A brief discussion on PEPS technology

       Today our theme is PEPS. Some people may feel unfamiliar when they talk about PEPS, but when it comes to RKE and PKE, everyone should be familiar with it. PEPS is an integration of RKE, PKE/PKG, and IMMO. This article will introduce PEPS from the perspective of system composition and working principle.

1. PEPS noun explanation

       PEPS-Passive Entry Passive Start, keyless entry and start
       RKE-Remote Keyless Entry, remote keyless entry by remote control.
       PKE-Passive Keyless Entry, passive keyless entry.
       PKG-Passive Keyless Go, passive keyless start.
       IMMO-Immobilizer, anti-theft control system.

       RKE is now quite mature and has become the standard configuration of automobiles. However, people's pursuit of "convenience" and "efficiency" is endless. Coupled with some weaknesses of RKE technology itself, it has promoted the development and maturity of PKE/PKG technology. The function of the PEPS system is more powerful: press the door handle switch or touch the door handle sensing area, the door will automatically unlock (PKE), and the owner only needs to press the button or turn the knob to start the engine (PKG). There is still a way to start the engine (IMMO) when the key runs out of power. High-end models have always had high requirements for configuration, so powerful PEPS technology has become standard for high-end models.

2. PEPS components

          The main components of PEPS: base station chip, electronic key, LF antenna, one-button start button.
          The base station chip-control antenna transmits a low-frequency signal, receives a high-frequency unlocking signal from the key, and sends information to the car lock module, which is responsible for the communication with the electronic key and the interaction with the equipment.
          Electronic key-accepts low-frequency trigger signals while transmitting high-frequency unlock signals
          LF antenna-arranged in the trunk of four doors +, to ensure that the owner can achieve a keyless switch no matter which door is opened. The short transmission distance of low-frequency signals increases safety: the owner only opens the door when he walks in, reducing the risk of the vehicle being stolen.    

3. How PKE/PKG works

         The original intention of PEPS technology design is to enable users to carry an electronic key with them, and they can enter the vehicle without pressing a button (remote unlocking).

         Unlike RKE's one-way communication, PKE/PKG uses two-way communication. The working process of PKE/PKG is roughly divided into two stages: low-frequency wake-up and high-frequency authentication. Low-frequency wake-up: When the user appears in the detection range of the base station with the electronic key and pulls the door handle/presses the rotating start button, the door handle/button will send a start signal to the low-frequency antenna, the low-frequency antenna sends a trigger signal, and the electronic key will receive a low-frequency signal. If this signal is the same as the low-frequency antenna, the electronic key will receive a low-frequency signal.The data stored in the key matches, and the key will be awakened; high-frequency authentication: After the key is awakened, the "password" sent from the host will be analyzed, and the corresponding data will be calculated according to a certain algorithm and encrypted and sent back to the host to send a high-frequency unlock signal. After the base station receives the high-frequency unlocking signal, the host analyzes the received data and compares it with the calculated data. If the two are matched successfully, the door lock will be opened to notify the vehicle to unlock/ignite. The whole process, from waking up to opening the door lock, only takes a few milliseconds, so from touching the door handle to opening the door, the user does not feel any delay.

                                                   Figure 1 Schematic diagram of PKE/PKG work

4. How IMMO works

         IMMO is mainly enabled in an emergency state. When the smart key runs out of power or the PKE operation fails, the smart key is placed close to the IMMO coil (shared antenna) and charged through mutual inductance. Low-frequency authentication can be achieved, and emergency start-up can be achieved after the authentication is passed.

                                                                 Figure 2 Schematic diagram of IMMO's work

      As can be seen from the figure, IMMO is a low-frequency communication between the IMMO transceiver and the backup transponder on the key side through a shared antenna. IMMO, together with RKE and PKE/PKG, forms a powerful and safe PEPS system, which enhances the experience of car owners.

      The next article will introduce the LF low-frequency transmitting antenna in PEPS. If you are interested, please stay tuned.

       Reference: AN-SCA1602-B-NJJ29C0A-Joker (2.0)