Do not be afraid of designing wireless systems, but before locating elements analyze if a wired version is better.
Juan Tamayo *
The industry has sold the idea that, technologically, wireless signals are the best, since the savings in the cost of wiring will make the project more efficient cost / benefit. How good is it that your corporate project is wireless? Does it justify the wireless cost for the operation of your room or workspace? I do not pretend to discourage the reader about the use of wireless systems. With this column I intend to generate an awareness of the use of the radio frequency spectrum and how misuse can affect the operation of your project.
The designer before offering a complete wireless system must analyze if the RF radio frequency spectrum is viable. Possibly in projects that involve the construction of a new building is a bit complex because there is no way to measure the signals that have not been installed, but having meetings with the parties involved can have the design information and generate a protocol for using RF signals . However. For projects already built, it is important to have the necessary tools, as a designer I recommend using at least two elements: RF analyzer and Wi-Fi signal analyzer.
The RF spectrum is divided into segments that almost all of us who work in the industry at least know two VHF and UHF. A few years ago it was common to hear 'work better in the UHF because it is freer'. A third segment of RF that is also well known, but little investigated by the technical staff is the 2.4 GHz. In this segment there are signals such as Bluetooth, Zigbee, Wi-Fi and many others. The characteristic of this segment is that its use is free and does not require operating licenses from government entities (in theory, in some countries they limit the transmission power of the elements and / or require transmission certification, such as Mexico and Peru).
For the frequency range of RF of VHF and UHF it is necessary to have certain basic knowledge of how RF signals operate (in 2.4 GHz also but it is not so complex). I think that the first thing is to analyze how is the legislation of each country, investigate what range of frequencies are operated by mobile telephony and digital terrestrial television. In recent years the growth of these technologies has been exponential and their occupation means that other RF technologies do not operate correctly, as is the case with wireless microphones.
Having a panorama of free space, assign by priority what wireless signals can operate in space, remember that your microphones system will coexist with communication radios (surveillance), cellular telephone operators, radiofrequency systems operating in the city ( official radios, radio taxis) among many others. Ideally, make an analysis and deliver the priority signals that within your design you can control. For example, what is more important or easier, change the wireless microphone signal or change all the surveillance radios?
With the digital terrestrial television transition, VHF channels have been released, so as a designer you can use these channels. The recommendations you should have are:
- In some Latin American countries it has not yet been the total change of digital television technology, there are still analog channels in the VHF.
- The lower the operating spectrum, the less number of channels you can use.
- In analogue UHF television transmission you can locate microphone type audio channels in the middle of signals. In digital transmission the bandwidth consumption is complete and you can not do anything (in theory).
Adjustment of signals
Additionally, apart from having meters, in order to make a good adjustment of signals in UHF and VHF, I consider it important to study the consequences of the Distortion by Intermodulation or IMD. Basically they are the concepts of how the RF signals are related and generate inconveniences of operation.
Remember that although you select digital models that operate in VHF or UHF, they will comply with the same rules as the analog models, the way you send the information varies.
The operation of RF signals in the range of 2.4 GHz is totally different. I believe that the first thing to do is an operation analysis of each signal, protocols such as Bluetooth and Wi-Fi use channel hopping. The first thing is to analyze which signals have static frequency, take note of this and block those channels in devices that have jumps (if possible).
If the protocol to be used is Wi-Fi, analyze the bandwidth that it consumes, because a high consumption of information can damage the performance of other systems that share the Wi-Fi channel. Remember that the use of IP protocols can generate a latency in the sending of information, even adding the Wi-Fi negotiation protocol its latency and communication errors will be unpleasant technologically. Having many routers is not the solution, because these devices will interact with each other. Try to be very efficient in the design of your RF system.
Do not be afraid of designing wireless systems, but before locating elements analyze if a wired version is better. At Audio-Technica we have several types of wireline and wireless solutions for the development of any audio project involving audiophiles, microphones and playing records. If you have any questions or want to know more about the subject, do not hesitate to contact me.
* Juan Tamayo is a senior applications engineer for Audio-Technica Latin America, with more than 10 years of experience doing audiovisual projects as a designer, integrator, consultant, among other functions. You can write to email@example.com