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Have tried to show this graphically in time axis, the lowest frequencies are delayed the most as it is the one that was sent out first
and goes through all the delay circuits. Higher frequencies are delayed less so that the echoes with different frequency come
through the receiver at the same time and at the end of the receiver are summed and mixed into one strong echo.
The signals is delayed each
time it goes through the
delay circuit
Time axis
Low frequency
Medium
frequency
High frequency
The problem with such a long transmitter pulse is that it is not possible to receive an echo if the pulse is transmitted. Transmitting
the pulse in the longest range will shade out to 1.5Nm. To solve this problem, a short signal is transmitted on one at a different
frequency than the long transmitter pulse. This signal is used to create the radar image close to the boat.
The pulse length of this is 0.07µs - 1.14µs depending on the area of the radar, which is like the transmitter pulse of a magnetron
radar, the frequency of this radar is 3035MHz.
The pulse that changes in frequency 3060 or 3065 and changes ± 4MHz and is 4.6µS to 18.3µS depending on the distance setting
on Radar, Both signals are then used to create a radar image that goes from the center and all the way to the maximum range
1.2 Limitations in radar resolution.
Separation in distance
The radar pulse moves out of the radar at 300m / µS (microsecond).
overall speed is then 150m / µS
If the transmitter pulse is 1µS, two targets must be at distance more
than 150m, then echo number 2 will come as a separate echo and
not as an extension of echo 1. To separate echo, select shorter
transmitter pus.
The differentiating capability of a CHIRP radar depends more on the
narrow bandwidth of the filters in the receiver
JMR-5400 User Manual 20201214 temp
The signals arrive
at the same time
Signals
Summed and
Filtered,
amplified
7
End pulse
sum of all
pulses
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