Carrier Frequency Shift Research Articles

Soliton position jitter caused by periodic amplification and self-frequency shift

The formula for soliton timing jitter due to self-frequency shift and pulse width fluctuations caused by spontaneous-emission noise has been deduced. Such timing jitter is compared with that caused by the carrier frequency shift due to spontaneous-emission noise. It is shown that the timing jitter due to the self-frequency shift can be as large as the timing jitter due to carrier frequency shift when the total transmission distance is 100 times longer than the soliton period.

Solitary Pulses in an Amplified Nonlinear Dispersive Medium in the Presence of Gain Saturation

Abstract The steady state solitary solution in a two-level homogeneously broadened amplifier with host nonlinearity and dispersion is perturbatively studied by consideration of gain saturation up to second-order energy terms normalized to the saturation energy of the transition. Carrier frequency shift occurs as a result of the saturation. The chirped solitary pulses derived exist in the anomalous group velocity dispersion region only.

Ultrafast polarisation-independent optical demultiplexer using optical carrier frequency shift through crossphase modulation

A novel polarisation-independent all-optical 1:N demultiplexer is proposed using optical carrier frequency shift induced by a strong pump pulse in Kerr media. A 1:4, 60Gbit/s polarisation-independent demultiplexing operation at 1.307μu is demonstrated using a 70 ps broad pump pulse from an Nd:YLF laser.

Observation of collision induced temporary soliton carrier frequency shifts in ultra-long fiber transmission systems

Multiwavelength soliton interaction over 10000 km in an Er/sup 3+/-doped fiber amplifier based system is studied in a fiber loop configuration. Collisions that takes place over distances significantly longer than amplification period are found to produce nonpermanent shifts of the soliton carrier frequencies, thus acting as collisions in a lossless medium. The spectral shift is found to be inversely proportional to the wavelength separation and is reduced with increasing pulse width. The effects of these unavoidable collisions will impose a limit on the minimum channel spacing in ultra-long-haul soliton based communication systems. >

Synchronization of remote digital clusters via satellite for ISDN

AbstractPresently, there are several countries in the process of converting their national communication system to an integrated digital communication system and eventually, to an integrated services digital network (ISDN). In some developing nations, where a satellite is used for long‐haul transmission to remote and isolated areas, and where there is no terrestrial connection to those areas, the question has been raised whether the satellite can remain a part of such a network, and if so, can it be used to synchronize the remote digital clusters.The matter of concern is the satellite's residual motion. The residual relative motion between the satellite and a ground station produces doppler and therefore, frequency shifts which may cause loss of information, the amount of doppler or carrier frequency shift is location dependent, in general it increases with station latitude and satellite inclination. However, for a given geographic area and a given accuracy in satellite station keeping, it can be shown that satellite links can provide network synchronization to remote digital clusters within the slip rate requirements of a domestic integrated services digital network. In order to permit a less stringent orbit maintenance, or to include earth‐stations of higher geographical latitudes, it is practical to include doppler buffers as part of the satellite earth‐station equipment.

Pioneer Saturn Celestial Mechanics Experiment

During the Pioneer Saturn encounter, a continuous round-trip radio link at S band ( approximately 2.2 gigahertz) was maintained between stations of the Deep Space Network and the spacecraft. From an analysis of the Doppler shift in the radio carrier frequency, it was possible to determine a number of gravitational effects on the trajectory. Gravitational moments ( J(2) and J(4)) for Saturn have been determined from preliminary analysis, and preliminary mass values have been determined for the Saturn satellites Rhea, Iapetus, and Titan. For all three satellites the densities are low, consistent with the compositions of ices. The rings have not been detected in the Doppler data, and hence the best preliminary estimate of their total mass is zero with a standard error of 3 x 10(-6) Saturn mass. New theoretical calculations for the Saturn interior are described which use the latest observational data, including Pioneer Saturn, and state-of-the-art physics for the internal composition. Probably liquid H(2)O and possibly NH(3) and CH(4) are primarily confined in Saturn to the vicinity of a core of approximately 15 to 20 Earth masses. There is a slight indication that helium may likewise be fractionated to the central regions.

Measurement of Doppler Shift in a Pulsed Radar

In this paper different techniques used for determining doppler shift in carrier frequency due to a moving target have been described. The first technique, basically a swept receiver which has a CRT display, is commercially available and commonly used in tracking radars. The other two techniques employing synchronous demodulator along with band-pass filters and autocorrelation method are used for sophisticated type of experiments. The system based on the autocorrelation techniques is under development for the back scatter radar operating at 54·95 MHz.

Effect of Carrier-Frequency Shift on Short-Pulse Holography*

We have assembled a single-transverse-mode, single-longitudinal-mode ruby laser with a pulse length of ~6–12 ns (intensity half-height full width). Pulsed holograms have been made by use of this laser. The laser carrier-frequency shift (or chirp) has been measured and is found to be the limiting factor on the depth of field of the hologram. In order to demonstrate this, we present a quantitative measurement of hologram quality.

Traveling-Wave Tube Nanosecond Pulse Generator In 24-Gc Region

A 24-Gc traveling-wave tube of the type ECL-1180 /24W80 was used for generating nanosecond carrier pulses. The helix of the traveling-wave tube was modulated by a 40-Mc high voltage sine wave. Duration, power and carrier frequency shift of the output RF pulse were examined quantitatively with respect to the modulating voltage. It was found that the delay time of a traveling-wave tube has a large effect on the characteristics of the output pulse. The theory of transmission line modulators was developed to explain the pulse shaping mechanism in the traveling-wave tube. Observations of output pulses were made with three measuring devices, i.e., video-sampling oscilloscope with crystal detector, interferometer, and spectrum analyzer. The interferometer was found to be useful for measuring half-amplitude duration of carrier pulse. Output pulses with half-amplitude duration of as short as 1 nsec were observed.

A 2500-Baud Time-Sequential Transmission System for Voice-Frequency Wire Line Transmission

The Sebit-25 is a full duplex terminal equipment designed to transmit digital data at rates up to 2500 baud. The equipment has been completely transistorized and thoroughly evaluated under environmental conditions. In operation, binary information at 2500 baud is converted to minimum bandwidth and used to amplitude modulate a 2500cycle carrier. The resulting signal is converted to vestigial sideband prior to transmission, to further compress the bandwidth. At the receiver terminal, amplitude and delay compensation are provided to correct for distortion introduced by the transmission line. Synchronous sampling of the recovered signal by a slaved time standard reproduces the original binary information even though line distortion may be severe. Excellent performance results were obtained from a series of laboratory tests conducted on the Sebit-25 to determine error probability vs noise, level changes, delay distortion, carrier frequency shift, and line filter variations.

An Improved Transmitted Carrier System for Telephone Lines of Short or Medium Length

This paper describes a stackable 1-, 2-, or 3-channel short-to-medium haul telephone carrier system, which has been developed primarily to meet the needs of the independent telephone field. Features of this type number 5 carrier system are transmitted carrier frequencies in harmonic relationship, ringdown signaling by carrier interruption, dial signaling by carrier frequency shift, excellent transmission capabilities, particularly in the second and third channels, and simple installation, testing, and maintenance procedure. Partial suppression of the transmitted carrier frequencies is available, for the occasional application in which the normally higher carrier level on the line might prove objectionable. Through particular attention to the engineering design, the significant objections to transmitted carrier have been overcome, while its greater convenience to the user has been employed to good advantage. The feasibility and desirability of this system have been amply proved by hundreds of successful installations, some of which are on difficult lines where other carrier systems previously failed.

Frequency-Shift Radio Transmission

The different methods of obtaining carrier-frequency shift of communications transmitters are described, as well as the results of using the different methods, and the final model that has proved satisfactory for this type of service.