Here is the expanded list of vocabulary needed to understand dual-time slot TDMA under the ETSI DMR standard.
- ETSI (European Telecommunications Standards Institute): An independent, non-profit organization that specifies and standardizes digital telecommunications technologies globally. The open technical standard is here:
https://www.dmrassociation.org/dmr-standards.html
- TDMA (Time Division Multiple Access): Technology dividing a single 12.5 kHz radio channel into discrete, repeating time segments to allow multiple simultaneous transmissions on one frequency.
- Time Slot (TS 1 / TS 2): The individual, alternating communication paths within a TDMA channel where Timeslot 1 and Timeslot 2 carry completely independent audio streams on the SAME repeater. It’s like 2 repeaters in one box.
- Frame: The foundational 30 millisecond repetitive timing unit in DMR, which is structurally divided into two 15 millisecond time slots.
- Burst: The actual data or voice packet transmitted in rapid succession during a specific time slot while the radio rapidly switches between transmitting and listening.
- Color Code: The digital equivalent of an analog PL tone (0–15) used to separate local repeaters and ensure proper slot timing synchronization.
- Talk Group (TG): A logical channel or digital chat room assigned to a specific time slot, organizing traffic so only radios tuned to that group hear the audio.
- Group Call: A one-to-many transmission where a single radio transmits to an entire Talk Group, allowing all operators monitoring that specific group and time slot to listen.
- Private Call: A direct, one-to-one transmission targeted to a single radio’s unique ID, occupying the assigned time slot so other users cannot join the conversation.
- Promiscuous Mode (Digital Monitor): A radio receiver setting that bypasses Talk Group and Color Code filters, letting a ham hear all traffic occurring on a specific time slot.
- Synchronization (SYNC): The critical alignment of internal clocks between radios and repeaters to prevent slot-timing errors and overlapping transmissions.
- DMR Tier II: The official ETSI standard for conventional, licensed digital radio systems that mandates the use of two-slot TDMA operation.