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Puerto Rico and the US and British Virgin Islands

Winds are beginning to ramp up on Puerto Rico and the US and British Virgin Islands. 8AM weather observations show winds 15 to 25 MPH with gusts to 30 and a few bands of showers have moved across the islands over the last few hours. Flash Flood watches are up on Puerto Rico and for USVI and a tropical storm warning is in place. Rainfall amounts of 4 to 8 inches are possible with isolated amounts of up to 10 inches in some locations and tropical storm force winds in the 30 to 40 MPH range with some higher gust are possible. 1 to 3 ft storm surge with isolated higher levels on SW Puerto Rico and St. Croix this afternoon. Isolated tornadoes and waterspouts are possible. Small craft should remain in port with rough seas of 13 to 16 ft. Power outages have already been a problem on some parts of Puerto Rico this week and Isaac looks to aggravate the situation.

Florida

Yesterday at this time we stressed the importance of Florida residents and tourists to get ready, 24 hours later the message hasn’t changed. Folks in the Florida Keys should begin to think about what they are going to do today if and when an evacuation order is issued for the Keys. Might want to beat the rush and fill up the car with gas and stock up on some staples that you might need. At this point: Winds in the Keys should slowly ramp up late Saturday into Sunday with a close approach of Issac Sunday night into Monday. Will talk more about South Florida and its impacts later but the message is clear: If your anywhere south of I-4 at this point you need to get ready. A little more real estate has been added to the 5 day cone this morning including parts of the Eastern Panhandle (Panama City, Destin, Bonifay, Marianna) and a good chunk of South Georgia (Thomasville, Moultrie and Valdosta). Now is the time to get ready folks. Florida takes center stage next week with the Republican National Convention in Tampa and with Isaac lurking in the neighborhood there will be lots to talk about in the days ahead.

I have always been fascinated with weather especially weather satellite reception.

A Little History

The first weather satellite, Vanguard 2, was launched on February 17, 1959. It was designed to measure cloud cover and resistance, but a poor axis of rotation kept it from collecting a notable amount of useful data. The first weather satellite to be considered a success was TIROS-1, launched by NASA on April 1, 1960. TIROS operated for 78 days and proved to be much more successful than Vanguard 2. TIROS paved the way for the Nimbus program, whose technology and findings are the heritage of most of the Earth-observing satellites NASA and NOAA have launched since then.

POES Satellites

Polar orbiting weather satellites circle the Earth at a typical altitude of 850 km (530 miles) in a north to south (or vice versa) path, passing over the poles in their continuous flight. Polar satellites are in sun-synchronous orbits, which means they are able to observe any place on Earth and will view every location twice each day with the same general lighting conditions due to the near-constant local solar time. Polar orbiting weather satellites offer a much better resolution than their geostationary counterparts due their closeness to the Earth.

The United States has the NOAA series of polar orbiting meteorological satellites, presently NOAA 17 and NOAA 18 as primary spacecraft, NOAA 15 and NOAA 16 as secondary spacecraft, NOAA 14 in standby, and NOAA 12. Europe has the Metop-A satellite. Russia has the Meteor and RESURS series of satellites. China has FY-1D and FY-3A. India has polar orbiting satellites as well.

POES=$$$

For the longest time, there were no cheap ways to bring in 137MHZ NOAA Satellite Reception. You could buy a $200 receiver, $300 Antenna, $300 Low noise Amplifier, $100 worth of cable and $200 software package for decoding the imagery and you spent $1100 on a system that takes pictures of your neck of the woods twice a day. If you have a degree in electronics you could build a kit or modify a police scanner and save a few dollars but for most folks (including yours truly) has been out of the reach of the general public.

Enter The Dragon ( Low Cost TV Tuner Cards from China)

An article caught my attention back in June on Ultra Cheap TV Tuner Cards from China that could be easily be modified with software to turn these gems into full featured Software Defined Radios or SDR’s. I picked up one from Hong Kong on Ebay, waited 3 weeks and it arrived by mail at home. Most of these TV Tuner cards are designed for international TV reception so a trip to the local Radio Shack for a European TV Adapter(278-261). This adapter will couples male F and PAL-type antenna jack. Price is around $7 with tax and worth every penny. From the F connector and a short piece of coax you can go to any type of antenna adapter (PL-259, BNC etc, etc etc)

The Home Built 137MHZ Antenna.
The Antenna is the most important thing you will need for reception. There are a number of ways to go but most everything I read said you cant go wrong with a Quadrifilar Helix Antenna or QHA for short. All the parts with exception of a short piece of coax I had on hand can be picked up at Lowes, Home Depot or your local hardware store. All the parts can be purchased for under $75 dollars and can be put together in a few hours. The QHA Antenna is based on the plans by George Goodroe (KF4CPJ) design.

Here is the website: http://www.qsl.net/kf4cpj/qha/

In addition to this website I found a blog posting on construction of the QHA by Gregory Strike with photos, tips and more.

The address of the article is: http://www.gregorystrike.com/2010/05/16/quadrifilar-helix-antenna-137-mhz/

With the Antenna finished and the SDR Card in hand lets talk software.

SDR#
There are a number of SDR wares on the web that work with the RTL-SDR but after trying a half dozen different pieces of software I went with SDR#. Great piece of software that is free and will give you hours of listening enjoyment. Has 8 different audio modes and is all around an easy piece of software to use once you get it going. The driver installation is a little clunky and if you have hair ( I don’t) you may be pulling some of it out. But you wont be disappointed once you get it going. SDR # is available for download at http://sdrsharp.com/

One PC or Two PC Approach.
Now In my shack I am using a 2 PC approach one PC that acts as the SDR Computer, the audio is patched into an external mixer and then fed into the decoding PC. You can do everything on one machine but you will need an extra piece of software called Virtual Audio Cable. A trial version is available at http://software.muzychenko.net/eng/vac.htm . Now I have heard through some of the Weather Satellite Boards that this will work well even with the trial version but have not verified it so Buyer Beware.

Decoding Software
Now for decoding software I am using WXtoImg. This software does one thing and does it well decodes APT and WEFAX signals from weather satellites. It has good documentation and the freeware version can do basic decoding. You can upgrade and get a full range of features for $67 for the standard version or $99 for the professional. The freeware version is still a pretty good piece of software and highly recommend it. Make sure you read the documentation as you will need to update the orbital pass information for your location. You will also need to calabrate audio, the first time you use it. You can find WXtoIMG on there website http://www.wxtoimg.com/

Tracking
This piece of software is good to have but not a necessity. I like to know where the NOAA satellites are in relationship to my home location so I use WXTrack to track the positions of all weather satellites as well as the International Space Station. Developed by David Taylor in Scotland, it is hand down the best satellite tracking programs available. A beautiful piece of software and recommend it highly. You can download at http://www.satsignal.eu/software/wxtrack.htm

SDR# Audio Settings
There was not a whole lot out there on decoding NOAA satellites except a few YouTube videos but after countless trial and error, I have found the best settings. First you will need to enter the frequencies of the passing satellites into SDR#.

The NOAA APT FREQ. ARE AS FOLLOWS=

NOAA 19- 137,100,000
NOAA 17- 137,500,000
NOAA 15- 137,620,000
NOAA 18- 137,912,500

You should set the software to decode Wide FM (WFM) and set the Filter Bandwidth to 50,000. You wont need squelch on Wide FM. As the satellite comes into range a clicking sound will begin and will get louder and louder till the satellite passes and will eventually fade away as the satellite goes over the horizon. If everything is set correctly the decoding software will decode the clicking sound and the image will build as the satellite passes. A normal satellite pass last from 9 to 11 minutes.

The first satellite pass you try may not live up to expectations but don’t give up. Once you see the clouds on your first few images you will truly be amazed by the reception of your POES Earth Station.