This paper introduces a comparison system of cold noise generator, mainly describes the operational principle, system design, basic method, error analysis of the system and the application examples.

With the development of computing technology and cryptography, high-speed digital physical noise generator is urgently required in cryptography at present.

According to the result of uncertainty analysis, we think that using spectrum analyzer to calibrate noise generator is practicable in certain conditions.

Annex B to ITU-T recommendation G. 729 defines the Voice Activity Detection(VAD), Discontinuous Transmission(DTX) and Comfort Noise Generator(CNG) algorithms.

Based on the M series and the inverse M series, this paper puts forward the structure of the multi dimensional inverse M series generator, which is approximate to a cyclic white noise generator with D.

A formula is derived that linearly relates this duration to the signal from the antenna, in which the noise temperatures of the semiconductor noise generator and the matched load act as two reference values.

A large-aperture shf blackbody noise generator with a brightness temperature of 104 K

Correction to the noise temperature of a waveguide thermal noise generator due to nonuniform heating of the channel

The temperature distribution in the waveguide channel of a millimeter-band thermal noise generator is calculated.

Calculation of the temperature distribution along the transmission line of a thermal noise generator

A low frequency noise generator using radioactive material as its noise source is dis-cussed in this paper. Four types of noise, i.e., the Gaussian, Rayleigh, random impulses and random square wave signals with poisson distribution can be obtained. The output of the generator is sufficiently large and stationary for analoque computation.

A thermal standard noise, gas discharge noise generators and a calibrating radiometer for 4mm band are discussed. Advantages and weak points of both the total-power and Dicke radiometers are evaluated. A calibrating system of total-power radiometer with IF attenuator has been set up, and its equalization and error equations are derived and analysed in this paper. An advantage of this system is that it can be used in all frequency bands. Furthermore, it uses fewer waveguide components, and the microwave...

A thermal standard noise, gas discharge noise generators and a calibrating radiometer for 4mm band are discussed. Advantages and weak points of both the total-power and Dicke radiometers are evaluated. A calibrating system of total-power radiometer with IF attenuator has been set up, and its equalization and error equations are derived and analysed in this paper. An advantage of this system is that it can be used in all frequency bands. Furthermore, it uses fewer waveguide components, and the microwave precision attenuator can be substituted by a precision IF attenuator. This is of practical significance for millimeter and submillimeter bands. This system, when used to calibrate gas discharge noise generators, gives an excess-noise ratio of 16.2 dB, the total error being ±0.45 dB. If the accuracy of the IF attenuator is 0.02 dB, the total crror will be ±0.3 dB.

Simulating the stellar observation is a sort of very useful implement for the analysis and the reduction of photon counting data on Transit Instrument. In some cases, it is difficult to estimate the errors directly from the observed data because the data noise and the function of real signals is complicated. With the method of simulating observation, this problem would be solved. And the simulated data can be used to compare with the observed data in order to find out an experiential method for estimations....

Simulating the stellar observation is a sort of very useful implement for the analysis and the reduction of photon counting data on Transit Instrument. In some cases, it is difficult to estimate the errors directly from the observed data because the data noise and the function of real signals is complicated. With the method of simulating observation, this problem would be solved. And the simulated data can be used to compare with the observed data in order to find out an experiential method for estimations. The simulated data can be also used to study the reduction methods from a various number of methods and to determine the optimal one in order to get the best precision. The simulating observation is also worthy to study the instrumental accuracy and the influence of the hardware upon the precision of the observed data and their determinations. It has been found that the slit micrometer is very important to the precision. The optimal size of the slit is existed. With the method of simulation, the optimal slit size can be calculated. So that, better precision of the stellar observation will be achieved and fainter stars can be observed. In this paper, the simulating principle and process of photon counting data of meridian observations with one or muitislit micrometer will be discussed. In general, the output signal of meridian photon counting observation can be expressed as a convolution of the image profile function plus the background photon counts and their noise signal(cf.equation <1>)with a trapezoid weighting function.Because the atmospheric agitation is a random process, the image profile will be a gaussian function. The weighting function is determined by the constants of the slit, δ and the time interval of sampling. Asume Am is the amplitude of starlight counts with magnitude m_v, in order to get Am., we can observe the stars with magnitude m_0, and get their amplitude A_0. Am will be calculated from A_0. The background counts b can not only be experientially but also analytically determined. Using a Poisson random noise generator, the noise signal will be got. When the constants of the slit, the time interval of sampling,the variance of the image profile,the magnitude of the observed star and its declination are known, we can therefore simulate the meridian photon counting observation of the star. As an exaple, the application of the simulating method will be discussed. First, we analyse the image profile of a star, Simulated data will be used to find an experiential equation for the meridian observation on the Transit Instrument at Shaanxi Astronomical Observatory. This equation expresses a relation of an estimated parameter to the variance of a gaussian distribution. In comparison with the simulated data, the variance σ~2 of image profile can be calculated from the observed data of a star. By means of this method, we got σ=0″.7～1″.9. The second example is to discuss the influence of the slit width on the determining precision of meridian time. By experiences, we come to. the conclusion that the slit width of 20.6265 (used in the Transit Instrument at Shaanxi Astronomical Observatory) is not ideal one for stellar meridian observation. If the slit with 5″.width of the transparent part and with 15″ width of the reflective part were used, the determined precision of meridian time would be better,and fainter stars would be observed.