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J.P. McGeehan

Bio: J.P. McGeehan is an academic researcher. The author has contributed to research in topics: Phase-locked loop & Transponder. The author has an hindex of 2, co-authored 3 publications receiving 8 citations.

Papers
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Journal ArticleDOI
01 Aug 1989
TL;DR: In this article, the design and characterisation of an optimum tracking receiver, and the new problems which the system poses in this, is described with an identification of the factors in existing receivers which limit the performance of the electronic tracking technique.
Abstract: Many types of satellite tracking system have been suggested in recent years, and most have found applications in either the civil or military telecommunications sectors. However, all systems so far proposed have advantages and disadvantages, and hence considerable effort is still being directed towards the design of systems which are more economical but still offer high performance. One such system, utilising an electronic beam-control technique, is detailed here with particular reference to the design and characterisation of an optimum tracking receiver, and the new problems which the system poses in this. The system is described with an identification of the factors in existing receivers which limit the performance of the electronic tracking technique. By means of a computer simulation, a fundamental understanding of the physical processes involved is presented and some experimental results are included to validate the conclusions and proposed solutions.

6 citations

Journal ArticleDOI
01 Feb 1990
TL;DR: In this paper, the behavior of a first-order phase-locked loop is critically examined under conditions where it is tracking a carrier corrupted by discontinuous (square-wave) amplitude modulation.
Abstract: The behaviour of a first-order phase-locked loop is critically examined under conditions where it is tracking a carrier corrupted by discontinuous (square-wave) amplitude modulation. The transient response of the system is first derived for the simple case of a PLL without time delay, and a comparison is made with a series of practical results obtained from a first-order loop. The agreement between the predicted response and that observed in practice is found to be extremely good. The theoretical behaviour of the loop is further analysed for the case of a system incorporating time delay. It is shown that such delay is detrimental to the tracking performance of the loop, when it is necessary to track a carrier modulated in the manner outlined above.

2 citations

01 Jan 1990
TL;DR: In this article, a phase-locked receiver/down-converter system was proposed to enable an accurate, stable and wide coverage terminal to be realized at a reduced cost.
Abstract: The design and resultant performance of the terminal equipment in a mobile satellite system is vitally important in respect to the overall cost/performance compromise of the whole system. Improvements in system performance which also result in a reduction of the equipment cost are rare. However, this paper details a significant advance in terminal design, utilizing a novel form of 'split-loop' phase locked receiver/downconverter system to enable an accurate, stable and wide coverage terminal to be realized at a reduced cost. The system has the capability of automatically locking onto any carrier within a complete transponder, and can cope with severe amplitude modulation and fading effects.

Cited by
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Journal ArticleDOI
TL;DR: In this article, a new method for finding and measuring amplitude-phase cross-frequency coupling in time series with a low signal/noise ratio was proposed to study the variability of the severity index in the Baltic Sea since the 15th century and its possible connection with solar activity.

18 citations

Journal ArticleDOI
TL;DR: A novel pseudo-monopulse tracking method for Ku-band Satcom-on-the-move (SOTM) using an antenna architecture consisting of multiple distributed panels capable of moving back and forth mechanically is presented, which can effectively reduce the overall height.
Abstract: A novel pseudo-monopulse tracking (PMT) method is presented for Ku-band Satcom-on-the-move (SOTM). An antenna architecture consisting of multiple distributed panels capable of moving back and forth mechanically is introduced firstly, which can effectively reduce the overall height. Two independent beams with hybrid beam steering approach are introduced to keep the excellent performance in terms of tracking accuracy and antenna gain over wide scan coverage. Then, a hybrid compensation method using switched delay lines and phase shifters is applied to solve the frequency scan effect. Finally, the tracking beam is sequentially scanned at a prescribed offset angle in different directions, and the pointing error is calculated by comparing the corresponding received beacon signal strengths. Simulation results confirm the veracity of the proposed tracking method.

10 citations

Journal ArticleDOI
TL;DR: Electronic beam-squinting is capable of a performance approaching that of the most expensive systems currently available for fixed earth stations and is also applicable to mobile terminals.
Abstract: Since the first television pictures were received from Telstar by aerial 1 at Goonhilly Down in Cornwall, commercial operation of satellite systems has dictated that the earth-space link must be maintained as consistently as possible. Any break in transmission or lowering of quality results in huge losses for the operator and as a result the performance of the antenna tracking system has received a great deal of attention. Recently a new technique, termed ‘electronic beam-squinting’, has been developed to solve this problem both elegantly and economically. It is capable of a performance approaching that of the most expensive systems currently available for fixed earth stations and is also applicable to mobile terminals.

8 citations

Journal ArticleDOI
TL;DR: An improved step tracking algorithm that will be used in mobile direct broadcasting satellite (DBS) reception using a highly efficient simultaneous perturbation approximation to the gradient using only two noisy measurements of the received signal strength.

8 citations

Journal ArticleDOI
TL;DR: It is shown that the digital counterpart of the split-loop offers an additional advantage, since the first oscillator can already convert the incoming signal down into the baseband, and the noise bandwidth of the loop is reduced significantly without changing the acquisition and tracking ranges.
Abstract: The advantages of the split-loop technique for analog phase-locked loops with a time delay are well known. In this paper, it will be shown that the digital counterpart of the split-loop offers an additional advantage, since the first oscillator can already convert the incoming signal down into the baseband. If this signal is used for the demodulation, the noise bandwidth of the loop is reduced significantly without changing the acquisition and tracking ranges. The resulting noise bandwidth is calculated and compared to a conventional digital high-gain second-order loop. Furthermore, the effect on the BER performance for DQPSK modulation is simulated.

4 citations