SITIS Archives - Topic Details
Program:  SBIR
Topic Num:  AF071-164 (AirForce)
Title:  Virtual GPS Jammer Airborne Wavefront Simulator Technology
Research & Technical Areas:  Weapons

  Objective:  Research and development of a small, mobile, GPS jammer wavefront simulator capable of supporting GPS static and dynamics testing.
  Description:  The technology to accurately assess the capability of emerging anti-jam (AJ) GPS munition technologies in a high dynamic environment is limited. Current methods rely on a mix of contractor and government facilities including laboratory simulations and flight test environments. The current methods do not provide an accurate assessment of AJ GPS system performance under high dynamics in the presence of persistent dense high J/S environment. The current systems are based on old technology and methods. Current analysis is based on a mix of Laboratory and open air tests. The Laboratory instrumentation systems used to date are rather large, suffer in their ability to accurately provide a suitable stimulus to the GPS system under test, and cannot support flight testing in high dynamic inertial environments. The problems associated with open air testing is that the test environment is not controllable and flight clearances for denial of GPS signals must be coordinated and approved before testing can occur. Obtaining a clearance to jam the GPS spectrum is becoming extremely hard, especially with high J/S levels, limiting testing to a small number of remote test areas during restricted time slots. The increased sophistication of GPS anti-jam technology and resulting jamming immunity against a multiple high power GPS ground transmitters precludes the practicality of open air jamming. The purpose of this effort is to investigate novel technologies to develop a mobile, digital GPS jammer wavefront simulator capable of supporting static laboratory testing, ground based mobile testing, and airborne high dynamic testing.

  PHASE I: Investigate the feasibility of developing a jammer wavefront simulator capable of accepting dynamic inertial inputs and generating simulated jammer wavefront RF outputs relative to the platform, CRPA and virtual jammer locations. The goal is a system capable simulating 20 jammers to a 5 CRPA.
  
  PHASE II: Development and demonstration of a Phase I prototype system. Prototype must demonstrate the capability to accept platform inertial, jammer location and antenna configuration data then generate virtual jammer wavefronts relative to the host platform and jammer locations. Wavefront simulator output will be mixed with GPS satellite signals and injected into a candidate receiver.

  DUAL USE COMMERCIALIZATION: Military application: Potential military applications include testing of advanced anti-jam technologies Commercial application: Potential commercial applications includes testing of future civilian systems, in particular systems that may use advanced GPS systems.

  References:  1. www.navsys.com, "NAVSYS Corporation - GPS Systems, Receivers, and Signal Processing" 2. Lagier, Craig, Benshoof, Holloman AFB, NM, AIAA-2004-6853 “JAMFEST, A Cost Effective Solution to GPS Vulnerability Testing”, USAF Developmental Test and Evaluation Summit, Woodland Hills, California, Nov. 16-18, 2004 3. “GPS Vulnerable to Jamming.” Boat/Magazine, Nov. 2001. http://www.findarticles.com/p/articles/mi_m0BQK/is_6_6/ai_80223827

Keywords:  Jamming, Wavefront, controlled reception pattern antenna (CRPA), Training, Modeling, Simulation, GPS

Questions and Answers:
Q: For Phase II, is the responder required to provide a GPS constellation simulator in addition to the jammer simulator?
A: The topic does not require the capability to generate a GPS constellation but it would be desirable and at a minimum proposers should show a path forward to include that capability.
Q: 1) What types of jammers are you interested in simulating. Can you give some general characteristics (bandwidths, center frequencies, signal types, etc.)?

2) Is the RF mixer (to mix the live GPS signals with the simulated jammers) something that would be delivered under this effort?

3) Can you give me an idea of your size, weight, and power requirements. Is there a specific container size or form factor that you're looking to fit this solution into?

4) What kind of aircraft would this be deployed on? Would the wavefront simulator be placed next to the antenna, next to the receiver, or somewhere in between?

5) Would this initially be an L1-only system, or L1/L2? Are there any other frequencies of interest?
A: 1. Any noise source type jammer in the 25 MHz GPS band to include; Wide Band (full GPS spectrum), narrow band (CW), Gaussian noise, pulsed, swept etc…

2. It would be desirable to include the GPS signal as part of the simulator as that would allow for laboratory type testing. Unless my memory is incorrect, the topic as written does not include the GPS signals but only the jammer signals. The concept is to perform signal injection testing where the wave front simulator output would be mixed with the GPS signal in space on the backside of the CRPA prior to being injected into the GPS receiver. The addition of the GPS simulator would eliminate the need for the CPRA. At a minimum, a path forward to a system that could be expanded to include a GPS simulator would be a positive.

3. I want to be able to fly this in a small plane, C-12J or Beachcraft type, so the simulator needs to fit in a standard 19” rack mount. I’m assuming this can be done in a single chassis or on as a modular approach. I would expect each unit not exceed the standard 6U size (10.5 inch), and prefer it to be as small as possible. If your design will require multiple racks of equipment, it is probably not a feasible solution. The system needs to be able to run off a 28 Volt supply and not exceed 5 Amps in load. We do not have a platform weight limitation per say but we will have to install the items so my back would prefer it be within reason.

4. The airborne platform will be a C-12J or Beachcraft type aircraft. The concept is that the simulator would be in front of the receiver and that it would include mixers to mix the GPS signal in space from the CRPA with the simulated jammer signals. A typical installation would have the GPS receiver in the same chassis as the simulator.

5. L1/L2/L5 is desired. The design should all any single band or combination of bands be selected.
Q: For Phase II, is the responder required to provide a GPS constellation simulator in addition to the jammer simulator?
A: The topic does not require the capability to generate a GPS constellation but it would be desirable and at a minimum proposers should show a path forward to include that capability.
Q: Will the GPS receiver under test have a digital beamforming antenna, or analog CRPA antenna electronics? If the answer is the former, can the GPS receiver itself be used to calibrate the simulator, or will the responder have to supply calibration hardware?
A: The system should be designed independent of the GPS receiver type. The intent is to develop a generic capability that generates a GPS jammed environment. All types of GPS receivers will use the wave front simulator including those that incorporate CRPAs, FRPAs (even though a wave front simulator is not required), Beamforming, Nulling, etc... The receivers that need antenna electronics will have them.

The operational concept for this system is to use the wave front simulator to generate a dynamic, high GPS jamming environment for testing purposes. The simulated environment will be injected into the GPS receiver at the base of the antenna. If a GPS constellation(wave front version) is not included as part of the system, the output of the GPS jamming wave front simulator will be mixed with the signal in space on the back side of the antenna (FRPA/CRPA). The proposed solution must include the capability to mix the jamming environment with the GPS signal in space.

It is expected that the proposed system will include the required hardware and procedure to calibrate the system independent of the GPS receiver being tested.
Q: 1) What types of jammers are you interested in simulating. Can you give some general characteristics (bandwidths, center frequencies, signal types, etc.)?

2) Is the RF mixer (to mix the live GPS signals with the simulated jammers) something that would be delivered under this effort?

3) Can you give me an idea of your size, weight, and power requirements. Is there a specific container size or form factor that you're looking to fit this solution into?

4) What kind of aircraft would this be deployed on? Would the wavefront simulator be placed next to the antenna, next to the receiver, or somewhere in between?

5) Would this initially be an L1-only system, or L1/L2? Are there any other frequencies of interest?
A: 1. Any noise source type jammer in the 25 MHz GPS band to include; Wide Band (full GPS spectrum), narrow band (CW), Gaussian noise, pulsed, swept etc…

2. It would be desirable to include the GPS signal as part of the simulator as that would allow for laboratory type testing. Unless my memory is incorrect, the topic as written does not include the GPS signals but only the jammer signals. The concept is to perform signal injection testing where the wave front simulator output would be mixed with the GPS signal in space on the backside of the CRPA prior to being injected into the GPS receiver. The addition of the GPS simulator would eliminate the need for the CPRA. At a minimum, a path forward to a system that could be expanded to include a GPS simulator would be a positive.

3. I want to be able to fly this in a small plane, C-12J or Beachcraft type, so the simulator needs to fit in a standard 19” rack mount. I’m assuming this can be done in a single chassis or on as a modular approach. I would expect each unit not exceed the standard 6U size (10.5 inch), and prefer it to be as small as possible. If your design will require multiple racks of equipment, it is probably not a feasible solution. The system needs to be able to run off a 28 Volt supply and not exceed 5 Amps in load. We do not have a platform weight limitation per say but we will have to install the items so my back would prefer it be within reason.

4. The airborne platform will be a C-12J or Beachcraft type aircraft. The concept is that the simulator would be in front of the receiver and that it would include mixers to mix the GPS signal in space from the CRPA with the simulated jammer signals. A typical installation would have the GPS receiver in the same chassis as the simulator.

5. L1/L2/L5 is desired. The design should all any single band or combination of bands be selected.
Q: Will the GPS receiver under test have a digital beamforming antenna, or analog CRPA antenna electronics? If the answer is the former, can the GPS receiver itself be used to calibrate the simulator, or will the responder have to supply calibration hardware?
A: The system should be designed independent of the GPS receiver type. The intent is to develop a generic capability that generates a GPS jammed environment. All types of GPS receivers will use the wave front simulator including those that incorporate CRPAs, FRPAs (even though a wave front simulator is not required), Beamforming, Nulling, etc... The receivers that need antenna electronics will have them.

The operational concept for this system is to use the wave front simulator to generate a dynamic, high GPS jamming environment for testing purposes. The simulated environment will be injected into the GPS receiver at the base of the antenna. If a GPS constellation(wave front version) is not included as part of the system, the output of the GPS jamming wave front simulator will be mixed with the signal in space on the back side of the antenna (FRPA/CRPA). The proposed solution must include the capability to mix the jamming environment with the GPS signal in space.

It is expected that the proposed system will include the required hardware and procedure to calibrate the system independent of the GPS receiver being tested.

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