Whether it is an intelligence-gathering receiver system or a portable power system, each plays an important role in modern warfare. And we very well know that such systems have to be thoroughly tested to ensure full reliability and dependability. Any failures or malfunctioning can be tragic.

We have seen in recent years how rapidly the modern combat environment is changing. Advances in microprocessors, digital signal processing and modulation techniques have resulted in new types of radios, radar and tactical communications systems. Existing radio-frequency (RF) intelligence-gathering and jamming platforms have difficulty countering current frequency-hopping and combat networked radios, and find it even more difficult to counter the new generation of software-defined radios, low-power packet networks and radar systems. Hence, these signal-intelligent (SIGINT) receivers have to be fully tested so that they have enough margin to successfully perform the desired functions when deployed.

In fact, this issue is even further magnified in the case of a SIGINT receiver. Unlike other traditional receivers where the signal can be easily predicted and tested thoroughly in the lab, a SIGINT receiver is required to receive and analyze unknown modulation at unknown carrier frequency. For example, two emitters closely spaced in carrier frequency with different modulation should be correctly analyzed. Another example could be to test the receiver for a scenario having a frequency-hopping emitter coupled with normal transmission at one of the hopping frequencies. The SIGINT receiver should be able to accurately analyze such scenarios. The user also might want to create a SIGINT waveform with a low signal-to-noise ratio depicting a far-off and/or low-power emitter. Hence, it is imperative that these receivers are tested against all real-world impairments and interferences so that the receiver design is robust and can take enough margin under these unknown conditions that it may encounter in the real world.

In the first feature of this year's first issue of Defense Electronics, Tektronix addresses the challenges involved in generating a wide range of real-world signals required to test an effective SIGINT receiver. In this article titled “Creating test signals for SIGINT receivers” by Sampath kumar Desai and Iqbal Bawa, the authors show how software-based tools combined with high-performance AWG instruments provide an easy, effective way to ensure that SIGINT receivers are able to handle these environments. It allows a designer to add impairments to ensure that the receiver is robust and can operate effectively in an unknown environment.

The second feature in this issue focuses on the importance of electronic loads in accurately testing portable power systems, such as fuel cells and batteries, used in field military equipment. Because there are a variety of electronic load types, understanding the strengths and weaknesses of each type is necessary to select the appropriate load for the power system. For instance, high-speed battery testing requires good understanding of the chemical slew rate of the battery to ensure that the slew rate of the load does not exceed the battery slew rate. Likewise, for a fuel cell system, it is important to know the cell voltage or stack voltage of the fuel cell. Second, the current of the cell (or the entire fuel cell stack) must also be determined.

To address this challenge, Executive Engineering has developed a solution. In the article, “Testing a power system with appropriate load platform” by David Weber, the author investigates traditional load characteristics and looks at a myriad of factors that must be considered when selecting the appropriate electronic load for the desired portable power system.

Here, the author discusses electronic load blocks specifically developed by Executive Engineering for this purpose. Each block is a miniature module that can be connected in different ways to produce an electronic load that is tailor made to fit the needs of any project. These blocks can be connected to each other to increase the current or connected in series for special charging and discharging circuits. Using these electronic loads, the author shows that it is simple to build a customized power-system test platform.