scholarly journals Comparison of Radio Interferometers with Analog and Digital Extraction of Recorded Signal

2020 ◽  
Vol 23 (2) ◽  
pp. 6-18
Author(s):  
N. E. Kol'tso ◽  
S. A. Grenkov ◽  
L. V. Fedotov
Keyword(s):  
Frequency Band ◽  
Group Delay ◽  
Narrow Band ◽  
Digital Signal ◽  
Intermediate Frequency ◽  
Noise Signal ◽  
Signal Extraction ◽  
Radio Telescopes ◽  
Long Baseline ◽  
Band Signal

Introduction. Radio telescopes of Very Long Baseline Interferometry (VLBI) networks usually record several signals with relatively narrow (up to 32 MHz) bands, which are extracted by means of base band converters (BBC) from an analog noise signal of an intermediate frequency (IF) with bands up to 1 GHz. When processing data, frequency band synthesis is used. At new small radio telescopes (for example, RT-13), directly wideband IF signals are digitized. An ability to connect the RT-13 radio telescope to the “Quasar” VLBI complex and to international VLBI networks provides by a digital narrow-band signal extraction module developed in 2019.Aim. Determining the measuring accuracy of an interferometric group delay of a signal by a radio interferometer with a digital narrow-band signal extraction module and comparing the sensitivity of interferometers with analog and digital signal extraction systems.Materials and methods. Sensitivity losses of interferometers with different systems for detecting recorded signals were calculated. The accuracy of a multi-channel interferometer with the synthesis of a frequency band and of an interferometer with recording of digital broadband IF signals without band synthesis was compared. The results were confirmed by VLBI observations in the observatories of the “Quasar” complex.Results. When replacing the analog system of signal extraction with digital system the sensitivity losses of the interferometer were slightly reduced. The measurement accuracy of the interferometric group delay had not changed. Accuracy increased when digitally recording broadband IF signals and when synthesizing a frequency band significantly larger than the IF bandwidth. Conditions and minimum synthesized bands were determined under which the accuracy of the interferometer with the registration of narrowband signals can be higher than the accuracy of the interferometer with the registration of wideband IF signals.Conclusion. The problem of combining RT-13 radio telescopes with VLBI networks with recording of video frequency signals was solved. The efficiency of the installation of digital signal conversion systems at radio telescopes was shown.

ON SOFTWARE IMPROVEMENT OF IMAGE CHANNEL SUPPRESSION IN SDR RECEIVERS WITH ANALOG CONVERSION TO A LOW INTERMEDIATE FREQUENCY

2020 ◽  
pp. 45-52
Author(s):  
A. S. Yurkov
Keyword(s):  
Signal Processing ◽  
Direct Method ◽  
Digital Signal ◽  
Intermediate Frequency ◽  
Algebraic Equations ◽  
Recursive Filter ◽  
Linear Algebraic Equations ◽  
Reception Channel ◽  
Image Channel ◽  
Parasitic Phase

A method for digital signal processing in SDR receivers with analog conversion to a low intermediate frequency is proposed. In contrast to known systems, the proposed approach does not consider parasitic phase and amplitude distortions, but uses the direct method minimizing of the signal of the mirror reception channel. Generally speaking, this can be done simultaneously at several frequencies. It is shown that in computational terms, this is reduced to signal processing by an algorithm similar to a digital non-recursive filter, and to determine its coefficients, it is sufficient to solve a system of linear algebraic equations.

scholarly journals Eliminating unwanted signals in sound by using digital signal processing system

2020 ◽  
Vol 18 (2) ◽  
pp. 829
Author(s):  
Amer T Saeed ◽  
Zaid Raad Saber ◽  
Ahmed M. Sana ◽  
Musa A. Hameed
Keyword(s):  
Signal Processing ◽  
Digital Signal Processing ◽  
Digital Filters ◽  
Processing System ◽  
Digital Signal ◽  
Noise Signal ◽  
Time Range ◽  
Signal Processing System ◽  
Digital Signal Processing System ◽  
Sound Files

<p><a name="_Hlk536186602"></a><span style="font-size: 9pt; font-family: 'Times New Roman', serif;">Unwanted signals or noise signals in sound files are considered one of the major challenges and issues for a thousand users. It is impossible to reduce or remove these noise signals without identifying their types and ranges. Therefore, to address one of the big problems in the digital or analogue communication, which is noise signals or unwanted signals, an adaptive selection method and noise signal removal algorithm are proposed in this research. The proposed algorithm is done through specifying the types of undesirable signals, frequency, and time range, then utilizing digital signal processing system which includes design several types of digital filters based on the types and numbers of unwanted signals. Four digital filters are used in this research to remove noise signals from the sound file by implementing the proposed algorithm using Matlab Code. Results show that our proposed algorithm was done successfully and the whole noise signals were removed without any negative consequence in the output sound signal. </span><span style="font-family: 'Times New Roman', serif; font-size: 9pt;">Unwanted signals or noise signals in sound files are considered one of the major challenges and issues for a thousand users. It is impossible to reduce or remove these noise signals without identifying their types and ranges. Therefore, to address one of the big problems in the digital or analogue communication, which is noise signals or unwanted signals, an adaptive selection method and noise signal removal algorithm are proposed in this research. The proposed algorithm is done through specifying the types of undesirable signals, frequency, and time range, then utilizing digital signal processing system which includes design several types of digital filters based on the types and numbers of unwanted signals. Four digital filters are used in this research to remove noise signals from the sound file by implementing the proposed algorithm using Matlab Code. Results show that our proposed algorithm was done successfully and the whole noise signals were removed without any negative consequence in the output sound signal.</span></p>

scholarly journals Improvement of description of finding out a narrow-band signal with a hindrance in frequency

2011 ◽  
Vol 1 (27) ◽  
Author(s):  
В.М. Шутко ◽  
Ю.М. Барабанов ◽  
C.Л. Квасюк
Keyword(s):  
Narrow Band ◽  
Band Signal

scholarly journals Narrow Band Power Line Communication (NB-PLC) frequency band review under residential load noise

2019 ◽  
Vol 1402 ◽  
pp. 033102
Author(s):  
K G H Mangunkusumo ◽  
N W Priambodo ◽  
K M Tofani ◽  
G Supriyadi
Keyword(s):  
Frequency Band ◽  
Narrow Band ◽  
Power Line ◽  
Power Line Communication ◽  
Band Power ◽  
Load Noise

Design of 6-gon-Shaped Notch Filter for Cognitive Radio Applications

2018 ◽  
Vol 27 (06) ◽  
pp. 1850085
Author(s):  
A. Uma Maheswari ◽  
K. Latha
Keyword(s):  
Cognitive Radio ◽  
Return Loss ◽  
Group Delay ◽  
Bandpass Filter ◽  
Narrow Band ◽  
Notch Filter ◽  
Structural Features ◽  
Fractional Bandwidth ◽  
Multiple Mode ◽  
Mode Resonator

This paper presents a 6-gon-shaped bandpass and notch filters for Cognitive Radio (CR) applications. The bandpass filter consists of a 6-gon-shaped multiple mode resonator with interdigital coupling at both ends. The notch filter is derived from bandpass filter by embedding four identical Embedded Open Stubs (EOS) nearby the multiple mode resonators that introduce narrow band suppression in the desired passband. Such bandpass filter with notching band is required in practical CR systems in order to effectively sense the spectrum and avoid the interference between the systems working in same environment with the same frequency. The filter is simulated using an electromagnetic solver, IE3D. The group delay obtained for bandpass filter is below 0.2[Formula: see text]ns. With the above structural features, the overall dimension of the filter is [Formula: see text][Formula: see text]mm2 and the fractional bandwidth (FBW) of the proposed bandpass filter is more than 100% with optimal performances in terms of insertion loss, return loss, group delay and phase.

The Design of TIG-AWP Based on Inverter and DSP

2012 ◽  
Vol 236-237 ◽  
pp. 484-487
Author(s):  
Chun Tian Li ◽  
Yi Luo ◽  
Chang Hua Du ◽  
Gui Sheng Gan
Keyword(s):  
Digital Signal Processor ◽  
Pulse Width Modulation ◽  
Welding Process ◽  
Feedback Regulation ◽  
Digital Signal ◽  
Intermediate Frequency ◽  
Control Circuit ◽  
Experimental Result ◽  
Modulation Control ◽  
The Stability

The main circuit of tungsten inert gas (TIG) arc welding power (AWP), which is mode of the inverter for intermediate frequency and full-bridge IGBT, is designed based on DSP (Digital Signal Processor). The control designing, also based on DSP, include the sampling signal circuit, the control circuit for external characteristics, the PWM (Pulse-Width -Modulation) control circuit of TIG-AWP, the IGBT drive circuit and etc. This designing can strengthen the reliability of feedback regulation property on TIG-AWP; can enhance the stability of the parameters from the power system. The experimental result shows that the designed TIG-AWP has good feedback regulation and stability properties during the TIG welding process.

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