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Where to start: Simultaneous Translation Equipment 101

Where to start: Simultaneous Translation Equipment 101

What is the difference between FM and IR technology? Can both of them be used in any situation?

Even though both technologies are used for simultaneous interpretation, there are situations where FM systems are recommended, while others require the use of IR systems. FM wireless systems provide a strong and reliable signal, which is able to pass through walls and opaque objects. It’s the most economical, simple-to-operate and with an easy set-up system for churches, auditoriums, courtrooms, stadiums, classrooms and boardrooms.

If your wireless system must function in large spaces, even on multiple channels, as a rule of thumb radio frequency systems are your best bet. This is especially true outside, where IR transmitters and receivers will often not function due to interference from sunlight.

In the US and in most of the Americas the most convenient and the only approved frequency by the FCC for Language Interpretation is 72-76 MHz. This frequency band is out of the range of commercial FM radio stations and cellphone stations and is free from interference. The coverage range is between 150 and 1500 feet depending on the transmitters and antennas. An FM system can be expanded by adding as many receivers and headphones needed, the only limitation being the coverage area of the transmitter.


IR (Infrared) systems are frequently used for confidential meetings since IR signals don’t pass through walls, and/or when there is a need to use more than 6-8 languages in one room. With IR wireless listening systems, transmission is confined within opaque walls, making it a good choice for sensitive translation applications requiring confidentiality.

IR systems require at least one IR transmitter (modulator), as many IR radiators as needed to cover the desired area and IR receivers. This technology is similar to the one used with remote controls. The transmitter, radiators and receivers should be in the line of sight. This means that you need to carefully mount sufficient radiators in the room to cover the whole area. Larger areas require more radiators. Some infrared systems require additional radiators depending on the total amount of channels (languages) to be used. In the case of infrared systems, generally only one multi-channel transmitter (modulator) is required per system.

Whether infrared or radio frequency is better for you, depends on how, why, and where you’ll be using the equipment. For most applications including but not limited to meetings and conferences, religious services, guided visits, tours of factories, training sessions, corporate events, school related activities, etc., FM technology will be more appropriate. Whereas infrared can be better in some highly confidential environments such as classified military meetings and when more than 6-8 languages are required in one same room.


If you are looking for privacy within an enclosed space, then an IR wireless system is commonly considered the best way to go. But in general, infrared systems are more costly and require more equipment to cover a larger area, and are also more difficult to set up – especially for applications that demand a more portable wireless system, such as for meetings that occur in different rooms of an office building.


To summarize, if you are looking for portability or there is a need for a wireless system that is not expensive and easy to setup, then an FM system is your best choice.

Now that we know the difference between both technologies, let´s focus on the System. The following questions will help to determine the type of system needed.


What is the total number of people who will need language interpretation per room?

The number of people requiring language interpretation will determine the number of receivers with headphones needed. The key is to determine exactly how many people will need interpretation, as it´s unusual that the entire audience requires translation. This depends on how many people speak the language of the speaker, and how many don´t: that´s the section of the audience that will need receivers.

For example, let’s consider a church of 100 people, of whom 10 speak only Spanish. If the preacher will always be speaking in English, just 10 receivers will be needed for the people who speak Spanish. The other people present will not need translation at any time.

Now let’s consider the case of a meeting attended by 200 people where there will be speakers speaking in English, French and German. In this case, 200 receivers will be needed unless part of the audience is multilingual and speaks all three languages.

It doesn´t matter how big your audience is; you can add as many receivers as needed. The only limitation is the operating range of the transmitter. On the contrary, the number of transmitters working together in the same room has some limitations, on the following section you will see why.


What is the total number of target (foreign) languages in addition to the source (main) language?

This issue is very important because once you determine the number of foreign languages that  will be translated, you solve the second variable of the system: the number of transmitters required. FM systems require one transmitter per language. For example, let´s suppose that your audience speaks several languages and you require translation into Spanish, Portuguese and German, all at the same time. In this case you will need three transmitters, one for each of the foreign languages. Stationary transmitters typically allow for up to six interference-free simultaneous languages in one room in the frequency range of 72-76 MHz.


Can I use the unlimited transmitters to translate unlimited languages at the same time?

No. Stationary transmitters typically allow for up to six interference-free simultaneous languages in one room in the frequency range of 72-76 MHz. When you have many transmitters working together interference appears, and the nearer the transmitters are to one another, the stronger this effect. In order to avoid this, it is recommended that the frequencies of each transmitter be separated (leaving at least 0.4 Mhz. between them).

Therefore, for the 72-76 Mhz. band in the United States, we recommend using no more than 6 channels (languages) in the same room. In addition, if you are working in different rooms, it is possible to work with more channels as long as there is a certain distance between the rooms.


What type of event will require language interpretation? Is it going to be one-way or two-way interpretation?

The type of event that will need interpretation is important to determine some features of the system. For example it´s not the same to have a lecture with one-way interpretation only into foreign languages, than a PTO meeting with interaction between principal and parents, using two-way interpretation from English into the foreign language and vice versa.

Two-way interpretation is used when the language spoken in the room changes and interpretation must be carried out to and from a language. If the audience is made up of both English and Spanish speakers, the Spanish speakers will need translation when a speaker speaks in English, and the English speakers will need translation when a speaker speaks in Spanish. There can be just one interpreter, but it is advisable to use two transmitters, one per language to have a dedicated channel for each language.

It is not advisable to use just one transmitter in a two-way event. If you do so, the interpreter must always transmit through the same channel and the audience must use their receivers with the appropriate headphones when the speaker speaks in the language they do not understand. When a speaker speaks in their own language, they must take off the headphones, as the interpreter will be translating on that same channel for the rest of the audience.

When a professional transmission is made, each language is always transmitted on a separate channel and the audience has the option of taking off their headphones or leaving them on while the speaker speaks in their own language. Remember, too, that as well as providing the translation, the receiver also serves the purpose of producing a clear sound of what is said in the room. This is very useful for people with hearing problems.


And what if I also have an event occurring in a round table or board room meeting where the same people needing translation will also be speaking?

In that case, you will probably need push-to-talk microphones or wireless microphone systems in addition to your simultaneous interpretation system.


Will the language interpretation be conducted indoors or outdoors?

If your event is a tour of the school with people moving around, or a religious retreat, you will require a system with a portable, battery-operated transmitter, allowing the interpreter to move around along with the speaker.


What is the maximum distance my FM interpretation system can cover?

The maximum distance a system can cover is determined by the transmitters and not the receiver. Due to the restrictions established by the FCC, a portable transmitter transmits up to approximately 150 feet (50 meters). A stationary transmitter transmits up to approximately 450 to 600 feet (150 to 200 meters) with a normal antenna, and up to 1200 feet (400 meters) with an extended antenna.


Will the system be used in the US?

Answering this question is important in order to determine the frequency band and voltage needed. As it was mentioned before, in the US the frequency band of 72-76 Mhz. is exclusive for Language Interpretation and Assistive Listening, so it´s always recommended using equipment that works in this frequency.

Knowing where the equipment is going to be used is important because of the voltage of the electric system in the country. As we know, the operating voltage in the US, Canada, Mexico and many other countries is 110 V., but if you need to buy equipment for Brazil or Argentina (as well as for European countries), you have to be careful that the equipment is designed to work with 220V. In Europe, for example, the 863 MHz frequency band is mostly used.


Using a stationary transmitter means that I can´t move it once installed? What is the difference between a stationary transmitter and a portable transmitter?

The difference between a stationary and a portable transmitter is that the portable transmitter uses batteries while the stationary transmitter is plugged into an electrical outlet. Both can be transported easily, as they are very small and light weighted. The portable transmitter allows you to work in environments where the interpreter must move around, for example, guided tours of a facility, sightseeing tours, etc.


Is it advisable to use a stationary transmitter?

A stationary transmitter has a greater coverage range than a portable transmitter, and in general, the tuning is more precise. That means that with a stationary transmitter more channels can be used in one room than with a portable transmitter, and you´ll get better sound quality.


Is it necessary to have a soundproof environment for interpretation, such as an interpreter booth?

No, although it is highly recommended for professional interpretation. The interpreter booths provide acoustic separation between the interpreters and the conference participants, which makes for a comfortable work environment. This allows the interpreters to maintain the intense concentration necessary to do their job and decreases the sound of their voices outside the booth to avoid disturbing the audience and the other interpreters in the other booths. The most widely used booths are tabletop booths as they are an economical solution for 1 or 2 interpreters, are easy to transport and can be set on a 6 or 8 ft table in seconds. Full-size, walk-in booths consist of several panels, are heavier and set up takes somewhat longer. But they are recommended for optimal sound isolation to accommodate 2 or 3 interpreters and they also exceed ISO 4043 international standard.