What is an LFM pulse?
This paper examines the Linear Frequency Modulation (LFM) pulse compression. technique on a generic signal model. Pulse compression allows achieving the. performance of a shorter pulse using a longer pulse and hence gain of a large spectral. bandwidth.
How is pulse compression achieved?
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.
How do you calculate 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 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 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 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.
What is PFM mode?
PFM mode is also referred to as power save mode in TI data sheets. A converter operating in power save mode uses PFM at light load currents and pulse width modulation (PWM) at heavier load currents. This type of operation allows the converter to maintain high efficiency over a wide range of output current.
What is LFM modulation?
A Linear Frequency Modulation (LFM) waveform is the most popular type of pulse compression and has been adopted for many radar systems due to its ease of hardware implementation and good range resolution.
What is non linear frequency modulation?
Nonlinear Frequency Modulated (NLFM) waveforms utilize a nonlinear modulation function to achieve a tapered spectrum which results in low Auto-Correlation Function (ACF) sidelobes.
In which radar the frequency varies linearly over the pulse time?
A linear FM chirp has a linear time frequency description as its frequency varies linearly over the pulse duration of the signal. In case of LFM frequency increases (up chirp) or decreases (down chirp) linearly with time. Following figure shows the time frequency characteristics of the signal.
What is linear modulation signal?
Linear modulation is a scheme in which the base-band signal is linearly related to the modulated signal; that is, the modulated signal reflects a continuously variable range of values of the base-band signal. Linear modulation has very limited use in space systems.
What is PFM and PWM?
Pulse-frequency modulation (PFM) is a modulation method for representing an analog signal using only two levels (1 and 0). It is analogous to pulse-width modulation (PWM), in which the magnitude of an analog signal is encoded in the duty cycle of a square wave.
What is DCM and CCM?
Continuous-conduction-mode (CCM) means that the current in the energy transfer inductor or transformer never goes to zero between switching cycles. In discontinuous-conduction-mode (DCM) the current goes to zero during part of the switching cycle.
Why FM is non linear modulation?
For Frequency Modulation, the relationship between received power and quality is non-linear (Rapid increase in quality for an increase in received power). For Amplitude Modulation there is a linear relationship between the received signal quality and received signal power.
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.
Why is PWM important?
The main advantage of PWM is that power loss in the switching devices is very low. When a switch is off there is practically no current, and when it is on and power is being transferred to the load, there is almost no voltage drop across the switch.