In Windows Phone 8.1 there is a new feature called Project my screen. I've not been able to make it work.
How do I use it?
In Windows Phone 8.1, there are two ways to project your screen.
Projecting your screen wirelessly uses Miracast technology. This requires a compatible receiver (e.g. a Smart TV, or something like the Netgear PTV3000), and will only be supported on newer WP 8.1 handsets. Paul Thurrott reports in his Windows Phone 8.1 review:
But as you might expect, Miracast is limited to newer devices that support it, including the Nokia Lumia 1520, Icon, and 930.
This was also alluded to by Microsoft's Joe Belfiore on Twitter:
WP8.1 supports Miracast but it will require new HW. MAYBE 1520 is new enough, I'm not sure. most WP8 hw won't be.
Supposedly some older devices like the 820, 920 and 1020 also have a SoC that can support Miracast with a firmware update, but that's yet to be confirmed.
To use Miracast, assuming your receiver is hooked up to your TV (or other display) and the same WiFi network as your phone, simply open the "Project my screen" app and tap on your receiver to connect to it (you may have to wait a bit for your phone to find it).
To project your screen via USB, you need a PC running the Project My Screen app. Simply install the app on your PC and launch it, then connect your phone and it should pop up a prompt asking you if you want to allow screen projection:
Going through a PC is required, you can't just hook up directly to a TV. From this post at Microsoft Answers:
Note that the USB capability is going to be supported by an app on a PC. It is not just a cable to HDMI in on a TV/Projector. You need that intermediate PC if you are going for a big screen.
If screen projection over USB doesn't work, try the following steps:
To stop projecting over USB, you can do any of the following:
Under settings > notifications+actions you can manage the quick actions - one of those is "project my screen", and if allocated to a quick action slot, simply swiping the screen down and choosing the project my screen option then searches for compatible displays that it can project to.
On a Nokia Lumia 820, the "project my screen" settings page states:
This phone can't project your screen with a wireless connection. Connect with USB.
To project via USB, you need to download and install the "Project my Screen" application, available free from the Microsoft website.
Once that is installed, and running, connecting your phone will prompt on the phone to allow the projection.
If it doesn't (and mine didn't at first), you may need to go to Control Panel -> Device Manager, and uninstall the drivers for the phone under both under "Portable Devices" and "Universal Serial Bus devices" - in my case a reboot was required, but then it just worked.
Scott Hanselman has posted a link to the Project My Screen App that you need to install on your Windows PC to project your WP 8.1 screen to it via USB.
Scott's blog entry: http://www.hanselman.com/blog/WindowsPhone81HasMyAttentionNow.aspx
Or if you have Nokia phone, you can use the Nokia Beamer app. It's tuned more to an over-the-Internet or cellular type of bandwidth though.