In this section of my WEB pages I am listing various weather project related information.

The weekend of July 30th, 31st of 2011 I got distracted reading on the web, information about NOAA weather satellites. In particular, how one can easily receive the satellites data transmission of the weather data being collected and transmitted as it passes overhead. These older NOAA-xx series satellites send the data on vhf and microwave frequencies. My scanner will receive the 137.00 through 138.00 range of vhf transmissions.

You too can receive these NOAA APT satellites. Here is a good link to get you started or at least better informed.

That Saturday I went out on my observation deck with a old Uniden handheld scanner, my old tv rabbit ears and a laptop running Windows XP with the free satellite data capture application APTDecoder. Below is one of the better data capture results.
The left half is the Infrared (IR) image and the right is the visual. This image is loaded with problems of lacking signal strength and signal to noise ratio(snr) problems. Remember, I was standing on the deck with a cheap TV rabbit ears trying to keep a physical position that delivered the strongest signal.

If it is not obvious, looking at the visual image on the right half, you can see the Baja peninsula below California on its left. Across the mainland of Texas and Mexico you can see the Gulf of Mexico.

Meanwhile I have built a better antenna, a tall narrow 90 degree Quadrifilar Helix antenna (QHA) at a center frequency of 137.50mHZ using the fine article A Quadrifilar Helix Antenna for 137 MHz. By George Goodroe, KF4CPJ.
A little info on why this antenna style: The satellites use a similar style antenna to transmit the signals down to earth. The transmission is of a spiral counter clockwise rotation. This antenna matches the satellites signal phase. Another plus of the antenna is that it performs best for horizon to horizon coverage as the satellite passes.

This improved antenna along with some minor mods to my receiver, an old 1985 Uniden Bearcat BC100XL scanner have made for a modest improvement in my received images.

All I did was tap onto the audio out pin of the integrated circuit top right with a small resistor connected to the yellow wire going to the earphone jack. I simply removed the two leads for the earphone, connected them together and taped them. This was a unused pin on the IC and provides unfiltered / unmodified audio. This unfiltered audio then connects to the input of a computers audio for decoding and image processing.
APTDecoder running on an older PC with XP Pro does the image acquisition. Through my network I pull the acquired images from the capture PC to my main desktop Linux PC and further process the images using WXtoImg. This program can also acquire images but is not as full featured as APTDecoder unless one purchases the "Enhanced" version.

The Uniden scanner's shortcoming is that there are three good working satellites I use to get images. If I leave the scanner in scan mode to receive all three, weaker signals are missed or broken up. Therefore better images are gotten if the scanner is set on a single channel. My goal is to either modify the Uniden by attaching a circuit to the keypad input that can then connect to the capture computer. This will allow APTDecoder to switch channels as different satellites are in range thus getting more images and a chance for some good ones.

Another option I am working on now, late August 2011, is to modify a digital tv tuner to be a 50mHZ through 800mHZ receiver with a computer control for the satellite reception program control. This tuner will require some aditional circuitry to allow it to fine tune to these three satellite frequencies. More on this later.

A third option would be to purchase a kit designed just for receiving these satellites. But that is still between $200 and $300.

August 26th, 2011, I left the receiver and computer in the observatory running with the receiver set to the NOAA 19 satellite frequency and managed this image of hurricane Irene. The image is time stamped 110825 185556 UTC.


Another of the Hurricane Saturday Saturday Aug27, 2011. I highlighted the eye of the hurricane in red.


I'm still working on better image acquisition. This probably means better antenna and receiver.

Here are other images that turn out fair. Tropical storm Lee, Labor Day weekend 2011



The Independent Organization for Weather Satellite and Earth Observation Enthusiasts.

A Quadrifilar Helix Antenna for 137 MHz. By George Goodroe, KF4CPJ.

For more information Email Don

? , 2010, 2011

Created: Tue Aug 02 17:14:12 CDT 2011, laste edited 04/01/2018 by Don Lewis