DRAFT
In general, the front-end processing functions encompass all of the mechanics associated with integration of SIGINT, IMINT, and MASINT sensors into the various platforms, sensor data capture and recording, special pre-processing, and interfacing the front-end functions with the rest of the FRM. Due to the nature of the physical phenomenon being exploited, the specific functions of the front-end sensors are different. The common front-end functions are discussed in the next subsection followed by discipline-specific functions for SIGINT, IMINT, and MASINT.
3.2.1 Common Front-End Functions
The following functional elements are common across the three front-end functional areas (color coded green): Sensor/Platform Integration Mechanics, Sensor Control Functions, Special Pre-Processing Functions, and Mission Recorders.
Figure 3-1: Airborne Reconnaissance FRM
3.2.1.1 Sensor/Platform Integration Mechanics
Standards for this functional area are:
The integration of the sensor into an airframe is a complex task. In addition to the classic interface specifications of size, weight, and power; airframe integration must include balance, pressurization, cooling, and unique mounting configurations. Dynamic operational conditions that must be addressed are vibration, shock, torque, pressure and atmospheric changes. Integration of any sensor into an airborne platform covers several areas and requires a total system analysis.
In the case of a SIGINT system, the platform antenna (or antenna arrays) frequency range, sensitivity, directional patterns, and calibration must match the SIGINT sensor capability. Although this matching is done through engineering design processes it is not sufficient to ensure achievement of performance specifications when installed on a physical airframe and connected with prime (Group B) SIGINT receiving equipment. Additional modeling may be needed in such cases. Thus anechoic chamber work on platform scale models is standard practice to accommodate anomalies in performance that occur in interferometric DF. These anomalies are typically caused by the antenna elements interacting with the airframe causing resonance at some frequencies. The resonant frequencies effectively cause signal nulls or signal drop-outs, and ambiguous DF answers can be adjusted by slightly readjusting antenna locations in the anechoic chamber modeling before installing them on the airframe. This avoids problems before expensive airframe modifications are made. The addition of antenna (or antenna arrays) requires modification of existing RF distribution to match RF feeds from new antenna elements and proper RF outputs to receivers, tuners, or converters.
Imagery sensors are typically mounted in the nose of the airframe, the underside of the fuselage, or in a pod. The enclosure covering the sensor may be either part of the airframe, part of the pod, or part of the sensor system. The sensors are typically enclosed in an unpressurized compartment and image through a window. The imaging window must maintain optical quality and sustain a pressure differential from buffeting winds. If the sensor is in a pressurized compartment, the window strength becomes even more important. High quality sapphire windows are typically used, but there are also substitutes. Sapphire windows are just now being produced in sizes large enough (12 inch) to be used for high quality electro-optical sensors with large apertures. Infrared and multi-spectral sensors have the most severe specifications for the optical window. The sensor enclosure may move to keep the window centered on the optical axis. Although this increases sensor to airframe mounting complexity, it is not practical to make the windows large enough to cover the complete sensor field of view. The windows may require heating or cooling to eliminate condensation and maintain performance. Radar systems used for collecting IMINT are enclosed in radomes that typically can be produced as uniformly transparent, and they do not have to rotate or move in unison with antenna movements.
There are no special requirements to integrate MASINT sensors which are the same as SIGINT or IMINT sensors. Other MASINT sensors require appropriate integration, for example, MASINT sensors exposed to the atmosphere for air sampling purposes. Future MASINT sensors - including tunable or programmable sensors - may be pod mounted or be enclosed as part of the airframe.
The only standard identified for sensor/platform integration is for Prime Power: MIL-STD-704E.
3.2.1.2 Sensor Control Functions
Standards for this functional area are:
Commands to various SIGINT, IMINT, and MASINT front-end equipment flow through the sensor control component of the FRM. In actual implementations, command and control messages may flow directly to equipment through either the C2 network or the high speed data flow network.
There are no standards currently identified for sensor control functions. However, this may be an area worthy of further analysis. A standard command set may be an effective means to stimulate design and marketing of competitive equipment. A simple example of the benefit of a standard command set is seen in the common modem used in virtually every personal computer and office workstation - they all use the basic Hayes command set.
3.2.1.3 Special Pre-Processing Functions
Standards for this functional area are:
The FRM allows for variations of special pre-processors to coexist in the system. The variations will be optimized to provide specific mission functions, but will have common interfaces for timing, to include both coherency and absolute time, and for command and control.
The FRM provides for special pre-processing functions that either (a) cannot be implemented in the digital domain, or (b) are optimized by analog pre-processing. The output of the pre-processors will interface to the high-speed data flow network and, if applicable, to the multimedia network.
Pre-processing functions are performed to the sensor data for the purposes of enhancing data utilization. Functions may include analog-to-digital conversion, data compression, and data formatting.
Although there are no standards for special pre-processing functions, standards should be developed for assuring end-to-end quality.
Standards for this functional area are:
IMINT payloads:
- DCRSi for the U-2 (ASARS-II recorder)
- ANSI X3B5/94-024, 19 mm helical scan digital tape (F/A-18 ATARS)
- ANSI X3.175-1990, ID-1 digital tape (F/A-18 ATARS)
- VHS and Super-VHS for recording video
- Hi 8 mm (e.g., for ARL and gun cameras)
- Preferred implementation is Y/C (component analog) video recorders with Society of Motion Picture and Television Engineers (SMPTE) vertical interval time code VITC generators/readers and two audio tracks (one for mission audio, one for ancillary data)
- Dual-capable analog/SMPTE 259M video recorders (to support the migration from analog to digital video)
- SMPTE 259M-compliant recorders capable of 259M input and output
SIGINT payloads:
Timing:
Mission recorders are used to capture the raw, pre-processed sensor data together with associated navigation, timing, and ancillary data. Additionally a computer controlled interface for basic recorder functions such as start, stop, shuttle, fast forward, and rewind is included.
In conjunction with recording the raw sensor data, timing data will be recorded (on a separate track) in accordance with the "IRIG-B" (Inter-Range Implementation Group) standard: IRIG-106-93, Telemetry Standards, Analog Digital Adaptable Input Output Data Format Specification Annex. The IRIG-B standard was written specifically for magnetic tape storage, but it is applicable to disk storage media as well.
The standards cited above include legacy systems. In conjunction with migrating to all digital systems, mission recorder standards will be reevaluated to emphasize digital and de-emphasize analog.
3.2.2 SIGINT Front-End Functions
SIGINT front-end standards are concerned primarily with functional elements that receive and process radio frequency (RF): from low frequency (LF), 30 KHz to 300 KHz, through extra high frequency (EHF), 30 GHz to 300 GHz, received by the platform antenna/antenna arrays. These RF antenna/antenna array types may be omni-directional, directional, beam-steered, steered dish, interferometric, or spinning dish. In addition to the common front-end functions, the SIGINT front-end functional elements include the RF distribution, low and high band tuners, set-on receivers, IF distributing IF digitizer and sub-band tuners, digitizers and channelizers. Figure 3-2 displays the functional elements of the SIGINT front-end. Hardware implementation may not match Figure 3-2: SIGINT Front-End FRM (e.g., low/high band tuners, IF switching, and IF digitization functions can be combined into a single receiver unit).
Figure 3-2: SIGINT Front-End FRM
Standards for this functional area are:
RF from antenna normally flows through an RF distribution function. The RF distribution function allows for appropriate signal flow from the multitude of platform antenna of varying types and frequency coverage and provides for the conditioning and distribution to the functional receiver/tuner elements.
The conditioning component of the RF distribution provides for the requisite preselection or band filtering to frequency band-limit incoming antenna paths from potentially interfering signals (both off-board and on-board) and preamplification to optimize the system-level noise while providing an acceptable signal saturation level (i.e., intercept point). Phase/gain matching of multiple discrete antenna paths for interferometric direction finding (DF) is also a function of the RF distribution conditioning.
The distribution function provides appropriate RF switches, RF power dividers or coupler, attenuators, and blanking interface to facilitate the necessary quantity and type of signal paths to the various platform SIGINT receiver/tuners. This allows multiple signal paths to be routed or selected to one or more receiver paths for maximum flexibility and to reduce the number of dedicated antennas that otherwise would be required on the platform.
Traditionally, RF from antenna has been distributed to tuners, band converters, and receivers through 50 Ohm fixed impedance coaxial cable in agreement with Electronic Industries Association (EIA) RS-225, dated 1959. Replacement of coax with fiber optics is being researched for ELINT antenna to RF distribution. Early digitization (analog to digital (A/D) conversion) and precise time tagging of this digital data are essential elements of this architecture. Properly bandwidth-limited RF is passed on to ELINT and COMINT tuners, receivers, or band converters.
3.2.2.2 Low and High Band Tuners
Standards for this functional area are:
Highband RF covers the UHF through EHF (300 MHz to 300 GHz). Low band RF covers LF through UHF (30 KHz to 3 GHz). The LF, UHF, and EHF designations follow the Institute for Electrical and Electronic Engineers (IEEE) definitions. However, signal densities and properties, propagation factors, and semiconductor physics necessitate different basic implementations. Actual implementation must provide seamless processing of all specified signals of interest. The frequency coverage and number of channels will be a function of the individual platform and mission requirements.
The tuners (several types are required) will provide preselection of a portion of the RF spectrum and convert it to one of the standard intermediate frequency (IF) center frequencies of 21.4 MHz, 70 MHz, 160 MHz, 1000 MHz, and 5000 MHz. The tuner's technical specifications should reflect the requirements to allow direction finding, time difference of arrival, differential Doppler, co-channel interference reduction, pulse code modulation, etc. The IF from the high band tuners may feed through a coaxial based (50 Ohm) IF distribution into the RF distribution function to allow further selection and processing by the low band tuners and assets for narrowband signals. The IF from the low band tuners may feed into the high band IF distribution function to allow further selection and processing for wideband signals.
Standards for this functional area are:
The FRM incorporates provision for a pool of set-on receivers to enhance collection based on a platform's operational mission. These receivers would be included when system constraints prohibit contiguous coverage, when additional throughput is required, or when additional coverage of specific high priority signals is to be provided. The set-on receiver outputs may be digital audio, digital IF (filtered), or analog (pre- or post- detected). The numbers, types, frequency range, modulations, and outputs of these receivers will be determined by the individual platform's requirements. There are currently no formalized standards for set-on receivers and conventional practice is to use commercially available equipment.
Standards for this functional area are:
The FRM allows for multiple IFs to exist in the system. The IF distribution function accepts the various inputs from the tuners and receivers and routes them to the outputs via the C2I network. The IF switches and distribution elements must support the dynamic range, phase noise, linearity, bandwidth, isolation and other functional specifications required of their collective applications. As with the RF, IF signals are also distributed through 50 Ohm coaxial cable.
Standards for this functional area are:
The IF digitizer accepts the output of the tuners and IF distribution, and performs the analog to digital (A/D) conversion. It may include such functions as down-conversion and signal conditioning. This digital output is connected to the high-speed data flow network. The digitizers may be comprised of multiple-speed bandwidth and dynamic range converters (reflecting the different processing bandwidth / dynamic range tradeoffs required for different signals). The data will include a precision time stamp and system clock. Precise time-tagging of data will take place at the point of digitization.
3.2.2.6 Sub-Band Tuners/Digitizers/Channelizers
Standards for this functional area are:
The sub-band tuners/digitizers/channelizers accept the output of the high band tuners and IF distribution functions. This module will support: automatic and manual search of signals with direction finding (antenna/array dependent); signal characterization; sample incoming IF energy; and measurement of phase shift of IF energy. These functions must provide high performance (e.g., sensitivity, dynamic range, interference cancellation) and allow for reprogramming (scan plans, signal parameters, etc.). Signal data will be provided to the high-speed data flow network. This functional block must accept time synchronization and system clock and also time-tag the digitized data as required.
3.2.3 IMINT Front-End Functions
As shown in Figure 3-3, IMINT front-end functions are divided into ten major areas: seven types of image acquisition sensors, sensor control functions, special pre-processing functions, and mission recorders. The following subsections describe the seven types of image acquisition sensors and the specific technology standards that apply. The other areas are discussed in Section 3.2.1.
Figure 3-3: IMINT Front-End FRM
Standards for this functional area are:
Film cameras typically used in airborne reconnaissance systems employ advanced optics (lenses and/or mirrors) and focusing subsystems to capture high quality imagery on large-format film. Film width is not standardized, but ranges from four-to-nine inches wide depending on the design of the camera. Lens focal lengths vary from 25 inches for wide area coverage to almost 150 inches for high resolution imaging from greater distances.
Film cameras are being phased out as IMINT systems migrate to electronic/digital imaging sensors which offer superior performance and image processing capabilities.
3.2.3.2 Electro-Optical Sensors
Standards for this functional area are:
Electro-optical (EO) sensors are essentially the same as traditional film cameras except that electronic imaging is used in place of film. EO sensors offer higher quality and faster response to warfighters by enabling the use of digital image processing technology, direct data link communications, and more sophisticated storage and dissemination capabilities.
EO sensors typically cover the panchromatic (or Pan) part of the spectrum and use digital techniques to collect image data (i.e., staring arrays and linear scanning arrays). In a strict sense the term "panchromatic" means the light spectrum that is visible to the human eye. In practice this usually applies to a modified spectrum in which the EO sensor operates. Typically, Pan EO sensor sensitivity may exclude some of the blue region of the spectrum and may include some near infrared (IR) wavelengths of the spectrum. The blue may be excluded to reduce the effects of haze in long range viewing, whereas near IR penetrates the haze better than visible wavelengths and provides better contrast between vegetation and camouflage. More detail on IR is in Section 3.2.3.3.
Staring array sensors use a two-dimensional array that acquires the entire frame at a single instant, just like a handheld film camera. These sensors are capable of taking between a few frames a second to a frame every few seconds. Typical focal plane arrays vary from between 500 to 2,000 detectors on each side, and they are usually square. The images formed generally have the same number of pixels as the array has detectors. These sensors need to be physically stabilized to keep each detector focused on the same target for the duration of the exposure - a platform/sensor integration consideration. The resulting images are a series of still frames.
Linear scanning array sensors use a string of electronic detectors to record only one line of the image at a time. The linear array is typically 2,000 to 20,000 detectors wide. This determines how many pixels are in each line of the processed image. An image is formed as the aircraft and sensor motion continuously scans new parts of the scene. The resulting image formed by a scanning array sensor is a continuously moving, or waterfall image. Nothing on the image moves as in a video or movie; rather the scene itself is continuously moving as the sensor scans the ground given the motion of the aircraft.
Currently there are no formalized standards governing the design of EO sensors, but the following two technical attributes tend to be common among various sensor designs:
Standards for this functional area are:
Infrared (IR) sensors detect radiation (reflected and emitted) at wavelengths longer than visible light. The IR part of the spectrum is broader than the visible part and the types of IR sensors can be subdivided into near wavelength infrared (near IR or NIR), short wavelength infrared (SWIR), middle wavelength infrared (MWIR), long wavelength infrared (LWIR), and any number of subsets of these major categories. Each broad category of wavelengths has unique reflection and emittance characteristics, analogous to visible colors. NIR has most of the characteristics as Pan, but has better haze penetration and higher reflection by water bearing cells in plants that facilitates healthy vegetation characterization and camouflage detection. SWIR has even better haze penetration than NIR and some reflective properties for camouflage detection. MWIR is sensitive to thermal imaging as well as reflective infrared and works well in low light-level applications. LWIR provides true thermal imaging that can be used in total darkness.
As the operating wavelength of an infrared sensor increases, the technology required to design and construct the sensor becomes complex and more expensive. The transmittance of optical glass stops at SWIR and greater wavelengths, so the sensors need special lens material or more likely will use reflective optics (mirrors). The longer the wavelength of operation, the more thermal noise will have to be reduced. This requires cooling of the detector array, to cryogenic levels for LWIR operation, and possibly the optics and other parts of the sensor. The composition of the detector array is different for IR than it is for Pan, and sometimes multiple arrays need to be employed for different IR wavelength categories. These characteristics can put demands on platform integration for cooling and on digital signal processing functions for calibration and noise reduction. There are no standards for IR sensors.
Standards for this functional area are:
Motion video adds a time dimension to imagery, where motion of objects and other time-dependent activities can be directly observed. Video is really a series of still images that overlap the same coverage and repeat the scene nominally 30 times per second which is the commercial broadcast standard frame rate. Video cameras usually employ zoom lenses or multiple optics for adjusting viewing area and detail. In addition, dynamic flight control permits close range imaging for high resolution, and far range imaging for increasing area coverage with lower resolution.
Video cameras are most often used on UAVs where they originally served to support the remote pilot during takeoff and landing. Now they have become recognized as a highly valuable reconnaissance asset. The cameras are very similar, if not identical, to commercial models available for commercial broadcast and/or home use. Real-time video can be broadcast directly to the warfighters and other receivers through various communications systems using the same technology that the commercial television broadcast industry uses.
For current legacy systems, the base analog video standard is the National Television Standards Committee (NTSC) signal provided in RS-170 format. This standard defines the broadcast industry standard image with 525 lines of analog luminance (density) trace signals. It has 30 unique frames per second. The video trace is interlaced so that there are actually 60 fields or traces per second of 262 lines each. The increased frame rate is used to reduce scene flicker on the cathode ray tube or TV screen used for display.
Commercial industry is currently migrating away from analog video components to all-digital systems. It is anticipated that within five years, professional-quality analog video products will no longer be manufactured. Airborne reconnaissance systems will leverage advances in commercial television technology which provides the standards base for interoperability among commercial broadcast and military video systems. Additional benefits include improved video quality; inter-service and NATO/allied forces interoperability; improved protection from obsolescence; and lower life cycle costs. In fact, COTS solutions are currently available for a complete end-to-end digital video system implementation, adhering to the following standards:
The key outstanding standards problem for video, from an airborne reconnaissance point of view, is metadata - data about data. Developing a standard for video metadata is one of the highest priority tasks being worked in the CIO's Video Working Group. (See Section 5.1.1 for more details.)
3.2.3.5 Synthetic Aperture Radars
Standards for this functional area are:
Radar systems transmit radio signals and measure the reflected energy from the target. Power, frequency, and modulation of the transmitted signal can be altered to achieve different effects of range, resolution, and penetration. Radar sensors have the ability to operate day and night and penetrate clouds, offering true all-weather operation.
Synthetic aperture radar (SAR) is the most commonly used type of radar for imagery reconnaissance applications. The systems are called synthetic aperture because the combination of the individual radar returns effectively creates one large antenna with an effective aperture size equivalent to the flight path-length traversed during the signal integration. The formation of this large synthetic aperture is what enables these radars to produce images with fine in-track (for azimuthal) resolution; the high bandwidth and pulse repetition interval enables the SAR's fine cross track (or range) resolution. The image can be produced with ground resolutions less than one foot, when operating in "spot" mode, and approach photographic appearance and interpretability. In search modes, ground sampled distances (more correctly radar impulse response) is often ten feet or more.
The classic SAR (above) is ill suited for imaging targets which have rotational motion. They tend to defocus and blur the image unless the rotational motion is accurately predicted and compensated for in the processing algorithms. Inverse SAR (ISAR) systems use different algorithms that exploit the object's rotational motion, rather than the radar's relative velocity, which results in sharper images.
Interferometric Synthetic Aperture Radar (IFSAR) systems produce three dimensional images (i.e., they also produce elevation data). The IFSAR system operates by using two separate antennas spaced a meter to several meters apart. The systems employ two receivers and measure the phase difference of the received signal at the second antenna, using the received signal at the first antenna as a reference. The phase difference measurement is made by an interferometric technique. This phase difference is then processed to provide the third dimension of information. IFSAR systems are predominately experimental (e.g., R&D prototypes).
Currently there are no standards for SAR sensors or for their interfaces with associated pre-processors. The need for such interface standards will be addressed in a future version of the ARTA.
3.2.3.6 Moving Target Indicator Radar
Standards for this functional area are:
Moving Target Indicator (MTI) Radar systems detect the movement of objects within the radar's field of view. The range of speed detectable is different for each system and is limited by many design considerations. Fields of view are typically very large and can extend up to 200 miles distance from the radar. The processed MTI data is normally displayed on a map background and used for area surveillance and command and control of force deployments. If the MTI radar also has a SAR capability, then images of specific targets can be acquired, or low resolution search imagery can be taken of limited areas for use in place of the map background when displaying the MTI data.
Currently there are no standards for MTI sensors or for their interfaces with associated pre-processors. The need for such interface standards will be addressed in a future version of the ARTA.
Standards for this functional area are:
Spectral sensors provide unique targeting and intelligence data based on collection from multiple bands of reflected radiance, and from combinations of bands. The primary reconnaissance application for spectral data is to detect, locate, and identify exigent targets. Some of the spectral sensor data will be used to form images; other uses involve MASINT exploitation techniques as described in 3.2.4.6.
Spectral sensors are defined and categorized in the scientific community according to the number of non-redundant spectral bands within the sensor. The following nomenclature is generally accepted:
Spectral sensors have individual detector arrays with various spectral responses (i.e., one detector array for each spectral band). Each detector array produces an image (or image layer) corresponding to the spectral response in the given band. Multiple image layers are captured nearly simultaneously and registered to each other. Spectral bandpass filters may be used to change the spectral response of one or more of the detector arrays.
Spectral imagery is only beginning to be developed for operational use. It is possible to use the different scene reflectance in each band to detect and distinguish specific targets. Details that are not observable with panchromatic (visible) sensors may be detected from the image variations between multispectral layers. Spectral data may also be used in automatic target recognition (ATR) and/or cueing (ATC) software to provide more dependable performance than panchromatic imagery.
Spectral sensors typically produce very large quantities of data due to the fact that there are several layers (corresponding to the different bands), where each layer contains the same quantity of data as a panchromatic or IR image. This increase in generated imagery data and the technical challenges it presents are often a limiting factor in the design and use of spectral sensors. Recording and storing the data, as well as processing and exploiting it are more difficult than for single spectral imagery. Transmitting the larger quantity of information over a data link, especially in real time, is a formidable challenge.
Currently there are no standards for spectral sensors.
3.2.3.8 Image Quality Standards
Standards for this functional area are:
There are different National Imagery Interpretability Rating Scales (NIIRS) for visible, IR, and SAR imagery. There are no corresponding scales for video or spectral imagery. However, a video scale is being developed under CIO direction.
Measuring image quality with the NIIRS requires the subjective judgments of experienced imagery analysts. One potential airborne reconnaissance operational use of image quality measures is monitoring image quality in a ground station. Images could be prioritized so analysts could decide to exploit the images with lowest quality last. Another use could be to detect problems in processing. One candidate standard metric for this use is based on an objective metric - digital power spectrum analysis.
However, the Video Working Group (VWG)-sponsored Video Image Quality Control Board (VIQCB) is currently working on a video quality metric to accommodate the unique temporal aspect of video.
3.2.4 MASINT Front-End Functions
The following sections apply to the MASINT front-end components of the airborne reconnaissance functional reference model (Figure 3-4). Two important distinctions between MASINT and other intelligence systems are the maturity and diversity of the component systems. The MASINT discipline encompasses seven technological areas of remote sensing. Within each of the seven areas there are numerous implementations, many of which are still in the R&D phase, which makes the creation of standards a much more difficult task. Where possible, standards for MASINT systems are specified in this document; however, much work is ongoing to complete a set of standards. Instead, references to specific systems are given in this section to indicate the broad scope and relative immaturity of the MASINT discipline.
Figure 3-4: MASINT Front-End FRM
3.2.4.1 Chemical/Biological Weapons Sensors
Standards for this functional area are:
Within the Chemical and Biological Weapons (CBW) area, there is currently a broad cross section of emerging technologies with few common elements. The DARO's Technology Program Plan and Airborne Reconnaissance Technical Architecture Program Plan have shown, for example, that there are at least ten different sensor technologies that can be applied to the mission area of chemical and biological weapons detection. No operational sensor systems for airborne MASINT missions exist as yet. However, two prototype chemical sensor systems have been field tested on DARO UAV systems. The tested systems include a passive sensor system called the Lightweight Standoff Chemical Agent Detector and a point detector system called the Surface Acoustic Wave Chemical Agent Detector. No airborne biological systems have been fielded or tested.
CBW sensors can be logically categorized into four groups as follows:
Passive, optical-based standoff detectors
Active, optical based standoff detectors
Point detectors
Collateral sensors
The platforms used to carry CBW sensors include tactical UAVs, manned aircraft, hand launched UAVs, and cassondes (canisters with sensor payloads ejected from aircraft or UAVs). Tactical UAVs would be the ideal candidates for passive optical based standoff detectors but probably not point detectors because of post mission decontamination problems. LIDARS, with sufficient detection ranges must reside on a manned platform because of power considerations. Since chemical agent clouds are rapidly dissipated by wind and rain, toxic agents must be deployed in close proximity to the targeted forces and consequently, point detectors must also be close in. Point sensors would be hosted by cassondes, small UAVs, or other attritable platforms that sample toxic clouds and relay information back to analysis nodes. This alleviates the decontamination problem for more expensive reconnaissance assets, and in many cases could obviate the need for manned platforms, with all their inherent risks.
Accurate knowledge of weather conditions is crucial to predict the boundaries of CBW agents. Miniature meteorological sensors that measure and transmit data will be ejected from platforms (dropsondes) to detail atmospheric conditions (wind, temperature, humidity, position, and barometric pressure) while descending through the air. Sensor types can be configured to send meteorological data after ground impact as well. The CBW architecture must accommodate these sensors and input this data to meteorological models along with all other CBW sensor data.
The standard used for unattended ground sensors (SEIWG-005), cited in Section 3.2.4.3, is also applicable to CBW sensors.
3.2.4.2 Laser Warning Receivers
Standards for this functional area are:
Laser intelligence (LASINT) encompasses collection sensors for signature development and laser threat characterization. This function provides near-real-time battlefield laser warning and counter-measures. Essentially, laser warning receivers (LWR) provide an inexpensive, quick capability to detect, identify, and characterize foreign laser weapons and designators.
The following sensors are considered part of a comprehensive set of airborne LWR/LASINT systems:
Laser warning receivers must have interfaces to on-board alarm systems and connect to warning dissemination systems for alerting other aircraft and/or ground systems. This dissemination could be implemented through the direct reporting functions described in Section 3.7.1, but there are no alarm interface standards available. Raw LASINT data for signature analysis and Order of Battle (OB) requires a different communications or recording path than the alarms. As with most MASINT functionality, a dual path is required with LASINT/LWR, one that gives immediate reconnaissance information/identification and another that transfers huge data files to ground exploitation centers.
3.2.4.3 Unattended Ground Sensors
Standards for this functional area are:
Unattended ground sensors (UGS) are MASINT sensors that can be emplaced by airborne platforms, hand emplaced by special forces, and use platforms as relay communications back to a common exploitation station. Typically, UGS systems are fairly small, have autonomous power and communications, and transmit alarm messages when seismic, acoustic, magnetic, infrared (day-night imaging), and other sensors are activated.
Advanced UGS systems contain embedded automatic target recognition algorithms to recognize specific targets such as SCUD launchers and mobile command centers. This is accomplished by extracting key attributes from target signatures such as engine type, transmission type, exhaust location, number of axles, weight and weight distribution.
Available sensors include:
Sensors in development include:
The following is an "all-encompassing" military standard that governs the design of unattended ground sensors (e.g., it covers RF, data formats, transmission protocols, connectors, etc.): Interface Specification, Radio Frequency Transmission Interfaces for DoD Physical Security Systems, SEIWG-005, 15 December 1981.
Standards for this functional area are:
Of all the MASINT functions, air sampling is the oldest and most unique technique. Air sampling captures physical samples of atmospheric gases and particles. Additionally, beta and gamma radiation detectors are used on WC-135s to guide the flight path through the plumes. This MASINT function is not real time: no on-board processing is required, only power, space, and inlet ports within the airframe. The high degree of precision needed to analyze the samples can only be achieved in the laboratory.
3.2.4.5 Synthetic Aperture Radars
Standards for this functional area are:
Functionally, SAR sensors are common to both IMINT and MASINT disciplines. MASINT does not require additional SAR instruments but uses the raw data from the IMINT collection systems (Section 3.2.3.5) for specialized MASINT processing and exploitation. Although MASINT processors will normally process the data post mission, future systems will include on-board SAR phase history (PH) processing with products, along with raw in-phase and quadrature-phase (I&Q) data, available to ground systems. Therefore, standards affecting interoperability with MASINT SAR phase history processing systems must be considered.
Currently there are no standards for SAR sensors or for their interfaces with associated pre-processors. The need for such interface standards will be addressed in a future version of the ARTA.
Standards for this functional area are:
MASINT functions exploit spectral data acquired with the same spectral sensors as those used for imagery applications (see Section 3.2.3.7). One key difference is that rather than using imagery analysis techniques, MASINT applications process the spectral data directly (i.e., spectral signature analysis) to detect, classify, characterize, and identify various chemicals, biological compounds, and other affluents.
The technologies discussed in the following subsections make up the RF portion of the MASINT technical architecture.
3.2.4.7.1 Passive Bistatic Radar
Standards for this functional area are:
Passive bistatic radar technology is based on non-cooperative coherent exploitation of random background ambient signals. Signal exploitation is for purposes of airborne and ground based target detection, tracking, and identification. The non-cooperative exploited signal can be narrowband or wideband at, any carrier frequency from HF through X-band. The technology employs several processing modes that utilize cooperative and non cooperative emitters from commercial broadcast services through surveillance radars.
Standards for this functional area are:
Exploitation of foliage penetration (FOPEN) signatures will detect and potentially classify targets that are underground or concealed by dense foliage. Systems ideally would be used to gather information on communications, oil, gas, and power lines; toxic waste dump sites; underground tunnels; command bunkers; antipersonnel mines; and all concealed man-made objects using RF and acoustic technology. RF based systems generally employ broadband (nominally 200-400 MHz) low power emitters (1 watt). FOPEN processing algorithms require multiple polarization antennas (normally one vertical antenna, one horizontal polarized receive antenna, one transmit antenna) to optimize signatures from man made objects and eliminate return clutter from large natural objects such as large tree trunks. Acoustic FOPEN combines acoustic signatures analysis, for example, artillery fire sound, with phased microphone direction finding arrays to locate and identify hidden targets. Microphone arrays would be integrated on a UAV or other platform as part of an exigent target detection suite, feeding sensor information into advanced MASINT automatic target recognition functions with direct sensor-to-shooter product dissemination.
Standards for this functional area are:
Ultra-wideband sensors exploit non-intentional RF, detect wideband communications and tracking systems, or provide all-weather missile launch (plume) detection by characterizing rocket motor propellants and consequently the launch vehicle. An ultra-wideband receiver requires nominal operation over a band extending from 100 MHz to 10 GHz with greater than 2 GHz instantaneous bandwidth (10 GHz for strong signals with post processing). This is achieved through the use of antennas and receivers specifically developed for ultra-wideband (wideband blade antenna) use with fiber optic feeds and fiber optic distribution of intercepted RF signals.
3.2.4.7.4 Non-Cooperative Target Identification
Standards for this functional area are:
This is a broad category of MASINT RF techniques including analysis of radar cross section (RCS) signatures, feature modulation spectrum, and in general, it characterizes targets using the totality of all unintentional RF emissions. Ultra-wideband RF sensors collect against a wide variety of RF emissions from military equipment including directed energy weapons.
DRAFT