A Software Defined Radio (SDR) Approach to Radar Part 1

hello my name is Don Metzger this video is an update to a previous video which showed a software-defined radio approach to radar in this update which is part one of a new series we will be using an Analog Devices Pluto and quicksystems quick radar software here's a block diagram showing our setup the transceiver chip uses one transmit channel to send a signal through an RF splitter to a transmit antenna the other output of the splitter is routed to one of the received channels of the Pluto the receive antenna is routed to the second receive channel of the Pluto this is an analog device's adalm Pluto we are using rev-c of the module we communicate with the module using a USB 2.0 connection the Pluto module that we are using has been updated to a to receive two transmit system using the excellent tutorial by John craft you can find that tutorial on YouTube under the title enable dual receive and dual transmit for the new revision of Pluto our antennas are Wi-Fi flat panel antennas mounted in steel buckets which provide isolation between the transmit and receive halves of the system we have cut holes in the bottoms of the buckets to allow for connection to the antennas for a radar reflector we will use a dihedral corner reflector otherwise known as a bent sheet of aluminum mounted on a stand a detailed listing of all the items used will be given near the end of the video after starting the quick radar software a dialog box will appear asking for an activation code an activation code is not needed when using the software of Pluto so just cancel the dialog next maximize the size of the main window to fill the screen on the main menu select windows and then active Windows this brings up a dialog that allows us to choose which windows will be displayed for the case we are doing in this video we will choose transmitter waveform receiver waveform receiver spectrogram transmitter correlation receiver correlation scrolling radar range and measured results after applying these choices go to the main toolbar and hit the arrange Windows button this will snap the windows into an evenly distributed pattern in the main window frame quick radar works with several Analog Devices eval boards so we need to tell the application which device we are using and how to communicate with the device on the main menu select instrument and connection in the dialog make sure that adalm Pluto 2rx 2tx is selected and iio over USB Auto as the connection type and hit apply next let's choose a transmit waveform file this is the IQ Data that will be transmitted by the chip on the main menu choose file and transmitter file quick radar comes with a variety of example input files you can find them in quick tools slash data slash radar we will use the linear frequency modulation with a 20 megahertz chirp bandwidth a chirp duration of 200 microseconds and a 30 Mega sample per second sample rate after choosing a transmit file the dialog displays various parameters for the data in the file if the waveform file was created using quick generator then it will also contain information about the signal on the main menu choose instrument and 80 936x control we will use a center frequency of 2.5 gigahertz choose Channel 1 for the transmitter with 0 DB of attenuation set the receiver acquisition time to 900 microseconds the transmitter monitor should be set to channel 1 with a gain of 10 DB the return signal should be set to Channel 2 with a gain of 60 DB depending on your hardware setup you may need to adjust the attenuation level for the transmitter and the gain levels for the receive channels at the bottom of the dialog is the baseband configuration the baseband configuration sets the transmit and receive sample rates and creates filter settings inside the transceiver chip which are compatible with those sample rates when the instrument settings are complete press the apply and close button on the main menu choose processing and lfm set the oversample rate to 4 or 5 or 10. this controls the oversampling of the received signals to make finding the timing for The Signal Peak more accurate if your system is running slow try a smaller value like four for more Precision try a larger value like 10 set the maximum range to 50 meters set the equipment configuration to antennas the final step that we will perform is to set the repeat type on the main menu choose processing and then repeat make sure the repeat type is set to continuous on the main toolbar click the start button this will begin the transmit and receive operations the plot in the top left is a Time domain view of the data acquired by the receiver Channel which is monitoring the transmit signal note how the chirp signals pulse on and off the plot in the bottom left is a Time domain view of the radar return signal it is smaller in amplitude and closer to the noise floor at the top of the second column we see a spectrogram of the measured return signal here we can clearly see the chirp and frequency at the bottom of the second column we see a plot of the correlation of the measured transmit signal with the transmit waveform file the correlation Peaks when the two signals are aligned in time at the top of the third column we see a plot of the correlation of the measured return signal with the transmit waveform file at the bottom of the third column are the measured results the top of this window we see some calculated values for the input waveform at the bottom we see measured values for the time delay of the radar return and the associated distance away for our scatterer the right hand side of the window is the radar range plot the horizontal axis is the range that is the distance from the antennas to a scatterer in the scene that we are observing the vertical axis is the time at which the measurement was made the color is the magnitude of the radar return signal warmer colors indicate larger values for the return signal now that we have the system set up let's do a couple of measurements for the first let's vary the distance from the antennas to a corner reflector here's the transmit received setup using a laptop and the Pluto here's our Corner reflector we will move the reflector from 5 meters to 10 meters to 15 meters and then back to 5 meters pausing at each location for a few seconds you can observe the change in range in the radar range plot and in the measured value for range in the results window for the second measurement let's keep the distance to the corner reflector constant but rotate the direction that the reflector is facing a corner reflector does not reflect the same in all directions as say a metal ball does I will rotate the Reflector by hand and we will see the reflection increase and decrease by the change of color in the range plot we will start with the reflector turned 90 degrees to the side we will rotate it toward the maximum reflection then we will continue turning it until it is 90 degrees to the other side here's a list of the RF devices that we used for these measurements and suggestions for where to get them here's a list of other supplies that were used to create the setup quick radar currently works with several chips and eval boards from Analog Devices look for other parts of this video series which will use Quick radar with higher bandwidth systems yielding better resolution to obtain a copy of quick radar visit quicksystems.com and download the application after installing if you are using a Pluto you are ready to go if you want to use a different chipset you can request an activation code by sending an email message to sales at quicksystems.com thanks for your time

Channel: QIQ Systems

Views: 9,331

Keywords: SDR, ADALM-PLUTO, Pluto, Radar, Software Defined Radio

Id: MQi-sQ1GZcY

Length: 9min 47sec (587 seconds)

Published: Thu Oct 27 2022