Contents
What is LFM waveform?
LFM waveform commonly known as linear chirps are the most commonly used waveform in radar systems as it can be easily generated, have good range resolution and more doppler tolerant than NLFM. In case of LFM frequency increases (up chirp) or decreases (down chirp) linearly with time.
What is linear frequency modulation?
The linear frequency modulation is used to resolve two small targets that are located at long range with very small separation between them. The primary focus of this paper is the time frequency analysis and generation of LFM waveform using Direct Digital Chirp Synthesis (DDCS).
What is LFM pulse?
Abstract: Radar system uses Pulse compression techniques to provide the benefits of larger range detection and high range resolution. In the past several pulse compression techniques are used, out of which the well known method is linear frequency modulation (LFM).
What is non linear frequency modulation?
Non Linear Frequency Modulation (NLFM) method can suppress the peak sidelobe level without additional windowing function. NLFM has a variable frequency deviation function due to the relation between frequency and time of the signal which is not linear so that it is possible to suppress of peak sidelobe level.
Which pulse modulation technique is least expensive?
Which pulse modulation technique is least expensive? Explanation: Out of all the pulse modulation techniques, Pulse amplitude modulation is the least expensive and simplest to implement. In pulse amplitude modulation, the amplitude of the pulse varies with the amplitude of the modulating signal.
Why FM is called nonlinear modulation?
Non linear modulation act as nonlinear system: the bandwidth of the modulated signal is wider and can be alterated in terms of ratio between two spectral components with respect to the modulating signal.
What is meant by LFM ( linear frequency modulation )?
An LFM pulse is one in which the “instantaneous frequency” changes linearly over the duration of the pulse. By “instantaneous frequency” I mean the rate of change of phase.
What is the bandwidth of a LFM waveform?
Over its τ = 500 μ s duration, a pulse with “bandwidth” B = 50 k H z and center frequency f c = 150 k H z would be defined by We can see that this sweeps from 2 π ( f c − B / 2) to 2 π ( f c + B / 2) over the duration of the pulse.
How to create linear frequency modulated pulse waveforms?
The example illustrates how to specify property settings. Create a linear FM pulse with a sample rate of 1 MHz, a pulse duration of 50 μs with an increasing instantaneous frequency, and a sweep bandwidth of 100 kHz. The pulse repetition frequency is 10 kHz and the amplitude modulation is rectangular.
What is the complex envelope of a linear FM waveform?
The complex envelope of a linear FM pulse waveform with increasing instantaneous frequency is: where β is the bandwidth and τ is the pulse duration. If you denote the phase by Θ (t) , the instantaneous frequency is: which is a linear function of t with slope equal to β/τ.