Proceedings of the British Society for Research into Learning Mathematics

The Collaboration for Astronomy Signal Processing and Electronics Research (CASPER) has been working for a decade to reduce the time and cost of designing, building and deploying new digital radio-astronomy instruments. Today, CASPER open-source technology powers over 45 scientific instruments worldwide, and is used by scientists and engineers at dozens of academic institutions. In this paper we catalog the current offerings of the CASPER collaboration, and instruments past and present built by CASPER users and developers. We describe the ongoing state of software development, as CASPER looks to support a broader range of programming environments and hardware and ensure compatibility with the latest vendor tools.

A Decade of Developing Radio-Astronomy Instrumentation using CASPER Open-Source Technology

This review gives an introduction to spectrometers and discusses their use within radio astronomy. While a variety of technologies are introduced, particular emphasis is given to digital systems. Three different types of digital spectrometers are discussed: autocorrelation spectrometers, Fourier transform spectrometers, and polyphase filterbank spectrometers. Given their growing ubiquity and significant advantages, polyphase filterbanks are detailed at length. The relative advantages and disadvantages of different spectrometer technologies are compared and contrasted, and implementation considerations are presented.

Spectrometers and Polyphase Filterbanks in Radio Astronomy

Solar radio spectra and their temporal evolution provide important clues to understand the energy release and electron acceleration process in the corona, and are usually used to diagnose critical parameters such as the magnetic field strength. However, previous solar radio telescopes cannot provide high-quality data with complete frequency coverage. Aiming to develop a generalized solar radio observing system, in this study, we designed a digital receiving system which could capture solar radio bursts with a broad bandwidth and a large dynamic range. A dual-channel analog-to-digital converter (ADC) printed circuit board assembly (PCBA) with a sampling rate of 14-bit, 1.25 Giga samples per second (GSPS) cooperates with the filed-programmable-gate-array (FPGA) chip XC7K410T in the design. This receiver could realize the real-time acquisition and preprocessing of high-speed data of up to 5 GB/s, which ensures high time as well as spectral resolutions in observations. This receiver has been used in the solar radio spectrometer working in the frequency range of 35 to 40 GHz in Chashan Solar Observatory (CSO) established by Shandong University, and will be further developed and used in the solar radio interferometers. The full-power bandwidth of the PCBA in this receiving system could reach up to 1.5 GHz, and the performance parameters (DC 1.5GHz) are obtained as follows: spur free dynamic range (SFDR) of 64.7 78.4 dB, signal-to-noise and distortion (SINAD) of 49.1 57.2 dB, and effective number of bits (ENOB) of >7.86 bit. Based on the receiver designed, real-time solar microwave dynamic spectra have been acquired and more solar microwave bursts with fine spectral structures are hopeful to be detected in the coming solar maximum.

A broadband digital receiving system with large dynamic range for solar radio observation

The Graphics Processing Unit (GPU) has become an integral part of astronomical instrumentation, enabling high-performance online data reduction and accelerated online signal processing. In this paper, we describe a wide-band reconfigurable spectrometer built using an off-the-shelf GPU card. This spectrometer, when configured as a polyphase filter bank (PFB), supports a dual-polarization bandwidth of up to 1.1 GHz (or a single-polarization bandwidth of up to 2.2 GHz) on the latest generation of GPUs. On the other hand, when configured as a direct FFT, the spectrometer supports a dual-polarization bandwidth of up to 1.4 GHz (or a single-polarization bandwidth of up to 2.8 GHz).

/pdf/a-gpu-based-wide-band-radio-spectrometer-34u0fa54hy.pdf

A GPU-Based Wide-Band Radio Spectrometer

Wavelet based recognition for pulsar signals

The sensitivity of our pulsar observation system with typical integration time of 16 minutes has reached 0.4 mJy after we have upgraded the receiver cooling system of NanShan 25-m radio telescope (NSRT) at Xinjiang Astronomical Observatory (XAO) in 2002. About 280 pulsars were observed after the upgrade. The NanShan station pulsar data is transmitted to the data center at XAO headquarters via a 300Mb/s dedicated data link for long-term storage, and the remote backup is realized by synchronous data transmission between NanShan station and XAO headquarters. Metadata extraction, archiving, and releasing are completed by the data release servers which are located in XAO headquarters. At present, more than 84000 pulsar observation data files in the PSRFITS format have been released with a maximum file size of 1GB. XAO pulsar data online service provides cone search and multiobject constraint query. We have published our data based on Virtual Observatory (VO) standards. The online pulsar data service is registered in the International Virtual Observatory Alliance’s Registry. Users can access the data through common VO tools.

/pdf/the-xinjiang-astronomical-observatory-nsrt-pulsar-data-52hbpbtkeu.pdf

The XinJiang Astronomical Observatory NSRT Pulsar Data Archive

The dynamic geometry system is a typical CAI application that utilizes computer technology to guide geometry learning. In our research of the dynamic geometry on handheld devices, we have successfully implemented a brand new system called "Mathematic Sketchpad", a part of the Noah graphing calculator. Compared to other similar products like TI or CASIO graphing calculator, the sketchpad owns features such as advanced mathematic functions, true color screen and touch-pen operations that emphasize powerful and user-friendly purpose. Different from PC software, the sketchpad have advantages such as portability, mobile teaching and classroom interactive teaching that are good for mathematics education. Besides, the dynamic geometry system on "Mathematic Sketchpad" is built on computer algebra basis that allows numeric-symbolic combination to handle even difficult tasks. In this paper, we will briefly introduce the implementation of sketchpad, corresponding theories that make dynamic geometry possible, and give some examples that can be used in teaching.

Dynamic Geometry in Graphing Calculator

To test the efficiency of different programming languages and find out the suitable one for solving the calculation problem of spherical distance between two points, we have developed serial and parallel calculate algorithms according C, Python programming languages, and tested the execution speed of all algorithms. As for the inefficiency of Python, we improved the performance by replacing some functions and variables of Python procedure with Cython. The experimental results show that Python programs can get the same execution efficiency as C language does with the same Large-scale computing environment.

Program performance test based on different computing environment

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