Benefits and Challenges

Integrated Sensor Systems of

Barry A. Rich Lockheed Sanders, Patrick J. Lehnerd

Westinghouse Electronic Systems and

James A. Gracia Harris

ABSTRACT

Projection of avionics system costs shows unacceptable escalation as a percentage of flyaway cost. Time sharing of RF modules between Radar, EW and CNI offers savings. The Air Forces’ PAVE PACE program defined the benefits and initial architecture approaches. From this, an optimum Integrated Sensor System (ISS) design was defined that reduces the life cycle cost of the fleet of vehicles using the common modules. The ISS program’ will design, build and test modules to prove the approach. Challenges to overcome include system complexity, real time control, test and calibration, and diagnostics. The most stressing requirements were determined by analyzing requirements for Radar, EW and CNI. Open interface specifications and module partitioning were developed that can meet all the requirements.

INTRODUCTION

Mission requirements continue to stress the functional and performance requirements of tactical aircraft avionics

’ Integrated Sensor System ( I S ) program sponsored by WLIAAAS-I

Authors’ Current Addresses: B.A. Rich, Lockheed-Sanders, 1x50 Parkway Place. Suite 4211. Marietta. GA 30067: P.J. Lehnerd, Westinghouse Electronic Systems. and J.A. Gracia, Harris

Based on a presentation at NAECON ‘95.

OXX5-X9X5-95/$4.(N 0 1995 IEEE

systems, driving them to represent a larger percentage of tactical aircraft flyaway cost. Projections of avionics system acquisition costs - based on the cost of fielded systems - show an escalation that will exceed 35% of tactical aircraft flyaway cost in the year 2000 (Figure 1 next page).

attributed to RF and E-0 sensor systems. The reliability of fielded avionics systems directly affect maintenance costs - avionics systems comprise 37% of unscheduled tactical aircraft maintenance actions (Figure 2 next page).

Moreover, there is a five-fold increase between uninstalled and installed avionics system weight which affects tactical aircraft system operating costs. Together, thesc factors comprise the prime motivation for the development of a low cost, more reliable, lighter weight integrated sensor system.

ways: 1) share multifunction modules to increase hardware utilization; 2 ) promote competition for common module production by use of an open architecture; and 3) incorporate maturing technologies with improved size, weight, power, ani reliability. The Lockheed Team’s approach to an integrated sensor system advances the state-of-the-art in each area to dramatically reduce avionics system life cycle cost.

The ISS program has evolved from a succession of avionics integrations programs including PAVE PILLAR and PAVE PACE. Based on the results of the PAVE PACE Phase 1 program, the Air Force decided to focus on improved commonality and integration of the sensor and RF equipment

A major component of this cost, approximately 63%, is

Integrated sensor systems produce these savings in three

IEEE AES Systems Magazine, September 1995

Avionics Porti on of Aircraft Fly-Away Cost ? %

'.%tn 0%

Breakdown o f Avionics Fly-Away

PVI, VM, & Stores

1960 1970 1980 2000+ Fig. 1. Avionics Cost Analysis

Sensor edicate pertures F-MFH Processor Core 1

S stem perture

c a s t

Sensors (RF&EO

63%

I Federated RF Sensors I .RF resources only avallable

to speclflc functions *mlnlmal commonallty

Sensor edlcate perture

.maximum resource availablllty

.increased functionality -Nearly Toyo of that attributable to RF 8

Procrsror Srnror System

Triple rellab ility

Fig. 2. Motivations for RF Sensor Integration

VGeneration 4aGeneration LowCodInt+ (PAVE PILLAR) (PAVE PACE) grated Avionics

Fig. 3. Evolution of Avionics Integration

suite. Eventually the core processing system will need a technology update. However, given the rapid pace of digital processing advancement, optimum strategy dictates that the program begin as late as possible to take advantage of the best available technology (Figure 3).

CHALLENGES

challenges. The most prominent establish the need for specific approaches that must be addressed in order to realize an integrated sensor system (Table 1 next page). The Lockheed

The vision of an integrated RF sensor system has many

12 IEEE AES Systctiis Magazine. September 1995

Table 1. Key Challenges to be Addressed by the ISS Program

Challenges 1. Integrated system's complexity and cost

effectiveness

Approach - Increase average utilization through time sharing Employ proven RF packaging technologies to

I reduce module cost and size. 2. An Integrated system is difficult to control I Establish a control scheme that provides

and manage as real-time events cause conflicts and compromise on-going, high priority functions.

3. An integrated system is difficult to test. verify, and calibrate because of the plethora of hardware combinations re- quired to execute the required functions.

.

4. An integrated system makes it difficult to perform built-in-test, diagnostic tests, and fault isolation and re-configure the system's assets.

graceful degradation. Establish a flexible control scheme that supports parallel control processing. Establish rational module partitioning that incorporates manufacturability and testability concepts: Use digital IF processing to reduce the amount of calibration required and improve testability. Establish module and sub-module level built- in-test and diagnostics to support O-level module replacement. Establish an architecture that provides the necessary spares to support in-flight hardware

Table 2. CNI Modes Required for Superior Tactical Aircraft

Communication HF Voice, Anti-Jam HF Link 11 VHF AM, Encrypted VHF FM VHF Encrypt SINCGARS VHF AM/FM Guard VHF ACARS UHF Clear, Guard UHF Encrypted HQ11 Link 11 Air Phone JTIDS FLTSAT COM SatCom Receive, Transmit

ADF ILS Localizer ILS Glideslope ILS Marker Beacon VOR DME/PDME Receive DM E/PDM E Transmit TACAN Receive TACAN Transmit GPS (CA Code) L1 MLS GLONASS Radar Altimeter

Identification , - - ATCRBWIFF MKI 2 Xpond IFF MK12 Interrogate Mode SIXAS Xpond Mode S/TCAS Interrogate

Team will focus on addressing each of these challenges during the course of the ISS Program.

ISS REQUIREMENTS

Preliminary requirements used for the ISS are based on previous PAVE PACE documents and applied Lockheed Team experience. This team has not eased requirements levels to reduce the challenge of ISS; the performance allocations selected for ISS modules are typical of the current tactical avionics practice. While no set of universal requirements will

fulfill all needs, relevant experience can allocate requirements to common modules designed for wide application.

CNI functions are essential for flight navigation and safety, and, in tactical situations, provide effective combat identification and data links to leverage off-board asset battlefield information. To a large measure, allocation of CNI requirements involves selecting which functions are appropriate and what level of simultaneity is necessary. Key CNI challenges are obtaining compatibility with systems usin non-1SS implementations, providing a high degree of availability to perform flight essential and flight critical functions, and delivering needed performance within platform

IEEE AES Systems Magazine, September 1995

Table 3. Key Stressing Requirements Driven by CNI Functions

Frequency Coverage 2 MHz to 2 GHz 2 MHz - 18 GHz (mmW

I I I programmable R

Spur Free Dynamic Range 80 dB min. 80 dB min. Modulation Types AM,FM,FSK,QPSK,Pulse,SSB AM,FM,FSK,QPSK,Pulse,SSB Frequency Tuning Time 20 us 20 us Transmit S~urious -70 dBc min. -70 dBc min.

Table 4. Required Radar Modes by Aircraft Mission Type

Table 5. Key Stressing ISS Parameters Driven by Radar Function

ent with dynamic

constraints. Table 2 (previous page) lists CNI functions to be performed by the ISS. Table 3 lists key CNI retirements that 1SS must address.

Key radar modes and their application to various types of platforms is summarized in Table 4. This table illustrates the typical modes available on Air/Surface Attack and Air/Air

14 IEEE AES Systems Magazine, September 1995

Table 6. Key EW Function Modes oscillator phase noise and spurious levels. Dynamic range requirements allocated to the ISS are comparable to current high performance radars in development, allowing the program to verify that the ISS architecture will not reduce achievable Air/Air radar performance. The key requirements for Air/Surface radar modes involve spurious levels. Dynamic range waveform diversity and modulation bandwidth. The significant driver is high resolution SAR, requiring wideband precision linear FM waveforms. Selection of exact radar specifications without clear definition of missions is

Table 7. Key Stressing ISS Parameter Driven by EW Function

Electronics W d e instantaneous bandwidths *Multiple bandwidths *Diverse detection / demodulation

RF Distribution *Access to multiple apertures *Enable reconfiguration W d e band frequency conversion

Siqnal/ LO Generation *Spectral punty *Wide frequency coverage *Diverse waveform generation

*AID performance

Apertures & Core Processor *Not generally part of ISS (physically)

Fig. 4. Driving Requirements for Selected Technologies

Fighter types of aircraft. Also shown is an assessment of the modes likely in a true multirole attack/fighter aircraft and an RPV configured for Aidsurface surveillance. These platform types illustrate the wide range of ISS application.

The key stressing requirements for these modes have been reviewed and are summarized in Table 5 (previous page). Key mode parameters have been described in previous PAVE PACE documents and reviews. The key driver of Air/Air modes to the ISS is dynamic range, impacting receiver linearity, A/D conversion parameters, and exciter/local

admittedly a subjective task; therefore, requirements parameters are being specified over ranges of performance. From this range of performance levels, common modules wil be built to target the most stringent requirements that can be cost-effectively achieved. The modularity of the architecture allows any tailoring necessary to be performed for any application.

The diverse EW modes used for tactical defensive and offensive functions are briefly summarized in Table 6. Receive functions acquire, track, and analyze various radar

IEEE AES Systems Magazine, September I995

Shared E I Fig. 5. Top Level Block Diagram

n1.d LO DidbulUl f

Fig. 6. Detailed Block Diagram

and CNI emissions. These functions can employ widebeam and steered narrowbeam antennas. Transmit functions provide electronic countermeasures using onboard or towed decoy transmitters. Other countermeasures are directed by the ISS receive modes. RF functions performed by the ISS are used synergistically with non-RF sensors and countermeasures.

The key stressing parameters imposed by the ISS are summarized in Table 7 (previous page). Wide instantaneous bandwidth is a key driver on the frequency plan. The need to simultaneously detect multiple emitters impacts receiver type selection. Pulse Predictive Tracking and countermeasures coordination drives the frequency switching time. Sensitivity requirements are platform specific, depending upon RCS, antenna patterns, cable losses, and instantaneous bandwidth.

The approach for the ISS is to achieve the lowest noise figure consistent with dynamic range requirements. The ISS is required to perform precision DF measurements with interferometer or multi-beam antennas such as multi-arm spirals, and with narrowbeam antennas. Specific countermeasures implementations are also platform specific. The ISS architecture is required to support ECM modes needed for self-protect, escort, and stand-off functions.

Given the key requirements for each function of ISS (Radar, EW & CNl), combined requirements to create multi- function common modules are derived. The top level functional requirements that characterize each functional area are shown in Figure 4 (previous). These driving requirements summarize the challenges that must be met on ISS.

16 IEEE AES Systems Magazine, September 1995

APPROACH

The ISS architecture consists of interface specifications and common module designs. The interface specifications are first because they support the open architecture and allow system designers to create modules that interoperate. The ISS architecture must meet the following key challenges:

Achieve commonality across RF functions without degrading performance Establish open architecture interfaces Provide additional capability without added hardware Maximize modularity for technology growth and wide application Minimize number of common module types Reduce RF sensor volume, weight, and cost.

An ISS architecture definition has been successfully developed that addresses all these needs. This ISS open architecture is derived from previous PAVE PACE Program Concept Development phases. Using this as a point of departure and the criteria defined above, trade-off candidates will be defined and analyzed to ensure that an optimal ISS design is achieved. The focus of the ISS architecture design will be on minimization of overall fleet life-cycle cost rather than focusing on optimizing for a given platform point design. The ISS design point emphasizes satisfying the needs of the widest range of candidate insertions of ISS, while incorporating enough flexibility for the architecture to adapt to the very low and very high-end platform needs. This architecture consists of functional blocks which have standardized interfaces, forming the basis for an open

architecture that can serve diverse avionics applications and allow new technology to be inserted with minimal impact.

The block diagrams defining the ISS open architecture functional blocks shows how the RF and IF signals flow between processing modules and switching functions (Figure 5,6 on previous page).

RF signals are received and transmitted via shared apertures and their associated aperture electronics. The RF Switch allows common frequency conversion hardware to be shared among the various apertures. The Frequency Conversion functional block converts signals to and from a common IF interface to enable the resource sharing necessary for an ISS. The IF Switch complements the RF Switch in maximizing the reconfigurability available to maximize ISS capability and achieve high fault tolerance. While the interfaces are specifically defined, each definition is intended to provide a significant degree of design flexibility allowing an optimal solution for each platform implementation. As technology advances, new module types may be introduced into functional blocks without having to redevelop the entire ISS.

SUMMARY

The ISS program will develop the design techniques to support Radar, EW and CNI within a common module suite. Time sharing these common modules between mission functions allows system designers to create avionics systems with dramatically fewer modules, yielding reduced cost, weight, power, and failure rate.

29th Annual IEEE International Carnahan Conference on Security Technology

October 18-20,1995 + Sanderstead, Surrey, England This International Conference is directed toward the research and development of electronic security technology. It establishes

a forum for the exchange of ideas and dissemination of information on both new and existing technology. Conference participants will be stimulated to consider the impact of their work on society. The Carnahan Conference also provides a basis for long range support and assistance to authorities and agencies responsible for security, safety and law enforcement in the use of available and future technology. A conscious effort will be made to communicate the significance of developments to other interested groups. Liaison is maintained with professional societies and information media not especially related to engineering.

TOPICS Papers describe recent developments in the following fields:

1 . Sensor and detection technology, including principles of

2. Alarm devices, searching aids and systems. 3. Monitoring command, control and communication systems. 4. Computer systems security and privacy. 5. Information surety. 6. Communication security and privacy, including modulation

7. Biometrics identification systems, utilizing voice, handwriting,

8. Entry control systems, access delay technology and surveillance.

operation and signal analysis.

techniques, spectrum management and encryption.

fingerprints, etc.

9. Counter-terrorism techniques and technology. 10. Impact on society of security systems and technology. 11. User experiences of operating security systems including their

introduction and testing. 12. Police and forensic technology. 13. Cryptology. 14. Less-than-lethal weapons technology. 15. Counter Proliferation. 16. Airport Security. MEETING PLACE

Sheldon Park Hotel, Sanderstead, South Croydon, Surrey CR2 8YA; Telephone: 081-6578811, Fax: 081-6516171, Telex: 945002

IEEE AES Systems Magazine, September I995