ATEN VE819 - ATEN VE819 - testing the projector wireless connection kit
Tell me, have you ever encountered a situation when, during a meeting in the meeting room, one of the speakers pokes his finger at the screen of his laptop and turns it so that it is visible to others? Needless to say, there are people of different mentalities, with different vision at the same table, and few people who look at the numbers and graphs are ready to understand the details. An awkward silence is followed by the catchphrase "send the materials by mail", and consider the meeting a failure. It is doubly disappointing that all this is happening in a brand-new hall, where a modern projector hangs under the ceiling, with support for both 3D and Full HD, but only the HDMI cable is laid permanently, and even then one, per device. In such situations, when you need to ensure that each speaker has their own connection to the projector, no matter what corner of the meeting room it is, it makes sense to abandon the cable altogether, using modern wireless transmitters instead.
ATEN has a solution in the form of a set of VE819, designed specifically for the above case: a wireless HDMI signal transmitter at a distance of up to 10 meters, - a fully hardware solution that does not require the installation of drivers and SOFTWARE, which allows you to connect up to 4 signal sources (laptops or media players) with a resolution of [email protected], with support for HDCP and 3D.
WHDI - wireless broadcast standard HDMI
The ATEN VE819 uses the WHDI (Wireless Home Digital Interface) standard to broadcast an HDMI signal over the air. Transmission is carried out in the unlicensed frequency range of 5 GHz with a channel width of 40 MHz at speeds up to 3 Gbit/s, which, by the way, is faster than modern Wi-Fi routers of the IEEE-802.11 ac standard, whose speed rarely exceeds 1.7 Gbit / s. However, this high speed imposes some limitations: in particular, the maximum communication distance between the receiver and transmitter is 10 meters, and Aten guarantees perfect image quality at a distance of less than 7 meters, which is quite enough for a typical meeting room. But where does the variation in quality and distance between the transceiver and receiver come from?
The fact is that the WHDI standard uses a very interesting video translation algorithm. The input of the transmitter receives an uncompressed video stream, which is divided into fragments. The transmitter processor filters the received fragments according to their degree of importance to the viewer: those fragments that have received a high priority are given a large share of the radio channel resources, and those that are not particularly important from the transmitter's point of view are distributed over the remaining radio channel resources. As a rule, the human eye does not detect small deviations in pixel color that occur as a result of radio transmission errors, so data correction is not performed on fragments with a low degree of importance. At the same time, optimizing the power level and spectrum allows you to transmit priority fragments completely without distortion, and as a result, the image looks the same as if it was transmitted over a wire.
It is obvious that the gradation in the ratio of important and secondary video objects is the little "Twister" with which one manufacturer can produce a wireless kit with a range of 30 meters on the same element base, and another - 5-7 meters, and here everything depends on the finesse of the end user for whom the kit was developed. Most cheap Chinese WHDI kits are designed for lazy people who will gladly take advantage of the opportunity to watch TV in the kitchen from a media player in the hall, without having to drill the walls and pull the cable, but if you show a commercial at a presentation, then you are responsible to the customer for every pixel, and here the equipment must work with the same quality that a wired connection offers.
When transmitting "over the air", the issue of broadcast protection becomes particularly relevant, so both the HDCP 2.0 Protocol and data encryption using the AES-128 algorithm are supported. However, in our particular case, the manufacturer is modestly silent about the HDCP version implemented in ATEN VE 819.
Of course, along with the video stream, the audio signal is also transmitted according to the WHDI standard, and ATEN VE819 supports 5.1-channel audio transmission at any image resolution.
It is worth emphasizing that the WDI standard provides for a delay of up to 3 MS on the part of wireless sets, but in the corporate segment, even such values are an unacceptable luxury, so Aten developers were able to achieve a delay of up to 1 MS regardless of the operating conditions of VE819.
Of course, following the recommendations of ATEN, the VE819 kit should be used in line-of-sight conditions, as is often the case in meeting rooms and conference rooms where the projector is suspended from the ceiling and there are no obstacles in the way of the radio signal. The manufacturer warns that walls, wires, or other objects between the receiver and transmitter can not only reduce the quality, but lead to loss of signal, but I noticed that nowhere in the instructions does it say about the impact of wireless Wi-Fi networks on the operation of the kit, so in our testing we will make up for this shortcoming and look at how the ATEN VE819 works in an area of heavy use of 802.11 ac wireless channels. Well, first let's look at the design of this wireless kit.
ATEN VE819 Construction
The receiver is designed to be mounted on a ceiling bracket, for which a screw thread is provided on the case, although you can simply put it on the projector. Power is provided from an external unit with a Mini-USB connector, so if there is no free electrical outlet near the projector, this is not a problem. USB power is not stated by the manufacturer, but our tests showed the following:
- Connecting to an Orico a3h13p2 USB hub-works
- Connecting to the USB 2.0 port of the Macbook Pro-works
- Connecting to a PC's USB 3.0 port-works
The receiver has two led indicators and a transmitter selection button. The ATEN VE819 model came to us for testing unassembled and without a remote control, so we can't show its operation, although make no mistake - when you buy the device, the remote will be in the box.
The transmitter looks like a regular USB modem, it connects to the laptop's HDMI output and is powered by a USB port. However, the Mini-USB socket is planted unsuccessfully: the cable connected to it blocks the neighboring USB port, so some laptops will have to be exhausted. Fortunately, the included USB cable is long enough to reach the opposite side of the laptop.
As soon as the Aten VE819T transmitter detects a video signal at the input, it selects the most appropriate channel for broadcasting and communicates with the receiver. Our first test will show whether the radio congestion at the time of connection setup. The typical connection time is 12 seconds, and does not depend on whether 5-Gigahertz access points work nearby or not. Similarly, the connection time does not depend on the distance between the receiver and the transmitter.
Let's move on to the most interesting part - compression quality, for which we will use an online test www.monteon.ru. Let's start with the toughest "flicker" test, where black and white dots are consistently displayed on the monitor screen. In total, such a picture should not be compressed, so for ATEN VE819 this case is more an academic study of the algorithm than a real task.
HDMI cable at left vs ATEN VE819 at right
We see that when the mouse moves, the cursor area is redrawn with a long shadow, and obviously the traffic prioritization that was mentioned in the description of the WDI standard is not here, and the transmitter divides the entire band of the radio channel evenly for all pixels.
If you complicate the test and increase the distance of VE819 from 50 centimeters to 5 meters, then artifacts appear in those areas of the screen that are not redrawn when the cursor moves, which once again confirms the uniformity of the band distribution regardless of the dynamics in the frame.
Here you need to make a remark and show that after the movement is completed, the image is restored to the original quality and there are no traces of compression in the static.
Okay, we have full compression, but how does it manifest in real-world tasks? In static images, such as diagrams or slides, as you have already realized, there is simply no visible difference between the HDMI cable and the ATEN VE819, which is confirmed by the following photo.
HDMI cable at top vs ATEN VE819 at distance of 10 meters (bottom)
If you use the extended dynamic range on your monitor, you will notice a difference in color reproduction between the HDMI cable and the ATEN VE819, although this is not relevant for presentations.
As for Web presentations, vertical scrolling is just fine, and there is no feeling that a radio channel is being used. So you can scroll through word documents, tables, and web pages without fear that the image will be damaged.
Another thing is horizontal movements, such as a running line or the appearance of an object on the screen. Here, the typical JPEG compression around the border with maximum contrast is shown in the form of barely noticeable gray spots, which can be removed if you reduce the contrast of the monitor or projector itself.
From top to bottom: 1) HDMI Cable, ATEN VE819 at distance 50 cm,
ATEN VE819 at distance 5 meters, ATEN VE819 at distance 10 meters
In this test, photos are shown without post-processing to preserve the original color of the pixels captured by the camera. To our surprise, the quality is almost independent of the distance, and objectively for ATEN VE819 that 50 centimeters, 10 meters - the same thing.
More important is the "purity" of the 5-gigahertz range. If an 802.11 ac access point that transmits streaming data via a radio channel (for example, an Apple Time Machine backup) is operating within the range of the ATEN VE819, compression artifacts appear over the entire frame area at a distance of more than 5 meters. But there is no particular pattern here: the influence of the access point and traffic over the 5-gigahertz range depends on the location of the hotspot and the location of the connected devices.
In general, the reliability of the Aten VE819 radio channel in line-of-sight conditions was pleasantly surprised - during testing with active use of Wi-Fi and 4G communication on two smartphones, the broadcast was never interrupted, but if there is a 15-cm concrete wall between the receiver and the Aten VE819 transmitter, the wireless connection is not established.
The cost of the Aten VE 819 kit, consisting of a receiver, transmitter and remote control, is $ 700. One Aten VE819T transmitter will cost you $ 350. Let me remind you that you can connect up to 4 transmitters to one receiver. In conditions where the projector is installed and connected, such a kit can be cheaper than re-routing additional HDMI cables, in addition, no special personnel is needed to connect the ATEN VE819, and there is no configuration as such.
Given that the ATEN VE819 uses compression for signal transmission, this kit should not be considered as a replacement for traditional cable, but as a solution when you need to add mobility and flexibility for visitors in a ready-made meeting room or conference room for relatively little money. This is the simplest device that any employee can handle: the transmitter can be transmitted as a microphone among the participants of the event, or you can connect several sources once and quickly switch between them from the remote control. Thus, the customer has the opportunity to significantly save on retrofitting the existing infrastructure, and in principle, somewhere to do without HDMI switches and cable stretching.
This kit is perfect for presentations and displaying static images (graphs, charts, slides), but for situations where high image quality is required, it is better to use a matrix switch (see our review of Aten continuous matrix switches).
Michael Degtjarev (aka LIKE OFF)