Radio – Page 6

Turn off HDMI on Pi-Star (Easier)

Here’s an even easier way to turn off HDMI on your Pi-Star image running under Raspbian. If you’re running one of the Pi-Star 4.0 release candidates, the tvservice command may already be installed. You can check by issuing the following command:

which tvservice

If it is installed, just add the HDMI off command to /etc/rc.local.

# Turn off HDMI
/usr/bin/tvservice -o

If you’re running Pi-Star 3.x, I learned that you can install tvservice from a .deb package.

sudo apt-get install libraspberrypi-bin

For some reason this did not turn up during my initial searches but was pointed out over in the Pi-Star Forums by Dennis (W1MT).

It also seems that Andy (MM0MWZ) is considering adding a button in the future which would allow turning off HDMI from the web interface.

Turn off HDMI on Pi-Star Image

It is common practice on headless Raspberry Pi computers to turn off the HDMI to save some power. Even without a monitor attached, the HDMI hardware seems to draw ~ 50 ma of current. However, in the interest of saving space in the image, Pi-Star (as distributed) lacks the necessary tvservice command to turn off the HDMI hardware.

This command is part of the Raspberry PI “userland” package, which for some reason is not packaged as a .deb. So you’ll have to grab the code off github, but it is pretty easy. Before starting, make certain that you have expanded the filesystem of your image to fill the SD card.

sudo pistar-expand
sudo reboot

After the reboot, do the following:

rpi-rw
git clone https://github.com/raspberrypi/userland
sudo apt-get install cmake -y
cd userland
./buildme

Add the libraries to the ld.so search patch by creating a file named “userland.conf” in /etc/ld.so.conf.d. In that file add the following line:

/opt/vc/lib

Next, update the ld.so search path:

sudo ldconfig -v

You can now run the tvservice command:

## Status
sudo /opt/vc/bin/tvservice -s
## Turn off HDMI
sudo /opt/vc/bin/tvservice -o

All that is left to be done is to add the HDMI off command to your /etc/rc.local file so that it will run every time the system boots.

Will Opaqueness Kill Brandmeister?

In response to the ill-advised Brandmeister ban on the DV4mini devices by Corey Dean (N3FE), I approached some of the key personnel behind the Brandmeister DMR system to determine if I could put up a new master server in the USA. The purpose of the server would be to support the stations requiring extended routing who had been disenfranchised by N3FE.

Most of the Brandmeister core team do not publish email addresses, but I was able to get in touch with Yentel (ON3YH). He indicated that he was not active any more in the development process, but said the he would pass on my message to Artem (R3ABM) and Rudy (PD0ZRY). After a couple of weeks with no further response, I tried some social media channels where I put the following questions to Artem and Rudy:

“Does Brandmeister have a policy which supports the action of the USA Administrators who disabled access to TG 4999 (extended routing)?

“Thousands of USA users who require access to extended routing have been abandoned by the current admins. Therefore, I propose to put up a new master server in the USA which will support those abandoned users by explicitly supporting extended routing. Will you permit/support this?”

Finally Artem came back to me. Not with a straight answer mind you, but a roadblock:

“Please discuss this with Corey Dean”

Talk about opaque. Not a yes, not a no, not a statement of policy. Not an answer on behalf of the core development team as to whether they support the actions of the USA team. Rather, appeal your execution to the executioner and don’t bother me. This is not exactly an answer in keeping with the amateur radio objectives of mentoring and experimentation.

The team running Brandmeister has a published list of policies. Policy number 9 for master server operators is:

“Promote a positive image of BrandMeister”

It seems that the leaders of this project could better comply with their own policies. Their image is not looking too shiny to me right now.

What happens next? What if someone decides that MMDVM boards made in China or Kenwood repeaters or you fill-in-the-blanks are not to their liking and decides to ban them? It is ironic that the Brandmeister project sprang up because of the closed nature of the DMR-MARC C-Bridge networks which preceeded them. The Brandmeister devs were the freedom fighters.

Now, they are the bureaucrats.

Brandmeister USA Team Kills DV4mini

It has been apparent for some time that at least one of the members of the Brandmeister USA team has it in for the DV4mini. There have been occasional actions to block users of the DV4mini from connecting to the master servers operated by the USA team. Comments in a Facebook group by a team member have long indicated a desire to eliminate connections from this somewhat flawed, but useful and prolific device.

While investigating why my DV4mini stopped working on the Brandmeister network, I learned that the USA team disabled reflector access. Reflector 4999 is needed on the Brandmeister DMR network to take advantage of extended routing. I note a comment from Corey Dean (N3FE) on the Brandmeister USA Facebook group back in October that states, “DV4MINI and reflectors are disabled on all US masters.” This shows what I believe to be the true intent of disabling reflector access, although the DV4mini is not specifically mentioned in the Brandmeister USA wiki. He later makes comments about this freeing up talkgroups in countries whose codes start with 4. However, there is no code assigned to a country that starts with 499, so extended routing could still be allowed and not interfere with any Asian or Middle Eastern nation that wants to jump on the Brandmeister wagon.

So, DV4mini users in the USA who connect to one of the 4 master servers (3101, 3102, 3103, and 3108) now need to resort to connecting to a server outside of the USA.

Dissatisfaction and requests for reconsideration to allow extended routing should politely be directed to dmr-admins@repeater.net.

Baofeng UV-3R+ Repeater Offset Broken

I was recently in search of a small, low power HT that has dual band (2m/70cm) capability. A bit of interwebs reading pointed me in the direction of the now discontinued Baofeng UV-3R+. For less than $25 each, including slow boat shipping from China, I grabbed a pair from Ali Express during the recent 11.11 sales.

The form factor of the radio is just right for my XYL’s purse, so she will carry it as an emergency radio. She also has a tiny Puxing PX2R purchased years ago via eBay, but it is UHF only and we wanted dual band capability so that she could hit KC2GOW’s new machine near her work QTH.

However, programming via software was quite difficult. It turned out that both the native software and CHIRP fail to adequately handle repeater offsets. A bit of reading came up with a couple of references to using .006 MHz rather than .600 as the VHF offset and then using .05 rather than 5.0 as the UHF offset. As you can see, the value has been shifted two decimal places to the left. Anyway, this is how it works with CHIRP.

Even worse is Baofeng’s own software, which requires entry of separate transmit and receive frequencies, rather than an offset. So, for a repeater which transmits of 146.76 and receives on 146.16, the Baofeng software needs a transmit frequency of (146.76 – .006) or 146.754 MHz.

OK, the radio is cheap. It is worth what I paid. But it is no Yaesu or even Alinco. Caveat amateur!

noaacap with Dire Wolf

I’ve heard from Patrick (N3TSZ) who says that noaacap works well with Dire Wolf as an alternative to aprx. While I have not tested this myself, Patrick writes,

I discovered that noaacap works in Direwolf. Install noaacap as per your instructions. Then add the following line to direwolf.conf:

CBEACON EVERY=2 INFOCMD=”noaacap.py”

The string returned by noaacap is inserted in the information portion of the packet and transmitted. If a string is not returned, “INFOCMD failure” is displayed, and Direwolf continues on

Thanks for this useful feedback!

Look here for more information on noaacap.

DV4mini image supporting RPi3B+

Just in time for Cinco de Mayo, let’s celebrate the latest iteration of the K2DLS DV4mini image for the Raspberry Pi 2, 3, and 3+. Thanks to the folks on the Facebook DV4mini support group for pointing out that the November release did not contain code to boot on the new Raspberry Pi 3 Model B+.

This is a fresh build, based upon the latest Raspbian Stretch. ssh and RealVNC are ready to go and it works nicely with the official 7″ touchscreen. The DV4mini console and the Brandmeister XTG Dialer start up automagically.

Default user: pi
Default password: raspberry (please change on first use!)

You will find the new image here.

Art Bell and the Alien Pirates

You’ve probably heard by now that Art Bell, known to radio amateurs as W6OBB, is now a silent key. That’s what us ham ops call a dead guy. Well Art may be physically dead, but I think he is alive somewhere (or many wheres) in time.

Art Bell, amateur radio operator and talk show host extraordinaire.

My favorite memory of Art goes back to a show he probably did about 20 years ago. I don’t remember the exact date, but he announced one night that if aliens were really trying to contact us we should agree upon a common radio frequency. He threw a frequency out on the air and said that people should listen in case the aliens call. So I listened.

Sure enough, after some time listening to static, someone turned on a transmitter and started playing the sounds from Close Encounters of the Third Kind. I don’t know if it was transmitted by Art himself, but what a prankster.

73 Art, you will be missed.

A New Raspberry Pi for π Day

The Raspberry Pi Foundation has announced the new Raspberry Pi 3 Model B+. This incremental design improvement provides some interesting features.

1.4GHz 64-bit quad-core ARM Cortex-A53 CPU
Dual-band 802.11ac wireless LAN and Bluetooth 4.2
Faster Ethernet (Gigabit Ethernet over USB 2.0)
Power-over-Ethernet support (with separate PoE HAT)
Improved PXE network and USB mass-storage booting
Improved thermal management

The 5 GHz wifi and power over ethernet capabilities are especially interesting improvements. The Raspberry Pi is a great experimenter’s computer. Many amateur radio operators and makers are using them in purpose built applications such as digital hotspots and home control. You can see more here.

Update: 03/19/2018 — One difference that I failed to note betwee the RPI 3 Model B and the B+ is that while the RPi 3 Model B sported 1 GB of RAM, the B+ cuts it back down to 512 MB. While 512 MB may be enough for your application, if it is not, you may with to stick with the original RPi 3 Model B.

Update: 05/03/2018 — I have verified that RPi 3 Model B+ does still have 1 GB of RAM. The reference to 512 MB RAM came from the specifications listed on the RPi Foundation web page when originally released.

2018 SWL Fest Talk Links

Here are the links mentioned in my 2018 SWL Fest presentation, “RTL-SDR: more SDR on the cheap!”

Receiving NRSC-5 by Theori
NRSC-5 Proof of Concept Code
NRSC-5-D Standard
Other NRSC-5 Related Standards
NRSC-5 Metadata GUI by K2DLS
dump1090 blog post
Dire Wolf source code
Xastir wiki
Xastir source code
Raspberry Pi Foundation