Showing papers on "Pulse-position modulation published in 1986"
TL;DR: It is shown that the increase in signal power needed to compensate for the imperfect synchronization is small and the bit error rate performance of the PLL synchronized PPM system is analyzed and compared to that of the perfectly synchronized system.
Abstract: Receiver timing synchronization of an optical PPM communication system can be achieved using a phase-locked loop (PLL) if the photodetector output is properly processed. The synchronization performance is shown to improve with increasing signal power and decreasing loop bandwidth. The bit error rate performance of the PLL synchronized PPM system is analyzed and compared to that of the perfectly synchronized system. It is shown that the increase in signal power needed to compensate for the imperfect synchronization is small (less than 0.1 dB) for loop bandwidths less than 0.1 percent of the slot frequency.
50 citations
TL;DR: This paper examines the slot clocking design associated with a direct detection, photodetecting optical PPM system and considers several types of practical slot synchronizers, including digital synchronizers in which time samples are used for loop control.
Abstract: Maintaining slot clock synchronization in a baseband pulse position modulated (PPM) communication link is vital to its performance. This paper examines the slot clocking design associated with a direct detection, photodetecting optical PPM system. Although theoretical PPM synchronizers for optical links have been derived in the past, there is still interest in finding more practical, simpler, and easier-to-implement clocking subsystems. In this paper several types of practical slot synchronizers are considered. A basic design involving analog correlators and slot gating is presented, along with an indication of its performance. Several alternative designs are also presented, including digital synchronizers in which time samples are used for loop control. The advantage in digital systems is that more extensive processing can be handled in software, allowing the loop to perform closer to the ideal. Design procedures for digital clocking are presented, and optimal laser pulse shaping and filtering are discussed. Performance in terms of loop models and tracking error variance is included.
45 citations
DOI•
01 Oct 1986TL;DR: In this article, a bound on the probability of optical fiber PPM receivers based on APDs was derived and it was shown that optical fibre PPM receiver with APDs offer some improvement over optical fibre receiver based on PINFETs and a big improvement when compared with PCM receivers.
Abstract: The question of performance evaluation in digital pulse position modulation (PPM) transmitted over slightly dispersive optical fibres and detected by avalanche photodiodes (APD) is considered. In view of numerical complexity implicit in exact average error probability evaluation, a bound on this probability is derived. Making use of this bound we conclude that optical fibre PPM receivers based on APDs offer some improvement over optical fibre PPM receivers based on PINFETs and a big improvement when compared with PCM receivers.
30 citations
TL;DR: Analytical bounds and simulation results on synchronization probability show that the high SNR ML rule has a performance approaching that of the optimum ML rule over a wide range of signal-to-noise ratios.
Abstract: The problem of locating a periodically inserted frame synchronization pattern in random data is considered for a directdetection optical communication channel. Both pulse-position modulation and on-off keying with known symbol synchronization are considered. The high signal-to-noise ratio approximation of the maximum likelihood decision rule is derived for each of these cases. Analytical bounds and simulation results on synchronization probability show that the high SNR ML rule has a performance approaching that of the optimum ML rule over a wide range of signal-to-noise ratios. This decision rule also provides a substantial performance improvement over the correlator rule with virtually no additional implementation complexity.
25 citations
TL;DR: In this paper, the frequency modulation due to injection current modulation of vapor phase transported distributed feedback (VPT DFB) semiconductor lasers is measured as a function of modulation frequency from 10 kHz to 1 GHz.
Abstract: The frequency modulation (FM) due to injection current modulation of vapor phase transported distributed feedback (VPT DFB) semiconductor lasers is measured as a function of modulation frequency from 10 kHz to 1 GHz. A large frequency modulation response of 350 MHz/mA is obtained for the modulation frequency range of 10 to 1000 MHz. Demodulation of optical frequency shift keying (FSK) at 560 Mb/s is demonstrated, indicating that frequency modulation due to thermal modulation does not pose a significant limitation at this bit rate or higher. The large FM response together with modulation bandwidths up to 8 GHz makes the VPT DFB laser an attractive source for high bit rate optical FSK transmission.
17 citations
15 Nov 1986
TL;DR: In this paper, detailed calculations of received optical signal and background power in optical communication systems, with emphasis on analytic models for accurately predicting transmitter and receiver system losses are presented, with a focus on analytical models for predicting system losses.
Abstract: The factors affecting optical communication link performance differ substantially from those at microwave frequencies, due to the drastically differing technologies, modulation formats, and effects of quantum noise in optical communications. In addition detailed design control table calculations for optical systems are less well developed than corresponding microwave system techniques, reflecting the relatively less mature state of development of optical communications. Described below are detailed calculations of received optical signal and background power in optical communication systems, with emphasis on analytic models for accurately predicting transmitter and receiver system losses.
15 citations
TL;DR: In this paper, the authors analyzed the effect of low duty-cycle pulsed modulation formats such as pulse position modulation on the average power of AlGaAs semiconductor lasers.
11 citations
01 Jan 1986
TL;DR: In this article, a delay-tracking algorithm for maintaining synchronization between optical PPM (pulse position modulation) pulses and a receiver clock by means of a delay tracking loop is described and analyzed.
Abstract: A technique for maintaining synchronization between optical PPM (pulse-position modulation) pulses and a receiver clock by means of a delay-tracking loop is described and analyzed. The tracking loop is driven by a doubly stochastic Poisson process that contains information about the location of the desired slot boundaries. The slot boundaries are subject to slowly varying random delays that are ultimately tracked by the loop. The concept of fractional rms delay error is introduced to quantify the effects of signal and background induced shot noise on the performance of the delay-tracking loop.
8 citations
Patent•
27 Jun 1986TL;DR: In this paper, a high-frequency signal generator (5) fitted with a modulation control input (10) to supply said pulses at its output in relation to a modulation signal applied to its modulation input and a modulation generator (15) to provide the modulation input with the modulation signal.
Abstract: This device comprises a high-frequency signal generator (5) fitted with a modulation control input (10) to supply said pulses at its output in relation to a modulation signal applied to its modulation input and a modulation generator (15) to provide the modulation input with the modulation signal. This device also includes a replica circuit (18) to supply a replica of the pulse transmitted, a management circuit (25) to compare this replica wtih said pattern and to alter the modulation signal from the modulation generator so that the pattern complies with the replica.
4 citations
01 Jan 1986
3 citations
Journal Article•
TL;DR: In this article, the authors describe modulation techniques of modulation: modulation par deplacement minimum, modulation par de deplacement de frequence, modulationpar deplacement duobinaire et polybinaire.
Abstract: Description de 4 techniques de modulation: modulation par deplacement minimum, modulation par deplacement de frequence, duobinaire et polybinaire, modulation par deplacement de phase
15 Nov 1986
TL;DR: In this article, a delay-tracking algorithm for maintaining synchronization between optical PPM (pulse position modulation) pulses and a receiver clock by means of a delay tracking loop is described and analyzed.
Abstract: A technique for maintaining synchronization between optical PPM (pulse-position modulation) pulses and a receiver clock by means of a delay-tracking loop is described and analyzed. The tracking loop is driven by a doubly stochastic Poisson process that contains information about the location of the desired slot boundaries. The slot boundaries are subject to slowly varying random delays that are ultimately tracked by the loop. The concept of fractional rms delay error is introduced to quantify the effects of signal and background induced shot noise on the performance of the delay-tracking loop.
TL;DR: The mean squared error (MSE) in the estimate of the threshold-crossing instant for the received pulse of an optical fiber PPM communications system is calculated for the case of a Gaussian shaped pulse.
Abstract: The mean squared error (MSE) in the estimate of the threshold-crossing instant for the received pulse of an optical fiber PPM communications system is calculated for the case of a Gaussian shaped
01 Oct 1986
TL;DR: In this paper, the authors compared the low probability intercept (LPI) performance achievable with optical and RF systems (specifically, millimeter wave systems) for ground-to-space communications.
Abstract: The purpose of this paper is to compare the Low Probability of Intercept (LPI) performance achievable with optical and RF systems (specifically, millimeter wave systems). The specific case of ground to space communications is considered. The LPI performance measure used in the comparison is the Circular Equivalent Vulnerability Radius (CEVR). Using the millimeter wave propagation model of Crane and Blood, a model for computing the CEVR of a millimeter wave earth to space link is described. We then show how the same model can be used to calculate the CEVR for optical systems using the optical propagation model developed by one of the authors (East). Optimal methods of intercepting frequency hopping millimeter wave systems and pulse position modulation (PPM) optical systems are also described.
01 Jan 1986
TL;DR: Theoretical results predict that using orthogonal modulation in direct detection fiber optic systems, the minimum optical power requirements can be reduced by up to 6 dB, compared to non-orthogonal systems as mentioned in this paper.
Abstract: Theoretical results predict that by using orthogonal modulation in direct detection fiber optic systems, the minimum optical power requirements can be reduced by up to 6 dB, compared to nonorthogonal systems. This letter reports on the results of an experiment comparing orthogonal and nonorthogonal modulation in fiber optic systems.