RADAR Target Simulation in a Field Signal Record and Playback System

Levon Grigoryan, 10X Engineering

"Real-time hardware-in-the-loop (HIL) radar target simulator (RTSim) is one of the most promising techniques to test and validate radar systems. RTSim can test radar systems starting from the initial algorithm development until the final field-testing stages. In this way, we can avoid costly field tests in constantly changing conditions and test the radar systems in controlled but highly complex environments."

- Levon Grigoryan, 10X Engineering

The Challenge:

10X Engineering needed to develop a highly flexible radar target simulator for multiple dynamic or static targets, with the option to reconfigure the main parameters on the fly, including the functionality of real in-field radar (synchronized, non-synchronized) signal record and playback.

The Solution:

10X Engineering used NI software programmable instruments to design and develop a wide-band, high-functional radar target simulator that uses a new innovative approach and meets all requirements.

Author(s):

Levon Grigoryan - 10X Engineering
Davit Zargaryan - 10X Engineering

 

About 10X Engineering

Founded in 2013, 10X Engineering LLC is an NI Silver Alliance Partner (RF and wireless specialty) with the knowledge and experience to deliver innovative engineering solutions for RF products (units, devices, components), quality and line testing, custom-designed automated test equipment (ATE) system assembly, verification, and development. Our offering includes solutions for a variety of industrial sectors, such as RF software defined radio, radiolocation, spectrum monitoring, and more. Our procedures ensure that every received request is followed, including project technical and software functional requirements clarification, RF measurement methodology selection, and hardware configurations. If needed, we take responsibility to prove a concept and demonstrate the flexibility and reliability of our solution.

 

Real-time hardware-in-the-loop (HIL) radar target simulator (RTSim) is one of the most promising techniques to test and validate radar systems. RTSim can test radar systems starting from the initial algorithm development until the final field-testing stages. In this way, we can avoid costly field tests in constantly changing conditions and test the radar systems in controlled but highly complex environments.

 

Developed RTSim consists of the following hardware:

  • PXIe-8880 Xeon 8-Core Controller
  • NI HDD-8266 24-Drive 5.7 TB SSD RAID
  • MXI-Express Cable 3 m
  • PXIe-8384 x8 Gen2 MXI-Express Daisy Chain Interface
  • PXIe-5646R Vector Signal Transceiver: 200 MHz Bandwidth
  • PXI-6683H GPS IRIG-B IEEE 1588 Sync and Time Module with TCXO
  • PXIe-6674T Timing and Synchronization Module with OCXO
  • PXIe-1085 18-Slot 3U PXI Express Chassis 24 GB/s System BW

 

The HDD-8266 SSD RAID provides 3.6 GB/s sustained read and write speeds for the entire storage capacity in RAID-0 mode. That allows us to use the whole RAID capacity for record and playback with full bandwidth. We used the PXIe 6674T to generate a highly stable 10 MHz clock, based on an onboard precise oven-controlled crystal oscillator (OCXO) reference. The 10 MHz reference has ±80 ppb accuracy within one year of calibration adjustment and within 0 °C to 55 °C operating temperature range. By using it as a PXIe-5646R VST reference clock, we can ensure recorded, generated, and transceived signal parameters with high stability. The PXI 6683 timing and synchronization module uses GPS to synchronize the testing system and perform synchronous events. The PXI 6683 generates events at the specified synchronized future times and time stamps input events with the synchronized system time.

 

 

FIRST TESTING OPTION: Utilizes Real-World Signals Record and Playback

The system delivers a 225 MS/s sustained sample rate in continuous record or playback modes (Figure 1). The PXIe-5646R VST DMA transfer limits the overall system data transfer rate. Mentioned above, the sampling rate corresponds to 180 MHz of instantaneous real-time bandwidth, which is less than the maximum possible Vector Signal Transceiver bandwidth. To exploit the maximum possible bandwidth of the VST, we suggest two new innovative approaches.

 

In the first case, we round IQ data from 16 bit down to 8 bit (on the fly). This approach reduces the record and future playback data rate and allows us to record and playback signals at 250 MS/s, which corresponds to the maximum possible 200 MHz instantaneous real-time bandwidth. We can round to reduce the record and subsequent playback data rate and at the same time twice lengthen the maximum record duration, which is limited by RAID capacity. We can use lengthening the maximum record duration for a variety of applications as well.

 

The second case takes into account the pulsed nature of a radar signal. In this case, we can record and play back the signal in a segmented manner only in certain moments. We can synchronize these moments with external triggers and be moved relative to it. As a result, we get a pulsed data stream. The average throughput of the pulsed data stream is calculated with the following formula:
average data rate = maximum data rate * duty cycle

 

Average data rate is less than maximum data rate, which means we can stream data with the maximum instantaneous real-time bandwidth, supported by the VST. The developed system allows the above mentioned two approaches to apply together and simultaneously record and playback signals in a segmented manner, with rounding IQ components down to 8 bits.

 

SECOND TESTING OPTION: Provided for Modeled Waveform Generation in Segmented Mode With Maximum Instantaneous Real-Time Bandwidth.

 

On a flexible user interface, the user can create different segments’ sequences for generation, add arbitrary time delays between segments, and group them in custom repetitions.

 

THIRD TESTING OPTION: Generates Skin-Echo Pulses That Simulate the Presence of a Static or Dynamic Object Into the Area of Sensitivity of Radar.

 

The system simulates skin-echo pulses by receiving the radar signal, making DSP processing, and transmitting the processed signal back. The combination of transmission and simultaneous DSP allows testing any type of radar with no need for redefining waveform patters. The transmission program consists of host and FPGA parts. Target skin-echo pulse configuration parameters are calculated in the host, later sent to the FPGA, and used to configure DSP blocks.

In this mode, the system has the following technical specifications:

  • Frequency range from 200 MHz up to 6 GHz
  • Instantaneous real-time bandwidth of 200 MHz
  • Number of independent dynamic or static targets is four (can be modified up to 20)
  • Supported radar cross-section changing algorithms are fixed, Swerling 1, Swerling 3, and normal distributed
  • Time delay configurable range from 1,264 µs up to 263,176 µs (to convert time delay into radar coverage we can see that our simulator can simulate targets in range from 379,2 m up to 78,953 km)
  • Supported time delay configuration algorithms are fixed, linear moving, polar flower
  • Time delay configuration step of 8 ns (or spatial resolution 2,4 m)
  • Doppler shift range – ±100 MHz

 

Additionally, users can configure the target parameter update rate. Any custom FPGA and host software additional functionality is possible. For more technical information and support, please contact us.

 

 

Author Information:

Levon Grigoryan
10X Engineering
Engineering City
Yerevan
Armenia
Tel: +37477212193
info@10x.am

Figure 1. Program Function
Figure 2. Radar Pulses
Figure 3. System Architecture