Frequency drift refers to the slight deviation in frequency that occurs during the operation of a chip due to internal heating. In the process of transmitting BLE (Bluetooth Low Energy) packets, the drift is not allowed to exceed 50kHz.

Due to inherent errors in crystal oscillators, the frequency of a Bluetooth chip is obtained through frequency multiplication of the crystal oscillator, thereby amplifying the crystal oscillator's error. For example, a 16MHz crystal oscillator needs to be multiplied by a factor of 150 to achieve a frequency of 2400MHz. If the actual frequency of the crystal oscillator is 16.0001MHz, the center frequency will deviate by 150kHz. This crystal oscillator error is referred to as 62ppm, which means 62 parts per million. Generally, the smaller the error of a crystal oscillator, the higher its price. As long as the error falls within our acceptable range, it is considered tolerable.

It supports low-power Bluetooth while also being compatible with Classic Bluetooth. Classic Bluetooth is characterized by high-speed transmission of large data, such as audio, video, and other data.

It means low-power Bluetooth mode.

Official term: EMI/RFI

Explanation: Speaking loudly on a busy street is necessary to be heard, while whispering is possible during a quiet night. External noises can affect a conversation between two people, just as external radio frequency signals can impact RF reception.

To deal with interference signals, one can increase the transmit power, similar to raising one's voice on a busy street to be better heard.

Another approach is to enhance the receiver sensitivity. A person with sensitive hearing can understand conversations more easily even on a noisy street.

Note: EMI stands for Electromagnetic Interference, while RFI stands for Radio Frequency Interference.

Just like a national identification number, if you try to find a person based on their name, you might encounter a list of people with the same name. However, if you search using their identification number, you can immediately locate the specific person you are looking for. In BLE (Bluetooth Low Energy), when you want to directly access a specific service on a peripheral device using a central device, if you know the UUID (Universally Unique Identifier) of that service, you can immediately pinpoint and access that particular service.

By amplifying the energy of the signal through a power amplifier, the transmitted signal can propagate in the air with reduced attenuation, allowing the receiving device to still receive a higher energy level.  

This indirectly leads to an increase in the communication distance. It's similar to a person speaking normally, where people within 1-2 meters can hear their voice, but when shouting loudly, people within 10-20 meters can hear their voice.

The GNSS module outputs a PPS (Pulse-Per-Second) signal only after acquiring satellite signals successfully.