Software Defined Radios (SDR) for Electronic Warfare

Elements of EW

Electronic Warfare (EW) refers to the strategic utilization of the electromagnetic spectrum (EMS) to manipulate, disrupt, or deter the use of the spectrum by others. There are three key components that make up EW systems which include electronic attack (EA), electronic protection (EP), and electronic support (ES). Each of these are described in greater detail below.

One of the most common elements of EW is electronic attack (EA) which is a form of electronic warfare that leverages the electromagnetic spectrum to target the enemy's electronic infrastructure, thereby impairing their combat capabilities. By using electronic warfare techniques, EA disrupts or disables the enemy's electronic systems, obstructing their ability to communicate, navigate, and gather intelligence. 

One of the commonly used EA techniques is signal jamming. This method involves transmitting radio frequency (RF) signals on the same frequency as the enemy's communication or radar signal, causing interference and preventing the enemy from communicating. Another technique is electromagnetic deception, or spoofing, which entails generating fake signals that resemble the enemy's signal to deceive or confuse them.

In addition to employing EA techniques, threat analysis and response are also crucial aspects of EA. By monitoring the electromagnetic spectrum, military forces can detect and identify potential threats, and take appropriate countermeasures such as signal jamming, spoofing, or using RF weapons to damage or destroy electronic components, rendering them inoperable. In modern warfare, EA is an essential component of military operations. It helps to disable the enemy's communication and control systems, thereby making it easier to launch offensive attacks and gain a tactical edge on the battlefield.

The opposite of Electronic Attack (EA) is Electronic Protection (EP) and refers to the measures taken to safeguard one's own electronic equipment from enemy electronic attacks. As technology has become increasingly critical to modern warfare, it has become essential to protect electronic equipment from attacks by adversaries. To achieve this, multispectral RF equipment is typically used for threat detection and immediate response. Additionally, EP employs techniques such as encryption, filtering, and frequency hopping to make it difficult for attackers to intercept or jam signals.

Effective EP is crucial to ensure that critical electronic equipment, such as communication systems, radars, and navigation systems, continue to operate despite hostile electronic attacks. Failure to implement effective EP measures could lead to significant operational losses if these systems are disrupted or destroyed. Various means, including specialized equipment, protocols, and techniques, can be used to achieve EP.

Electronic Support (ES) is the final crucial aspect of EW that involves monitoring of the electromagnetic spectrum to detect, identify, and track electromagnetic (EM) signals. The main purpose of ES is to collect data and provide signals intelligence support for tactical decision-making. This includes identifying and locating enemy signals, as well as determining their type and purpose. By gathering this information, military forces can gain an advantage over their adversaries and prepare for potential threats.

What are Software Defined Radios ?

Software Defined Radios (SDRs) are a type of radio communication system that uses software to perform functions that were traditionally performed by hardware. These systems have two main components: the radio front end (RFE) and the digital backend. The RFE can be comprised of multiple independent receive and transmit radio chains with each chain responsible for receiving and/or transmitting signals that can be tuned to a center frequency across a very wide range. 

Top of the line SDRs offer tuning ranges from near DC to 18GHz with very high bandwidths for each of the radio chains of either 1 GHz or 3 GHz. Each radio chain contains different blocks for performing different tasks including amplification, mixing, and filtering; all performed between a convertor device and an SMA (analog to digital convertor for the receive chain and a digital to analog convertor for the transmit chain). The digital backend contains an on-board FPGA which performs digital signal processing (DSP) including functions such as filtering, modulation, demodulation, upconverting, and downconverting with the capabilities of incorporating additional IP cores for additional functionality to be performed on the device.

Example Radio Receive Chain Architecture

How SDRs are Used in Each Application

With the ability to tune across a wide frequency range and with multiple receive and transmit radio chains, SDRs are an excellent fit for all elements of EW. Specifically, for EA applications, the SDR transmit functionality along with adjustable and high bandwidths, enables them to be utilized for high power broadcasts to damage, destroy, or otherwise impact the performance of enemy electronic equipment. By transmitting very precise signals that can target specific frequencies or modulation schemes, SDRs are able to target specific types of devices or frequency ranges. Another application in which EA is achieved using SDRs is for electronic deception, whereby SDRs can broadcast a similar friendly signal to deceive enemy systems.

SDRs for EP and ES applications rely more on the receive functionality of SDRs where the systems are typically used to protect against enemy attacks by detecting and analyzing incoming signals to identify potential threats. This can include signal identification, geo-location, and communication monitoring, which when combined with EA capabilities becomes a very powerful tool as specific actions can be taken with extremely low latency. These actions may include frequency hopping to avoid detection, signal filtering to prevent damage to other equipment, or to implement EA techniques such as jamming, spoofing, or otherwise disrupting the use of electronic devices used by enemy forces.

Critical Specifications

As discussed, SDRs that can offer both receive and transmit capabilities offer a solution for all elements of EW. To further ensure that the best system is selected, there are other important attributes that should be considered when selecting the appropriate SDR:

• Tuning range – This will define the part of the spectrum the SDR can operate in and therefore be the driving factor to ensure operation in the frequency range required. High end systems offer tuning ranges from near DC to 18 GHz.
• Bandwidth – This specification is crucial in ensuring that for EA applications you are able to output concurrently across a very wide part of the spectrum with the added benefit that comes with adjustable bandwidth in the instances where transmission should only be across a more narrowed focus. For EP and ES, being able to capture as much data as possible helps to ensure a high probability of intercept which is critical for detecting frequency hopping devices and equipment employing similar techniques. Top of the line COTS SDRs offer adjustable 1 GHz and 3 GHz of bandwidth per radio chain.
• Number of independent radio chains – In many instances there is a requirement to operate (both in receive and transmit) across a number of different radio bands separated by an amount of the spectrum that exceeds the bandwidth and other times where a greater number of antenna elements will lead to higher degrees of accuracy. These requirement leads to the need to support multiple Rx and Tx radio chains that are independently controlled where high performance SDRs can offer up to 16 independent radio chains.
• FPGA and DSP resources – This is a driver for those EW systems that require very low latency or additional processing that may be done in parallel which can reap the benefits of FPGA resources. SDRs that offer large FPGAs on-board can save significant latency and external equipment requirements.

Top of the Line Cyan SDR

SDRs play a crucial role in EW systems and offer very compelling solutions for electronic attack, electronic protection, and electronic support. The flexible nature of the systems, including wide tuning range, high bandwidths, a large number of radio chains, and on-board DSP capabilities makes SDRs an attractive option and should be considered when designing next generation EW systems with enhanced capabilities.

Per Vices is a leading developer of Software Defined Radios for Electronic Warfare. Click here to learn more about them.