Sunday, April 21, 2019

DMR Tip 02 - What Time Slot Should I Use?


I’ve had a few people ask me what “time slot” (TS) they should use when setting up a talkgroup on a particular repeater.  For DMR Tip 02, I'll focus on answering this and give you links for more information on finding repeaters and configuring your radio correctly.

Here is a good description of what a time slot is by  NEDECN:
With a TDMA (time division multiple access) system like DMR, the mobile or portable radios are synchronized typically by a repeater and assigned a time slot. In DMR Tier 2, there are two time slots, i.e. 2-slot TDMA. A mobile radio transmits for 30 milliseconds and then receives for 30 milliseconds. It listens for a permission to transmit and then begins a call to all other talk group members who will also receive on that same time slot, e.g., Time Slot 1. Meanwhile, a different group of users on another talk group could be using Time Slot 2 simultaneously. Well almost simultaneously, offset by 30 ms., but you would never know the difference, because two voices can come out of two radios simultaneously from the same repeater.

Tuesday, April 9, 2019

SoCal Spring SOTAFest 2019


This is a recap of my adventures at Socal Spring SOTAFest 2019.  My friend Adam, K6ARK, organized a trip for ham radio operators that enjoy doing “summits on the air”, (SOTA).  We planned to meet at a campground, hike up to bunch of nearby summits to “activate” them, getting contacts in the US and beyond, and then do the next peak.  There will also be a lot of stories about past epic conquests, radio and antenna gear, and techniques.  Hams also build a lot of different pieces of their own gear, from custom radios to antennas, and other gizmos. 

The original destination was near Big Bear, CA but the weather called for a chance of rain so we went out to the southern desert region to Sawtooth Campground, which is surrounded by SOTA summits.  Although Adam announce the meetup on a few different mailing lists, we only had two other hams that were going to be able to join us, Scott (N0OI), and his wife, Corrine (N2ZIP).  I’ll take some of the burden and help with the marketing campaign next time.      (Click on photos for larger)