Wireless video transmission - The most common problems with wireless video on live shows and how to solve them
Maybe you already experinced the following situation. All wireless cameras were tested before a show starts. Every single position works well without any loss of signal. The signal strength reaches the maximum on the RSSI (Receiver Signal Strength Indicator). Everything seems to be well-prepared for the show.
Under live conditions with audience things might change. Wireless video that was tested well before might be of poor quality or not work at all anymore. Did you ever experience something like that? How could that happen? Well, the answer is simple. The audience has got a major influence on wireless video. WHDI technology works with reflections and people absorb wireless signals very well, because they consist in a large part of water. More people in a space increase humidity and by warming up the air they even increase its moisture holding ability. The third point is that everybody has got its smartphone which creates wireless noise, too. Basically, what was tested has got nothing to do with the actual live situation.
First of all you should use a spectrum analyzer to see what is happening. There are many different devices available; even free applications for smart phones. Choose whatever you feel convenient with. In our new wireless receivers, ULR1 and LR2 we already implemented a spectrum analyzer, which can be viewed over the HDMI port, also when transmitting live.
Compared to complex license-based systems, WHDI technology still provides several advantages:
It is easy to use, has got low latency, is relatively cheap and ensures higher image quality as a result of uncompressed
transmission. Occasionally, when working under difficult conditions, the ability of this broadcast technology to cover
significant distances may become somewhat limited. In exceptional cases the available bandwidth may become overloaded.
To ensure the optimum broadcast levels in such cases, please respect the following points:
1. Screw the antennas properly and position them as indicated on transmitter and receiver.
2. The transmitter and receiver
should be set up parallel to
each other at a similar height.
3. Avoid obstacles such as walls, trees, water and steel constructions.
4. Make an active channel management by analyzing the 5GHz band and stay as far away as possible from other wireless traffic.