It sounds like you're asking about the Bluetooth feature for connecting a YG Dongguan (YGD) car stereo to an Android phone.
While "YGD" isn't a widely recognized major brand, it often appears in the context of generic Bluetooth adapters FM transmitters ygd car bluetooth android
Before the rise of smart interfaces, car audio was limited to physical media and radio. The introduction of Android-based head units transformed dashboards into multifunctional tablets. The YGD interface is a staple for many of these "generic" or aftermarket units, providing a dedicated environment to manage Bluetooth connections that are often more flexible than standard factory systems. Key Features and Functionality It sounds like you're asking about the Bluetooth
detail how to build and control small-scale vehicles using Android-Bluetooth interfaces. ScienceDirect.com App-Specific Context Ygd Car Bluetooth Android - Google Groups The YGD interface is a staple for many
Since the device plugs into the cigarette lighter, many YGD units show your car battery's voltage. This is an excellent security feature for Android users who might drain their battery while listening to music with the engine off.