Homologation of Wireless Microphones and Headphones

Wireless microphones and headphones are typical equipment that require approval from the local telecommunication agency to be commercialised in Brazil. We will outline in this article the main requirements set by Anatel for homologation of these types of wireless equipment.

Wireless microphones and headphones are typical equipment that require approval from the local telecommunication agency to be commercialised in Brazil. We will outline in this article the main requirements set by Anatel for homologation of these types of wireless equipment.

We have discussed in other articles that equipment that operates in certain regulated frequencies or that makes use of Bluetooth technology as a way to peer to another device, must undergo a process called homologation. The standards used in the homologation process are set by the National Telecommunications Agency, known by the acronym Anatel. The procedures set by Anatel involves the analysis of the specification of the product and laboratory testing to determine if the product is in accordance with local regulations.

Anatel do not carry out the homologation process themselves, but rather appoint third party organisations, called OCDs, to be responsible for the verification of the specification and management of the testing procedures including the verification of the laboratory reports. Therefore OCDs are instrumental parts of any homologation process and must be the first organisation to be contacted should you need to homologate any product in Brazil. Master Certificações is a renowned OCD who will be able to carry out the homologation of wireless microphones and any Bluetooth equipment on behalf of manufacturers or representative.

Conditions for homologation of wireless microphones

Wireless microphones are considered to be equipment of restricted radiation, and Anatel has two different categories where microphones are placed, depending upon the frequency that the equipment operates.

The first is related to microphones operating on the frequencies ranging between 88 - 108 MHz, which needs to meet the following conditions:

• Emissions must be confined within a frequency band of 200 kHz, which centers of the band is the nominal operation frequency. The frequency band of 200 kHz must be entirely contained within the range of 88 - 108 MHz
• The intensity of the field of the any emission within the specified band of 200 kHz must not exceed 250 microvolts per meter measured 3 meter from the device. The emission outside of this band cannot surpass 150 microvolts per meter

If the wireless microphones operate in the frequency bands 54-72 MHz, 76-88 MHz, 174-216 MHz, 470-608 MHz and 614-806 MHz, the conditions are as follows:

• The frequency band cannot exceed 200 kHz and must be entirely contained within the range specified above
• The emission in any discrete radiofrequency outside of the authorised band must be attenuated in relation to the average output power of the transmitter in 43 + 10 log10(P) dB, where P is the average output power in Watts
• The transmitter radio frequency stability must be 0,005%
• The non-modulated carrier power measured in the input connector of the antenna must be limited to the following values:

  Radio frequency Bands (MHz)	Power (milliwatt)
  54-72	50
  76-88	50
  174-216	50
  470-608	250
  614-806	250

• When the frequency modulation is used, the maximum deviation allowed is ±75 kHz, but other forms of modulation are also allowed

Technical requirements for homologation of wireless headsets

One of the most popular accessories for phones or computers, wireless headsets need to go through a certification process with Anatel as they use Bluetooth technology to peer with other devices. Bluetooth equipment is included in the category of frequency-hopping spread spectrum transceivers that operate within the frequencies of 2.40 GHz and 2.48 GHz.

We have previously covered in detail the process for Bluetooth equipment homologation in the article Homologation of Bluetooth Equipment in Brazil, but here is a recap of what the main tests performed on devices.

The following tests are performed on wireless headsets powered with batteries that are rechargeable with power supplies or PoE:

• Resistance to electrical disturbances in power input port and telecommunication ports, if present in the equipment
• Resilience of signal to electromagnetic disturbances
• Immunity to reduction and temporary absence of power
• Protection against overheating, fire ignition and electric shocks
• Resistance to electrical discharges conducted by air and by direct contact

If the headset is powered by other types of batteries, such as button or coin batteries, only the resistance to electrical discharges conducted by air and by direct contact test applies.

Anatel also establishes specific requirements for the category regarding frequency-hopping, which will determine the device compliance with Bluetooth standards as well as its ability to interfere with other systems that operate at this frequency range. The requirements verified by the agency include:

• Transmission frequencies of communication systems must be separated by a bandwidth of at least 25 kHz, or by the bandwidth of the hop channel at 20 dB, if that value is higher than 25 kHz
• On average, communication systems must make even use of all transmission frequencies they operate in
• Receptors of the communication system must accept signals within the same frequency range of the systems transmitters and must hop frequencies in synchronicity with the transmitted signals
• Communication systems must use at least 15 radio frequencies for data transmission
• The average use of a single communication frequency must not exceed 0.4 seconds, when measured during a period of 0.4 seconds multiplied by the number of frequencies the system is stated to operate in
• Systems can avoid or suppress transmissions at determinate frequency channels, if at least 15 remaining channels are utilised
• Systems that make use of less than 75 communication frequencies must not exceed peak transmission power of 125 mW
• Systems that make use of over 75 communication frequencies must not exceed peak transmission power of 1 W

For headphones operating technologies other than Bluetooth, Anatel approval will depend on the frequency that the device operates. Headsets with DECT technology are often homologated following the same requirements as the ones used for cordless phones. For these devices, operating in the frequency band between 1910 and 1920 MHz, the agency requirements are:

• Maximum peak output power of the transmitter must be limited to 250 mW
• In case the system makes use of antennas with a gain higher than 2dBi, the maximum output power at the transmitter must be reduced by the correspondent quantity in dB that was exceeded from 2dBi
• The band occupied by the channel should be narrower as possible in order to reduce interference between adjacent channels and cannot occupy a band larger than 2 000 kHz

It is also possible to obtain homologation for headsets using point-to-point transmission in other frequencies, but in this article we will focus on the range of 915-928 MHz. The homologation of these devices will follow the same parameters as the ones used to evaluate equipment that uses technologies of spectral spread of digital modulation. For these headsets, Anatel sets an extensive list of requirements regarding the radio frequency hopping channels, which are:

• Carrier radio frequency of the hopping channels must be separated by a minimum of 25 kHz or for the bandwidth of the hopping channel at 20 dB, whichever is the highest value
• The system must hop to the selected radio frequencies at a hop rate from a list of hop radio frequencies ordered in a pseudo random manner
• On average, each transmitter must equally each use one of the radio frequencies
• The receptors should have an input bandwidth compatible with the width of the channel hopping band of its transmitters and must change the frequencies in synchrony with the transmitted signals
• The maximum peak power of the output of the transmitter should not be superior to 1 Watt for systems that use a minimum of 35 hopping channels and 0.25 Watt for systems with less than 35 hopping channels
• If the bandwidth of the hopping channel at 20 dB is inferior to 250 kHz, the system must use at least 35 hopping radio frequencies and the average occupation time of any radio frequency cannot be superior to 0.4 seconds in an interval of 20 seconds
• The maximum occupied bandwidth of the hopping channel at 20 dB must be limited to 500 kHz

For systems using direct sequence or other digital modulation techniques, Anatel also require the following characteristics:

• The bandwidth at 6dB must be at the minimum of 500kHz
• The maximum peak power of the output of the transmitter should not be superior to 1 Watt
• The peak of the power spectral density, at any 3kHz band during any interval of time of continuous transmission, cannot be superior to 8 dBm

Starting the certification process with Anatel

As previously discussed in this article, the certification process with Anatel must be started by an OCD. Choosing the right OCD is vital to get your products certified in Brazil without any headache. The OCD will not only review the specifications of the product to verify which testing procedures are required to obtain the certification, but will also be able to suggest any changes to your current design to make sure your product is 100% compliant to Brazilian regulations. Master Certificações is one of the most reliable OCDs accredited by Anatel to carry homologation processes with Anatel, having been in the market for over 15 years, handling homologation of all category of products with Anatel.

Upon analysing the specification, the OCD will be able to determine which laboratories may be able to conduct the testings necessary to obtain the reports needed to issue a conformity certificate. A conformity certificate is proof that the product met Anatel requirements, and will be issued by the OCD based on results from the laboratories. Anatel demands that the tests occur in Brazil, but in some rare instances, they accept reports issued by laboratories abroad.

Once the product obtains a certificate of conformity, the OCD will formally request the homologation of the product to Anatel. Anatel will include the product on their database and issue a legal document of homologation. The Anatel stamp, which must be produced in accordance to Anatel regulations, needs to be included by the manufacturers on all products commercialized in Brazil. The stamp will have an identification number which allows the buyer to verify the homologation authenticity on Anatel’s website.