Heres some basic info on how the DMR is setup to GB3CU. This is the same on the other repeaters I manage. This info is also on QRZ under GB3CU.
GB3CU Repeater – Cumbria, UK
Updated: 05/07/2025
Basic Information
- Output Frequency: 438.3875 MHz
- Input Offset: -7.6 MHz
- Mode Support: DMR (Colour Code 13), FM, C4FM/YSF, D-STAR
- CTCSS: 77.0 Hz (Use Tone Squelch to reduce interference from unsupported modes)
- Repeater Hardware: Home-built MMDVM using Kenwood TK-8080
Network Connectivity
- FM/Analog: AllStar Node 601040 – cumbriaCQ.com
- C4FM/YSF: YSF Room 89134 – cumbriaCQ.com
- DMR (CC13):
- BrandMeister UK
- TGIF Network – Main talkgroup: 5089134 (cumbriaCQ)
- Time Slots: TS1 & TS2 active — Use TS2 for cumbriaCQ
- D-STAR: Connected to XLX921 A – cumbriaCQ.com
Programming Notes
Please program your radios with:
- TX/RX: 438.3875 MHz / 430.7875 MHz
- CTCSS: 77.0 Hz (TX/RX)
- DMR Colour Code: 13
- Use Tone Squelch for analog operation to filter digital noise
Recommended DMR Usage
- To Connect to cumbriaCQ on TGIF: Use TG 5089134
- To Disconnect the Repeater After Use: Dial TG 4000
Talkgroup Summary
| Talkgroup | Description |
|---|---|
| TG9 | Local RF only |
| 5089134 | cumbriaCQ via TGIF Network |
| 4000 | Disconnect command |
For a full list of TGIF Talkgroups:
Understanding DMR Talkgroups on GB3CU (MMDVM Repeater)
The GB3CU repeater in Cumbria uses an MMDVM (Multi-Mode Digital Voice Modem) setup. This allows it to connect to multiple digital voice modes and DMR networks, including BrandMeister and TGIF. Because MMDVM supports more than one network, it’s important to understand how to correctly format talkgroup numbers.
What Is a Talkgroup?
In DMR, a talkgroup (TG) is like a virtual channel. When you transmit on a talkgroup, your audio goes to everyone listening to that same TG on the network. Different networks have different numbering formats, so it’s important to use the correct one for each.
Talkgroup Formats on GB3CU
1. BrandMeister Network
- Use the talkgroup number exactly as it is.
- Example: Worldwide TG 91 → Just program TG 91.
- No prefixes or padding are needed.
2. TGIF Network
- All TGIF talkgroups must start with a 5. This tells the repeater to send the traffic to the TGIF network.
- TGIF requires all talkgroups to be 7 digits long.
- If the TG number is less than 6 digits, add a 0 after the 5 to fill the format.
Examples:
- cumbriaCQ is TG 89134 on TGIF → Program as 5089134 (5 + 0 + 89134)
- TGIF TG 1234 → Program as 5001234
- TGIF TG 100001 → Program as 5100001
Time Slot Use
- Both TS1 and TS2 are enabled on GB3CU.
- Use TS2 for cumbriaCQ (TG 5089134) and general TGIF access.
- BrandMeister TGs can also be used on either time slot, depending on your preferred configuration.
Understanding Time Slots on DMR (Digital Mobile Radio)
What is a Time Slot?
DMR repeaters like GB3CU use a system called TDMA (Time Division Multiple Access). This splits one radio frequency into two separate “time slots” — Time Slot 1 (TS1) and Time Slot 2 (TS2).
Think of it like two virtual channels running on the same physical frequency. The repeater rapidly switches between the two slots so fast that users don’t notice, but it allows two separate conversations or network links at the same time.
Why Time Slots Matter
Each time slot can be used for a different talkgroup or network. This means:
- Two users can talk at the same time on different talkgroups
- Two different networks can run simultaneously on the same repeater
So, for example:
- TS1 could be used for BrandMeister TG 91 (Worldwide)
- TS2 could be used for TGIF TG 5089134 (cumbriaCQ)
Both users would be using the same repeater frequency, but their traffic is kept completely separate because it’s on different time slots.
Time Slots on GB3CU
- GB3CU has both TS1 and TS2 enabled
- You can use either time slot depending on your needs
- It is recommended to use TS2 for TGIF and cumbriaCQ
This allows TS1 to remain free for other users, such as those on BrandMeister or other dynamic TGs.
Summary
- Time Slot 1 (TS1): One half of the channel. Can be used for a specific talkgroup or network.
- Time Slot 2 (TS2): The other half. Also independent and can be used at the same time.
- TDMA technology makes this possible by alternating transmission in short bursts.
- Two users or two networks can operate at once without interfering with each other.
Example Setup for GB3CU
| Time Slot | Suggested Use | Example Talkgroup |
|---|---|---|
| TS1 | BrandMeister | TG91 (Worldwide) |
| TS2 | TGIF / cumbriaCQ | TG5089134 (cumbriaCQ) |
Using time slots correctly improves efficiency and avoids tying up the repeater for others. If you’re setting up a codeplug, assign talkgroups to the appropriate slot based on usage and network type.
Local and Control Talkgroups
- TG9 – Local RF-to-RF only (no network link).
- TG4000 – Disconnects any active dynamic talkgroup link. Always use this after finishing a TGIF or BrandMeister contact.
- TG5089134 – Main cumbriaCQ talkgroup on TGIF.
Summary Table
| Function | Talkgroup | Notes |
|---|---|---|
| Local RF | TG9 | Repeater-only, no internet/network link |
| cumbriaCQ (TGIF) | TG5089134 | Use TS2, 5 + 0 + 89134 |
| BrandMeister World | TG91 | Use as-is, no prefix needed |
| Disconnect TG | TG4000 | Ends current dynamic talkgroup connection |
For a list of TGIF talkgroups, visit:
For more information, repeater status, and updates, see:
https://cumbriaCQ.com