scholarly journals Origin of Major L-Band Interference Received by the HALCA Space Radio Telescope

2001 ◽  
Vol 196 ◽  
pp. 335-340
Author(s):  
S. Yu. Lioubtchenko ◽  
M. V. Popov ◽  
H. Hirabayashi ◽  
H. Kobayashi
Keyword(s):  
Atlantic Ocean ◽  
Radio Telescope ◽  
Frequency Resolution ◽  
Frequency Range ◽  
Simple Criterion ◽  
Space Radio Telescope ◽  
Geostationary Satellites ◽  
L Band ◽  
Satellite Service ◽  
Tolerable Level

About 40 hours of observing data received by the space radio telescope HALCA at L-band (1.6 GHz) were analyzed in order to investigate interference received by the space radio telescope. Autocorrelation spectra for this study were specially prepared at the DRAO S2-correlator with a 7.8125 kHz frequency resolution in each 16 MHz channel. It was found that during 20% of the observing time the interfering signal was above the tolerable level of 1% of total receiver noise in a 16 MHz channel. The major source of interference is identified with uplink communication from ships to geostationary satellites in the International Maritime Satellite service (INMARSAT). The frequency range allocated for INMARSAT is 1636.5–1645.0 MHz. INMARSAT uses four geostationary satellites, two of which are located above the Atlantic Ocean where the strongest interference was observed. To avoid this interference it is recommended to move the HALCA observing frequency range from the currently used 1634–1666 MHz to 1645–1677 MHz. A simple criterion is proposed to predict harmful interference from INMARSAT. This criterion may be used in scheduling of future HALCA observations at L-band.

scholarly journals SPAN512: A new mid-latitude pulsar survey with the Nançay Radio Telescope

2012 ◽  
Vol 8 (S291) ◽  
pp. 375-377 ◽  
Author(s):  
Gregory Desvignes ◽  
Ismaël Cognard ◽  
David Champion ◽  
Patrick Lazarus ◽  
Patrice Lespagnol ◽  
...  
Keyword(s):  
Radio Telescope ◽  
Large Scale ◽  
High Time ◽  
Frequency Resolution ◽  
Integration Time ◽  
Sensitivity Limit ◽  
Long Period ◽  
Large Bandwidth ◽  
L Band ◽  
Better Than

AbstractWe present an ongoing survey with the Nançay Radio Telescope at L-band. The targeted area is 74° ≲ l < 150° and 3.5° < |b| < 5°. This survey is characterized by a long integration time (18 min), large bandwidth (512 MHz) and high time and frequency resolution (64 μs and 0.5 MHz) giving a nominal sensitivity limit of 0.055 mJy for long period pulsars. This is about 2 times better than the mid-latitude HTRU survey, and is designed to be complementary with current large scale surveys. This survey will be more sensitive to transients (RRATs, intermittent pulsars), distant and faint millisecond pulsars as well as scintillating sources (or any other kind of radio faint sources) than all previous short-integration surveys.

An L-Band Low Spurious Multi-Tuned Frequency Synthesizer

2013 ◽  
Vol 850-851 ◽  
pp. 441-444
Author(s):  
Fei Yan Mu ◽  
Bao Sheng Ye ◽  
Jie Lin ◽  
Zhong Jian Kang
Keyword(s):  
Frequency Synthesizer ◽  
Frequency Resolution ◽  
Frequency Range ◽  
Improve Performance ◽  
Loop Bandwidth ◽  
Spurious Suppression ◽  
Frequency Source ◽  
L Band ◽  
High Level ◽  
Better Than

This paper designs an L-Band 1880-1980 MHz low spurious Multi-tuned frequency synthesizer. The frequency source utilizes a DDS to directly stimulate a PLL, which makes a balance between the DDS and the PLL complementary to each other, realizing better specifications. Meanwhile, in order to achieve better spurious suppression with wide loop bandwidth, a method based on triple tuned algorithm is introduced. This algorithm avoids the high level spurious components triggered by the DDS falling in PLL’s bandwidth, refining the structure of the DDS-directly-stimulating PLL circuit frequency lock time and spurious to improve performance. The simulation result shows that the frequency source achieves a frequency range of 1880MHz～1980MHz, a frequency resolution of 1MHz, a spur better than 80dBc, a phase noise of -103dBc/Hz@100kHz and a frequency lock time less than 2 μs.

scholarly journals DESIGN OF CARTESIAN FEEDBACK RF POWER AMPLIFIER FOR L-BAND FREQUENCY RANGE

2008 ◽  
Vol 2 ◽  
pp. 207-222 ◽  
Author(s):  
Jit Singh Mandeep ◽  
Anand Lokesh ◽  
Syed Idris Syed Hassan ◽  
mohd nazri Mahmud ◽  
Mohd Fadzil Ain
Keyword(s):  
Power Amplifier ◽  
Rf Power ◽  
Frequency Range ◽  
Band Frequency ◽  
Rf Power Amplifier ◽  
L Band

scholarly journals Radio-frequency interference mitigating hyperspectral L-band radiometer

2017 ◽  
Vol 6 (1) ◽  
pp. 39-51 ◽  
Author(s):  
Peter Toose ◽  
Alexandre Roy ◽  
Frederick Solheim ◽  
Chris Derksen ◽  
Tom Watts ◽  
...  
Keyword(s):  
Radio Frequency ◽  
Thermal Emission ◽  
Absolute Error ◽  
Radio Frequency Interference ◽  
Frequency Range ◽  
Passive Remote Sensing ◽  
Extended Frequency ◽  
L Band ◽  
Radiometric Signal ◽  
Microwave Radiometers

Abstract. Radio-frequency interference (RFI) can significantly contaminate the measured radiometric signal of current spaceborne L-band passive microwave radiometers. These spaceborne radiometers operate within the protected passive remote sensing and radio-astronomy frequency allocation of 1400–1427 MHz but nonetheless are still subjected to frequent RFI intrusions. We present a unique surface-based and airborne hyperspectral 385 channel, dual polarization, L-band Fourier transform, RFI-detecting radiometer designed with a frequency range from 1400 through  ≈  1550 MHz. The extended frequency range was intended to increase the likelihood of detecting adjacent RFI-free channels to increase the signal, and therefore the thermal resolution, of the radiometer instrument. The external instrument calibration uses three targets (sky, ambient, and warm), and validation from independent stability measurements shows a mean absolute error (MAE) of 1.0 K for ambient and warm targets and 1.5 K for sky. A simple but effective RFI removal method which exploits the large number of frequency channels is also described. This method separates the desired thermal emission from RFI intrusions and was evaluated with synthetic microwave spectra generated using a Monte Carlo approach and validated with surface-based and airborne experimental measurements.

scholarly journals Status of the Thai 40-m Radio Telescope

2017 ◽  
Vol 13 (S337) ◽  
pp. 346-347
Author(s):  
Phrudth Jaroenjittichai
Keyword(s):  
Radio Telescope ◽  
Radio Astronomy ◽  
Time Domain ◽  
Phased Array ◽  
Low Frequency ◽  
Great Leap ◽  
Great Leap Forward ◽  
Astronomical Research ◽  
L Band ◽  
K Band

AbstractSince the first light of the 2.4-m Thai National Telescope in 2013, Thailand foresees another great leap forward in astronomy. A project known as “Radio Astronomy Network and Geodesy for Development” (RANGD) by National Astronomical Research Institute of Thailand (NARIT) has been approved for year 2017-2021. A 40-m radio telescope has been planned to operate up to 115-GHz observation with prime-focus capability for low frequency and phased array feed receivers. The telescope’s first light is expected in late 2019 with a cryogenics K-band and L-band receivers. RFI environment at the site has been investigated and shown to be at reasonable level. A 13-m VGOS telescope is also included for geodetic applications. Early single-dish science will focus on time domain observations, such as pulsars and transients, outbursts and variability of maser and AGN sources.

scholarly journals Probing the ionosphere by the pulsar B0950+08 with help of RadioAstron ground-space baselines

2019 ◽  
Vol 491 (4) ◽  
pp. 5843-5851
Author(s):  
Vladimir I Zhuravlev ◽  
Yu I Yermolaev ◽  
A S Andrianov
Keyword(s):  
Geomagnetic Storm ◽  
Radio Telescope ◽  
Preliminary Analysis ◽  
Very Long Baseline Interferometry ◽  
Electron Content ◽  
Ionospheric Disturbances ◽  
Total Electron ◽  
Space Radio Telescope ◽  
Long Baseline ◽  
Ionospheric Total Electron Content

ABSTRACT The ionospheric scattering of pulses emitted by PSR B0950+08 is measured using the 10-mRadioAstron Space Radio Telescope, the 300-m Arecibo Radio Telescope, and the 14 x 25-m Westerbork Synthesis Radio Telescope (WSRT) at a frequency band between 316 and 332 MHz. We analyse this phenomenon based on a simulated model of the phase difference obtained between antennas that are widely separated by nearly 25 Earth diameters. We present a technique for processing and analysing the ionospheric total electron content (TEC) at the ground stations of the ground-space interferometer. This technique allows us to derive almost synchronous half-hour structures of the TEC in the ionosphere at an intercontinental distance between the Arecibo and WSRT stations. We find that the amplitude values of the detected structures are approximately twice as large as the values for the TEC derived in the international reference ionosphere (IRI) project. Furthermore, the values of the TEC outside these structures are almost the same as the corresponding values found by the IRI. According to a preliminary analysis, the detected structures were observed during a geomagnetic storm with a minimum Dst index of ∼75 nT generated by interplanetary disturbances, and may be due to the influence of interplanetary and magnetospheric phenomena on ionospheric disturbances. We show that the Space Very Long Baseline Interferometry provides us with new opportunities to study the TEC, and we demonstrate the capabilities of this instrument to research the ionosphere.

scholarly journals How Geostar Radiodetermination Technology Minimizes Interference to Radioastronomy

1991 ◽  
Vol 112 ◽  
pp. 201-204
Author(s):  
Martin A. Rothblatt
Keyword(s):  
Radio Astronomy ◽  
Federal Communications Commission ◽  
Time Difference ◽  
Frequency Allocation ◽  
Sharing Rule ◽  
Frequency Bands ◽  
Geostationary Satellites ◽  
The Earth ◽  
Satellite Service

Geostar Radiodetermination Satellite Service (RDSS) measures the position of vehicles on the earth using geostationary satellites and time-difference ranging techniques. One of the RDSS frequency bands overlaps with a radio astronomy frequency allocation. The Federal Communications Commission (FCC) mandated a unique spacetime frequency sharing rule to minimize interference.

scholarly journals An Analysis of the Elements of an all Sky Survey

1985 ◽  
Vol 112 ◽  
pp. 405-410
Author(s):  
Edward T. Olsen ◽  
Anatoly Lokshin ◽  
Samuel Gulkis
Keyword(s):  
Observation Time ◽  
Frequency Resolution ◽  
Frequency Range ◽  
Broad Frequency Range ◽  
Sky Survey ◽  
Microwave Signals ◽  
Celestial Sphere

One component of the NASA search for microwave signals of extraterrestrial intelligent origin will be an all sky survey at a significantly low limiting flux over a broad frequency range. We are currently designing an overall strategy which will permit this survey to be: (1) carried out using existing antennas in less than 3 years of observation time, (2) uniform in sensitivity (within 0.5 db) over the celestial sphere for any given frequency, and (3) complete to 6×10−23 W/m2 or better over the frequency range 1.2GHz⩽ν⩽10GHz with a frequency resolution of 32 Hz.

scholarly journals Space-VLBI observations of OH masers

2002 ◽  
Vol 206 ◽  
pp. 105-111 ◽  
Author(s):  
Vyacheslav I. Slysh ◽  
Maxim A. Voronkov ◽  
Irina E. Val'tts ◽  
Victor Migenes ◽  
K.M. Shibata ◽  
...  
Keyword(s):  
Brightness Temperature ◽  
Lower Limit ◽  
Radio Telescope ◽  
Angular Resolution ◽  
Main Line ◽  
Radio Telescopes ◽  
Space Radio Telescope ◽  
Vlbi Observations ◽  
Interstellar Scattering

We report on the first space-VLBI observations of the OH masers in two main-line OH transitions at 1665 and 1667 MHz. The observations involved the space radio telescope on board the Japanese satellite HALCA and an array of ground radio telescopes. The maps of the maser region and images of individual maser spots were produced with an angular resolution of 1 mas, which is several times higher than the angular resolution available on the ground. The maser spots were only partly resolved and a lower limit to the brightness temperature 6 × 1012 K was obtained. The masers seem to be located in the direction of low interstellar scattering.

scholarly journals Pulsar Searches at Effelsberg

2004 ◽  
Vol 218 ◽  
pp. 133-134 ◽  
Author(s):  
B. Klein ◽  
M. Kramer ◽  
P. Müller ◽  
R. Wielebinski
Keyword(s):  
Radio Telescope ◽  
Galactic Center ◽  
Millisecond Pulsars ◽  
Highly Dispersed ◽  
L Band ◽  
Under Construction ◽  
5 Ghz ◽  
Key Aspects ◽  
Pulsar Searches

We report on the progress of our search for highly dispersed pulsars near the Galactic Center at 5 GHz using the 100-m radio telescope in Effelsberg. We also present key aspects of our new survey for millisecond pulsars at 21 cm in parts of the northern sky. This survey will greatly benefit from the L-band multibeam receiver and a new FFT-based backend which are currently under construction at the MPIfR.

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