Figure 1 Air defense radar. Source: Shutterstock.
Figure 2 Typical ATC/ATM radar display. Source: bbc.co.uk.
Software-defined radios (SDRs) are becoming increasingly popular across various applications, including electronic warfare (EW), radar and military communications (MilCom). The flexibility and versatility of SDRs enable them to adapt to changing requirements and challenges, making them an ideal choice for these applications. For instance, in EW applications, SDRs can detect and identify signals from various sources and jam them to disrupt communication, providing a significant tactical advantage on the battlefield. In the same way, SDRs can be used for radar applications to detect and track targets in real-time, making them an ideal choice for military applications. In MilCom, SDRs offer interoperability between different types of radios, allowing different forces to communicate seamlessly, regardless of the radio system used all while being able to adapt to changing requirements, making them ideal for dynamic battlefield conditions. This flexibility enables troops to communicate effectively, make critical decisions in real-time and improve overall battlefield situational awareness. All these features and applications are enabled by SDRs and the underlying use of field-programmable gate arrays (FPGAs).
FPGAs are semiconductor devices based on a reconfigurable matrix of logic blocks. Unlike traditional processors that are hard-wired to perform specific functions, FPGAs can be programmed and reprogrammed to perform different functions, making them extremely versatile. FPGAs typically consist of configurable logic blocks, digital signal processing blocks, input/output blocks and random-access memory (RAM).
This article discusses how the integration of FPGAs into SDRs enables key performance benefits across EW, radar and MilCom applications. The use of FPGAs as the digital logic in SDRs provides several advantages. These include waveform storage, external triggering, channelizing capabilities, processing (filters, decimation, interpolation, etc.) and the implementation of modulation and demodulation on board. Figure 1 shows a typical air defense radar that might benefit from SDRs with FPGAs. Figure 2 shows a typical air traffic control/air traffic management radar display.
FPGAs have been an integral part of many modern systems because of their superior performance and flexibility. Unlike an application-specific IC, which is designed for a specific application and cannot be reprogrammed, FPGAs can be programmed and reprogrammed to perform a wide range of tasks. In recent years, FPGAs have gained increasing popularity in SDRs for EW, radar and MilCom applications due to their unique advantages. When integrated into SDRs, FPGAs are incredibly powerful and can sustain high data throughput, providing both the I/O bandwidth and processing capabilities needed for these applications. FPGAs can be programmed to perform real-time signal processing tasks, such as demodulation, filtering, modulation and encoding, enabling SDRs to handle the high data rates required for all these applications.
Why Use FPGAs in an SDRs?
FPGAs are increasingly being used in SDRs due to their ability to handle high speed data processing and provide a high degree of flexibility and reconfigurability. Their ability to support high data throughput enables SDRs to process in real-time, the enormous amounts of data collected during a mission or exercise. FPGAs can be used to implement high speed digital signal processing algorithms and to perform parallel processing, which allows for the efficient processing of the data captured or sent by SDRs.
FPGAs can be programmed and reprogrammed to implement various signal processing algorithms, modulation and demodulation schemes and other signal processing functions. This makes FPGAs ideal for implementing the complex signal processing functions required in SDRs, such as frequency-hopping, adaptive filtering and channel equalization. One of the main benefits of using FPGAs in SDRs is the ability to store waveforms, enabling faster and more efficient signal processing. Waveform storage allows SDRs to record and store large amounts of data, which can be processed and analyzed later.
The use of external triggering is another benefit of using FPGAs in SDRs. External triggering enables SDRs to synchronize with other devices, such as radars, enabling more accurate signal processing and reducing system complexity. This capability is essential in radar applications, where accurate synchronization is required for precise target tracking.
Overall, the combination of high speed data processing, flexibility, storage and triggering and reconfigurability make FPGAs an ideal choice for SDRs. By using FPGAs, SDRs can provide a high level of performance and flexibility. This makes them suitable for a wide range of military applications.
Benefits of FPGAs in SDRs for Radar Applications
Figure 3 Representative radar system block diagram showing the Per Vices solution.
As mentioned above, one of the most significant benefits of FPGAs is their ability to handle high data throughput rates. Radar systems generate large amounts of data that need to be processed in real-time, and FPGAs are capable of processing this data efficiently. FPGAs can be used to implement advanced digital signal processing algorithms, such as fast Fourier transforms, that are required to extract useful information from radar signals.
Another benefit of using FPGAs in SDRs for radar systems is their ability to perform real-time signal processing. FPGAs can be used to implement real-time filtering, decimation and interpolation, which are essential processes for removing noise from the radar signals and improving the accuracy of the system. FPGAs can also be used to implement adaptive filtering algorithms, which can automatically adjust the filter parameters based on the incoming signal and enable signal processing tasks such as Doppler processing, pulse compression and target detection, providing high-resolution images of the radar environment.
In addition to these benefits, FPGAs can also be used to implement advanced modulation and demodulation schemes that are required in radar systems. For example, FPGAs can be used to implement pulse compression techniques that are used to increase the range resolution of the radar system. FPGAs can also be used to implement frequency-hopping techniques that are used to reduce interference and improve the reliability of the system.
