The UK based Raspberry Pi Foundation has announced the availability of the latest advancement in the Raspberry Pi single board computer series. The Raspberry Pi 4 Model B offers:
1.5 GHz quad-core 64 bit Arm Cortex-A72 CPU
Up to 4 GB RAM
Full throughput gigabit ethernet speed
Dual band wireless networking
4k video decode in hardware
For the first time, the amount of memory is an option selected at time of purchase.
While some may view this upgrade as incrememental, those with larger memory or dual monitor needs will see this as a transformative improvement. A new release of the Raspian operating system based upon Debian Buster will support the RPi 4 B+ and its new features.
A complete desktop kit is also being offered. Can the Raspberry Pi replace your desktop PC? Perhaps.
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:
If it is installed, just add the HDMI off command to /etc/rc.local.
# Turn off HDMI
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.
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.
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.
Note: This article was originally published in March 2017. I’ve revisited and updated it in preparation for a talk that I’ll be giving at the 2018 Winter SWL Fest. I’ve simplified the installation process. While doing so, I learned that Google now requires an API key for the application to have access to their maps. My github fork of the dump 1090 code has been updated to account for this development.
A key component of next generation air traffic control is Automatic Dependent Surveillance – Broadcast (ADS-B). The current FAA mandate is for all included aircraft to output ADB-B transmissions no later than January 1, 2020. But you don’t have to wait to receive and map ADS-B. There is a lot of air traffic to be seen.
Some folks are using complete downloadable images that are set up to feed flight tracking services such as FlightAware. If you’re interested in doing this, The SWLing Post featured an article that you’ll enjoy. I wanted to explore whether I could use some items already on hand to see a map of overhead aircraft on any computer on my home network.
I pulled out an older Raspberry Pi Model B and a 4 GB SD-Card and installed a copy of Raspbian Stretch Lite. The Model B has been retroactively called a Raspberry Pi 1 Model B. It is equipped with 512 MB of RAM, two USB ports and a 100mb Ethernet port.
I decided to use a spare older RTL-SDR stick based on the RTL2832U and R820T chips. This USB device comes with a small antenna that I hoped would be good enough to get me started. It is not in any way optimized for the 1090 MHz signals that are used by ADS-B and is roughly 19 parts per million (ppm) off frequency. It cost a bit over $10 at a hamfest a couple of years ago. The designs have improved since the early models were offered. Newer models include a TCXO (thermally compensated crystal oscillator) for stability and accuracy.
I needed software to take signals from the RTL-SDR stick and plot them on a map. That software is “dump1090”, originally written by Salvatore Sanfilippo. I added an install stanza to the Makefile, along with a systemd service file, for a smooth system install. I also needed to install the RTL-SDR USB drivers. The complete installation runs “headless”, meaning no monitor, keyboard or mouse need be connected. Remote management can be done via ssh.
There is a security change that comes along with Stretch. ssh is now disabled by default. After copying the initial Stretch image to the SD card and BEFORE removing it to place the Raspberry Pi, mount the boot partition and create an empty file named “ssh”. If you are not using ethernet, you could also pre-configure wifi settings.
First, bring the Raspbian Stretch installation up to date.
–quiet runs in the background
–net starts a webserver so that you can access via a web browser
–lat set to YOUR decimal latitude (negative for South)
–lon set to YOUR decimal latitude (negative for West)
–ppm if you know the ppm tolerance of your device (otherwise omit)
–gain -10 which sets gain automatically
A full parameter list can be reviewed by typing dump1090 --help.
With an antenna connected you can perform a quick device check by typing dump1090 --interactive. If all is well you’ll see a screen like this:
Hex Mode Sqwk Flight Alt Spd Hdg Lat Long Sig Msgs Ti/
A39D11 S 6 1 4
A25D36 S 1775 7 4 3
AAA593 S 2575 205 075 7 2 7
A25238 S 4 1 12
A0480B S 19650 8 28 3
ACF4DD S 3825 7 2 14
A41F61 S FDX3018 2800 211 025 40.428 -74.332 23 83 0
A6FFFE S 1753 LXJ550 30475 371 226 8 63 0
C060B3 S 4625 6 14 1
ACF69B S 23250 6 25 1
A2D27C S 24000 13 42 2
A0BF90 S 9500 249 257 5 3 9
A7D30A S 40000 8 111 1
AE0192 S SPAR958 32675 22 93 0
ACC040 S 7825 8 146 2
ACA5DF S 26600 6 79 0
A80C7B S 4550 9 108 1
A7CC00 S 7825 35 123 0
ACF841 S 1507 14425 50 132 0
A8C802 S NKS149 23575 332 216 39.995 -74.262 12 160 0
A61949 S UAL1105 2725 14 60 0
AC2E20 S 1006 19925 22 130 0
AB766A S DAL1526 8525 216 038 40.444 -74.213 81 249 0
AA4440 S 5400 253 066 6 6 13
Control-C exits this screen.
Now start the dump1090.service.
sudo systemctl start dump1090.service
If all goes well, a netstat -an will show that there is a binding to port 8080.
tcp 0 0 0.0.0.0:8080 0.0.0.0:* LISTEN
Now you can start up a web browser from any computer on your home network and see a map of planes overhead. If your router supports internal dynamic DNS you can name the RPi and access via something like http://skynet:8080. Alternatively, use the IP address, which can be obtained via ifconfig.
In this case, the URL would be http://192.168.1.123:8080.
Once the map appears, re-position it to your part of the world and enjoy learning about what is flying overhead. You can enhance your enjoyment by listening to your closest airport tower or air traffic control frequencies on a scanner. These transmissions use amplitude modulation (AM) and can be monitored an another RTL-SDR stick or a scanner, even a relatively old model.
The K2DLS DV4mini image for the Raspberry Pi 2 and 3 (only!) has been updated to include the October 12 release of the DV4mini Control Panel. This includes XRF through letter Z and REF up to 100 for the D-Star users. The image will fit nicely on an 8 GB SD Card.
A common concern of those running applications on a Raspberry Pi is SD Card exhaustion. It seems that after some amount of write activity, some SD cards fail to record further data. I first noticed this on an APRS system when system updates disappeared upon reboot.
The systemd journal is a useful tool that has largely replaced the syslog in modern Linux systems. It can also be redirected from the SD card to volatile memory. Note that by changing this you will reduce the number of SD card writes but your journal will not survive reboots.
The key to changing the storage location of the journal is found in /etc/systemd/journald.conf. Look for this line:
Uncomment the line by removing the #. Change auto to volatile:
Restart the systemd journal and your journal data will be written to /run/log, which is memory resident.
sudo systemctl restart systemd-journald.service
Only use good quality SD cards such, such as the SanDisk Ultra Class 10 memory cards. I recently had one that failed but was pleased when the SanDisk warranty program replaced the card at no charge.
I’ve created an updated image for use with the DV4mini and the Raspberry Pi 2 and 3. It incorporates changes through dv4mini software version date 20170517. It also includes my Brandmeister XTG Dialer for use with extended routing.
Changes include enhacements for YSF reflectors, DMR, DStar as well as the introduction of a text chat window.
Thanks to Ulrich Prinz (DC3AX) for his hard work in support of the DV4 community!
The Brandmeister XTG Dialer (BMXTG) has been updated to version 1.2. Enhancements include automatic download of the masters address list and automatic download of talkgroup IDs and labels. Any talkgroup label may be changed through use of the talkgroups.conf file. Be sure to review the README file for changes.
The changes will make BMXTG easier to configure and the user no longer needs to be concerned about IP address changes of the BM servers. A simple stop and start of the program will refresh the server list and talkgroup list automatically.
I’ve also updated the DV4mini Raspberry Pi 2/3 image to include BMXTG v1.2.
Retrogaming, the enjoyment of older computer based games and platforms, has been growing in popularity. I was intrigued a couple of years ago when, at a Vintage Computer Fest, I saw a multigame platform with hundreds of game ROMs copied onto a single emulation device. I had been wondering what the old games would look like connected via an HDMI input as opposed to the old low resolution RF transmitter method.
Then I came across the RetroPie project. RetroPie is a framework, delivered as an image, that allows you to run a number of game and computer system emulators on a Raspberry Pi. RPi models 2 and 3 are much better than older versions for this application. It is very simple to install and I was even able to use an old Colecovision controller to play Donkey Kong, Ladybug, and Carnival.
To connect the old controller, I came across a device called the Vision-daptor. One side sports a DB9 male connector, the other a USB B jack. It arrived just a couple of days after my order. The RPi recognized the device as a joystick controller without adding any additional drivers.
The Coleco emulation is handled by an optional component called CoolCV. CoolCV will also run under Linux, Mac and Windows. If you use a controller, rather than a keyboard, you may need to make some changes to key mappings in a configuration file.
There are plenty of sources for games online, but remember that games may still be covered by copyright. Some folks copy the contents of ROMs that they have purchased allowing them to play games for which they no longer have a gaming device. This requires some specialized hardware.
If you do download games via the internet, keep in mind that some sites may be vectors for the transmission of viruses and other malware. Exercise caution while you kill off those space invaders. And the games do look great on an HDMI monitor!