EMWIN Information

The Emergency Management Weather Information Network (EMWIN) is a satellite service of the National Weather Service targetted to emergency managers. The EMWIN homepage provides detailed information about the service and products. There is competition both in hardware and software, and I will shamelessly share my preferences and rationals. Ultimately, you are responsible for the decision you make and the consequences.

Links to EMWIN information

Marine Forecast Information
Yahoo EMWIN users group
Yahoo EMWIN developers group
NOAA background document on EMWIN
EMWIN search results from Yahoo!
EMWIN search results from Google

Hardware Summary

An EMWIN system consists of the following items:

Antenna: Collects and concentrates the weak EMWIN satellite and focuses it on the LNA/LNB.
Low Noise Amplifier / Block (LNA/LNB): Amplifies the collected signal to a usable level.
Down converter: Converts the satellites signal to a lower frequency for the receiver. (IF or intermediate frequency)
Receiver: Converts the radio signal into a signal that can be converted into data (Baseband)
Demodulator: Converts the baseband into data that can be delivered to the computer.
Processor: Converts the EMWIN data into a product that can be manipulated and used by people.
Application software: Actual software run by the processor to convert the EMWIN data into information that can be used by people.

My System

I'm operating an EMWIN system out of my apartment in Arlington, Virginia. I have a clear shot at the southern sky from my balcony with limited obstructions. Here is a list of my hardware:

1m prime-focus dish with patio ring mount
Wilmanco combined low noise amplifier and down converter
Wilmanco bias-T for power since I used to run WEFAX also
Tigertronics ESP-96 receiver/demodulator
Pentium 4 computer with 256MB of memory, LAN, modem, and dual video cards running XP Home
Weather Message 2.8 application software
Cable modem and IP phone for paging, email, and fax service
UPS backup on all system and network nodes


The current EMWIN signal needs a minimum of a 1m (3 foot) parabolic antenna to receive the signal in the lower-48 states (CONUS) and Hawaii. Folks in Alaska may need to go to a 2m (6 foot) dish because of the low elevation of the EMWIN satellite above the horizon.

I got my antenna at Dave's Web Shop. I went with a "prime focus" antenna since I don't have any experience working with an offset antenna. An offset antenna might be preferred if you're in a northern area and have trouble with snow in your dish. Zephyrus Electronics, Ltd. is a Pansat dealer and may be able to hook you up with a better dish than Dave's Web Shop if you ask what they can get you.

Low Noise Amplifier / Block

This is where the two design schools diverge primarily because of cost. The "expensive" equipment consolidates the low noise amplifier and down converter at the dish. They then amplify the intermediate frequency (Usually 137 MHz) down a 50 ohm transmission line to the receiver/demodulator.

The less expensive approach is to directly amplify the collected signal, buffer it to a 75 ohm transmission line, and send it to an integrated receiver/demodulator.

One of my initial requirements was to be able to half-split the system for installation and troubleshooting. Since there is no bias-T to power the less expensive approach, I could not insert a spectrum analyzer into the system. Also, line loss with 1.690 GHz is a significant issue that I did not want to face. Admitedly, the advent of consumer satellite equipment has made inline amplifiers and the like available, but that was not always the case.

Early comparisons (10+ years ago) of the two systems indicated that the more expensive systems would be more reliable in the harsh marine environment where I work. This was validated when a dish was torn from a building during a wind storm and throw a quarter of a mile into a parking lot. I replaced the dish, bolted on the Wilmanco LNB, and all was well.

Tests at the same time of the alternate system indicated in a high failure rate for antenna amplifiers, and an unacceptable amount of corrosion. I am under the impression that much of this has been resolved.

Looking ahead, folks with the integrated LNB/downconverter will probably have an easier time migrating to the new data stream expected in a few years.

There are two vendors of combined LNB/downconverter feeds:

Wilmanco WWFD1609.6-137
Quorum Communications IFD-1691.0

A bias-T for powering the LNA through the feed line is convenient for setup, test, and capturing other data from the same transponder.


If you go with either the Wilmanco or Quorum LNB/downconverter, then you want a Tigertronics ESP-96D receiver/demodulator. This is a compact receiver that I have never had any trouble with.

If you decide to go with an integrated system, then you want to visit Zephyrus Electronics, Ltd.. Their WX-12 and WX-13 systems have mad a lot of people happy.

New kid in town (12/1/2005) Avtec Systems is a new player in the EMWIN field as of October, 2005. They are marketing a turnkey system as well as a new type of receiver that looks rather interesting. The receiver needs a combined LNB/downconverter, but it can can receive a rather wide range of IF frequencies, and it supports both the current and future modulation schemes. No prices or availability were available as of 12/1/2005, but I expect that we'll be hearing more from them soon.

More players Software Systems Consulting appears to have had an EMWIN system on the market with their own LNB/downconverter/receiver technology. You can get a good look at it on page 4 in their catalog.

Our former landlord, England, has an outstanding group of folks called the Remote Imaging Group. Although the don't have an EMWIN system per se, they do have a nice collection of satellite kits. You need to join to buy, but that's not hard, and they have a great magazine. (I was a member for a few years.)

Application Software

In the beginning there was WeatherNode, and it was good. (FREE)

Then came RealEMWIN ($69.95), and Weather Message ($40).

I have legal licenses for all three packages, and I commend all three developers for breaking ground and making EMWIN friendly and available to the masses. But, like everything, there are pros and cons to each package.

WeatherNode is now free, but is so limited that I discourage people from using it for any safety-of-life operation. Your lawyers will thank me.

RealEMWIN and Weather Message much better, and suitable for a safety-of-life operation. I prefer Weather Message because of it's technical approach and documentation. I strongly recommend that you download the evaluation copy of both packages and judge for yourself which package best suites your requirements.


EMWIN is an established and robut method of pushing urgent and routine information to emergencies managers in all 50 states, the Carribean, and out into the Trust Territories. Like all technology, the technology behind EMWIN is evolving to provide greater throughput to handle future needs. I strongly recommend that ALL interested parties register under the Request For Information (RFI) that's on the street.

Please register your EMWIN installation with NOAA! NOAA does not have an accurate count of installed systems since registration is not required for operation. The National Weather Service needs to know who you are so they can make sure that senior leadership is aware of our community and how important EMWIN is to us. Please follow this link:

NOAA Satellite User Survey

I understand that NOAAPORT is a competing technology, and I hope to add content about it sometime soon.

Best regards to all! Al Yelvington

December 3, 2005