Surviving the ‘Big One’ with Diwata-2’s Amateur Radio Unit

| Written by Andre DP Encarnacion


Last month, the Philippines experienced two strong earthquakes in Luzon and Leyte —each measuring at least 6.0 in magnitude—reviving anxieties about the “Big One,’’ an extremely powerful quake that experts predict could hit with devastating effect during our lifetime.

A catastrophic event of such magnitude struck Haiti in 2010, when a magnitude 7.0 earthquake with an epicenter near the capital of Port-au-Prince quickly took the lives of hundreds of thousands. Compounding rescue efforts, the quake also devastated the country’s communication infrastructure.

In that desperate time, an unexpected group of people heroically acted as bridges between emergency responders and survivors. Amateur radio operators or ‘hams’ tuned into the appropriate frequencies and, with the help of satellites, acted as the eyes and ears of the rescue teams. Once a mere backup system, the amateur radio band became a lifeline, handling most emergency communications in the immediate aftermath of the quake.

It is easy to imagine how communication in the Philippines, despite a population of 60 million social media users, could be similarly crippled should the ‘Big One’ strike. Luckily, not only does the country have a close-knit community of amateur radio enthusiasts ready to assist, but we also now have a satellite that can facilitate their communication to any place in the archipelago.

The innovation responsible for this is Diwata-2’s Amateur Radio Unit (ARU), which was formally unveiled on April 26. Described by its makers as something of a “walkie-talkie in space,” the ARU allows radio operators to communicate with anyone anywhere in the country.

Recently, the UP MPRO had a conversation with three STAMINA4Space engineers behind Diwata-2’s ARU. Izrael Zenar Bautista, Lorenzo Sabug, Jr., and Mary Ann Zabanal-Constante had worked persistently to fit what could become the country’s last line of communication into the microsatellite’s 56-kilogram frame.

Bautista, currently a PhD student at the Kyushu Institute of Technology (Kyutech), said the ARU is primarily responsible for Diwata-2’s functionality as a communications satellite. More than any other item in its payload, it is the ARU that allows people to converse over vast distances.


STAMINA4Space engineers communicate via Diwata-2’s amateur radio unit (ARU). Photo by Jun Madrid, UP MPRO.


The unit was born out of a need to improve an already great thing. After Diwata-1 was launched in 2016, the team was already thinking of ways to make its successor better. The engineers were specifically looking to bring the technology closer to ordinary citizens. Bautista said he believes that the ARU democratizes the use of Diwata-2, because even regular citizens with inexpensive equipment can use it.

“That’s because the frequency is free for all to use,” he said. “Theoretically, anyone can use it.” This is especially true for amateur radio enthusiasts, many of whom prefer to “homebrew” or self-construct rather than buy their equipment.

“You just need to have the right equipment in order to participate,” Bautista added.

The two primary functions of Diwata-2’s ARU are to be an FM voice repeater (FMVR) and an Automatic Packet Reporting System (APRS) message repeater. The voice repeater, allows people to wirelessly converse through voice, with the satellite facilitating the communication.

“Actually, with the altitude of Diwata-2,” Bautista added, “you can talk to someone from anywhere in the Philippines. You don’t need to spend for load or the internet; you just need a radio and an antenna.”

The APRS message repeater, on the other hand, acts more like a text message. It allows you to receive messages sent by fellow amateur radio enthusiasts via the ARU. Not only can you now send messages to first responders in the event of a major disaster; you can also transmit temperature, weather information and GPS data to others.


Diwata-2’s ARU makes use of two radio signals familiar to amateur radio operators worldwide—ultra-high frequency (UHF, 437.500 MHz); and, very-high frequency (VHF, 145.900 MHz). According to Lorenzo Sabug Jr., this familiarity is a benefit.

“This means that hams who have accessed other amateur radio satellites only have to do what they’re used to in order to access Diwata-2. And there are so many affordable handheld transmitters that we can tune to UHF and VHF frequencies that make communicating with satellites much more cost-effective.”

Sabug noted that there are three steps that an amateur radio operator should follow in order to connect to Diwata-2’s ARU. The first is tracking the satellite as it passes overhead.

“We have available orbit tracker apps for mobile phones or PCs. We can track when Diwata-2 is passing over and its direction in the sky,” he said. One should then tune their equipment to 145.900 MHz to receive transmissions from Diwata-2 or 437.500 MHz to transmit messages to others.


UP and STAMINA4Space research engineers Izrael Zenar Bautista (3rd from left) and Lorenzo Sabug, Jr. (rightmost) with UP EEEI Associate Professor Marc Caesar Talampas and DOST-ASTI Director Joel Joseph Marciano, Jr. Photo by Jun Madrid, UP MPRO.


He noted that Diwata-2 typically passes at around noon and in the middle of the night, which makes it easier for amateur operators to anticipate it. From these we get an idea when Diwata-2 is coming and where it’s coming from so we can point our antennas in the right direction.

Indeed, that pointing is the second necessary step. Taking a directional antenna, a radio operator should physically track Diwata-2’s movement with it as it moves. Lastly, an operator should always follow ham radio etiquette, ensuring that others have already finished their transmissions before making their own. Ideally every user should have an opportunity to use Diwata-2 for their emergency response needs.

Aside from its coverage and accessibility, another advantage of Diwata-2 is its virtual immunity from the effects of earthbound calamities. Orbiting at an altitude of more than 600 km., Diwata-2 is higher than any raincloud and is unreachable by tremors or waves that can knock out telephone lines or cellular towers. This makes it a conduit of communication that we can reliably use despite massive devastation on the ground.

Balikbayan Box

Getting a radio unit with so many functions to fit within a tiny satellite was one of the challenges the team had to overcome. Few know this better than Mary Ann Zabanal-Constante who worked on the ARU’s antenna deployment. “I compare Diwata-2 to a balikbayan box,” she said, “where we try to fit all the important things in so our people can get their money’s worth when we finally send it out.”

“To put it simply, a careful study of design and optimization was required from creating the circuit boards, to the enclosure, to the antennas, to Diwata-2 itself to fit all those components in,” Constante said.


Details of Diwata-2’s amateur radio unit with handwritten messages by its makers. Photo courtesy of Lorenzo Sabug, Jr., STAMINA4Space and UP EEEI.


Completing the ARU was both a national and a practical success. Not only did we now have a working unit built by Filipino experts, but the STAMINA4Space team also touched base with industry partners who can produce the components needed to build more satellites. Constante aims to eventually produce a catalogue of locally built satellite components that have “flight heritage” or have been proven to work in space. The resulting reduction in overhead costs would mean more and better satellites, not to mention better ARUs, which can be locally built by our engineers.

For now, however, Constante and the rest of the STAMINA4Space engineers are inviting all interested individuals to keep using Diwata-2’s existing ARU. “We hope you keep using it, and we hope it can continue to serve even more of our people.” Our nation may never be fully ready to cope with disasters like the ‘Big One’, but with more satellites and with amateur radio units patrolling our skies, Filipinos will at least have a fighting chance.

Track Diwata-2’s arrival by following its Twitter account.

To learn more about amateur radio in the country, visit the Philippine Amateur Radio Association website.