September 19, 2025 Publication of the Results of the Solicitation for Opinions on the Draft Directive for the Partial Amendment of the Radio Act-related Examination Standards (MIC Directive No. 67 of 2001) (hereinafter the "Draft Directive")
- Development of Legal Frameworks for Prefectural Digital Integrated Communications Systems (hereinafter the "Prefectural Digital Systems") -

　To additionally introduce a system usable in the Prefectural Digital Systems, the Ministry of Internal Affairs and Communications (MIC) solicited opinions on the Draft Directive. The opinion solicitation period ran from Tuesday, July 8, 2025, to Wednesday, August 6, 2025.

　As a result, a single opinion was submitted. The submitted opinion, together with the MIC’s position on it, will be made publicly available. Based on the submitted opinion, the MIC has formulated the final directive, which will also be made publicly available.

Note: The published materials are available in Japanese only.

1. Overview

　A legal framework has been established for the Prefectural Digital Systems* that operate in the 260 MHz band using π/4-Shifted Quadrature Phase Shift Keying (π/4-QPSK) in a TDMA system (hereinafter the "TDMA system"). The Prefectural Digital Systems are currently being transitioned from analog to digital.

(*) Prefectural Digital Systems:

　The refer to communications systems that comprehensively include the following: (1) Mobile communications systems between prefectural offices, branches, terminal offices, or related organizations and mobile devices, (2) Mobile communications systems between mobile devices, (3) Fixed communications systems for prefectural offices, branches, terminal offices, and related organizations that share the frequencies of the mobile communications systems, (4) Fixed communications systems between water level or rainfall observation stations and dam management offices, and (5) Fixed communications systems between dam management offices and centralized management organizations.

　The Draft Evaluation Results of Effective Use of Radio Waves in the FY2024 Radio Wave Usage Survey on Various Wireless Systems and Frequency Bands below 714 MHz recommend considering the use of 4-Level Frequency Shift Keying (4-FSK) in an SCPC system (4-FSK in SCPC), in addition to the TDMA system, which is available to prefectural disaster prevention administrative radio systems. The 4-FSK in SCPC reduces costs and is suitable for long-distance communications. In response to this recommendation and requests from prefectures, the MIC permits the introduction of SCPC systems by prefectures. To specify the conditions for frequency sharing between TDMA and SCPC systems, the MIC prepared the Draft Directive and solicited opinions from Tuesday, July 8, 2025, to Wednesday, August 6, 2025.

2. About the materials

　The published materials will be available in the "Public Comments" section on the e-Gov website (https://www.e-gov.go.jp).