Standard radio or cellular radio: which one to choose?
It depends on where the team works. Digital radio (DMR) uses its own frequency and infrastructure and covers basements, warehouses and industrial plants, generally with a license from Anatel (Brazil's telecom regulator). Radio over the cellular network (PoC) uses the carriers' network and connects teams in different cities, and many operations combine the two.
6:50 a.m., shift change. In the second basement, the guard calls the front desk and the radio only hisses. At the same moment, in another city, the supervisor wants to know where the team is and has to call each person one by one. These are two different problems. Each one calls for a different type of radio.
How does digital radio (DMR) work?
A standard radio is a device that talks to another device over a radio frequency, directly or through a repeater installed on site. DMR is its digital version: an open standard, created by the European institute ETSI, in which each channel carries two conversations at the same time.
The network is yours. It doesn't go through a carrier or the internet. In return, the range extends only as far as your infrastructure covers.
How does radio over the cellular network (PoC) work?
On the outside it is a radio: press the button and talk to the group. On the inside, the voice travels as data over the cellular network or Wi-Fi to a server, which delivers the message to everyone in the group. Each device uses a data SIM card.
The range is that of the network: different neighborhoods, cities and states. The limit is also the network's. With no cellular signal or Wi-Fi, there is no conversation.
When does each one fit best?
| Situation | Tends to fit | Why |
|---|---|---|
| Basement, garage, warehouse, industrial plant | Digital radio | Coverage is built on site |
| Teams in different neighborhoods or cities | Radio over the cellular network | Uses the network that already exists |
| Location with no cellular signal | Digital radio | Without a data network, PoC can't transmit |
| Operations center that tracks the team on a map | Radio over the cellular network | The platform brings together groups and location |
The table is a starting point. What decides is a coverage test at your address, walking through the spots where the team works.
What depends on the carrier and what depends on Anatel?
With PoC, you depend on the carrier's coverage, each device's data plan and the platform's server. The manufacturers themselves warn that the cellular network has areas with no signal, difficulty penetrating buildings and a risk of congestion. Because the frequency belongs to the carrier, you don't request a radio frequency license.
With digital radio on its own frequency, the use falls under the Private Limited Service (Serviço Limitado Privado). You must request authorization to use the radio frequency from Anatel and license the stations.
The exception is general-use, low-power radios (up to 500 mW, in bands defined by Anatel). They are classified as restricted radiation and are exempt from licensing. The trade-off is in the rule: they have no right to protection against interference.
In both cases, the device must be type-approved by Anatel. The authorization rules have exceptions. Confirm how your case is classified before buying.
A potentially explosive area calls for a certified radio
Where there is gas, fuel or flammable dust, the radio must be designed for that environment. Inmetro (Brazil's national metrology institute) requires mandatory certification for electrical equipment used in explosive atmospheres (Ordinance No. 115/2022), and that includes portable radios known as intrinsically safe. It applies to either technology.
Can you use both together?
Yes, and often that is the answer. Digital radio covers the building and the basement. PoC connects those on the street and at other sites. A bridge device, the gateway, lets one group hear the other. Hytera, for example, documents a model that links one channel per site. What crosses the bridge depends on the design.
If the question is which of the two fits your operation, ARX can help you test before you decide.
Sources
- DMR Association. The DMR Standards, developed by ETSI.
- Hytera. What Is PoC Radio? A Simple Guide to Push-to-Talk Over Cellular.
- Hytera US. Push-to-Talk over Cellular: Complete Guide to PoC Radios and Systems.
- Hytera US. Hytera BRIDGE: PoC to DMR RoIP gateway.
- Anatel. Private Limited Service and Licensing of SLP Stations.
- Anatel. Authorization Exemption.
- Anatel. Resolution No. 680, of June 27, 2017, regulation for restricted radiation equipment.
- Anatel. Act No. 14448, of December 4, 2017, item 15, general-use radiocommunication equipment.
- Anatel. Product certification: frequently asked questions.
- Inmetro. Regulations applicable to intrinsically safe portable transceiver radios.
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