Electronic surveillance (ES) systems are used on all modern Navy ships and receive RF signatures in the form of pulse data. The data is digitized and processed in order to identify and determine the nature of the signals – threatening or non-threatening. Processing is accomplished by sending the data through a pre-sorter, filtering it, and comparing the filtered data to stored sets of parameters. Monitoring the performance of processors within ES systems currently in use is required for continued improvement in recognition capabilities.
Such monitoring has been accomplished by analyzing the ES system’s response to control data – injected RF modulated pulses into the ES system. The RF modulated pulses are processed into pulse descriptor words (PDW). The ES system responds to the PDW by either displaying the correct threat identification or producing active transmissions based upon a correct threat identification. Recordings are made of the response and by analysis, a judgment can be made on how well the system works.
Due to the ever-increasing complexity and density of emissions in the RF spectrum this method of assessing ES system performance is outdated and insufficient. It does not allow for a more detailed analysis, based upon a realistic and comprehensive RF environment, to determine the cause of an incorrect response. Adequate assessment of the performance capabilities of a particular ES system requires an in-depth analysis of all RF pulse activity for a given time period. Only with such a thorough assessment can there be improvement in the development of radar and threat recognition algorithms.
Many ES systems and electronic counter measure (ECM) systems have the ability to sample and temporarily store the RF parameter data of a singular received RF pulse. This pulse is finely sampled across its duration. This sampling information allows the recreation of the pulse for output. However, modern ES and ECM systems do not possess long-term multi-pulse storage capability. In ECM systems the goal of the memory is to affect a short delay in the re-transmission of data. This delay equates to range when viewed from a hostile perspective. Digital RF memory is used to capture, store and then retransmit RF energy a short time later. This is often referred to as an RF delay line. Once the data has been re-transmitted, it is no longer held in memory.
To address the increase in data and difficulty in analysis, the Navy has developed a PDW collector and extractor to collect all RF pulse data as the ES system receives it without impacting normal ES operations. Received RF pulse data is formatted into PDW and forwarded to a pre-sorter and then on to the PDW collector and extractor which passively monitors, processes and stores the data. Using two random access memory (RAM) circuits, the extractor forms a read/write loop to ensure that no PDW are lost in the collection process as it simultaneously writes onto one RAM while reading from the other RAM to the computer. Stored data is available on demand for analysis and is used to monitor, assess, and update the threat identification capabilities of the particular ES system. The alternatives to this solution, including installation on each vessel of another independent ES system capable of collecting the required data or an invasive redesign of all ES systems, are cost prohibitive.
- Passively collects and records all digitized RF pulse data (time of arrival, angle of arrival, amplitude, pulse width, and frequency) received by a ship's ES system
- Collected data can be analyzed in order to test the detection and identification capabilities of current ES systems and to improve upon those detection and identification capabilities
- Convenient and cost-effective device that can easily be carried onboard a Navy vessel and integrated into its ES system
- US patent 6,876,321 available for license