Open Base Transceiver Station, or abbreviated as OpenBTS, is a software-based GSM BTS, which allows GSM cell phone users to make phone calls or send short messages (SMS), without using a commercial cellular operator network.

That is, with this technology users can make calls or SMS without the need for credit. In fact, by assembling OpenBTS, it’s actually like building your own cellular operator. It’s just that the signal range is limited, and can only communicate with other phones connected to the OpenBTS network.

The implementation of OpenBTS in Indonesia is being promoted by information technology practitioner Onno W Purbo. The following are the basic tools and software needed to use this technology as stated by Onno when met at his residence.

Hardware

Of course, the most basic thing is a set of computers, either a desktop or a notebook.

Then, for the minimal version of OpenBTS, hardware is needed to transmit radio signals called Universal Software Radio Peripheral (USRP) and two types of antennas, namely transmitter and receiver antennas.

This USRP replaces the role of the transmitter at the Base Transceiver Station (BTS) of commercial cellular operators. The minimum version of the USRP can be obtained at a price of 15 to 20 million.

Via a USB cable, connect the computer to the USRP. After that, the two cables in the USRP are connected to the two antennas.

Software

Previously, the computer used had to have a Linux operating system. Other operating systems such as Windows or Mac cannot be used to run OpenBTS.

All software used for OpenBTS can be downloaded for free, and all of them are open source software.

Use the GNU Radio software, to control the USRP. Then OpenBTS software, to control BTS operation. And there is also a telephone exchange software called Asterisk. This software is commonly used for 4G generation telephone exchange technology.

The protocol used by the Asterisk telephone exchange is the Session Initiation Protocol (SIP). This kind of protocol is also used by commercial cellular operators such as Indosat, Telkomsel, XL, Axis, and others.

USRP hardware thinking logic

Logic thinks USRP in OpenBTS is something like a sound card on a computer. A sound card must be programmed to output an audio signal.

So, the USRP is programmed to emit radio signals. Not only radio signals, this USRP can be set to issue AM, FM, or TV signals. All signals are programmed through software.

This is what causes OpenBTS to be assembled at a low price. Because the transmitter is set via software. If the transmitter is in the form of hardware, it will cost billions of rupiah.

The minimum range of OpenBTS is only 5 to 10 meters. Because, the electricity consumption is only 100 milli watts. If the power amplifier is changed to 10 watts, for 120 million rupiah (not including shipping), the range can reach more than 5 kilometers.

Try to compare it with BTS owned by cellular operators. For a similar version, it costs 1.5 billion rupiah.

How? Interested in assembling OpenBTS and raising operators yourself?

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