Showing papers on "Wideband published in 1971"
01 Sep 1971
TL;DR: The theory of pulse compression and data transmission using chirp signals is outlined, and an experimental communication system is described with measured error rates in noise and carrier interference.
Abstract: Swept-frequency or chirp signals are currently under investigation for data-transmission applications. In particular, long-range air/ground communication in the h.f. band may benefit from the use of these wideband signals owing to the inherent protection chirp signals offer against fading in a time-varying multipath channel. The theory of pulse compression and data transmission using chirp signals is outlined, and an experimental communication system is described with measured error rates in noise and carrier interference.
53 citations
TL;DR: In this paper, a one-dimensional nonlinear theory is developed to consider multisignal inputs and harmonic generation and includes the effects of RF space charge, distributed circuit loss, and the variation of tube parameters with frequency.
Abstract: As a result of the inherent nonlinearity of the beam-circuit wave interaction process in high-power microwave amplifiers, there are harmonics generated when one signal is applied to the input and both harmonics and intermodulation products are generated when multiple component signals are applied. The effect of these generated signals is to reduce the available power levels of the fundamental signals. In this investigation multiple signals, noise, and combinations of these are considered as inputs to high-power traveling-wave and crossed-field amplifiers. A one-dimensional nonlinear theory is developed to consider multisignal inputs and harmonic generation and includes the effects of RF space charge, distributed circuit loss, and the variation of tube parameters with frequency. The theoretical results for the case of two input signals reveal both a strong larger amplitude capturing effect as well as a pronounced lower frequency signal preference. Both of these effects have also been observed experimentally using a high-power continuous-wave octave bandwidth traveling-wave amplifier. In addition to the multisignal studies a band of noise and combinations of noise and single-frequency signals have been applied to the experimental device. Measurements are made on the formation of noise intermodulation sidebands and on the degradation of a single-frequency input signal when a band of noise is simultaneously applied to the input of the traveling-wave amplifier. The noise is noticeably more effective in reducing the signal power level when it is positioned lower rather than higher in frequency with respect to the single-frequency signal. Experimental studies on a high-power continuous-wave wideband crossed-field amplifier are presented for comparison purposes. While the two devices are very similar in some respects they differ in others. For example the crossed-field amplifier shows a preference for a higher frequency signal which is just opposite to the traveling-wave tube results. In general the agreement between the theoretical and experimental multisignal results is good especially when the effects of distributed circuit loss and space-charge forces are included in the non-linear multisignal interaction equations.
22 citations
Patent•
12 Feb 1971TL;DR: In this article, a tunable wideband coherent source consisting of a laser source and a microwave source was proposed, which can be used with means for utilizing the sum signal, the difference signal, or both of these.
Abstract: A tunable wideband coherent source comprising a laser source and a microwave source, means for combining and mixing the outputs of the laser and microwave sources so as to provide a combined output, and means for filtering the combined output so as to separate sum and difference components, with any undesired background being suppressed. Our source may be used with means for utilizing the sum signal, the difference signal, or both of these.
15 citations
Patent•
05 Aug 1971
TL;DR: In this paper, a conference control cirCUIT is used to monitor the audio transmissions from each station on a conference call and to send the broadcast signal to all the other stations in the conference call.
Abstract: WIDEBAND CONFERENCING SERVICE BETWEEN STATIONS SERVED BY A KEY TELEPHONE SYSTEM INTERCOM LINK IS PROVIDED BY A CONFERENCE CONTROL CIRCUIT ARRANGED TO MONITOR THE AUDIO TRANMISSION FROM EACH STATION ON A CONFERENCE AND TO TRANSMIT WIDEBAND SIGNALS FROM A CURRENTLY AUDIOACTIVE STATION TO ALL OTHER STATIONS INCLUDED IN THE CONFERENCE. WIDEBAND TRANSMISSION FROM ALL OTHER CONFERENCE STATIONS EXCEPT FROM THE LAST AUDIOACTIVE STATION IS INHIBITED WHILE THE WIDEBAND TRANSMISSION FROM THE LAST AUDIOACTIVE STATION IS TRANSMITTED TO THE CURRENTLY AUDIOACTIVE STATION. IN SITUATIONS WERE TWO STATIONS ALTERNATIVELY BECOME AUDIOACTIVE, PROVISION IS MADE TO ENSURE CONTINUOUS UNINTERRUPTED BIDIRECTIONAL WIDEBAND TRANSMISSION BETWEEN THOSE STATIONS. D R A W I N G
10 citations
16 May 1971
TL;DR: In this paper, the electrical characteristics of the ferrite substrate microstrip circulator having wider magnetized region than conventional one have been studied and a compact and simplified wideband circulator without the impedance matching networks was proposed.
Abstract: The electrical characteristics of the ferrite substrate microstrip circulator having wider magnetized region than conventional one have been studied. This work enables us to compose a compact and simplified wideband circulator without the impedance matching networks. The electric field measurement shows that the wideband characteristics are realized by the combination of the conventional n=1 mode and a nonresonant mode different but compatible to the former. A C-band version measuring 15 mm in diameter offers more than 20 dB isolation and an insertion loss less than 0.5 dB over a bandwidth of 50 percent or more with the center frequency of 6.3 GHz.
5 citations
Patent•
27 Oct 1971TL;DR: In this paper, a deflection modulated microwave traveling wave electron beam semiconductor amplifier was proposed to obtain wideband performance by tilting the travelling wave collection circuit with respect to the electron beam axis such that the phase velocity of the collection circuit matches the longitudinal component of the electronbeam velocity.
Abstract: Wideband performance is obtained in a deflection modulated microwave traveling wave electron beam semiconductor amplifier by tilting the travelling wave collection circuit with respect to the electron beam axis such that the phase velocity of the collection circuit matches the longitudinal component of the electron beam velocity. Trimming of the longitudinal component to obtain this match is obtained by varying the beam voltage.
5 citations
01 Jan 1971
2 citations
TL;DR: Wideband heterodyne receiver provides detection and demodulation of incident frequency modulated laser signal; search and acquisition circuitry to align two stations; tracking circuitry to maintain spatial alignment; and laser frequency monitor to frequency lock the transmit and local oscillator lasers as mentioned in this paper.
Abstract: Wideband heterodyne receiver provides detection and demodulation of incident frequency modulated laser signal; search and acquisition circuitry to align two stations; tracking circuitry to maintain spatial alignment; and laser frequency monitor to frequency lock the transmit and local oscillator lasers.
2 citations
TL;DR: A new modulation method for data transmission is described for use on groupband communication channels (60?108 kHz), which is compatible with the existing group- and supergroup-reference pilots.
Abstract: A new modulation method for data transmission is described for use on groupband communication channels (60?108 kHz), which is compatible with the existing group- and supergroup-reference pilots. Dual single-sideband modulation permits a basic transmission rate of 48 kbit/s, which can be extended to 72 or 96 kbit/s by means of special multilevel coding.
1 citations
TL;DR: Use of the evolving Picturephone® network to provide common-user, switched wideband data service is another step in the continuing effort to satisfy the growing need for moving information faster, in greater quantities, over longer distances, and at lower cost than is now possible.
Abstract: Use of the evolving Picturephone® network to provide common-user, switched wideband data service is another step in the continuing effort to satisfy the growing need for moving information faster, in greater quantities, over longer distances, and at lower cost than is now possible. Full use is made of the planned network with but minor modifications to the basic face-to-face offering. Initial network capabilities permit synchronous data transmission at 460.8 kb/s; it is expected that data service at 1.344 Mb/s will become standard as network improvements are made.
1 citations
01 Aug 1971
TL;DR: In this paper, a modulated laser beam analog recorder was proposed to record up to several minutes at 100 Mbit digital writing at a high frequency of approximately 25?sec duration, but required synchronization of event to the rotating mirror camera of the recorder.
Abstract: The requirement for a wideband recording capability for instrumenting electromagnetic fields with nanosecond rise time perturbations and long duration reactions lead to the development of a modulated laser beam analog recorder. The original concept of the recorder yielded 100 MHz bandwidth records of ±40 db dynamic range of approximately 25 ?sec duration but required synchronization of the event to the rotating mirror camera of the recorder. Normalization of data required digital computer processing of densitometer conversion of film density data to analog electrical signal. An improvement of the original system, which permits continuous recording up to several minutes at 100 Mbit digital writing solves the major shortcomings of the analog recorder. Using techniques of signal conditioning and laser beam splitting and modulation of the previous system, the data stream is split into four channels recorded simultaneously and continuously on moving 70 mm film in a four-to-one interlace pattern. Each channel is organized into discrete blocks with data synchronizing words to provide block and timing identification. The physical arrangement of the recorder is such that film readout is effected on the same transport deck. Simultaneously scanned data tracks generate a parallel serial data train which is buffered, multiplexed, and recombined to produce the serial data stream.
16 May 1971
TL;DR: In this article, design techniques for high performance microwave delay lines which have superior bandwidth, phase linearity and spurious echo characteristics are presented, and utilization of these techniques to realize a 4 /spl mu/s L-band unit which has insertion loss of 30 /spl plusmn/0.5 dB over the 500 MHz band centered at 1.7 GHz.
Abstract: Design techniques for high performance microwave delay lines which have superior bandwidth, phase linearity and spurious echo characteristics are presented. Utilization of these techniques to realize a 4 /spl mu/s L-band unit which has insertion loss of 30 /spl plusmn/0.5 dB over the 500 MHz band centered at 1.7 GHz, with triple-transit suppression greater than 45 dB and phase deviation from linearity of less than /spl plusmn/2.5/spl deg/, are described.
TL;DR: In this paper, two wideband phase switches have been built for radio and microwave interferometry, where the directions of current flow in a balanced transmission line are reversed periodically, and the line is coupled into the interferometer via broadband baluns.
Abstract: Two wideband phase switches have been built for radio and microwave interferometry. In one, the directions of current flow in a balanced transmission line are reversed periodically. The line is coupled into the interferometer via broadband baluns. The second device switches between the E plane outputs of a magic T.
16 May 1971
TL;DR: In this paper, a charge-storage diode frequency tripler with a measured midband efficiency of 50% and a 3 dB band-width of 38% is presented, which is based on two cascaded impedance inverters.
Abstract: A charge-storage diode frequency tripler can be modeled as two cascaded impedance inverters. This approach has been used to design and construct a tripler at 1.06 GHz input frequency with a measured midband efficiency of 50% and a 3 dB band-width of 38%.
TL;DR: In this article, a K-shaped antiparallel microstrip amplifier with four high-efficiency avalanche diodes has been used to provide 400 W at 1.01 GHz with 8.8 dB power gain and 1.23% bandwidth.
Abstract: A K-shaped antiparallel microstrip amplifier having four high-efficiency avalanche diodes has provided 400 W at 1.01 GHz with 8.8 dB power gain and 1.23% bandwidth. A novel fishbone-shaped tuning plate has worked not only to widen the bandwidth to 10%, but also, together with stagger-tuned antiparallel pairs, to increase the gain bandwidth from 94.8 MHz to 447 MHz.
TL;DR: An optical synchronization technique is described for the demultiplexer of a wideband optical data transmission system, in which closely spaced optical pulses of interleaved PCM channels are "space sorted" by a coincidence detection technique using an optical reference waveform generated in the receiver.
Abstract: An optical synchronization technique is described for the demultiplexer of a wideband optical data transmission system. In this system, the closely spaced optical pulses of interleaved PCM channels are "space sorted" by a coincidence detection technique using an optical reference waveform generated in the receiver. For synchronization of the reference waveform with a spatial waveform produced by the received laser beam in the demultiplexer, a number of pulses on these two optical waveforms are coded with a pseudo-random sequence. Acquisition of the coded waveforms for synchronization is indicated in an optical matched filter. For automatic tracking, a synchronization error-control circuit is added.
01 Jan 1971
01 Nov 1971
TL;DR: In this article, the authors demonstrate that the design and fabrication of an RF subsystem, utilizing coherent demodulation of data, for wideband communications systems is now both feasible and practical.
Abstract: One of the problems inherent in the use of optical communication systems is the exceedingly high Doppler shift which can be expected. With the recent development of stable, linear, octavebandwidth, voltage-tunable oscillators, this problem has been solved. A laboratory tracking receiver which is capable of tracking a 1-GHz frequency shift at rates up to 12 MHz/s with subsequent coherent data demodulation was designed and tested. This work demonstrates that the design and fabrication of an RF subsystem, utilizing coherent demodulation of data, for wideband communications systems is now both feasible and practical.