Skip to main content

NOAA 19 Signal received using a RTL-SDR DVB-T usb receiver

A couple of years ago I tried to receive the NOAA 18 using a small in-door antenna and an RTL DVB-T USB receiver. The results were disappointing. However, I always had in the back of my mind that I will try again in the future with an external antenna. The era of cheap RTL-SDR hardware has come, so many people have started looking for receiving images from the weather satellites. Easy targets are the NOAA satellites that transmit weather images using Automatic Picture Transmission method (APT). These satellites provide images in different wavelengths of light.

So after following instructions from a site dedicated to the RTL-SDR receivers, I tried to receive some pictures using the simple TV antenna. However, this decision had many disadvantages, as the TV antennas are designed to receive signal on higher frequencies from NOAA satellites. Despite the poor reception and low cost (e.g.,. none, I had an old tv antenna installed, but not used) I was able to receive some pictures. I used the SDR# with the RTL-SDR plugin for receiving the signal (sound), orbitron for tracking the satellite, and WXtoImg for converting the images. Here is a screenshot of my setup:

Software setup for receiving NOAA 19. Left the SDR# tuned at 137.1 MHz using the RTL Dongle, right top the WXtoImg to decode the image, and right bottom orbitron for tracking the satellite.
Software setup for receiving NOAA 19. Left the SDR# tuned at 137.1 MHz using the RTL Dongle, right top the WXtoImg
to decode the image and right bottom orbitron for tracking the satellite.

After the first reception, the WXtoImg converts the APT signal to images. Here are two examples of the pictures received:

Raw reception 26 of May 2015 of NOAA 19. Note the big cloud approaching from the left. On the right is the infrared version of the picture.
Raw reception 26 of May 2015 of NOAA 19. Note the big cloud approaching from the left. On the right is the infrared version of the picture.

APT weather image reception from NOAA 19.
Raw reception 24 (?) of May 2015 of NOAA 19.
After the first reception, WXtoImg makes some processing on the pictures to improve the contrast. Here is the output of raw images:

Improved contrast of NOAA 19 APT image. Received using RTL dongle, SDR# and WXtoImg.
Improved contrast of NOAA 19. Received using RTL dongle, SDR# and WXtoImg.

Improved contrast APT image received from NOAA 19 using the cheap solution for Software Defined Radio (SDR)
Improved contrast of NOAA 19.
After that, WXtoImg can also create a color version of the picture:

Color view of the received APT image from the NOAA 19 using SDR# and WXtoImg.
Color view of the received image from the NOAA 19 using SDR# and WXtoImg.
Next target is to buy a proper antenna and a proper receiver, such as the  SDR play or the FUNcube Dongle plus.

Recent advancements in the RTL dongles packaging made affordable wide band receivers such as the  SDR Blog Receiver with Rtl2832u ADC Chip.
Labels:
Location: Rhodes, Greece

Popular posts from this blog

Processing Milky Way in RawTherapee

This text is an analysis of a video I did some months ago how to process photos of our Milky Way in RawTherapee. You can find the picture here . The photo was taken by wiegemalt. This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License. Editing: Step 1: Fixing lighting The first thing someone notices when opening the picture is the extreme noise due to high ISO used (1600 - check the picture on the right). The first thought is to de-noise the picture, however, if you do that you are going to loose the details of the night sky. The main reason for the high noise is the additional exposure Rawtherapee adds when the 'Auto' button is pressed. In particular, the RT adds +2.4 EV to equalize the picture. This is Wrong! What we want is to keep the noise down and at the same time bring the stars up. That's why we are going to play with the Tone Curve of the RT. To adjust the light properly we increase the cont...
Read more

RTL-SDR Blog V3 Arrived

I recently bought a new RTL dongle that supports Direct Sampling that allows frequencies less than 40Mhz. In particular, the model I ordered was the RTL-SDR BLOG V.3. DONGLE that was really cheap compared with other solution. It still can't reach the quality of the other more expensive receivers, but it still a step up. The Dongle comes with a long external antenna. The RTL dongle. So, the question now is how better is from my old SDR. I did a check with the RTL power tool to see what is the difference. My old SDR Dongle (Fitipower FC0013) has coverage from 22 to 1100 MHz. The new Dongle RTL Blog V3 a has Rafael Micro R820T has coverage from 24 - 1766 MHz, but it also contains Direct Sampling that allows for High Frequencies. A word of warning here, the reception using Direct Sampling is very bad, especially if you connect the antenna without a filter band or/and preamplifier. I did experiments using the rtl_power, and the results showed much more gain for the ne...
Read more

Auto - Vectorization with little help from GCC!

This tutorial helps the programmers to benefit the progress of the auto-vectorization algorithms that are implemented in modern compilers, such as gcc. Before you start playing with the vectorization of your code i assume that you don't have any bottleneck in you code (like dynamic memory allocation etc) in the critical path. In this tutorial we will use the gcc 4.4.1, but the same steps can be applied to newer or older versions.  First of all there are two issues with auto vectorization:  1) gcc must know the architecture (eg what SIMD instructions are available)  2) The data structures must by properly aligned in memory The first step is to find the architecture of your processor and point it to gcc using the flags -mtune=... / -march=... you specify the architecture.  For example, my laptop is core2Duo so i put -march=core2. You can find more more information  here .  The next problem we must solve is knowledge of memory alignment. ...
Read more