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Showing papers on "Dynamic range published in 1980"


Journal ArticleDOI
TL;DR: A computer-controllable variable optical attenuator has been developed and tested that has a wide dynamic range, wide spectral range, and is suitable for applications with high peak and average power laser sources.
Abstract: A computer-controllable variable optical attenuator has been developed and tested that has a wide dynamic range, wide spectral range, and is suitable for applications with high peak and average power laser sources. The device is based on Fresnel transmission through two pairs of wedged plates. A 35-dB dynamic range, an insertion loss of 1%, a precision of better than 1% and beam offset and deflection of <0.5 mm and 0.5 mrad, respectively, are demonstrated.

34 citations


Journal ArticleDOI
TL;DR: A 1030 X 128 element time delay and integration CCD image sensor has been developed for low-light-level (L/sup 3/) imaging applications and input signal levels of 500 electrons have been successfully imaged and amplifier noise levels of approximately 20 electron levels have been observed.
Abstract: A 1030 X 128 element time delay and integration (TDI) CCD image sensor has been developed for low-light-level (L/sup 3/) imaging applications. For L/sup 3/ imaging, output is derived from a high-gain low-noise floating-gate amplifier (FGA). For larger input signal levels, a second, resettable floating-gate amplifier (RFGA) with lower gain and wider dynamic range provides output in parallel to the FGA. The device features four-phase buried-channel construction and a polysilicon gate design tailored to produce optimum broad-band responsivity. Input signal levels of 500 electrons have been successfully imaged and amplifier noise levels of approximately 20 electrons have been observed.

30 citations


Journal ArticleDOI
TL;DR: In this article, a 1030 × 128 element time delay and integration (TDI) CCD image sensor has been developed for low-light-level (L3) imaging applications.
Abstract: A 1030 × 128 element time delay and integration (TDI) CCD image sensor has been developed for low-light-level (L3) imaging applications. For L3imaging, output is derived from a high-gain low-noise floating-gate amplifier (FGA). For larger input signal levels, a second, resettable floating-gate amplifier (RFGA) with lower gain and wider dynamic range provides output in parallel to the FGA. The device features four-phase buried-channel construction and a polysilicon gate design tailored to produce optimum broad-band responsivity. Input signal levels of 500 electrons have been successfully imaged and amplifier noise levels of approximately 20 electrons have been observed.

29 citations


Patent
17 Mar 1980
TL;DR: In this paper, the dynamic range of the input amplifier and of the mixer can be varied as a function of the received signal level up to a predetermined threshold value, and an input attenuator assumes increasing values which makes it possible to attain a wide dynamic range under optimum conditions of sensitivity and linearity.
Abstract: An HF receiver head having high sensitivity and capable of receiving variable-level input signals has characteristics which are adjusted as a function of the received signal level. The HF head essentially comprises a generator for delivering control voltages as a function of the amplitude of the received signals. The dynamic range of the input amplifier and of the mixer can thus be varied as a function of the received signal level up to a predetermined threshold value. Above this threshold value, an input attenuator assumes increasing values which makes it possible to attain a wide dynamic range of the HF head under optimum conditions of sensitivity and linearity.

24 citations


Patent
01 Oct 1980
TL;DR: An analog optical processor which performs complex transform operations oromplex correlations to yield quantitative (numerical) output is accomplished on data points which are used as inputs serially or simultaneously as mentioned in this paper.
Abstract: An analog optical processor which performs complex transform operations oromplex correlations to yield quantitative (numerical) output. This is accomplished on data points which are used as inputs serially or simultaneously. The dynamic range of the input function that may be operated upon is not limited, as heretofore, by the characteristics of a medium on which the input function is recorded or stored. The dynamic range of the output is also not limited by the characteristics of a discrete electro-optical sensor.

22 citations


Journal ArticleDOI
TL;DR: In this paper, the operation of a CCD TV camera sensor at low light levels is discussed, and the principal limitation is seen to be the output amplifier, and a new low-noise output detector, the "floating surface detector," is described in detail.
Abstract: Some limitations to the operation of a CCD TV camera sensor at low light levels are discussed. Transfer inefficiency with small charge packets is analyzed theoretically, and the prediction made that with good processing this should not be a serious problem. The principal limitation is seen to be the output amplifier, and a new low-noise output detector, the "floating surface detector," is described in detail. At -50°C it yields a noise equivalent signal of 16 electrons and a dynamic range of 85 dB over a 1-MHz video bandwidth.

18 citations


Proceedings ArticleDOI
24 Jun 1980
TL;DR: In this article, a passive visible to infrared image transducer is described which allows practical simulation of high resolution dynamic infrared imagery for the first time, and a theoretical performance analysis is presented which indicates an MTF of 50% at 5 cycles/mm is achievable with a time response of less than 20 msec and a required input power of less mw/cm2 per simulated degree ΔT.
Abstract: A passive visible to infrared image transducer is described which allows practical simulation of high resolution dynamic infrared imagery for the first time. A theoretical performance analysis is presented which indicates an MTF of 50% at 5 cycles/mm is achievable with a time response of less than 20 msec and a required input power of less than 2 mw/cm2 per simulated degree ΔT. Experimental results on working devices are reported which match theoretical predictions. Successful simulation of high speed real-world infrared imagery is described. Suggestions for future work are presented which should further enhance resolution and dynamic range.

12 citations



Patent
30 Jun 1980
TL;DR: In this article, an automatic level and gain control system is proposed to match the dynamic range of the display or other processing elements to the signal provided by the sensor for developing an image with improved dynamic range utilization (or contrast).
Abstract: An automatic level and gain control system operable with a sensor to match the dynamic range of the display or other processing elements to the signal provided by the sensor for developing an image with improved dynamic range utilization (or contrast). Peak detection is provided with a conditional integrator so that the effect of high level narrow peaks is substantially suppressed. This system rapidly reaches and maintains a condition of providing the video signal to the display (or other processing) at a desired voltage level and over a desired dynamic range to continually maintain an image having optimum contrast within the dynamic range limitations of the processor or display system.

10 citations


Patent
Chong K. Un1
19 May 1980
TL;DR: In this article, a hybrid companding delta modulation system is proposed for coding a speech signal, which employs both syllabic and instantaneous companding schemes, and the system can be made as large as the range of the input signal level.
Abstract: A hybrid companding delta modulation system is an improvement of adaptive delta modulation and is particularly suitable for coding a speech signal. It employs both syllabic and instantaneous companding schemes. The syllabic compandor provides a long term step size of the quantizer which varies relatively slowly by estimating either the envelope of slope or amplitude variation of the input signal. On the other hand, the instantaneous compandor adjusts the step size instantaneously according to a predetermined control logic in response to variations of the input signal. With the hybrid companding delta modulation system the dynamic range of the system can be made as large as the range of the input signal level. The signal-to-quantization noise ratio is improved over presently known adaptive delta modulation systems. Finally, the effect of channel errors is minimized.

9 citations


Patent
02 Jun 1980
TL;DR: In this article, the authors proposed to avoid the decrease in contrast at high luminance by compressing the input level only more than the standard white level and matching the entire analog signal after compression for a dynamic range of an A/D converter.
Abstract: PURPOSE:To avoid the decrease in contrast at high luminance, by compressing the input level only more than the standard white level and matching the entire analog signal after compression for a dynamic range of an A/D converter. CONSTITUTION:An analog signal Si outputted from an image sensor 10 is fed to a compression circuit 30 via a buffer amplifier 20. In the circuit 30, a compression start level decided with the forward voltage drop of a diode D and the DC voltage of a DC power supply E is set to the level of the signal Si. Further, the white peak level is the maximum input level of the signal Si after the compression and the compressing coefficient of the standard white level is selected to be 75-90% of the maximum input level. A compressed analog signal S0 is fed to an A/D converter 50 via an amplifier 10. The dynamic range of the converter 50 is matched to that of the signal S0. The digital signal SD outputted from the converter 50 is fed to a gamma compensation circuit 60 for gamma compensation.

Patent
11 Nov 1980
TL;DR: In this article, the mean value of the signal amplitude is used to control the gain of a linear amplifier in the main channel so as to adapt the dynamic range of the echo signals to that which can be handled by the fixed-echo suppressor.
Abstract: A receiver of a pulse-type radar has a main i-f channel feeding a fixed-echo suppressor of limited dynamic range and, in parallel therewith, an ancillary channel of extended dynamic range including a logarithmic amplifier and a processor. The latter averages the amplitude of incoming echo signals over a range-and-azimuth cell and then over one or more antenna revolutions. The resulting mean value of the signal amplitude is used to control the gain of a linear amplifier in the main channel so as to adapt the dynamic range of the echo signals to that which can be handled by the fixed-echo suppressor.

Patent
17 Jan 1980
TL;DR: In this paper, an input circuit is disclosed for variably adapting the dynamic range of an ultrasonic frequency electrical signal to the dynamic ranges of a signal receiver to which the signal is applied.
Abstract: An input circuit is disclosed for variably adapting the dynamic range of an ultrasonic frequency electrical signal to the dynamic range of a signal receiver to which the signal is applied. A band pass filter admits the appropriate band of signal frequencies to the receiver to provide optimum signal-to-noise conditions. A JFET device is shunted across the receiver input and its drain-to-source impedance is varied to control the peak voltage developed by the signal. Control of the impedance of the JFET device may be effected in a pre-programmed manner as a function of time, in response to the amplitude of the signal applied to the receiver input, or in response to both. In either case, the amplitude of the applied signal is constrained to remain substantially within the dynamic range of the receiver.

Journal ArticleDOI
TL;DR: The converter described herein was developed to digitize the output from a CCD in a space environment where telemetry is limited to achieve low power dissipation, moderately fast conversion time, and reliability.
Abstract: In background noise limited instrumentation systems, an analog-to-digital converter with a square root transfer function will allow a maximum dynamic range with a fixed number of data bits. The converter described herein was developed to digitize the output from a CCD in a space environment where telemetry is limited. The goals of low power dissipation, moderately fast conversion time, and reliability have been achieved using standard components and avoiding non-linear elements.

Journal ArticleDOI
TL;DR: Brennan and Reed [3] analyzed the effects of hard limiting, and their conclusions suggest that it does not degrade the steady-state performance of the adaptive processor.
Abstract: Adaptive antennas are often implemented with the Applebaum-Howells-type adaptive processor usually include a hard limiter between each antenna port and its correlation mixer, primarily for dynamic range compression. Brennan and Reed [3] analyzed the effects of hard limiting, and their conclusions suggest that it does not degrade the steady-state performance of the adaptive processor. Standard and hard-limited processors are compared and it is shown that when the two types of processor have the same sensitivity threshold, the hard-limited one can fail to provide sufficient interference cancellation when the correlation matrix of input signals has two or more eigenvalues of differing magnitudes. The consequence of hard limiting is that (depending on the processor design parameters) the larger of two or more signals can capture the hard limiter, allowing the smaller signals to pass through the processor essentially unattenuated. It is also shown that when a hard-limited processor is designed to provide the same cancellation as a standard one, it must have essentially as large a dynamic range as the standard, processor; therefore, it offers no advantage of dynamic range compression. Moreover, the hard-limited processor lacks a constant sensitivity threshold, which can be a desirable feature of a standard processor. Specific examples are presented for identical-element array antennas and for multiple-beam antennas.

Journal ArticleDOI
TL;DR: In this article, a dual-variable detection method is proposed to provide a wider dynamic range to the light intensity measurement by a photomultiplier, achieving a dynamic range as wide as seven orders of magnitude by controlling and analyzing both the dynode voltage and anode current.
Abstract: The dual‐variable detection method is a device to provide a wider dynamic range to the light intensity measurement by a photomultiplier. A dynamic range as wide as seven orders of magnitude is attainable by controlling and analyzing both the dynode voltage and the anode current. The electronic circuit is illustrated and its application to the simultaneous measurement of the absorbance and the circular dichroism, which have used to require different light intensity range for the optimum operation, is described.

Journal ArticleDOI
01 Jan 1980
TL;DR: This note presents round-off noise expressions for fixed-point digital filters realized in the error-feedback structure, and a comparison of theerror- feedback structure with other low round-offs noise digital filter structures in terms of output round- off noise variance.
Abstract: This note presents round-off noise expressions for fixed-point digital filters realized in the error-feedback structure, and a comparison of the error-feedback structure with other low round-off noise digital filter structures in terms of output round-off noise variance.

Journal ArticleDOI
TL;DR: In this paper, the effect of noise on backscattering was evaluated in order to optimize the precision of the measurement, its dynamic range, and the time required to collect the data.
Abstract: The backscattering method is now a well-established technique for the measurement of attenuation in multimode optical fibres. In this paper the effect of noise is evaluated in order to optimize the precision of the measurement, its dynamic range and the time required to collect the data. An experimental set-up is described and the experimental results reported.

Journal ArticleDOI
TL;DR: In this paper, a new automatic parallel intermediate frequency (IF) vector substitution principle is implemented in a dual-channel microwave vector ratio meter, and a combination of analog adaptive filtering and digital data processing provides short measurement times.
Abstract: A new automatic parallel intermediate frequency (IF) vector substitution principle is implemented in a dual-channel microwave vector ratio meter. A greater than 120-dB dynamic range and 0.001-dB and 0.1° resolutions are provided. A combination of analog adaptive filtering and digital data processing provides short measurement times. Theoretical performance limitations are analyzed.

Journal ArticleDOI
TL;DR: In this article, the authors describe a low light level, low resolution astronomical CCD (charge coupled device) spectrometer useful in the spectral range 5000-9000 A, with a second CCD channel for direct broad-band photometry of the region around the entrance slit.
Abstract: This paper describes a low light level, low resolution astronomical CCD (Charge Coupled Device) spectrometer useful in the spectral range 5000–9000 A. The instrument has a second CCD channel for direct broad‐band photometry of the region around the entrance slit. Both applications benefit from the high quantum efficiency, stability, dynamic range and linearity intrinsic to CCD’s. The detectors are cooled to 130 K which eliminates dark current and permits exposure times long enough to overcome the readout noise of ±30 electrons. At low spectral resolution the instrument has a signal‐to‐noise ratio which approaches the photon counting noise limit. The overall average quantum efficiency during observations is 1.3% between 5500 and 9000 A.

Patent
21 Jan 1980
TL;DR: In this article, a geophysical data acquisition system is disclosed having a dynamic range larger than that achievable with typical existing systems, where high amplitude input signals can be accommodated by the system if certain unneeded frequency components are filtered off at a sufficiently early point in the signal flow path.
Abstract: A geophysical data acquisition system is disclosed having a dynamic range larger than that achievable with typical existing systems. The range of input signals that can be accommodated by a system are limited on the lower end by the noise level of the system and at the upper end by saturation levels of the system. High amplitude input signals can be accommodated by the system if certain unneeded frequency components are filtered off at a sufficiently early point in the signal flow path. In the present invention this desirable filtering is accomplished while maintaining a high gain level in the signal flow path ahead of those components which introduce high noise levels. As a result, the system has an expanded dynamic range and the needed capability to faithfully acquire low amplitude signals.

Proceedings ArticleDOI
01 Apr 1980
TL;DR: The development of a block state-structure with minimum round-off noise subject to l 2 -norm dynamic range constraint and the block state realization of recursive digital filters is shown to be superior.
Abstract: The development of a block state-structure with minimum round-off noise subject to l 2 -norm dynamic range constraint is outlined. The pertinent equations for scaling and for round-off noise analysis of block-state structures are first derived. Next, a lower bound and the global minimum of the output noise due to the round-off of the block-state variables are derived. A method of deriving the minimum round-off noise block state-structure is outlined. A numerical example is included. With regard to computational complexity and overall noise performance, the block state realization of recursive digital filters is shown to be superior.

Patent
04 Apr 1980
TL;DR: A quadrature modulation analog transmission system provides an extended dynamic range of amplification by dividing the total gain desired between the two quad-ature channels without overloading the transmission medium as mentioned in this paper.
Abstract: A quadrature modulation analog transmission system provides an extended dynamic range of amplification by dividing the total gain desired between the two quadrature channels without overloading the transmission medium. The direct channel furnishes a higher gain for low-level background noise signals, while the quadrature channel furnishes a lower gain for high-level signaling tones.


Patent
01 Feb 1980
TL;DR: In this paper, the authors propose to increase the dynamic range as well as to prevent the lowering of the signal quality by carrying out instantaneously both compression and expansion of the amplitude for the audio signals in accordance with the signal level.
Abstract: PURPOSE:To increase the dynamic range as well as to prevent the lowering of the signal quality by carrying out instantaneously both compression and expansion of the amplitude for the audio signals in accordance with the signal level CONSTITUTION:The audio signals sent from input terminal of amplitude compressor A are applied to output terminal 2 via amplitude compression circuit 3, and at the same time part of the audio signals is applied to FM modulation circuit 5 to have the FM modulation The FM-modulated signal is applied to BPF6 And in case the modulated signal features a larger band width of BPF6, the output with AM modulation applied by slope of the filter characteristics is generated at the output of BPF6 This output is detected through detection circuit 7, and the signal of the positive pole area of the output signal is applied as the control voltage of circuit 3 Thus the compression is performed in accordance with the signal level On the other hand, amplitude expander B has the same operation as compressor 1 via FM modulation circuit 5', BPF6' and detection circuit 7' in order to expand the signal level for expander B

Patent
21 May 1980
TL;DR: In this paper, a bias light source was provided near the photosensitive part of CCD13 and was so constituted that light source 19 may irradiate this photo-sensitive part uniformly, thus obtaining a good picture inside as well as outside without making a dynamic range narrow.
Abstract: PURPOSE:To obtain a good picture inside as well as outside without making a dynamic range narrow by irradiating a solid image pickup device with a bias light and controlling the bias charge generated by this irradiation. CONSTITUTION:The optical image of object 11 is focused onto the photosensitive part of CCD13 through image pickup lens 12. Bias light source 19 using a LED is provided near the photosensitive part of CCD13 and is so constituted that light source 19 may irradiate this photosensitive part uniformly. Output signals of CCD13 are amplified into a prescribed level by amplifier 14 and are applied to process circuit 15 and are added to synchronizing signals there and are subjected to DC reproducing, gamma correction, pick signal clip, etc., thereby obtaining standard TV signals. On the other hand, a part of the output of amplifier 14 is applied to detection circuit 16 and is detected, and after that, it has the phase shifted by 180 deg. in polarity inversion circuit 17 and is applied to voltage control circuit 18. Circuit 18 controls a voltage applied to light source 19 and changes the output light quantity of light source 19.

Journal ArticleDOI
TL;DR: In this article, an alternating pretrigger shift was used to compare two pulse signals on one channel of a sampling system, and a quartz-stable c.w. sine gave a precise time reference.
Abstract: For an accurate comparison of two pulse signals on one channel of a sampling system, an alternating pretrigger shift is used. Simultaneously, a quartz-stable c.w. sine gives a precise time reference. A programmable data-acquisition system performs control and output operations. After averaging, the usable dynamic range is 70 dB with noise and drifts below 0.2 mVeff

Patent
22 Sep 1980
TL;DR: In this paper, an improved large dynamic range multiplier is disclosed that provides substantially ideal multiplication for signals within a maximal-ratio predetection diversity combiner, where it is essential that the mixer product signal be proportional to its input signals, which each have a dynamic range in excess of 40 db.
Abstract: An improved large dynamic range multiplier is dis-closed that provides substantially ideal multiplication for signals within a maximal-ratio predetection diversity combiner. Linear product multiplication is necessary in the second mixing stage of the maximal-ratio predetection diversity combiner, where it is essential that the mixer product signal be proportional to the product of its input signals, which each have a dynamic range in excess of 40 db. The multiplier, which in the preferred embodiment of the present invention is a field-effect-transistor device, provides a product signal that has a linear dynamic range approaching 130 db, far in excess of the 80 db necessary to accommodate typical input signals having a 40 db dynamic range.

Proceedings ArticleDOI
01 Jan 1980
TL;DR: In this article, a non-destructive read-out imaging device with high sensitivity and wide dynamic range is proposed. But the readout voltage is almost independent of the storage capacitance due to the existence of the floating n+p contact and the bit line capacitance.
Abstract: New imaging device characterized by non-destructive read-out operation is discussed theoretically concentrating on an optical sensing process and a read-out process. The light information is continuously stored in this imaging device even during the read-out process. It has been demonstrated theoretically that the stored voltage is almost independent of the storage capacitance due to the existence of the floating n+p contact and that the read-out voltage is almost independent of the bit line capacitance. The new imaging device has excellent features such as non-destructive characteristic, high sensitivity and wide dynamic range.

Proceedings ArticleDOI
03 Nov 1980
TL;DR: In this article, a mathematical model for a frequency-compensated detector/preamplifier appropriate for cryogenically-cooled infrared sensors operating under low background conditions is given.
Abstract: A mathematical model is given for a frequency-compensated detector/preamplifier appropriate for cryogenically-cooled infrared sensors operating under low background conditions. By use of a digital computer, this model is used to rapidly select the optimal combination of design values. These parameters include load resistance, compensation resistance, com-pensation capacitance, chopping frequency and detector area to meet desired specifications of noise equivalent power, frequency response, dynamic range, and level of output noise. This computer-aided optimal design approach is demonstrated using a contemporary infrared sensor application.© (1980) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.