I have been a ham since 1981. I got my technican ticket at the FCC field office in Boston, MA with my father, Clarence Williams, W1ROM - an avid 80 meter DX chaser in his time.
I did a career in the United States Air Force (21+ years) and most of it was spent in the Electronic Warfare field. Now, instead of jamming emitters, I help build them. A Wi-Fi engineer of sort for the last 10 years - working for a large cellular carrier.
For the past 10 years, we have been living in Euless, Texas. Most of that time was spent on HF operating a myriad of digital modes with a lean towards JT65A and JT9. These weak signal modes will always amaze me in what they can do with just a couple of watts of RF power applied to an odd bit of wire in the back yard. HF activities have been put aside in the past two years as other things required my attention.
Current interest is DMR and it global reach on the planet. On a whim, I picked up a Tera 7400 DMR HT from Ham Radio Outlet in Plano, TX. I spent the next few days learning about things like talk groups and code plugs. I do not have a D-Star or Fusion background, I jumped feet first. Next thing was a project to build up a DMR HotSpot. I was intrique by what a Raspberry Pi 3 could do - a simplex repeater which connected to the Internet and the world. I could not leave well enough along with the HotSpot. I chucked its "stub" antenna and made a Slim Jim antenna with the goal of improving coverage in to the park next to me. Best distance - .85 miles so far and the operators work reported that my audio was fine. Amazing what a 10mW HotSpot will do given a respectable antenna is attached.
Now, I am trying to working out text messaging via DMR. The results vary and I find it interesting to figure would what the root cause of the problem is. The fact that DMR is not perfect make it all the more interesting and inspires me to experiment.
Project Echo - The DMR HotSpot
The Echo project is my initial journey in to the wide world of Digital Mobile Radio (DMR). I had become bored with radio over the past year. However, in November 2016, I purchased a DMR HT - the Tera 7400 from Ham Radio Outlet in Plano, Texas.
Without any background in any of the other digital voice technologies, I jumped in - feet first, in the wide world of DMR. Next came a DMR HotSpot as I was intrigued with the concept of having a UHF simplex repeater which would provide not only good coverage around the home QTH, but also coverage in to a city park located across the street from our house. Thus began The Echo Project.
Echo 1 - 1st DMR HotSpot
The DMR HotSpot I threw together consisted of:
1 Each - Raspberry Pi 3
1 Each - DV MEGA VHF/UHF Radio Board
1 Each - Homebrewed Slim Jim 70cM Antenna (made out of 450 ohm window line)
1 Each Cisco USB Wi-Fi Interface Adapter
1 Each 20 Amp/Hour Sealed Lead Acid Battery (SLAB)
1 Each Powerwerx Power Meter and Analyzer
Operating System: Raspbian/Linux 8
HotSpot: MMDVMHost by Jonathan Naylor, G4KLX - https://github.com/g4klx/MMDVMHost
RX Frequency: 446075000Hz
TX Frequency: 446075000Hz
Transmitter Power: 5 mW
Antenna: 70 cM Slim Jim (450 Ohm Window Line)