The Function and Design of GPS PCBs

Key Takeaways

  • In systems requiring real-time location inquiry, GPS technology is used. 

  • The quality of the signal received by the GPS PCB antenna is significant in locating the coordinates. 

  • Shielding the GPS antenna traces minimizes noise levels and crosstalk in GPS PCBs. 

GPS navigation

Tracking systems are based on GPS technology

After shopping online, I often find myself obsessively tracking my shipment as it travels from the warehouse to my door. There is something satisfying about watching my purchase travel through the logistics pipeline. Tracking systems make the delivery process transparent to customers and ensure that packages don’t get lost on the way; the logistics industry has been forever changed because of tracking.

GPS technology enables tracking systems, with most tracking systems relying on GPS PCBs. In GPS PCBs, the GPS parameters are read using a GPS module. In this article, we will explore the details of GPS PCBs as well as key design guidelines. 

GPS Technology 

Satellite-based global positioning systems (GPS) utilize information sent from satellites to locate a position on the planet. The location is measured in terms of geographical coordinates, commonly referred to as GPS coordinates. GPS coordinates provide information regarding a location in the form of latitude and longitude. 

GPS PCBs

In systems requiring real-time location inquiry, GPS technology can be used. GPS PCBs are installed in such systems, and devices incorporate GPS modules to provide location details. A GPS PCB includes an antenna, depending on the type of GNSS system used on the board. The GPS PCB antenna can be either passive or active. An active antenna integrates a low-noise amplifier (LNA) along with it, while a passive antenna does not. The noise level in the output signal can be considerably reduced by using an active GPS antenna. Passive antennas incorporate an external LNA for noise reduction.

GPS Module

The quality of the signal received by the GPS PCB antenna is significant in locating the coordinates. GPS operation is completely dependent on the signal received by the GPS module in the GPS PCB. The GPS module receives information signals from GPS satellites in the radio frequency range of 1.1 to 1.5 GHz. The time taken by the signal to travel from the satellite to the GPS module is measured. From the equation relating distance, speed, and time, the distance from the satellite to the location is determined. Using the trilateration method, the location is calculated from the distance.

In a GPS PCB, the communication between the GPS module and controller or computer is established using protocols such as UART, I2C, etc. Let's look at the schematic of a GPS PCB where the GPS module is interfaced with a microcontroller

GPS PCB Schematic: GPS Module Interfacing 8051 Microcontroller

GPS PCB

The schematic of the GPS PCB interfacing GPS module with microcontroller 8051 is presented in the figure above. The GPS module consists of four pins:

  1. VCC - The power supply of 3.3 to 6V

  2. GND - Ground connection

  3. TX - From this pin, the location and time can be transmitted serially 

  4. RX - This pin can receive data serially

The TX pin of the GPS module is connected to the receive pin of microcontroller 8051. The receive pin of 8051 receives the signal serially from the GPS module. The microcontroller 8051 reads the serial data from the GPS module at the default 9600 baud rate. The microcontroller 8051 communicates with the GPS module using the UART communication protocol. From the data received in the NMEA (National Marine Electronics Association) string format, the required information, such as time, latitude, longitude, etc., is extracted. The latitude and longitude form the GPS coordinates and can be displayed on the LCD. 

Common Design Guidelines for GPS PCBs

While designing a GPS PCB, there are certain design guidelines to follow to ensure excellent performance and electromagnetic compatibility. Some recommendations are:

  • Start the design of the GPS PCB by placing the GPS antenna to achieve quality radiated performance.

  • When the system or device under fabrication has multiple antennas, design the layout so that there is a minimal amount antenna crosstalk.

  • Shield the GPS antenna traces to minimize noise levels and crosstalk. Shielding the power supply and other key components from the GPS antenna also improves the operation of the GPS PCB. 

  • If the GPS PCB design consists of multiple layers, maintain the antenna transmission line impedance to 50 Ω.

  • Route the PCB layers in such a way that excessive capacitance in routing is minimized.

  • Routing should take into account noise levels in the circuit. The GPS module should be separated from noisy routings. 

  • Long routing should be avoided, as it increases insertion loss.

  • Ensure a continuous reference ground plane above and below the GPS routing.

In the logistics industry, GPS technology is critical to gaining customer support and trust. In most real-time location tracking systems, GPS PCBs can extract the key location details that customers rely on.

To design GPS PCBs, Cadence software tools can be utilized. Cadence offers a complete set of system analysis and simulation tools to build GPS PCBs with excellent radiated performance and exact location tracking.

Leading electronics providers rely on Cadence products to optimize power, space, and energy needs for a wide variety of market applications. If you’re looking to learn more about our innovative solutions, talk to our team of experts or subscribe to our YouTube channel.

About the Author

Cadence PCB solutions is a complete front to back design tool to enable fast and efficient product creation. Cadence enables users accurately shorten design cycles to hand off to manufacturing through modern, IPC-2581 industry standard.

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