The Pocket Siren test network
The pilot network combines high-power main transmitters (HPHT, High Power High Tower) with lower-power gap fillers (LPLT). This makes it possible to test both wide rural coverage and reception in cities and inside buildings. The network complies with ETSI TS 103 720.
Five transmitters, two frequencies
| Site | Type | Height | Channel | Transmitter power | ERP | Role |
|---|---|---|---|---|---|---|
| Tallinn TV Tower | HPHT | 270 m | E40 · 626 MHz | 3 kW | 40 dBW | Main transmitter for northern Estonia |
| Koeru | HPHT | 337 m | E41 · 634 MHz | 3 kW | 39.3 dBW | Central Estonia, SFN with Pärnu |
| Pärnu | HPHT | 187 m | E41 · 634 MHz | 3 kW | 42.6 dBW | South-west Estonia, SFN with Koeru |
| Tallinn, Kristiina | LPLT | 97 m | E40 | 600 W | 29 dBW | City coverage, SFN with the TV Tower |
| Järvakandi | LPLT | 78 m | E41 | 600 W | 30 dBW | Area between Tallinn and Pärnu |
SFN: one frequency, several masts
Koeru, Pärnu and Järvakandi send the same signal on the same channel (E41), and the phone combines their signals. This covers a large area without spending more spectrum, but the transmitters must be precisely synchronised via GNSS.
MFN: different frequencies side by side
Tallinn runs on a separate channel (E40). This lets us study how areas on different frequencies work together and how a moving phone hands over from one transmitter to another.
System overview
NAKOLOS core (Big Blue Marble)
Receives CAP alerts automatically, manages TV and radio streams, and controls and monitors the network centrally. It is technically ready for device-based geofencing (WEA 3.0 DBGF).
TRedess Fourth Series
Energy-efficient transmitters suited to both high- and low-power use. Transmitter-side MER is above 40 dB, a good starting point for both public warning and media.
Measurement equipment
Gsertel Hexylon 5G, Rohde & Schwarz FSP and FSH, Kathrein MSK200, and test phones logging with NetMonster. Measurements were made outdoors, indoors and in moving cars.
Which phones worked in the tests
The signal is received by Android phones with a Qualcomm Snapdragon 8 Gen 1 or newer chip and FeMBMS support enabled. In the tests, the Xiaomi 13, OnePlus 10 Pro and 10T, Motorola Edge 50 Ultra and Razr 50 Ultra showed live TV.
The OnePlus 13R, Motorola Edge 50 Fusion, Samsung Galaxy S25+ (US model) and Nothing Phone 3 also received alerts.
iPhone
A US-model iPhone 13 finds the network, but the connection drops after a few seconds. Apple allows emergency alerts only for operators it has an agreement with. The Ministry of the Interior and Levira asked Apple for test access, and Apple replied that this is not possible during the Estonian test period.
Device-based geofencing
The newer WEA 3.0 geofencing feature (category 4400) does not yet work on any phone sold in Europe. The core is ready for it, but phone firmware lacks support. The next tests will use Qualcomm research devices (CRD).