You can make a signal device if you have something with shiny surface.

如果你有表面发光的物体，就可以做一个信号装置。

youdao

Can also be used to external lighting and signal device and vehicle lamps shell protection.

也可用于外部照明和信号装置及汽车灯具外壳防护。

youdao

Use speed signal generator of PZX-1, you can test every movement of switches of speed signal device.

利用PZ X - 1内置的转速信号发生器，可以试验转速信号装置的各个转速开关量动作状况。

youdao

The device sends a signal to a computer at the back of the car.

VOA: special.2009.11.03

Consumers have the right to receive a broadcast TV signal on any device they choose (originally just a TV) and by extension, record programs for their own personal use.

FORBES: By Putting Over-the-Air Online Legally, Aereo Clears The Way For ALL TV Everywhere

An LED power indicator glows to signal that the device is ready to charge, and its internal SmartFuse protects against power fluctuations as it charges with a built-in circuit breaker, and no fuses to replace.

ENGADGET: Griffin launches PowerDock 5 multi-device charging platform and ChargeSensor adapters

In the video, the major appears to be upbraiding the soldier for not using a laser warning device to signal the approaching truck.

NPR: Insider Attack Kills 2 US Troops, 2 Afghans