Skip to content

Instantly share code, notes, and snippets.

@CraigJPerry

CraigJPerry/GB7GG-Reflector-Notes.md

Last active February 6, 2018 13:14
Show Gist options
  • Star 1 You must be signed in to star a gist
  • Fork 0 You must be signed in to fork a gist
  • Save CraigJPerry/2e1816f67c5902df4e7a0ae5554a45ef to your computer and use it in GitHub Desktop.
Save CraigJPerry/2e1816f67c5902df4e7a0ae5554a45ef to your computer and use it in GitHub Desktop.
Download ZIP
GB7GG Reflector Notes
Raw
GB7GG-Reflector-Notes.md

GB7GG User Notes

Here are the notes i've built up while learning to use GB7GG, hopefully it's useful to others! Feel free to redistribute this wherever you want.

-- Craig, MM6ZKO

If you do update or make corrections below, please share them with me at craigp84@gmail.com and i'll make sure to re-distribute.

Frequencies & Modes

GB7GG transmits on 439.625MHz and recieves on 430.625MHz, operating a -9MHz shift.

Mode Repeater Transmits On Frequency Repeater Receives On Frequency
DMR 439.625MHz 430.625MHz
C4FM 439.625MHz 430.625MHz
Analogue N/A N/A
D-Star N/A N/A

NB: the same frequencies are used for c4fm & dmr modes

DMR

A DMR capable radio is required. The most popular models currently include:

  • Hytera MD785
  • TYT MD380 (and its clones)

GB7GG DMR mode is currently connected to 3 networks:

  • Brandmeister (DMR)
  • DMR+ (DMR)
  • D-Star (DMR cross mode)

DMR Glossary

I found the terms pretty overwhelming to begin with!

  • Repeaters and hotspots provide access to the various networks, typically via UHF but some repeaters and hotspots use VHF
  • Timeslots divide each 12.5KHz DMR radio channel in 2. A 12.5KHz channel can carry 2 concurrent conversations & signalling data without affecting each other
  • TDMA (Time Division Multiple Access) is the technology which underpins the timeslot feature in DMR. The 2 timeslots transmit one after the other in rapid succession. As only 1 timeslot uses the channel at a time, the full 12.5KHz channel bandwidth can be used
  • Talkgroups segregate traffic on a timeslot and are analogous to CTCSS tones commonly used in analogue FM radio. When traffic is received for another talkgroup, your radio will not open the squelch. If another talkgroup is causing radio traffic on the same timeslot, you will not be able to key up. Usually this scenario is indicated by some kind of LED light on the radio. Talkgroups are a factor of DMR radio use whether you access a repeater or not. Simplex communication is usually done on talkgroup 9 (TG9)
  • Static Talkgroups are permanently open on a repeater, the most common is talkgroup 9 (TG9) which is used, by convention, for local repeater traffic on timeslot 1. On timeslot 2, TG9 is used for the brandmeister network
  • Dynamic talkgroups are open for a period of time after a user local to the repeater keys up on that talkgroup. These are used for less frequently accessed talkgroups and this saves burning up the repeater unecessarily
  • Reflectors allow access to other talkgroups, typically remote talkgroups which are not otherwise relayed to your repeater

Brandmeister

Access the Brandmeister network by programming the following details in your radio:

  • Talk group: 9
  • Time slot: 2
  • Colour code: 1

Other useful details:

By default, GB7GG is connected to reflector 4405 (Scotland). You can select other reflectors to connect to. It will revert to 4405 after 15 mins of inactivity.

4405 reflects talkgroup TG2355, it connects various other repeaters across Scotland. There is a good volume of traffic from users of GB7EE & GB7DD on 4405 which definitely makes the experience better.

To check which reflector is currently connected, make a private call to 5000 while on time slot 2, TG9. A female announcer will respond with the currently connected reflector.

To connect to the UK calling reflector, 4400, make a private call to 4400 while on slot 2, TG9. The female announcer will verbally confirm then you will hear traffic from reflector 4400 (talkgroup TG2350).

A list of brandmeister reflectors is available here: http://www.bm-dmr.uk/dash/refdb.html

DMR+

Access the DMR+ network by programming the following details in your radio:

  • Talk group: 8
  • Time slot: 2
  • Colour code: 1

Other useful details:

NB: DMR+ is a different network from brandmeister, some talkgroups may have similar names but they are completely distinct from one another. You will not hear brandmeister 4405 Scotland traffic on DMR+ 4450 Scotland.

DMR+ is connected to the repeater, along with Brandmeister, using DMR Gateway. This means they must share the same timeslot. You can either access DMR+ or Brandmeister, but not both at the same time.

Anecdotaly, i'm hearing more traffic recently on DMR+

To check which reflector is currently connected, make a private call to 85000 while on time slot 2, TG8. A German male announcer will respond with the currently connected reflector.

The DMR+ reflector list is available here: http://dvscotland.net/dmrreflectorlist.html

XLX (DStar Cross Mode)

Access the DStar network from DMR by programming the following details in your radio:

  • Talk group: 7 (NB: this is a recent change as of 2/th Jan 2018)
  • Time slot: 1 (NB: this is a recent change as of 26th Jan 2018)
  • Colour code: 1

Other useful details:

I don't yet know much about this network.

C4FM

One of Yaesu's C4FM capable radios is required to access this mode.

GB7GG is connected to the "SC Scotland" reflector on Yaesu System Fusion (YSF). YSF is distinct from the proprietary WIRES-X network provided by Yaesu, however YSF re-uses the WIRES-X features on your C4FM radio for displaying information and navigating available rooms.

I don't yet know much about this network.

There doesn't appear to be any cross-mode ability to connect with DMR users.

DMR traffic on GB7GG will be emitted as digital noise on a C4FM radio. C4FM use is completely ignored by my MD380G.

Useful Links

Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment