I’ve been playing with the Shortcuts app a lot lately, there are so many opportunities for automation!
One would think that a shorter week would entail less work than a regular week; but alas, it seems like this week has more! I’m very much looking forward to my days off.
We’re pondering the big questions this morning, i.e., “can I convince them to give me a third breakfast?”
After being stuck inside for the past week, I was finally able to get outside for a walk this morning. I’m feeling very fortunate to live in such a sylvan part of Queens.
We made freezer jam today from cherries that we wouldn’t have had time to finish. It feels good to reduce food waste and make something delicious!
I’ve managed to keep a basil plant alive for nearly a month and a half now. What a rush! 🌱
After taking a week off due to illness, I was finally able to get back outside for a run! Hopefully the air quality stays good enough that I can keep it up the whole week.
📺 Strange New Worlds may be my favorite new Star Trek. I’m a sucker for ensemble casts and episodic storytelling.
Small victory: managed to set up a GitHub Action to run the tests provided with each nand2tetris project and update a status badge in the README. Not a difficult task, especially with all the documentation available, but is it ever satisfying to see those green “passing” badges!
I’m always a little surprised by how much better I sleep in the middle of nowhere vs. the middle of Queens. Although, I suppose it’s obvious that noise and light pollution don’t foster restful sleep — even with an eye mask and earplugs.
Managed to run another half marathon and grab a new personal record of 1:38:52! Feeling very exhausted. Time to take it easy for a few days.
Finished reading: Leviathan Falls by James S. A. Corey 📚 — I actually finished this last week. What a series! It’s been a while since I’ve finished a series that wasn’t a reread.
Making progress on my build of the Hadley 3D-printed telescope.
Now I need to find recipes to use up the quart of Korean BBQ sauce I have left over…
It’s disappointing when, after spending something like six hours spread out over two days, a recipe comes out looking nothing like the ridiculously perfect staged photograph in the book. But it’s delicious all the same, so I’ll count it as a win!
Managed to kill a whole day in CAD working on the conceptual design for our future house. Still needs work, but I’m happy with the progress!
Made the trek out to Central Park for my long run this morning. I think I should make a habit of this!
Successfully rooted my robot vacuum and installed Valetudo. Goodbye sketchy cloud service, hello local control!
Finished reading: Babylon’s Ashes by James S. A. Corey 📚
I’m not saying it couldn’t be worse, but I am not looking forward to my run tomorrow morning.
Satellite Imagery with RTL-SDR and GOES 16
Receiving full disk images of the Earth from GOES 16 with an RTL-SDR and a 2.4 GHz Parabolic Grid Antenna
👋 Heads up!
This article was originally posted on my old website in April of 2019. While the general process of receiving images from GOES 16 won’t have changed, the software tools may have evolved since then. Make sure to read the documentation for
goestoolsand don’t copy and paste any terminal commands below without fully understanding what you’re asking for!
After stumbling upon the online communities around software defined radio (mainly the RTL-SDR Blog and the RTL-SDR subreddit), I discovered it was possible to receive high resolution, full disk images of the Earth from NOAA’s GOES satellites using cheap and simple (relative to most other satcom systems) hardware setup. Since I’m located in the Northeastern United States, I’ve got a pretty good view of GOES-16, so I decided to see if I could actually manage to set up a receiver.
Based on a few guides I found online (see Notes below), I determined that I needed the following hardware:
- Raspberry Pi 3B+.
- An RTL-SDR software-defined radio dongle.
- A low noise amplifier (LNA) and SAW filter designed for the frequency that the GOES satellite uses (around 1.7 GHz). I used the SAWbird+ GOES Barebones from Nooelec.
- A 2.4 GHz parabolid grid antenna modified for 1.7 GHz.
- Various RF adapters and coaxial cables needed to connect everything together (depends on the specific setup, see Notes below).
To setup the software side of things, I followed lxe’s guide, summarized below.
Prep your Raspberry Pi and install necessary drivers and software.
0. Get your Raspberry Pi ready
- Download Raspbian Lite Image and Etcher
- Use Etcher to write the image to the SD card.
- Mount the SD card as a volume on your machine.
- Follow this procedure to configure WiFi and SSH.
- Plug the card into your Raspberry Pi and turn it on.
- Find the IP address of the Raspberry Pi using your gateway/router administrative interface.
Now you can SSH into your Raspberry PI as
piwith a default password
1. Get everything up to date
From now on all commands should be run on the Raspberry Pi.
sudo apt update sudo apt dist-upgrade sudo reboot
2. Install dependencies
sudo apt install git build-essential cmake libusb-1.0 libopencv-dev libproj-dev
Grab the latest librtlsdr source, compile it, and install the shared libraries/includes.
git clone https://github.com/steve-m/librtlsdr.git cd librtlsdr mkdir build cd build cmake -DCMAKE_INSTALL_PREFIX:PATH=/usr -DINSTALL_UDEV_RULES=ON .. sudo make -j2 install sudo cp ../rtl-sdr.rules /etc/udev/rules.d/ sudo ldconfig echo 'blacklist dvb_usb_rtl28xxu' | sudo tee --append /etc/modprobe.d/blacklist-dvb_usb_rtl28xxu.conf sudo reoboot
4. Test your the RTL-SDR dongle
You should see something like this:
Found 1 device(s): 0: Realtek, RTL2838UHIDIR, SN: 00000001 ...
If it hangs, just press
crtl-cto exit. It doesn’t have to finish.
If there are errors, or if the device is not recognized:
- Reinstall the driver from Step 3
- Ensure the dongle is secured in the USB port
- Remove all USB hubs and plug in into the Pi directly
- Make sure you power your Raspberry Pi with at least a 2.5A power supply
- Check the device using
lsusbcommand. You should see
ID 0bda:2838 Realtek Semiconductor Corp. RTL2838or something of the like listed there. If not, try the previous steps.
dmesgand check for errors such as
error -71related to the USB device. This may mean that your RTL-SDR receiver might be broken. This happened to me, so I ordered another one, which ran fine.
git clone https://github.com/pietern/goestools.git cd goestools git submodule init git submodule update --recursive mkdir build cd build cmake -DCMAKE_INSTALL_PREFIX:PATH=/usr .. sudo make -j2 install
cat <<EOF > ~/goesrecv.conf [demodulator] mode = "hrit" source = "rtlsdr" [rtlsdr] frequency = 1694100000 sample_rate = 2400000 gain = 5 bias_tee = false [costas] max_deviation = 200e3 [decoder.packet_publisher] bind = "tcp://0.0.0.0:5004" send_buffer = 1048576 [monitor] statsd_address = "udp4://localhost:8125" EOF
If you’re using a NooElec SmarTee dongle with an always-on bias tee, or if you’re powering your SAWBird through the micro USB port, set
bias_tee = falseunder
If you’re using RTL-SDR.com dongle, set
bias_tee = trueto power the SAWBird board.
7. Roughly point your antenna at the satellite
Find where the GOES-16 or GOES-17 satellites are in the sky at your location using agsattrack.com.
Note the azimuth and elevation.
Use an actual real compass to point your dish at the azimuth. I’ve been using the iPhone phone compass, which has a 20-30 degree error, rendering it practically useless.
Adjust your dish angle according to the elevation.
8. Run goesrecv and perform fine antenna adjustments
goesrecv -v -i 1 -c ~/goesrecv.conf
This will show output every second that looks something like this:
... 2018-09-15T21:52:03Z [monitor] gain: 8.44, freq: -2121.4, omega: 2.589, vit(avg): 2400, rs(sum): 0, packets: 0, drops: 55
vit(avg)stat shows the average viterbi error rate over 1 second interval (if running with
If there’s no signal, the
vitvalue should be over 2000. When signal is stronger it should decrease.
This should help you point the antenna correctly. Slightly rotate the dish right or left and note whether the
viterrors are increasing or decreasing.
Once you’re at the local error minimum, perform the same process to find the minimum error rate while slightly adjusting the vertical angle.
viterrors are at their lowest, you’ve pointed the antenna. Double check the antenna position again with a compass to make sure you’re pointed at the intended satellite; GOES-17 and GOES-16 are only about 15 degrees from each other in the sky.
goesrecvand play around with the config parameters.
viterrors are under 400, and you’re observing no packet drops, you’re all set!
If the average errors are at around 1500-1800, try the following:
Terminate and restart
goesrecv. This should allow it to readjust the gain and frequency offset to get a better read on the signal.
Cool the Raspberry Pi and the RTL-SDR dongle. I’ve noticed that temperature might significantly affect reception quality.
Play around with
goesrecv.confparameters. Try adjusting the
sample_rate. For the NooElec XTR or other E4000 tuners, you might need to set your gain to
Once you decreased the error rates, but your
vitis still over 400, try making very slight adjustments to the antenna again.
10. Process packets into images
While goesrecv is running, in a separate session, run:
goesproc -c /usr/share/goestools/goesproc-goesr.conf -m packet --subscribe tcp://127.0.0.1:5004
goesprocreceives enough packets, it will start writing images and text to the locations described in
Writing: ./goes16/m2/ch13/2018-09-15/GOES16_M2_CH13_20180915T231750Z.jpg Writing: ./goes16/m2/ch13_enhanced/2018-09-15/GOES16_M2_CH13_enhanced_20180915T231750Z.jpg Writing: ./goes16/m2/ch02/2018-09-15/GOES16_M2_CH02_20180915T231750Z.jpg Writing: ./goes16/m2/fc/2018-09-15/GOES16_M2_FC_20180915T231750Z.jpg Writing: ./goes16/m1/ch07/2018-09-15/GOES16_M1_CH07_20180915T231820Z.jpg ...
Here are some of the images I was able to get off of GOES 16:
This wouldn’t have been possible without the work of a lot of others before me. Some of the most usefull resources I found about this subject are:
Here’s a closeup of the screen — I can’t wait until this is functional.
Making progress on my Gaggiuino project. Baby steps here, but it feels great to see the screen and thermocouple working!
I need more houseplants in my life.
Keycaps finally came in — now to print a case!