asteroids only once every 60 years. Timings were sent by 130 observers in Florida, Louisiana, Texas, Arizona, Sonora, and Baja California, making it the best-observed asteroidal occultation to date. Asteroidal grazing phenomena were confirmed for the first time. The star is a spectroscopic binary. Several observers timed contacts of the 6th-mag. companion, determining the separation to ± 0.0004 arcsec. An elliptical fit to the timings projected onto the plane of the sky has been made. Unfortunately, clouds prevented timings from near the southern limit, so about 100° of Pallas’ circumference was not observed.