Demonstration of a Sub-Sampling Phase Lock Loop Based Microwave Source for Reducing Dick Effect in Atomic Clocks

We demonstrate a simple scheme of 6.835 GHz microwave source based on the sub-sampling phase lock loop(PLL). A dielectric resonant oscillator of 6.8 GHz is directly phase locked to an ultra-low phase noise 100 MHz oven controlled crystal oscillator(OCXO) utilizing the sub-sampling PLL. Then the 6.8 GHz is mixed with 35 MHz from an direct digital synthesizer(DDS) which is also referenced to the 100 MHZ OCXO to generate the final6.835 GHz signal. Benefiting from the sub-sampling PLL, the processes of frequency multiplication, which are usually necessary in the development of a microwave source, are greatly simplified. The architecture of the microwave source is pretty simple. Correspondingly, its power consumption and cost are low. The absolute phase noises of the 6.835 GHz output signal are-47 d Bc/Hz,-77 dBc/Hz,-104 dBc/Hz and-121 dBc/Hz at1 Hz, 10 Hz, 100 Hz and 1 kHz offset frequencies, respectively. The frequency stability limited by the phase noise through the Dick effect is theoretically estimated to be better than 5.0 × 10^-14τ^1/2 when it is used as the local oscillator of the Rb atomic clocks. This low phase noise microwave source can also be used in other experiments of precision measurement physics.

MULTIPLE FREQUENCIES ESTIMATION OF SIGNAL WITH SUB-SAMPLING

Based on time delay technology and MUSIC algorithm, a novel estimating multiple frequencies approach of signal with sampling rate which is least Nyquist sampling rate is presented in this paper. With choosing delay time properly, the estimated frequencies are unambiguous. Computer simulation confirms its availability.

A sub-sampling 4-bit 1.056-GS/s flash ADC with a novel track and hold amplifier for an IR-UWB receiver

A sub-sampling 4-bit 1.056-GS/s flash ADC with a novel track and hold amplifier（THA） in 0.13μm CMOS for an impulse radio ultra-wideband（IR-UWB） receiver is presented.The challenge is in implementing a sub-sampling ADC with ultra-high input signal that further exceeds the Nyquist frequency.This paper presents,to our knowledge for the second time,a sub-sampling ADC with input signals above 4 GHz operating at a sampling rate of 1.056 GHz.In this design,a novel THA is proposed to solve the degradation in amplitude and improve the linearity of signal with frequency increasing to giga Hz.A resistive averaging technique is carefully analyzed to relieve noise aliasing.A low-offset latch using a zero-static power dynamic offset cancellation technique is further optimized to realize the requirements of speed,power consumption and noise aliasing.The measurement results reveal that the spurious free dynamic range of the ADC is 30.1 dB even if the input signal is 4.2 GHz sampled at 1.056 GS/s.The core power of the ADC is 30 mW,excluding all of the buffers,and the active area is 0.6 mm^2.The ADC achieves a figure of merit of 3.75 pJ/conversion-step.

A high speed sampler for sub-sampling IR-UWB receiver

A high speed sampler for a sub-sampling impulse radio UWB receiver is presented. In this design, the sampler uses a time-interleaved topology with a single track and hold circuit, full custom clock generator, and off- set cancelled comparator. These three main blocks are also discussed and analyzed. The circuit was fabricated in 0.13 μm CMOS technology. Measurement results indicate that the sampler achieves a maximum 3 GS/s sampling rate. The power consumption of the sampler is 27 mW under a supply voltage of 1.2 V. The total chip area including pads is 1.4 × 0.97 mm^2.

Non Sub-Sampled Contourlet with Joint Sparse Representation Based Medical Image Fusion

Medical Image Fusion is the synthesizing technology for fusing multi-modal medical information using mathematical procedures to generate better visual on the image content and high-quality image output.Medical image fusion represents an indispensible role infixing major solutions for the complicated medical predicaments,while the recent research results have an enhanced affinity towards the preservation of medical image details,leaving color distortion and halo artifacts to remain unaddressed.This paper proposes a novel method of fusing Computer Tomography(CT)and Magnetic Resonance Imaging(MRI)using a hybrid model of Non Sub-sampled Contourlet Transform(NSCT)and Joint Sparse Representation(JSR).This model gratifies the need for precise integration of medical images of different modalities,which is an essential requirement in the diagnosing process towards clinical activities and treating the patients accordingly.In the proposed model,the medical image is decomposed using NSCT which is an efficient shift variant decomposition transformation method.JSR is exercised to extricate the common features of the medical image for the fusion process.The performance analysis of the proposed system proves that the proposed image fusion technique for medical image fusion is more efficient,provides better results,and a high level of distinctness by integrating the advantages of complementary images.The comparative analysis proves that the proposed technique exhibits better-quality than the existing medical image fusion practices.

Improved population mean estimator with exponential function under non-response

In this article,we consider a new family of exponential type estimators for estimating the unknown population mean of the study variable.We propose estimators taking advantage of the auxiliary variable information under the first and second non-response cases separately.The required theoretical comparisons are obtained and the numerical studies are conducted.In conclusion,the results show that the proposed family of estimators is the most efficient estimator with respect to the estimators in literature under the obtained conditions for both cases.

The Rb-Sr isochron of ore and pyrite sub-samples from Linglong gold deposit, Jiaodong Peninsula, eastern China and their geological significance

Here we report the first direct Rb-Sr dating of pyrites and ores using sub-sampling from lode gold deposits in Linglong, Jiaodong Peninsula, which is a supra-large lode gold deposit and propose this as a useful geochronological technique for gold mineralization with poor age constraint. The Rb-Sr data of pyrites yield an isochron age of (121.6±8.1) Ma, whereas those of ore and ore-pyrite spread in two ranges from 120.0 to 121.8 Ma and from 110.0 to 111.7 Ma. Studies of characteristic of gold deposit and microscopy of pyrite and quartz indicate that the apparent ages of ore and ore-pyrite are not isochron ages, only mixed by two end members, i.e. the primitive hydrothermal fluids and wall rocks, whereas the isochron age of pyrite sub-samples constrains the age of gold mineralization (121.6±8.1) Ma, i.e. early Cretaceous, which is in good agreement with the published SHRIMP zircon U-Pb ages.