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1. Introduction
1.1 Radar types
Radar Equipment
Use the radar only as a navigation aid. The crucial decisions about navigation must always be made by the operator. Navigating
only by radar can lead to accidents such as collisions or grounding.
There are two technologies that apply to radar, pulse and solid state (Chirp)
Pulse Radar
Pulse radar uses a magnetron to create the transmitter pulse.
It's a cheap and straightforward way to produce a powerful transmitter pulse. The magnetron
must be annealed to work, the filament will weaken after a while and the magnetron must then
be replaced. The service life depends on the method of use and possible vibration.
Solid state radar/ Chirp S-band Radar
The chirp signal is a frequency modulated transmitter pulse. The frequency modulated transmitter pulse goes from 4.6µs, 9.6µs
or 18.1µs depending on the radar range. The frequency of this signal is 3060MHz + 4MHz
JMR-5400 User Manual 20201214 temp
Chirp signal
sends pulse
increases in
frequency through
transmitting heart
The low frequencies are delayed the most and then less delay
at the higher frequency.
The goal of this delay is that reflections from one echo come
out of the receiver at the same time and are combined into
one powerful echo.
6
The transmitter starts with low frequency then the
frequency increases linearly. In order to utilize the
entire transmitter signal, the receiver has delayed
circuits on the video (radar) signal, mostly on low
frequencies and less on higher frequencies. The result
will be that echoes to one target are detected with
different frequency, but at the same time. When the
signal is summed in the receiver, echoes in the same
phase are summed to one strong echo, while noise is
suppressed. Have tried to illustrate this on the next
page.
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