DDS-Based Local Oscillator for Radio Telescope Receiver

2020 ◽  
Author(s):  
Eugene Alekseev ◽  
Vyacheslav Zakharenko ◽  
Vladislav Budnikov
Keyword(s):  
Radio Telescope ◽  
Local Oscillator

scholarly journals The multi frequency front end: a new type of front end for the Westerbork Synthesis Radio Telescope

1991 ◽  
Vol 131 ◽  
pp. 42-46
Author(s):  
G.H. Tan
Keyword(s):  
Radio Telescope ◽  
Local Oscillator ◽  
Frequency Bands ◽  
Front End ◽  
New Type

AbstractThe Westerbork Synthesis Radio Telescope will be equipped with new front ends. These front ends will cover 8 frequency bands in the range from 250 MHz to 8.6 GHz. For the frequency bands above 1.2 GHz the sensitivity of the instrument will be drastically improved. Two independent local oscillator systems make it possible to observe in two frequency bands simultaneously.

scholarly journals Radio telescope total power mode: improving observation efficiency

2020 ◽  
Vol 643 ◽  
pp. A126
Author(s):  
Laurent Pagani ◽  
David Frayer ◽  
Bruno Pagani ◽  
Charlène Lefèvre
Keyword(s):  
Radio Telescope ◽  
Signal To Noise Ratio ◽  
Local Oscillator ◽  
Reduction Technique ◽  
Total Power ◽  
Line Intensities ◽  
Front End ◽  
Power Mode ◽  
Baseline Removal ◽  
Green Bank Telescope

Aims. Radio observing efficiency can be improved by calibrating and reducing the observations in total power mode rather than in frequency, beam, or position-switching modes. Methods. We selected a sample of spectra obtained from the Institut de Radio-Astronomie Millimétrique (IRAM) 30-m telescope and the Green Bank Telescope (GBT) to test the feasibility of the method. Given that modern front-end amplifiers for the GBT and direct Local Oscillator injection for the 30 m telescope provide smooth pass bands that are a few tens of megahertz in width, the spectra from standard observations can be cleaned (baseline removal) separately and then co-added directly when the lines are narrow enough (a few km s−1), instead of performing the traditional ON minus OFF data reduction. This technique works for frequency-switched observations as well as for position- and beam-switched observations when the ON and OFF data are saved separately. Results. The method works best when the lines are narrow enough and not too numerous so that a secure baseline removal can be achieved. A signal-to-noise ratio improvement of a factor of √2 is found in most cases, consistent with theoretical expectations. Conclusions. By keeping the traditional observing mode, the fallback solution of the standard reduction technique is still available in cases of suboptimal baseline behavior, sky instability, or wide lines, and to confirm the line intensities. These techniques of total-power-mode reduction can be applied to any radio telescope with stable baselines as long as they record and deliver the ONs and OFFs separately, as is the case for the GBT.

Fundamentals of a Radio Telescope

2020 ◽  
pp. 33-55
Author(s):  
Kim Ho Yeap ◽  
Kazuhiro Hirasawa
Keyword(s):  
Radio Telescope ◽  
Local Oscillator ◽  
Orthogonal Polarization ◽  
Processing Unit ◽  
Radio Waves ◽  
Front End ◽  
Astronomical Instruments ◽  
Corrugated Horn ◽  
Working Principle ◽  
Feed Horns

In radio astronomy, radio telescopes are used to collect radio waves emanated from cosmic sources. By analyzing these signals, the properties of the sources could be unraveled. A telescope typically consists of the following astronomical instruments: a primary and a secondary reflector, receiver optics which usually includes a lens or a pair of mirrors and a pair of feed horns (one for each orthogonal polarization [or simply a corrugated horn with an orthomode transducer OMT]), waveguides, a mixer circuit, a local oscillator, amplifiers, a detector circuit, and a data processing unit. This chapter provides a concise but complete overview of the working principle of the astronomical instruments involved in the construction of a radio telescope. The underlying physics of the components in a radio telescope, ranging from the antenna to the front-end and back-end systems, are illustrated.

Interpretation of the Filament Depression at Millimetric and Centimetric Wavelengths

1979 ◽  
Vol 44 ◽  
pp. 131-134
Author(s):  
A. Raoult ◽  
P. Lantos ◽  
E. Fürst
Keyword(s):  
Radio Telescope ◽  
Active Regions ◽  
Simple Shape ◽  
Quiet Sun ◽  
Unstable Process

The depressions at centimetric and millimetric wavelengths associated with the filaments are studied using already published maps as well as unpublished observations from the Effelsberg 100 m radio telescope of the M.P.I., Bonn. The study has been restricted to large Ha quiescent prominences of relatively simple shape, situated far from the limb and from active regions. The data has been reduced employing one method whose main characteristics are choice of a local quiet sun definition and avoidance of the unstable process of deconvolution.

USE OF A CO2LASER AS A LOCAL OSCILLATOR FOR A 10 MICRON HETERODYNE DETECTION

1987 ◽  
Vol 48 (C7) ◽  
pp. C7-569-C7-571
Author(s):  
A. DELAHAIGUE ◽  
D. COURTOIS ◽  
C. THIEBEAUX ◽  
H. LE CORRE
Keyword(s):  
Local Oscillator ◽  
Heterodyne Detection
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