Call sign KI7ODK.
Before I begin, I would like to briefly introduce myself.
I have been an amateur radio operator since 2017, and currently hold a U.S. general class
license.
I am an aerospace engineer by profession, and I'm just about to receive my master's
degree in that same field.
Some of my interests related to amateur radio and engineering are emergency preparedness,
computer hardware and programming, and computer networking.
Today, I will be presenting about single-board computers, or SBCs, and their use in amateur
radio.
For those who are not familiar with SBCs, I will first go over what an SBC is.
We will then look into some of the advantages of SBCs.
The majority of my experience with single-board computers has dealt with the Raspberry Pi,
so I will be focusing my presentation today on the Raspberry Pi.
However, the Pi, as it is also known, is not the only SBC out there, so I will also be
showing a couple other options that you can look into if you're interested.
My plan today is to dedicate most of my presentation to introducing the Raspberry Pi, showing you
the various models of the Pi that are available, walk you through how to set up the Raspberry
Pi OS, and then show you just some of the many things that you can do using a Raspberry
Pi in the sphere of amateur radio.
So with that, let's jump right in.
Now a typical desktop or laptop and computer generally includes the following components.
A motherboard, which serves to interconnect the computer's various components.
Random Access Memory, or RAM, also known simply as memory.
A Central Processing Unit, or CPU, also just called the processor.
A graphics card, or graphics processing unit.
A hard drive for data storage.
And a power supply.
The pictures shown here for each of these components are showing what they may appear
like in a desktop computer.
While the same components used for laptop computers are usually more compact, the function
for each of these components is still the same.
As the name implies, a single board computer is a computer that has all of its essential
components assembled onto one board.
As noted in the explanation from Wikipedia, this usually includes, but is not limited
to, a microprocessor, memory, and input-output connections.
Because all of these components are built onto a single board, SBCs have several advantages
over their desktop and laptop counterparts.
First, modern single board computers are small and compact.
Similarly, they are very lightweight, even when compared to the lightest laptop computers
available today.
Their small and lightweight nature makes SBCs great for portable and or space-constrained
uses.
SBCs are also very versatile.
Because most SBCs run on Linux, they are very customizable.
Many SBCs also include what are known as GPIO, or General Purpose Input-Output connections.
I'll explain a little bit more about that later.
GPIO pins can be very useful for amateur radio and electronics purposes and projects.
Next, the use of smaller, low-power components on SBCs means that single board computer systems
often require very little power to run.
And finally, devices such as the Raspberry Pi have a large community of users that continue
to grow.
This means that there is a large group of people you can turn to for support with your
projects or to get ideas from.
Now let's be clear.
Single board computers are great, however, they do have some disadvantages.
Because SBCs are smaller and use small, low-power components, their processing power is limited
compared to a desktop or laptop computer.
However, this disadvantage has become less of a problem in recent years as the processing
power of SBCs has increased noticeably.
Another point that many may consider a disadvantage is the fact that single board computers typically
cannot run Windows.
Especially in amateur radio, there are many programs that can only run on Windows.
However, I myself do not consider this a great disadvantage.
The Windows operating system is great for home and office use where your Windows updates
probably don't mess you up too much.
In the end, Windows is not known for being the most stable operating system.
And let me just say right now, SBCs are not built or intended for hardcore gaming use
either.
Yes, you can run Minecraft on a Raspberry Pi.
You can also set up a Pi to run classic arcade games.
Just don't expect to be playing Call of Duty or something similar on a Pi, as is typically
done on a Windows desktop computer.
Now that I've said that, some of you may go out there to prove me wrong, and that's perfectly
fine.
All the more power to you.
I would love to see if you could run Call of Duty on a Raspberry Pi.
However, I digress.
That's not the point of this presentation.
Hopefully, this simply gives you a good idea of what SBCs are great for, and what areas
they aren't generally intended to be used in.
After going through those advantages and disadvantages, we can begin to see why single-board computers
are great for amateur radio.
As digital modes continue to grow in use and popularity, we will see an increasing use
of computer-connected radios.
SBCs do great running digital modes, and as I mentioned earlier, are also great for interfacing
with electronics.
This could allow you to easily set up a push-to-talk circuit using an SBC.
And that's just one simple example.
Now even though Windows doesn't typically run on SBCs, almost anything you can do on
a Windows computer for amateur radio can also be done on an SBC.
Looking at the advantages listed in the previous slide, we can see that SBCs are great for
portable operations, such as summits on the air and field day.
And as I alluded to earlier, Linux is a great and very stable operating system.
It's also open source, which means that you don't have to pay for the OS itself.
Here are some quick examples of single-board computers that are available on the market
today.
Now the first I have already mentioned is the Raspberry Pi.
The Raspberry Pi is probably, by far, the most well-known and popular single-board computer
available right now.
Next is the BeagleBone Black.
The BeagleBone shares some features with the Raspberry Pi, but includes a different processor
and GPIO setup, as you can see in that picture.
The other example that I have shown here is the BananaPi.
Now I honestly don't know too much about the BananaPi, but from what I've read, its design
was partially inspired by the Raspberry Pi, as you can probably see in that picture.
There are multiple other single-board computers out there that you can get.
Feel free to look around and see what interests you and what fits your needs.
Alright now that I have gone over and given a general explanation about single-board computers,
I will be talking from here on out specifically about the Raspberry Pi.
The original Raspberry Pi board was released in 2012 by the Raspberry Pi Foundation.
As of the end of last year, 2019, over 30 million Raspberry Pi boards have been sold.
Today, the Pi is available in three main form factors.
The first and most popular is the full-sized Model B.
The Model B includes four USB ports, an Ethernet port, GPIO header pins, an audio output, HDMI
output or outputs, depending on the model, a display ribbon output, a camera ribbon connector,
and a power input.
The second form factor is known as the Model A.
This model has one USB port, an HDMI output, a display ribbon output, GPIO pins, an audio
port, a camera ribbon input, and a power connection.
And last, the Pi Zero includes only GPIO headers, an HDMI output, USB connection, ribbon connection,
and power input.
The base Zero model does not include wireless capabilities, however the Zero W does.
You can also buy versions of the Zero W with pins pre-soldered onto the GPIO headers to
make it easier to do those connections.
Now here is a table showing the different Raspberry Pi revisions and models that have
been released since the first Raspberry Pi.
The most popular models currently available are the Raspberry Pi 3B+, and the Raspberry
Pi 4.
The 4 is now available with 2, 4, or 8 gigabytes of RAM, even though this table doesn't show
the 8 gigabyte model.
The 3A+, typically sells for about $25.
The 3B+, and the 4B 2 gigabyte models, both currently sell for $35.
You can see the other prices that I have listed there on the right for the various models
as well.
Notice that the price increases about $20 for each successive increment of RAM if you're
ordering the Raspberry Pi 4.
To buy a Pi, I would recommend going to raspberrypi.org.
The Raspberry Pi Foundation maintains a list of approved resellers on their website.
I would recommend that you avoid buying from Amazon.com and other similar sites.
Because of the popularity of the Raspberry Pi, sellers commonly try to buy stock from
the approved resellers, and then resell it at a markup.
I personally prefer to buy from Adafruit.
However, any of these resellers shown here are great.
Be aware that you can purchase the boards or computers alone, or in a kit.
The kits are nice if you're just starting out, but they can be a little more expensive.
Keep in mind that there are a couple components that you need to run your Pi, in addition
to just the board itself.
The first of those is an SD card.
The SD card is essentially the hard drive of the Pi.
It slides into a slot at the bottom of the board.
The next is a power supply.
With just a power supply and an SD card, you can run what is known as a headless Raspberry
Pi setup.
In other words, the Pi is not connected to any external displays.
This is how I run most of my Pis.
I have my Pis set up so that I can control them remotely over my home network.
I also have the Raspberry Pi I use for portable operations set up to create its own wireless
network when I am out of range of my home network.
This allows me to connect to the Pi using any other wireless computer, tablet, or smartphone
and remotely control the Raspberry Pi while I'm out operating.
To start out, it is often nice to hook up your Pi to an HDMI display, a keyboard, and
mouse.
This can help you set it up and go through the initial configuration process.
I also like having my Pis in a case.
Now a case is not necessary, but it can help protect your Pi and the components on the
board.
Alright, now that we've gone over all of that, it's time to jump into setting up a Pi.
To set up your Raspberry Pi, you will first need two things in addition to your laptop
or desktop computer.
First of those, as we mentioned earlier, is a micro SD card to set up and to install
the OS on.
The next thing you'll need for the SD card is an SD card reader of some sort that you
can plug into your computer so you can set it up and image it that way.
Once you have that plugged up into your computer, we'll then use one of two applications to
format and image this card.
On the computer, we can use, like I mentioned, one of two applications to image the SD card.
The Raspberry Pi Foundation has recently released the Raspberry Pi Imager application, which
makes it very easy to set up the SD card.
First we need to choose the operating system version that we want.
Now the one that they recommend currently is the Raspberry Pi OS with the desktop environment.
This will simply install the full operating system on your SD card and will include the
desktop environment so you can interact with the Pi just as you would any other desktop
computer using a keyboard and mouse.
There is other options that you can select here, such as Ubuntu, which is another type
of Linux, RetroPie for retro gaming, and things like that.
If you select Other Images for the Raspberry Pi OS, you can see that they have two other
options here.
The first is the Lite option.
The Lite OS image installs the OS with a command line interface only, so no desktop interface
will be included.
The second one here is the Full OS, so that will install the full desktop operating system
with a set of recommended applications, so you can have those applications already installed
and ready to go for your first use.
Once you select the operating system that you would like to use, for this example I'll
go ahead and select the recommended one, you then choose your SD card, and then you click
Write.
It will download the operating system image from the internet and then write it to your
SD card.
The second application that you can use, which is no longer recommended, but I'm going to
be using it today just for speed, is Bylena Etcher.
This application, you simply select an image that you've already downloaded, I have mine
here in OS Images, and I have the full image here to select.
You then make sure it has your SD card selected there for the drive, and then you click Flash.
Now this will take a little bit to flash or image the card, so I'll come back to you after
it's done.
Alright, Etcher is almost done flashing the image to our SD card.
Now I didn't mention earlier, but I'm using Etcher right now because I already downloaded
the image online, as you saw, and I found that Etcher can be a little bit faster if
you do that.
The Raspberry Pi imager does take a little bit longer, simply because it has to first
download the image from the internet, like I mentioned earlier.
I believe that once you have used the Raspberry Pi imager, once or twice, it will actually
store that image somewhere on your computer.
So if you use it sequentially multiple times, it will be faster in the future, and it will
simply use that downloaded image to flash to your SD cards.
Alright, Etcher is going to now take some time to validate the image that we just flashed
to our card, so I'll come back right after that has finished.
Etcher is about done validating the image that has been flashed to the SD card.
While that's finishing up, let me show you really quick where you can download the Raspberry
Pi OS images and the Raspberry Pi imager.
If you just go to raspberrypi.org, all you have to do is come up and click on the Downloads
page up here.
You can then download the imager application for Windows, Mac, or Ubuntu Linux.
You can also directly download the images for the OS by going down here and scrolling
down.
As we can see, the flash is now complete.
Alright, now that that's done, at this point, you can remove the SD card from your computer,
plug it into your Pi, and power up your Raspberry Pi.
If you were to hook your Raspberry Pi up to a monitor, keyboard, and mouse to complete
the rest of the setup.
However, I am now going to continue on and set up my Raspberry Pi for a headless setup.
Now, in my case here, I have to remove the SD card and put it back into my computer in
order for the computer to load up the card again.
So now that I'm done with Balana Etcher, I'll go ahead and close that out.
And you can see here that I have a drive showing up in my USB drive E now.
You can see all these files here are from the image that just got flashed to the card.
What's going to happen is once we plug this into the Raspberry Pi, the first time the
Pi boots up, it will take all these files and it will actually set up the OS.
So the files you see here are not necessarily the same way they're going to show up once
you have the OS set up and have run the Pi for the first time.
The first thing I'm going to do here is I'm going to follow the instructions here on the
raspberrypi.org documentation for setting up a Raspberry Pi headless.
Now you can see the first things you want to do here is if you're going to connect to
your Raspberry Pi with a wireless network, you need to set it up so it will connect to
your network.
If you're going to set it up and connect it with an Ethernet cable, you don't have to
worry about this step here.
But I'm going to go ahead and set this up.
So what we want to do is we are going to set up what's called a WPA supplicant configuration
file.
The contents of that file are shown here.
So I'm going to simply copy that and paste that over to my Notepad Plus document here.
We need to first verify that the settings are correct here.
So the first thing we'll check is to make sure that the country code is set.
In my case, that will be US.
You will then put in here the name of your network and whatever your password is for
your network in the PSK spot.
If your network is open and has no password, you can set that up by following the directions
for unsecured networks shown here.
So all you would do is put in key underscore MGMT equals none instead of having a password
there in the file.
So we're going to take that file and we're going to save that into our SD card there.
And I'll make sure that that is named WPA underscore supplicant dot CONF.
Save that there.
And when the Pi boots up for the first time, it will detect that file and it will set up
the wireless networking.
Now you notice Windows changed it to .conf.txt.
So I'm going to go in there.
And I'm going to make sure that it's .conf and not .conf.txt.
And yes, Windows is going to ask me if I want to do that, and I'm going to say yes.
All right, the next thing that I'm going to do here is I'm going to create a new file
in here.
Just a text document, and I'm just going to call it SSH with no suffix.
And I'm going to say yes.
Now with that SSH file in there, that will enable the SSH interface the first time the
Raspberry Pi boots up.
SSH is simply a remote control interface that you can do over command line.
And that's one thing that I use a lot with my Raspberry Pis that I'm remote controlling.
So now that I have those two things set up, all that's left to do is to plug the SD card
into the Pi and plug it into power.
So what we'll do is we'll go ahead and grab our SD card, and we'll go ahead and put that
in the SD card slot on the bottom of the Raspberry Pi.
You just insert that straight in there until it goes in all the way.
It's not really hard to put in.
You won't feel a click, but just make sure it goes in all the way so it's connected properly.
You'll then take your Raspberry Pi and hook it up to your power supply by hooking that
into the power in slot.
Now today, I'm simply going to be using a USB power bank to power my Pi as well for
setup and demonstration.
Alright once the Raspberry Pi has started up, you'll see the red light and green light
start to flash on the Raspberry Pi itself.
Give the Pi a minute or so to boot up and set up the OS.
And then, to complete the setup for the headless portion of the tutorial right now, what I'm
going to do is I'm going to go ahead and connect to the Pi using SSH.
Now there's multiple programs you can use to do SSH.
One of the popular ones is called PuTTY, P-U-T-T-Y.
Go ahead and Google that and you can download that and use that for SSH.
What I do is I use the Windows subsystem for Linux feature that's currently on Windows
10.
So I'm going to go ahead and pull up my Ubuntu installation and all you have to do in this
case is just type in ssh pi at and then the IP address of your Pi on your network.
You'll have to figure that out, what IP address your Pi connected with.
I'm going to go ahead and hit enter here and the first time I connect to this host it's
saying that the authenticity of the host cannot be established.
Well that's fine because this is the first time I'm connecting to the host after it's
been set up.
So I'm just going to say yes, that's fine.
Now it's going to ask me for the password.
Now notice that Pi I put in is the default username.
And the default password for the Raspberry Pi is simply raspberry.
So I type that in and apparently I did not type it correctly.
Let's see if I... there we go.
So once you're in and connected correctly you'll see the prompt there to change your
password.
You'll want to do that if you're leaving your Pi connected at all.
What I'm going to do here is I'm going to enter raspi underscore config.
And I'm going to have to look at the command now.
So what I want to do is I'm going to set up here some interfaces.
And I want to set up primarily VNC so I can remote control this Pi graphically.
So what I want is enabling this option at the command line.
Oh, and I wanted a dash, not an underscore.
So I was pretty close.
But I'm just going to do dash and that will bring up this.
It's telling me I need to do it as a root or basically as an admin user.
So I just need to do sudo as pi config.
All right, now that this has come up, you can use the keyboard here to navigate through
this menu.
I'm just going to do down arrow, two interfacing options, and I'm going to go over arrow, right
to select, and I'm going to hit enter.
And then I'm going to say VNC.
I want to select and I want to enable the VNC server.
It's now telling me that that's enabled.
And that should be the only thing that I have to do right now.
You can enable the other interfaces or explore the options right here that you have.
So what I'm going to do is I'm just going to do now go over over to finish and hit finish.
And now I'm going to do sudo reboot to restart the Pi.
It will close the SSH connection and it will reboot the Pi.
What we're going to do now is we will wait for the Pi to reboot so we can now connect
with it with VNC.
VNC is automatically installed on the Raspbian or the Raspberry Pi operating system.
Like we just saw, I just enabled the server.
So what you want to do is you can download the VNC viewer for your computer.
It's available for Windows, Mac, Linux, and there's also applications available for iOS
and Android.
So you can use those devices to remote control your Raspberry Pi as well.
Once you download that and install it, you can then connect to your Raspberry Pi.
So I'm going to pull up VNC viewer and these are a few of my devices here that I often
connect to.
Mine is 0.36.
Now since I have reinstalled the operating system on my Raspberry Pi, its catchphrase
and signature have changed.
So that's why it's alerting me here to this identity check failure.
I already know about that so I'm just going to click continue and I'm going to put in
the same password, raspberry, and connect to it.
There we go.
Alright, now it's going to give us a couple of warnings because we haven't changed the
password.
That's fine.
So the last thing that I'm going to go through right now is just show you this wizard that
helps you set up the Raspberry Pi.
It simply goes through and this is the graphical way that you can set up your Raspberry Pi.
First of all, make sure you've set up your country.
That's the thing that we set up earlier when we set up the wireless configuration.
Alright now it gives you an opportunity to change the password.
You would enter your new password here and confirm it.
I'm not going to worry about that right now but that's something I definitely encourage
you to do.
This gives you the opportunity here if you're using a monitor to make sure that the screen
is set up properly.
I'm not going to worry about that right now.
And then here is where you can set up your wireless networks if you haven't already.
So I'm going to go ahead and skip that.
And then finally, it gives you a prompt to update the system software and I would recommend
you do that at the end of your setup here just to make sure that everything is up to
date even though we just barely installed the operating system.
So most everything should be up to date but it's a good idea to check that.
The very last thing that I will do here is you can notice that the screen size for the
VNC viewer is a little small here.
What I'm going to go ahead and do is we can change that by going into the preferences
and into Raspberry Pi configuration.
If we go into display and set resolution, we can then make the VNC server emulate a
larger display.
So I'm going to just select 1280x720 and we'll go ahead and make sure that that is confirmed.
Can I get down to the...
Hopefully if I just close it, okay.
So it is going to confirm the settings there and it's just going to reboot the Pi.
So what will happen is the VNC viewer here will wait for the Pi to reboot and it will
reconnect.
And here we are.
We have a slightly larger screen.
So you can set that resolution to whatever fits your setup and needs.
Now that we have set up a Raspberry Pi, it's up to you to explore and figure out just what
you can do with a Raspberry Pi.
Pis are great for use in emergency communications and can enable effective communications for
Ares and Skywarn groups.
Using a software TNC such as Direwolf makes it really easy to hook a sound card up to
the Pi and your radio for things such as Winlink and APRS.
Other digital applications such as JSA Call and WSJTX work great on the Pi.
You can even hook your Raspberry Pi up to a software-defined radio device to expand
the capabilities of your setup.
These are just a few examples of what you can do with a Raspberry Pi.
And honestly, the sky is the limit.
Now I'm going to show you my setup and how I use my Raspberry Pi in amateur radio while
I am out operating.
So this is my portable setup as I currently have it.
Here I have a Kenwood TM-V71 interfaced with my Raspberry Pi 3B+.
The Raspberry Pi is hooked to a sound card and an RT-Systems control or programming cable,
which are both then hooked into the back of the TM-V71 here.
The Raspberry Pi is also hooked up to a 12V to 5V power converter.
If you don't want to hook your Raspberry Pi into your 12V battery system, you can also
consider using a USB power bank, as I mentioned earlier.
A power bank such as this will power your Pi for quite a few hours out in portable operations.
Now I'm going to give you a close-up of how this setup is currently arranged.
So here is the USB sound card that I mentioned that's currently hooked up to the Pi.
Typically you want to use a USB or external sound card because the Raspberry Pi only has an audio out.
It does not have a microphone input port.
I also have my RT-Systems cable that I mentioned here hooked into one of the other USB ports.
You'll notice here is a GPS receiver hooked up to the Pi.
This GPS receiver is not only receiving the position of the Raspberry Pi system,
but it also is able to sync up the time, the system time, with GPS time.
For data modes such as JSA Call and FT8 that require fairly precise timing.
This GPS receiver is simply the same as this GPS GLONASS UBLOX 7 receiver here.
I've simply taken off the plastic casing off the outside so that this would fit with my other USB connections there on the Pi.
Currently the Raspberry Pi is creating a hotspot or wireless network that I can connect to it using an iPad or another tablet or even a laptop.
Typically I use my iPad here to connect to the Raspberry Pi and control it wirelessly using the VNC app.
It's also handy if you want to have a wireless keyboard attached to your tablet or use the keyboard on a laptop.
And that makes typing much easier than trying to use an on-screen keyboard.
So now that I've shown you the physical setup of my Raspberry Pi portable radio box, let me show you some of the software that I have installed on my Raspberry Pi.
First thing you can see here on the desktop is DireWolf.
DireWolf is a software TNC application that is currently interfaced with the USB sound card that I showed you earlier.
You can see it currently decoding APRS packets in real time because I have my radio currently tuned to the APRS frequency.
DireWolf is also currently interfaced with LIN-BPQ, which is creating and providing a WinLink gateway.
Other stations could connect to my gateway and send and receive email over the WinLink service.
That WinLink gateway is managed by going to the local website created by LIN-BPQ.
This is a nice feature that many of these applications, these portable applications and digital applications do, is create a webpage service that you can access not only from the Raspberry Pi,
but you can access from any computer that's connected to the Raspberry Pi wirelessly, such as my iPad tablet.
LIN-BPQ hosts its website at port 8080.
And so this is a configuration page that I go to in order to manage my WinLink gateway and BPQ node.
Another application that I have installed on my Raspberry Pi is PAT.
Now PAT is a WinLink client.
So if I go here to port 5000, I will pull up my PAT web UI.
PAT can also connect to Direwolf to use my sound card TNC to send and receive messages.
This has a simple interface, just an inbox, your app box, your sent messages, an archive, and the action menu where you can compose messages and position updates.
Alright, in addition to those two applications that I have for WinLink, I have a variety of other applications currently installed on my Raspberry Pi.
These are all organized under the ham radio submenu here.
Some of these include Chirp for programming radios.
CQRLog, which is a logging program.
Direwolf, once again, is the sound card TNC.
I have FLdigi and FLrig for rig control and some digital sound card modes.
You can also see here JSA Call and WSJTX.
Additionally, I have Zaster and YAC for APRS clients.
And I have a couple additional tools here installed that help me manage the software and update the software.
Such as PapMenu, PiAPRS, and other things that have been developed by Jason, KM4AK.
These programs are really useful on VHF, UHF, and HF.
And you can interface your single Raspberry Pi to both a VHF radio and an HF radio simply using multiple sound card interfaces.
Alright, so you're probably wondering now, where do I start?
Here are a few of my suggestions.
First, check out raspberrypi.org.
There are many tutorials there and elsewhere online of projects you can do using the Raspberry Pi.
Next, check out YouTube.
KM4AK, Jason, and OH8STN, Julian, both have great channels on YouTube that I follow.
They both do some great things with their radios using the Raspberry Pi.
I would also suggest you take some time to decide what you would like to explore.
There is a lot that you can do with the Raspberry Pi and other single board computers.
Identify where you'd like to start first and go slow.
Don't burn yourself out.
Finally, put some effort into identifying your communications needs and how single board computers can empower your amateur radio setup.
Well, thank you very much for tuning in today.
I will be available to answer your questions in the designated channel.
Hello, thanks for joining us. Thanks for that great presentation.
If folks have questions, you can throw them either on Twitch or on the HRV Presentation Tech channel.
We actually have one. I'm curious, what's your wish list for the Raspberry Pi 5, whatever, right?
What would you love to see in there that we don't have today?
Interesting question.
I say that's interesting because the Raspberry Pi 4 has actually been a pretty good model so far that I can't think of anything I would necessarily add to it off the top of my head.
I mean, obviously, it's always good to increase the processor capability, and I think they're incrementally doing that.
And so as we see the capabilities of these processors on the Raspberry Pis, that will continue to increase what we can do with these single board computers.
I will mention with the 4, since they added the two USB 3.0 ports, that was a really nice addition.
So I guess one thing that I would like to see is maybe all four ports USB 3.0.
And that's really the only thing I can think of right now.
Okay, I'm curious. Do you know, is the power consumption on the 4 much higher than the 3, or is it about the same?
Correct, because they switched to USB-C power, right, on that?
Yeah, they switched to the USB-C power because there was a slight increase in the power consumption.
I think the 3B+, at max power, would use about 2.5 amps.
And the 3 can draw up to 3 amps, is my understanding.
But a lot of that will actually go to if you have USB devices hooked up to it.
A lot of the power draw comes from those USB devices.
So that's just something to keep in mind if you're connecting devices that require a lot of power.
Sometimes it's better to hook them up to an external hub that you can then power that way.
Cool. Related to that power, we had a question about how long can you run the Pi using a battery bank on a standard day?
So the battery bank that I showed in the presentation, that one can run it for upwards of at least, I would guess, 6 or 7 hours.
And a lot of the portable battery banks that you get for charging your phone, if you get upwards of...
there's some 20,000 mAh packs and stuff, and those are the ones that I have.
But then, of course, if you just power it off your 12V battery, you can run for probably days off a 12V battery.
Something like an 18Ah battery, a 12V battery that you're going to connect to a 5V converter, will give you operation for days just on the Raspberry Pi.
Great, thanks. We get a couple questions around, do you have a preferred SDR or do you use USB SDRs?
And what are your favorite SDR-based activities, if so?
Yeah, so as far as SDR goes, the only SDR device I've used is the RTL-SDR, and I've done a little bit with that.
I haven't done too much on the Pi, but that's the one I've played around with.
What I would really like to do is set up a receive-only iGate for EPRS using an SDR, and that's just a really cheap and pretty easy method to set it up that way with an SDR.
Instead of just taking up a full other ham rig, you can dedicate that to just sit in your house and receive EPRS packets in your local area.
So yeah, as far as SDR, I've used only the RTL-SDR, and I'm really right now playing around more with how to use that on the Raspberry Pi.
In general, on the computer, when I've just hooked it up to my laptop or PC, I've just been listening to voice traffic locally.
So that's as far as I've gotten with SDR so far.
Great, thanks. That's all the questions we had in chat. If you have any further questions, feel free to just hop in the village and ask away, and I'm sure I can get you there.
I want to thank you for giving that great talk, and hopefully everyone enjoys the rest of DEF CON Safe Mode.
Yeah, thanks for tuning in.
Transcribed by https://otter.ai