The INS (inertial navigation system) is a self-contained navigation system. It provides a continuous navigation output with short-term stability and high bandwidths. The accuracy of INS devices will degrade over time. To boost their efficiency and performance, INS devices have GPS (global positioning systems). Though the GPS/INS systems are more accurate compared to INS stand-alone devices, these devices are still vulnerable to spoofing and jamming.

To guarantee that your device remains accurate in the face of jamming and spoofing threats, INS simulation is essential. In a simulation, you will use different tools to recreate the common disruptions which might affect your device’s accuracy. This allows you to gauge the device’s performance with these threats and enables you to improve its design to counter the threats. Here are a few of the parameters your GPS/INS simulators will generate for the testing of your device:

Carrier Phase Generation and Code Quality Parameters

These parameters are reflected in simulators as uncertainty during your code’s offset, uncalibrated errors in your device’s range production, and pseudorange accuracy. An uncalibrated error in your device’s range production will include uncertainty in its distance, satellite clock errors, and tropospheric and ionospheric delays. The pseudorange accuracy of your simulator should be within 0.3 meters RMS. The carrier alignment and inter-channel code represent the difference between the carrier and code phases at the output of a simulator using the same satellite. This parameter should be approximately zero when using a digital simulator and more for analog simulators.

Generated Power Level Parameters

When using RPSes, the generated power level parameters are non-applicable. The uncertainty in the overall simulated power level for your simulator should be around one decibel though two decibels at most will also suffice for some devices. The simulator that you settle for should allow you to change its signal power independently with at least a decibel for each channel.

Quality of Simulated Signals Parameters

The quality of your device’s simulated signal is described by the carrier frequency stability and its phase noise. The carrier frequency for your simulator’s signal should be centered and have an accuracy of a few hundred hertz or more even after some years of operation. Your carrier’s quality depends on the simulator’s master clock quality. The ideal master clock stability over 24 hours should be about plus or minus 5×10-10.

Vehicle Dynamic Parameters

GPS inside a car

Your ideal simulator should support the parameters of various vehicle dynamics. Though not applicable to all GPS/INS devices, these parameters will give you an idea of the abilities of your simulator. Analog simulators are generally limited to low user dynamics while their front-end RF filters’ capabilities will define digital simulators.

There are multiple simulation devices currently available for the testing of positioning tools, but few will guarantee your device’s accuracy. The right simulation parameters, rather than a brand name or the cheapest machine, are the essential ones when testing the efficiency of your GPS/INS device. The given parameters are generally found on RF simulators and are designed to ensure the simulations are usable in the field and usable for repeat tests.