subject: Using optical RF delay lines to calibrate radars [print this page] Using optical RF delay lines to calibrate radars
In order to understand how to calibrate a radar with an optical delay line, let's first understand what it is.
The basic definition of a delay line is:
"A delay line is a device where the input signal reaches the output of the device after a known period of time has elapsed."
A RF delay line provides convenient RF input/outputs that connect to RFtransmitter and RF receiver. Internally, the RF signal is converted to an opticalsignal and transmitted over a fiber optic link to the receiver and provides the a pre-definedsignal delay time. The delay is determined by the length of the fiber in the box. RFOptic, the leader in optical RF delay lines, has a wide range of delay line units, from 100 KHz to 20 GHz. Frequency range, delay length, and link performancerequirements can be tailored over a wide range of performance levels to meetspecific requirements. These options include RF & microwave amplification inthe transmitter and receiver as well as optical amplification for longer delays.Analog RF delay lines offer superior performance forradar testing, signal processing and phased array antennas.
One of the most popular applications for optical delay lines is radar calibration. The main reason for that, is because radar signals are complex, and it is difficult to reconstruct them with a digital system. By using a high quality analog system, it is possible to easily test and calibrate radars in a lab environment, without going outside to target ranges.
It is not normally practical to delay radar pulses at the microwave transmission frequency as the delay time required represents at least tens of meters of line length. This would have to be in microwave cable or waveguide, which would be rather bulky and lossy, and would also need to be measured for group delay distortion. The optical delay method provides a more compact solution for accurate time delay for radar systems.
RFoptic is one of the world's leaders in suchspecialtyequipment. They have a range of optical delay lines which provide accurate analog RF delays for a variety of frequency ranges and delays.
For more information on delay lines, and especially on optical delay lines, please see the www.DelayLine.info website.
