Project Echo - Nextion Display - 3 January 2017
The Nextion came in, along a TTL <> USB adapter. Up and running in 15 minutes. Eye candy.
Here's a video of the Echo with the Nextion display.
Anyone played around with Zibee and a Raspberrt Pi 3B? A 900 MHz mesh looking attractive.
Project Echo - New Image - 31 December 2016
Happy News Year's Eve Everyone!
Nextion display on order from Amazon. The Raspian Jessie Lite on Echo is working without any issue. The image uses only 3Gbytes of space of the microSD card.
Project Echo - New Image - 29 December 2016
I have reach a point with the x-windows GUI has not purpose any more. Downloaded Raspbain Jessie Lite. No GUI - just the CLI. Echo moves toward being more of a wireless appliance. Same issue with the Rasp Pi's Bluetooth conflict with the DVMEGA board. I forsee 100 years from now, some poor sod still fighting with a port conflict.
One of the goals of this project was to provide some visual indication from Echo that it was alive and connected to the Brandmeister network. The solution is a 2.5" Nextion display - interface to the Rasp Pi via a USB>TTL interface. MMDVMHost supports this display, so after a few routing of wires and tweak of the code - Echo finaly has a face. Currently, the Nextion display is on order. Trips to the local sources in the Dallas Metro Area did were deviod of Nextion displays - bummer. Well, you can't win them all.
Project Echo - SMS Text Messaging - 21 December 2016
SMS messages is another feature of DMR and what attracted to this mode in the first place. Results to date, have been inconsistent. Moving text messages between DMR radio by different vendors requires some flipping of levers and spining of knobs and even then, it seems to be inconsistent.
I teamed up with Ken, SM3VRO, today for a round of text messaging. Ken used a TYT MD 380 and I was using my Tera 7400. We both use the MMDVMHost on a Raspberry Pi with the DVMEGA board. We are both jacked in to the Brandmeister network. Initial SMS messages from Ken produced interesting results:
The problem was remdied when Ken changes is Brandmeist profile setting "Brand" from "Chinese", to "ESTI".
Project Echo - Coverage Test - 18 December 2016
I did another test of Echo's coverage. This time, I hike to the West of my QTH. There is a ridge, 1 mile away, which looks down in to the development I lived in. A good place to do some radio checks. At a range of 1 mile to the QTH and running 4 watts on the Tera 7400 HT, I was able to hit the HotSpot. Radio checks on the Brandmeister Nationwide talk group stated my audio was clear with no noticeable packet loss.
Project Echo - The DMR HotSpot - Echo Goes Wireless
I added a Cisco/Linksys USB Wi-Fi adapter to Echo. While the Rasp Pi 3 does have an on board Wi-Fi radio, it is limited to 2.4 GHz. The 5 GHz band is relatively clean in my neighborhood and you can still find a clear channel - especially true on the UNII-3 band.
I need the wireless connect to three different SSIDs - 1 each for home , office and mobile. This requirement was met by changing the contents of wpa_supplicant.conf. One network entry for each SSID. Priorities were assigned to each SSID. This ensures Echo will stay attached to the home Wi-Fi system and the the T-Mobile HotSpot when it activated.
Applications requiring low delay and packet loss, like voice, is a challenge across any wireless media. An effective QoS policy is paramount. Really, that goes for any time sensitive traffic - even interactive application like SSH. To ensure SSH traffic is marked to indicate to the in and outbound queues on Echo, here's my first attempt:
# Marks in/out bound SSH traffic in IP Type of Service (TOS) - low delay
sudo iptables -t mangle -A PREROUTING -p tcp --sport ssh -j TOS --set-tos Minimize-Delay
sudo iptables -t mangle -A PREROUTING -p tcp --dport ssh -j TOS --set-tos Minimize-Delay
sudo iptables -L -t mangle -n -v
Chain PREROUTING (policy ACCEPT 185K packets, 17M bytes)
pkts bytes target prot opt in out source destination
0 0 TOS tcp -- * * 0.0.0.0/0 0.0.0.0/0 tcp spt:22 TOS set 0x10/0x3f
2663 128K TOS tcp -- * * 0.0.0.0/0 0.0.0.0/0 tcp dpt:22 TOS set 0x10/0x3f
After applying this policy to Echo, the delay I was encountering during a SSH session, has almost virtually dissappeared.
I am reading up tc an iptables, so as to build classification and marking policy for the voice traffic to and from Brandmeister.
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)