Car GPS Receiver Test Tool Guide

There are more and more people in China who own private cars, and the range of car owners and their family activities has also been greatly extended. Car GPS navigation will be a useful tool when they go on vacation on weekends, and car GPS navigation system testing has become a hot topic for engineers in the industry.

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Car GPS navigation systems are basically divided into two types, one is a simple GPS receiver with antenna plus mapping software and digital map, this system can be bought from the electronics store. The other is embedded in the car like a CD player. It is a GPS/inertial navigation system formed by a more powerful GPS receiver with multiple sensor inputs. Among them, gyro sensors, odometers, wheel interrupters and other sensors can improve the navigation accuracy when the vehicle is interrupted by a GPS signal such as a ramp or a towering building.

Testing of the first navigation system requires only a small amount of work. Each GPS receiver is factory tested, so there is no need to test its GPS performance again when these GPS receivers are sold in the store. The only thing that needs to be tested is whether the actual latitude and longitude position data can be correctly mapped to the digital map by the mapping software.

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Figure 1 depicts the collaboration mechanism between the simulator and the car package function.

There are generally two test methods. One is to test the on-board navigation system, put the measured navigation system in the car, and observe whether the GPS data can be correctly mapped into the digital map during most of the time. This type of in-vehicle navigation system is more suitable for use in areas with good GPS reception on most roads, such as most countries in the US or Europe, but not suitable for cities like Shanghai and Hong Kong, because many towering buildings block GPS signal. Another test method is to use a GPS constellation simulator. This approach saves engineers a lot of time and effort, and they can easily complete test tasks indoors.

For the second in-vehicle GPS/inertial integrated navigation system, the test challenges faced by engineers are mainly as follows:

Geographic barrier

The correct choice of different sensors
Different GPS receiving environments
Data synchronization between GPS data and inertial sensors
Vehicle control during testing
Human Resources
Time constraint
System performance analysis

Towering buildings in the city block GPS signals, while inertial sensors improve navigation accuracy in this situation. The amount of road test required to manually perform this type of integrated navigation system test is enormous. There are even times when testing is not possible due to geographical barriers. In addition, engineers are not likely to travel throughout China for testing, which is certainly unrealistic.

It is well known that it is important to choose the right gyro sensor for an integrated navigation system. The higher the price of the gyro sensor, the better the quality, but in practical applications, it is desirable to obtain acceptable performance at a reasonable price. The GPS constellation simulator with sensor emulation is the ideal tool for test engineers to find the right gyroscope type or model for the system.

Different GPS reception states are another challenge faced by test engineers. The GPS receiver can obtain a good and stable signal most of the time. However, when the GPS signal is unstable, the data in the signal is lost or the signal is weak, what happens to the navigation system? These situations do not always occur when people do field manual testing on the road, so this situation needs to be simulated. The LabPro GPS Simulator from NavLabs is the ideal tool to overcome this challenge.

NavLabs, a company that offers LabPro GPS simulators, has provided solutions to many customers in different countries, such as cellular manufacturers, NASA, GPS receiver manufacturers, and military. Dr. Frank Bletzacker is the planning designer for the LabPro GPS simulator. He previously worked in the Jet Propulsion Laboratory. Many of the new algorithms used by the simulator were invented by Dr. Bletzacker. These algorithms are very accurate and the pseudorange error can be controlled within +/- 1 cm of any other product on the market.

Unlike GPS constellation generation, LabPro has different sensor functions. LabPro's car package features help automakers efficiently test their integrated in-vehicle/inertial navigation systems to accelerate the processing of data synchronization between GPS receivers and inertial sensors, or at least provide control for engineers to integrate systems A more sexual environment. There are a variety of sensors for real-world simulations such as gyro sensors, speed sensors and acceleration sensors. Test engineers can use these sensors to perform high-precision test evaluations indoors.

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Figure 2: Automotive speed sensor model.

As shown in Figure 1, the car package has the following characteristics:

Proportional to the 5V analog output of the car's rate-of-turn;

a CMOS level pulse rate output proportional to the speed of the car;

Serial data message: provides wheel speed, steering and other navigation data in serial format via PC COM communication port;

Analog accelerometer output: 0-5V accelerometer output with 2 channels;

A user programmable wheel separation model is provided to support differential wheel discontinuities for inferring steering.

Wheel speed sensors can support different data formats, such as the Zodiac 1370 serial wheel speed format for Rockwell (Conexant) Zodiac 12-channel Dead reckoning receivers and various SirfDrive formats. Sensors can be used to simulate various events such as sliding, sliding, sideways and jumping. In the real world, test engineers are not stunt performers. It is difficult and dangerous to drive these simulations. The corresponding control panel is shown in Figure 2.

LabPro is a fully integrated GPS constellation simulator that is not only suitable for testing automotive navigation systems, but also for other applications such as GPS receiver research and development, avionics test beds and some spacecraft research. LabMate is a simplified version of LabPro, especially for mass production testing of GPS receivers and research on vehicle land handling. Thanks to the fully digital design of the product, LabMate can be easily upgraded to LabPro. Even if the GPS system has new features in the future, all NavLabs products can be upgraded smoothly. The GPS Navigation Data Logger is the latest addition to NavLabs and is an ideal tool for automotive manufacturers to test GPS/Inertial Integrated Navigation.

Controllers

Controllers include handsets and control boxes. They work together for users to control chair,  bed, and anything with linear actuators more easily. The input and output voltage can be customized from 12V DC to 230V AC. And multiple functions are available: controlling one, two, three or even more than four actuators at the same time; synchronizing function; memory function; etc. Controllers have passed Rosh, CE, UL certification.

Actuator Accessories

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