Estimating data-dependent jitter of a general LTI system from step response

We present a method for estimating data dependent jitter (DDJ) introduced by a general LTI system, based on the system's step response. A perturbation technique is used to generalize the analytical expression for DDJ. Different scales of DDJ are defined that characterize the probability distribution of jitter. In particular, we identify a dominant prior bit that signifies the well-known distribution of DDJ, the two impulse functions. We also highlight that system bandwidth is not a complete measure for predicting DDJ. We verify our generalized analytical expression of DDJ experimentally and show that estimation errors are less than 7.5%

Jitter Limitations on Multi-Carrier Modulation

A feasibility study is made of an OFDM system based on analog multipliers and integrate-and-dump blocks, targeted at Gb/s copper interconnects. The effective amplitude variation of the integrator output caused by jitter is explained in an intuitive way by introducing correlation plots. For a given rms jitter and error rate, high frequency carriers allow for less modulation depth than low frequency carriers. A jitter limit on the total system bit rate is calculated, which is a function of rms jitter, bandwidth, and specified system symbol error rate. It is concluded that, because of the high sensitivity to timing errors inherent in OFDM, traditional PAM systems with equal bandwidth and error rate are more feasible

Experimental feasibility of measuring the gravitational redshift of light using dispersion in optical fibers

This paper describes a new class of experiments that use dispersion in optical fibers to convert the gravitational frequency shift of light into a measurable phase shift or time delay. Two conceptual models are explored. In the first model, long counter-propagating pulses are used in a vertical fiber optic Sagnac interferometer. The second model uses optical solitons in vertically separated fiber optic storage rings. We discuss the feasibility of using such an instrument to make a high precision measurement of the gravitational frequency shift of light.Comment: 11 pages, 12 figure

NOSS/ALDCS analysis and system requirements definition

The results of system analyses and implementation studies of an advanced location and data collection system (ALDCS) , proposed for inclusion on the National Oceanic Satellite System (NOSS) spacecraft are reported. The system applies Doppler processing and radiofrequency interferometer position location technqiues both alone and in combination. Aspects analyzed include: the constraints imposed by random access to the system by platforms, the RF link parameters, geometric concepts of position and velocity estimation by the two techniques considered, and the effects of electrical measurement errors, spacecraft attitude errors, and geometric parameters on estimation accuracy. Hardware techniques and trade-offs for interferometric phase measurement, ambiguity resolution and calibration are considered. A combined Doppler-interferometer ALDCS intended to fulfill the NOSS data validation and oceanic research support mission is also described

Phase and amplitude pre-emphasis techniques for low-power serial links

A novel approach to equalization of high-speed serial links combines both amplitude pre-emphasis to correct for intersymbol interference and phase pre-emphasis to compensate for deterministic jitter, in particular, data-dependent jitter. Phase pre-emphasis augments the performance of low power transmitters in bandwidth-limited channels. The transmitter circuit is implemented in a 90-nm bulk CMOS process and reduces power consumption by pushing CMOS static logic to the output stage, a 4:1 output multiplexer. The received signal jitter over a cable is reduced from 16.15 ps to 10.29 ps with only phase pre-emphasis at the transmitter. The jitter is reduced by 3.6 ps over an FR-4 backplane interconnect. A transmitter without phase pre-emphasis consumes 18 mW of power at 6Gb/s and 600mVpp output swing, a power budget of 3mW/Gb/s, while a transmitter with phase pre-emphasis consumes 24mW, a budget of 4 mW/Gb/s

APOLLO: the Apache Point Observatory Lunar Laser-ranging Operation: Instrument Description and First Detections

A next-generation lunar laser ranging apparatus using the 3.5 m telescope at the Apache Point Observatory in southern New Mexico has begun science operation. APOLLO (the Apache Point Observatory Lunar Laser-ranging Operation) has achieved one-millimeter range precision to the moon which should lead to approximately one-order-of-magnitude improvements in the precision of several tests of fundamental properties of gravity. We briefly motivate the scientific goals, and then give a detailed discussion of the APOLLO instrumentation.Comment: 37 pages; 10 figures; 1 table: accepted for publication in PAS