Today, mobile devices in the form of smartphones and tablets are becoming more and more “smart”, and many of them are not inferior in their functionality to even powerful computer systems. And, interestingly, most of the new devices support MHL technology. What is it now and see. At the same time, we will determine the main points regarding the connection of gadgets to TV panels and the advisability of using such innovations.
MHL technology: what is it?
In general, the abbreviation MHL stands for Mobile High-Definition Link (almost HDMI), which, in ordinary language, can be interpreted as technology for mirroring the screen of a mobile device on a high-definition television panel.
It appeared relatively recently, so even the claimed MHL support in some devices may not work. To date, the most common and used are the MHL versions 1.x and 2.x, and only recently a third version has appeared, which, although it has sufficiently high prospects for implementation, has not yet received wide distribution.
As for the main features, the use of such a technology of screen duplication allows transferring a Full HD image with a resolution of 1080p from a mobile gadget to a television panel with surround sound standard 7.1 with minimal delay in transmission time. But this applies only to the first and second versions. In the third modification, to the surprise of many, the ability to broadcast images in 4k (Ultra HD) format was added.
Analogs MHL
If we consider some similar developments, it is easy to notice that this technology is very similar to, say, Miracast or Intel WiDi. In mobile devices and panels Samsung MHL is often called Screen Mirroring. This is wrong, although there is an analogy.
However, the similarity in our case concerns exclusively the principles of signal transmission, and certainly not the connection. From here - and cardinal differences in the basic principles that correspond to the use of MHL in practice.
The main differences between MHL and other standards
Now let's look at the well-known developments and the original MHL technology. It’s not difficult to figure out that this is by its connection principle, given that broadcasting is carried out exclusively using a wired connection of the HDMI type, and not using, for example, Wi-Fi connections.
In other words, in order to transfer an image from a mobile device to a television panel, you need to use special cables with adapters. This is where the new technology is very much similar to the usual connection via an HDMI cable.
But! If you connect a mobile device via either an HDMI connector or use a wireless connection, it will be discharged quickly enough when broadcasting a signal. But MHL, when connected, also allows the device to be charged by the type of how it happens through connecting to USB ports. In this case, there can also be two options: either charging is performed using an external source, or from the panel itself. It all depends on the type of adapter used. In addition, it is the connection of special adapters that allows you to broadcast a signal even if the MHL technology is not supported by any of the devices. And this is a significant plus.
How to connect via MHL-adapter
As already mentioned, for the correct connection should use special adapters. They are distinguished by two main types: passive and active.
Passive cable is very similar to standard cords for mobile devices. On the one hand there is a micro-USB connector, on the other - a plug that resembles a regular USB. In fact, the second connector is a standard MHL connector and must be connected to the TV panel through a special socket.
If there is no such jack on the panel, it makes sense to use a passive cable that has the same micro-USB connector (plug) and two more ports: HDMI (MHL) and a regular micro-USB input.
As for charging gadgets, in the first case a direct connection to the TV is used, in the second version it is supposed to connect an additional external source (remember how passive and active speakers work for computers). By the way, it is the presence of a passive cable that allows broadcasting on panels in which there is no MHL support.
Pros and Cons
So we got to know MHL technology a bit. What it is and why it is needed, I think, is already a little clear. Now let's look at some of its advantages and disadvantages.
The first category, of course, certainly includes support for high definition images (up to 4k), Dolby Surround 7.1 and DTS sound, as well as the ability to use multiple monitors at the same time, plus connecting a sufficiently large number of supported peripherals (mouse, keyboard, touch screens etc.). In addition, the technology itself is based on the basic principle of self-tuning Plug & Play devices, that is, you do not need to make any settings - plug and use.
As for the shortcomings, the main problem boils down to the fact that today there is a limited number of mobile gadgets and TV panels that have MHL support (version 3.0 is generally not worth talking about yet). Thus, most tests show that at best, you can transmit a 1080p image with a frame rate of about 50 fps. When trying to broadcast more videos with a smoother transition at 60 fps, alas, problems often arise. Finally, the current of 500 mA, provided in version 1.0, is clearly not enough to fully charge the mobile device.
What is the result?
That's probably all on the topic "MHL: what is it?" Of course, only the main aspects related to the technology itself, the principles of its use and practical application without an in-depth study of the technical part of the issue are given here. Nevertheless, it is thought that even such brief information can give an idea of how promising this technology is, despite even the wired connection between the devices. Naturally, I would like to hope that the developers will not stop there and will present some innovative development on this basis to the world, especially since wireless chargers are no longer a curiosity. It was interesting to see the combination of such charging with wireless image transmission ...