# An Efficient Ultra-Tight GPS/RISS Integrated System for Challenging Navigation Environments
## 4 Experiment Work  
This research used both simulation and real signal data to help in the design and validation of proposed method. Figure 6 illustrates experiment setup used in this research. For the GPS data, the GSS6700 Satellite Navigation Simulation Signal Generator, by Spinent, was used to design and generate the desired trajectory. The most important feature of the GSS6700 system is the repeatability function that enables it to provide wide dynamic capacity in GPS signal characteristics such as Doppler and signal power levels as well as enough channels to support in-view and multipath environments. To benefit from the trajectory scenarios generated by this system, it needs to be connected to a Front End (FE) unit. This research used the FireHose D17088, by NovAtel, as the front end unit to generate the in-phase (I), and quadrature-phase (Q) signals out of the data stream obtained from either the above-mentioned simulator or real trajectory data by connecting the unit to an antenna. This research also comprises real GPS signal jamming experiments. This obviously requires the re-broadcast of the GPS signal to expose it to the real jammer signal. Thus, an exclusive and very interesting setup was built for this purpose. The real jamming signal experiments took place inside the Anechoic Chamber room at the Royal Military College of Canada (RMC). The room is designed with impenetrable walls and doors blocking any signals from entering or exiting the room. This guaranteed that the re-broadcast GPS signals and the real jammer signals could not penetrate to outside the room. The complete real jamming experiment setup is shown in Figure 7.  
Figure 6: Schematic Diagram of the Hardware System. Note the use of a power amplifier at the transmitter side instead of a low noise amplifier (LNA) since the GPS signal power is normally below the noise floor. On the contrary, an LNA is used at the receiver side which will significantly amplify the received low-power GPS signal while keeping the noise induced by its circuitry minimum. Real pictures of the transmitter and receiver antenna inside the room are shown in Figures 8 and 9, respectively. A picture of most of the devices used outside of the room is shown in Figure 10. The NovAtel NEAT jammer can work in high power and low power modes. Only low power mode has been used in this research. Furthermore, the device can generate four types of jamming signals: Narrow Band (NB), Wide Band (WB), Chirp, and Continues Wave (CW). The CW jamming type is chosen for the experiment shown in this work. For the INS data sets, the INS Simulator, developed by the Mobile Multi-sensor Group at the University of Calgary, is used for simulating inertial measurement unit (IMU) raw data. This simulator can virtually generate the raw data measurements of any grade of IMUs such as navigation, tactical, and consumer-grade systems. While the simulator can generate raw IMU measurements using user-defined vehicle motion and dynamics, it can also accept externally injected vehicle dynamics from real trajectory data. The latter approach is used in this research. Figure 11 shows a high-level diagram of the trajectory data flow from the two arms of the complete signal/data simulation system used for both GPS and INS systems. The simulation process happens in three main steps. Step one-trajectory design when the general aspects of the trajectory such as the type of platform to be simulated, the satellite constellation, and the trajectory environment, are outlined. All of this is done using the Spinent SimGEN(tm) software. Step two incorporates the implementation of the selected scenario and generating the data stream that is fed into the signal generator hardware (Spirents SSS6700), which in turn transforms this into a Radio Frequency (RF) signal. At the same time, the reference trajectory data are logged on the same computer that hosts the SimGEN(tm) simulation software.