If you've ever felt threatened walking home late at night, chances are you've phoned a loved one to make sure they know you're safe.
如果你深夜步行回家时感到害怕，你极有可能向你爱的人打电话，向他们报平安。
But making calls not only makes your phone a target for thieves, it can also distract you from your surroundings, putting you at greater risk.
但是打电话不仅会暴露手机成为小偷的目标，还会分散你对周围环境的注意力，将自己置于更危险的境地。
Now there's an app that lets your family or friends track your journey and will call for help automatically if it senses you're in trouble.
现在有一款应用能让家人或朋友了解你的旅途足迹，当感应到你遇到危险时，自动求救。

Called Companion, the main feature that distinguishes it from other tracking and GPS apps, such as Apple's Find My Friends, is its 'Are you OK?' button.
这款应用名为“同伴”（Companion）。该应用的主要特色“你还好吗？”（“Are you OK?”）按钮使它与其他行迹和GPS应用不同。
Before setting off on a journey, users input their starting point, their destination and a designated 'companion'.
出发前，用户输入出发点和终点，然后授权一位“同伴”。
This can be anyone in the user's contacts book, and they don't need to have the app installed.
这个“同伴”可以是用户通讯录里的任何一个人，而他们不必安装此应用。
The 'companion' can then track the phone's GPS to see where their loved one is at any time, while the app will periodically show a button on the user's home screen asking 'Are you OK?'
然后这位“同伴”就可以跟踪手机的GPS随时了解他们爱的人所在的位置，而同时应用会定时在用户的主屏幕上显示一个按钮，询问“你还好吗？”。
If they don't press the button within 15 seconds, the companion is sent an alert.
如果用户15秒内没有按下按钮，指定的“同伴”就会收到提醒。
The user is also given the option to call the police from within the app.
而在用户的应用中也会出现报警的选项。
Elsewhere, the app can detect if a person has been running, or headphones have been removed from the audio jack suggesting the phone has been dropped, for example.
此外，这款应用还可以检测一个人是否在奔跑，或者耳机是否从插孔里脱落，这可能表明手机已经掉了。
If this happens, the 'Are you OK?' button appears and the 15-second countdown starts automatically.
如果这种情况发生，“你还好吗？”按钮就会出现，然后自动开始15秒的倒计时。
Companion is free for iOS and Android devices and users need to enter their mobile number to sign up to the service.
苹果与安卓设备可以免费使用“同伴”，用户需要输入手机号码注册来获得此服务。

Although the app was designed in the US, it works with international numbers when they are prefixed with their country's code.
尽管这款应用是在美国设计的，但是只要在前面输入国家代码，全世界的手机号码都可以使用。
'Companion lets you reach out to family, friends or your campus police and have them keep an eye on you as you travel late at night,' explained the app's makers.
应用设计者说，“当你深夜时分在外时，‘同伴’可以保持你与家人、朋友或校园警察的联系，他们可以实时注意你的动态。”
'If you start running, don't make it to your destination on time, have your headphones yanked out or your phone falls to the ground, we will check in on you to make sure everything is okay.
“如果你开始奔跑、没有准时到达目的地、耳机拔了出来或者手机掉到地上，我们都会尝试联系你，确认你一切安好。”
'You can also report areas that make you uneasy. Simply tap the 'I Feel Nervous' button and we'll pass this information on [the authorities].'
“你也可以举报令你感到不安全的地方。很简单，按‘我感到紧张’按钮，我们会把相关信息传达给有关部门。”

Companion is similar to SafeTrek, an app that uses the pressure sensor of smartphone touchscreens to create an alarm that will call for help if the user lifts their finger off.
“同伴”和SafeTrek功能相似。SafeTrek是一款利用智能手机触屏压力感应器的应用，当用户松开手指时，应用会发出呼救的警报。
Removing a finger triggers a screen asking for a four-digit pin code and if it is not entered it alerts the police and directs them to the user's location.
移开手指会触发一个要求用户输入四位的PIN码的屏幕，如果不输入PIN码，应用就会通知警方并指引他们到达用户的位置。