DIY Lightning Detection with SDR: (Updated!)

What follows is an informal experiment to detect lightning using a Software Defined Radio. I’m using an RTL-SDR version 3 dongle and GQRX in Linux, but any SDR and spectrum analyser software that can tune VLF should do it. Many dedicated lightning detectors work by listening to frequencies below the AM broadcast band and this part of the spectrum is relatively quiet, so I chose to monitor 0 to 600kHz. The antenna is a 1/2 wave trapped dipole for HF but any bit of wire at least a few meters long will work.

Lightning Detection using GQRX spectrum analyser.

In the above image, the waterfall display is the part in blue. Time is represented vertically and the span is ~30 seconds from top to bottom. The vertical line seen around 550 kHz is an AM radio station. The three thin horizontal lines are lightning. Here we can observe the broadband nature of lightning, comparative strengths and interval between discharges. Event #1 occurred first and was a large bzot producing thunder. #2 was a few seconds later and apparently weaker or farther away. #3 was a bit stronger than #2.


Lightning Detection with a spectrum analyser

In this image event #3 was a large burst not far from here.

Update: Shortly after midnight on August 14th 2017 there was a spectacular display of cloud to cloud lightning almost directly overhead. Not wanting to miss the opportunity, I fired up CubicSDR spectrum analyser and watched the mayhem unfold. On this run, I max’d the sample rate to 3.2MHz and tried several waterfall speeds so I could view the pulses closer in the time domain.


CubicSDR – 20 Lines Per Second waterfall speed.


CubicSDR – 126 Lines per Second waterfall speed.


CubicSDR – 1024 Lines Per Second waterfall speed.


CubicSDR – 1024 Lines Per Second waterfall speed.


CubicSDR – 1024 Lines Per Second waterfall speed.


Weather reports, satellite and radar images found online are not always accurate or on time. If you’re outdoors, boating or have antennas on the roof like I do, it can be helpful to know if an approaching storm brings lightning. I found that by tuning to a quiet part of the spectrum and setting squelch, lightning discharges produce an audible crackle, hence an audible alert without needing to listen to constant static.

There’s an interesting world-wide real-time lightning maps at:


  • Kenn Ranous



Monsoon at Roosevelt Lake – Arizona

On this episode of Kennazona Highways, a boating trip on Roosevelt Lake, July 23rd 2017.



Location: Roosevelt Lake, Arizona

Date: July 23rd 2017

Camera: Olympus e500

Lens: Zuiko 14-45mm

Filters: UV & Circular Polarize

Number of anchors lost during outing: One

Number of emergency U-turns to retrieve hat: Two

Photographer: Kenn Ranous

Vacuum the cat!

Installing RTL-SDR on a Raspberry Pi (Linux)

Thanks to Steve from AVT Marketing for making a clear & concise guide for installing drivers & software for RTL-SDR radio dongles on a Raspberry Pi Linux. This excellent video is based on my guide, RTL-SDR for Linux Quick-Start Guide with what you need to know to get it going on Raspberry Pi. Check out his other videos on his Youtube Channel.



  • Kenn Ranous

A 22 year old cat named Sue.

Meet Sue, a 22 year old kitty nick-named ‘The Tuna Roomba’ because of her appetite as she’ll just vacuum up all the tuna she finds like a robot. We’re fostering her from Fearless Kitty Rescue due to her age. She needs special attention and consideration, so she wasn’t made available to the general public for adoption. In our home, she has two other cats and a dog with whom she gets along with splendidly. She’s in charge and calls all the shots, no question about it.

Sue basking in the warm rays of an Arizona sun.


I have a personal affection for old girl cats. Recent blood & urine tests indicate her kidneys are in the early stages of renal failure, as is so common in cats. Sue came to us from her original owner who had passed away. She was under-weight at a touch under 5 lbs, but six months later I have her up to a touch over 6 lbs. Doctors orders are to feed her as much as she wants, of which she seems to have zero objections. I hope to have as much time as possible and fuss over her daily.


Sitting in the sun.


Nothing could be more accurate than the old saying “Dogs have Masters, Cats have staff”.


All of your tunas are mine.


  • Kenn Ranous

How to insulate a garage door for hot climates – DIY on da cheap!

If you live in a hot climate like Arizona, a metal garage door turns that space into a solar oven, especially if it’s facing South and/or West. There’s a number of products on the market as well as some creative DIY solutions for those on a limited budget. I did a ton of research and have done several doors so I’ll share that with you here.


1. Cardboard. It’s free, paintable and better than no insulation, but still lets some heat radiate in. Double cardboard works better, but on a double door the weight starts to add up and you might need to adjust your door springs to compensate. I tried a few panels and decided it wasn’t worth the effort to hunt down unmolested sections large enough to do the whole door. I also had some reservations about it being a fire hazard, especially as the heat dried it out and if it got hit with sparks from a metal working project. If any water got through the cracks in the door, it could get soggy and even heavier. So I went with option #2 on my most recent home.

2. Refectix radiant barrier insulation. This is two mylar reflective sheets over a bubble core. It’s a lot more durable than shipping bubble wrap, you can step on this stuff and it doesn’t pop. I did the entire double door for about $60 worth of materials, available at local hardware and home improvement stores. It’s lightweight and easy to cut with a utility knife & straight edge. Just measure the inside of each panel and trim for a snug fit. It’s pretty forgiving to work with and looks alright too. It’s April and we’ve already hit 100 in the afternoon, but standing inside the door I don’t feel like I’m facing a space heater.  It provides a minimal amount of sound deadening and if you damage a section you can fix it with aluminium foil tape or buy a small roll to repair what you need. It’s also reasonably fire resistant and unphased by water. If your goal is to mitigate heat and want to keep the costs down without looking ratty, this is a good way to go.


Finished Project


Here’s the thing about radiant barrier insulation: There must be an air gap between the insulation and the surface you’re trying to insulate against heat. I confirmed this by placing one section directly against the garage door panel and sure enough, it heated right up. See also the manufacturer’s product specification sheet. So I added a few double-thick cardboard strips behind the insulation to create a 1/2″ space and sure enough, it now keeps the heat at bay. One could also accomplish proper air gap spacing using strips double-sided tape or the insulation itself.


Air gap for radiant barrier



Spacers for air gap


If you trim your panels for a snug accurate fit, and your door is like mine, they’ll hold in place on their own on the top, bottom and right side. Along the left side, they’ll start to come out when the door is open. You can secure those with double-sided tape, foil tape or some strips of moulding cut for a snug fit. All are viable, choose what ya like! Also note that all garage door panels are not the same size even on the same door, so measure twice, buy & cut once. You can join sections of this material neatly by using foil tape.


Moulding retainers



3. Ridgid styrofoam. I’ve used this before and it does work quite well for heat and cold. It’s not too expensive when purchased in large sheets but it can be a bit messy to cut and work with and can break while bending it to fit within the panel. I wasn’t crazy about the appearance of the lettering either. They do make garage door insulation kits where one side has a thin plastic veneer and the other side has grooves to facilitate bending without breaking. This system looks very nice but will cost ~$150-200 and you can’t buy just one if a panel gets damaged. If you need to work against heat and cold and want a super clean factory look, those veneered panels are the way to go.

4. Fiberglass batting. Owens Corning makes a kit with a white plastic sheeting on one side. They come with plastic fasteners that look good in concept but in practice break easily. One could secure this in place with some wire or moulding. Cost for a double-door is almost $200, but if your goal is to stop heat and cold and need extra sound insulation in the garage, this option can’t be beat.

5. Spray in insulation. This is the one option I haven’t personally tried. Spray foam insulation is used in better modern homes and renovations. It’s well regarded for complete insulation and blocking all gaps. To the best of my knowledge it needs to be applied with proper equipment and if you don’t like it you can’t easily remove it. That’s why I haven’t tried it.

So there it is, for less than $100 you can greatly extend the hours and season you can work in your garage, plus all that extra heat isn’t radiating into your house nor degrading any items you store in the garage.

– Kenn Ranous


How to update a mainboard system BIOS in Linux in a nutshell.

This is just a quick note to help Linux users flash a BIOS upgrade to their system. It’s not a step-by-step so easy your Grandma could do it. Sorry, there’s too many variables to create that. If you’ve ever downloaded and installed Linux via a USB drive this should be just as easy.

If your mainboard BIOS has a built-in utility to upgrade it’s BIOS, use that. It’s the best most foolproof way to go. Visit the website of your MoBo manufacturer for the BIOS update and flashing instructions. Generally all that’s needed is a USB thumb drive formatted to FAT.

If your mainboard does not have a built-in BIOS update feature, check with the manufacturer for options. Unfortunately, many mobo makers assume you have Windows and provide a utility that only runs in Windows or DOS. If you’re setup to dual-boot Linux or Windows, boot into Windows and use their utility. If you’re running Linux only:

1. Download the DOS based BIOS package from your mobo maker. Extract it into a folder of your choice, but keep the name simple as we’ll be using DOS in just a moment.

2. Visit and download the USB Installer version. Extract it and write the .img file to your USB drive. (hint: use the USB Image Writer utility or Unetbootin)

3. Verify freedos is on your USB drive. You should see autoexec.bat and other DOS looking files. (You may need to reboot your Linux box after initially creating the FreeDOS.)

4. Copy the folder where you extracted the BIOS package onto the FreeDOS USB drive.

5. Reboot the computer and select boot to FreeDOS USB drive.

6. Follow the menus, but don’t choose to install FreeDOS. Instead, exit to DOS.


At the C: prompt.


7. You should now be at a good old fashioned C: prompt. Change to the folder you made in step 4. Run the executable that starts the DOS based flashing utility. Follow the manufacturer’s instructions.

8. Reboot and confirm you have the new BIOS. You can also verify BIOS version in Linux by using the hardinfo utility or in a terminal type:

sudo dmidecode -s bios-version

That’s all there is to it. Easy as making a bootable floppy but better.


FreeDOS also runs in VirtualBox.


Side note: FreeDOS also works well in VirtualBox, although I would NOT advise trying to flash your BIOS while running in a virtual environment, best to do that as described above. Good to know if you have some old DOS games you want to run.



  • Kenn Ranous