Table of Contents
What is pulse compression ratio?
The pulse compression ratio, which is the duration of the long pulse divided by the duration of the short (compressed) pulse, is equal to BT. Frequency and phase modulations have both been used for pulse compression.
What is pulse compression technique?
Pulse compression is a signal processing technique commonly used by radar, sonar and echography to increase the range resolution as well as the signal to noise ratio. This is achieved by modulating the transmitted pulse and then correlating the received signal with the transmitted pulse.
What is stretch processing?
Stretch processing is a way of processing large bandwidth waveforms using narrow band techniques. For our present purposes we want to look at stretch processing as applied to LFM waveforms.
What are range Sidelobes?
Range-time sidelobes are the result of convolving the radar return with the non-ideal filter response (i.e some energy remains outside the desired pulse bandwidth).
Why do we need pulse compression?
Pulse compression allows a radar system to transmit a pulse of relatively long duration and low peak power to attain the range resolution and detection performance of a short-pulse, high-peak power system.
What is LFM signal?
In modern radar and communication systems, Linear Frequency Modulation (LFM) signal is a kind of typical non- stationary signal. It is important to recognition and estimate the parameter of LFM signal fast and precisely for radar electronic reconnaissance and resistance system.
Why do sidelobes occur?
Sidelobes are an unfortunate reality of all directional antennas. They are a consequence of nature and are directly related to diffraction effects in light – and there are similar effects in sound and water waves. Diffraction occurs whenever there is a sharp discontinuity in a radiating or reflecting surface.
Are sidelobes desirable in primary radar?
The sides lobes are an important parameter and techniques in a radar system are used to reduce these such as amplitude weighting. So in the radar system they are not desirable, and reducing to a minimum is important.
What is pulse suppression?
Abstract. A practical digital clock noise mitigation technique based on pulse removal is presented. Clock frequency is increased to generate an excess pulse, which is removed in order to match the number of pulses in an average time frame.
What is an LFM pulse?
This technique is called Pulse Compression and is used widely in Radar applications where high peak power is undesirable. This paper introduces a new radar pulse compression system, using a type of Linear Frequency Modulation (LFM) signal which lacks components around zero frequency.
What is chirp modulation?
Chirp modulation This type of modulation employs sinusoidal waveforms whose instantaneous frequency increases or decreases linearly over time. These waveforms are commonly referred to as linear chirps or simply chirps. Hence the rate at which their frequency changes is called the chirp rate.
How are sidelobes formed?
Diffraction occurs whenever there is a sharp discontinuity in a radiating or reflecting surface. On the antenna arrays so far described we have a number of elements all radiating and suddenly the antenna ends, which creates diffraction or sidelobe type effects.
How do you stop grating lobes?
In previous metasurface apertures, grating lobes were suppressed by using high dielectrics (to decrease the wavelength of the guided wave) along with dense element spacing.
Why do antennas have sidelobes?
In a directional antenna in which the objective is to emit the radio waves in one direction, the lobe in that direction is designed to have a larger field strength than the others; this is the “main lobe”. The other lobes are called “sidelobes”, and usually represent unwanted radiation in undesired directions.
What is an LFM waveform?
An LFM waveform is a signal in which a frequency increases (up-chirp) or decreases (down-chirp) linearly with time, and the LFM waveform is obtained by. x ( t ) = exp j 2 π f 0 t + 1 2 α t 2 · 1 [ 0 , T p ] ( t )
What is a LFM signal?
INTRODUCTION. In modern radar and communication systems, Linear Frequency Modulation (LFM) signal is a kind of typical non- stationary signal. It is important to recognition and estimate the parameter of LFM signal fast and precisely for radar electronic reconnaissance and resistance system.
What is spreading factor?
The spreading factor (SF) impacts the communication performance of LoRa, which uses an SF between 7 and 12. A larger SF increases the time on air, which increases energy consumption, reduces the data rate, and improves communication range.
What is the pulse compression ratio?
The pulse compression ratio, which is the duration of the long pulse divided by the duration of the short (compressed) pulse, is equal to BT. Frequency and phase modulations have both been used for pulse compression. Amplitude modulation could also be employed, in principle, but it is seldom found in practical pulse compression systems.
What is phase-coded pulse compression?
Phase-coded pulse compression: In the phase-coded pulse compression, a long pulse with duration Tp is divided into N subpulses, called chips, of width Tc. The phase of each subpulse is chosen to be either 0 or π radian.
How is a compressed pulse produced?
The received signal is passed through a matched filter to produce a compressed pulse of width 1/B. The pulse compression ratio, which is the duration of the long pulse divided by the duration of the short (compressed) pulse, is equal to BT. Frequency and phase modulations have both been used for pulse compression.
What is the purpose of a pulse compression device?
Pulse compression. Pulse compression is a signal processing technique commonly used by radar, sonar and echography to increase the range resolution as well as the signal to noise ratio.