Avionics: Avidyne Datalink: Flood of Information

Avidyne takes datalink weather to the next level

June 1, 2008

As Avidyne was one of the first avionics suppliers to bring datalink weather information to general aviation cockpits, it seems fitting that the Lincoln, Massachusetts-based company is among the first to develop what can be considered the second generation of datalink hardware and related products.

At the top of Avidyne’s list is the MLB700 Broadcast Datalink Receiver, which, with WSI InFlight weather service and optional Sirius satellite radio programming, expands the range of weather and digital audio options available to users of the company’s EX500 and EX5000 multifunction displays.

This edition of the WSI InFlight weather service comes with the NOWrad radar mosaic of the U.S. Doppler Weather Radar network, a set of computer algorithms and up-to-the-minute surface observations that together assess the nature of precipitation—rain, mixed, or solid. Subscribers to the Avidyne Essentials weather data subscription service ($29.99 per month) receive this NOWrad data, along with graphical and textual metars, TAFs, TFRs, and lightning data.

Lightning information available on the MLB700 is derived from the United States National Lightning Detection Network, which consists of more than 100 remote ground-sensing stations located throughout the country. These remote sensors are able to detect the electromagnetic signals emitted by lightning strikes; their raw data is then broadcast to a control center in Tucson, Arizona; analyzed; and communicated to a wide range of interested parties.

Using the MLB700, lightning strikes up to five minutes old are depicted in yellow, while strikes 10 to 15 minutes old are shown in brown. Shading is used to indicate the relative age of the sensor sweep.

Pilots that opt for the Avidyne Performance subscription ($39.99 per month) receive all the features in the Essentials package, plus access to Storm Track Vectors. These indicate the height (echo tops) and movement of thunderstorm cells, including speed and forecasted direction.

When using this feature, pilots will see that an underlined number on the display shows the storm height in hundreds of feet; cell indicators are black for rain or snow, and white to show hail. Users also have access to winds and temperatures aloft, along with graphical airmets and sigmets.

Getting Sirius

The Sirius satellite radio option is less about situational awareness than pilot and passenger comfort and entertainment. It offers 130 channels of sports, news, talk, and commercial-free music programming—all accessible through aircraft audio systems.

Using Avidyne’s new RC70 remote control, users can browse and select the various audio channels from any seat in the aircraft. The RC70 has a built-in display for channel information, and the larger system can support multiple remote devices.

The service taps into data streaming from the Sirius satellite constellation, which employs three vehicles in geosynchronous orbit—Radiosats 1, 2, and 3—with a primary uplink located in Vernon, New Jersey. The name Radiosat is used, since there is already a fleet of telecommunications satellites named Sirius—launched by Sweden’s Nordic Satellite AB.

Two of the Radiosats are over U.S. airspace at any particular moment, with one satellite maintaining an elevation of 60 degrees or greater at all times to ensure a strong, reliable signal. These satellites fly in a highly elliptical orbit with a 24-hour orbital period. The Sirius signal broadcasts using 12.5 MHz of the S-Band, and is separated into three carriers. Each of the primary satellites has its own carrier, while the third carrier is used for a terrestrial repeater network where available.

According to Avidyne, the MLB700/Sirius application eliminates a problem common to earlier satellite communications products—signal loss because of interference with ground-based repeaters. This problem is typically at its worst when flying over large cities and other densely populated areas.

The new system uses a GEN3 chipset, Avidyne says, offering improved signal reception and better immunity to Doppler effects. A teardrop-pattern antenna is built to reject ground-based signals, even at low altitudes and bank angles of up to 30 degrees.

The MLB700 is available now—Avidyne is offering the data and audio version for $5,495. The data-only version costs $4,745.

Lightning—in color

Avidyne also recently debuted its new TWX670 Tactical Weather Detection system, which is designed to provide an instantaneous, or “tactical,” picture of surrounding weather. Like the MLB700, the TWX670 is a product of Avidyne’s Safety Systems Group in Columbus, Ohio—the former Ryan International, a company best known as the maker of the original Stormscope lightning detector.

The TWX670 operates the same basic way as the Stormscope, and under the assumption that lightning is the best determinant of dangerous thunderstorm activity. There are certain key differences, however. The TWX-670 is considerably more accurate than the earlier hardware, and it works in the critical zero-to-25 nm range—an area “blanked out” in most lightning detectors, and in datalink radar displays of the other prime indicator of thunderstorm activity, precipitation.

And, while lightning detectors typically show storm activity as a concentration of small, monochromatic symbols, the TWX670 converts its detection data into a colored contour map of a thunderstorm’s electrical activity over time.

In this “TWxCell” mode, color-filled hexagons highlight lightning strikes, allowing the user to spot the areas of greatest thunderstorm intensity, and thus bypass areas of convective wind shear, turbulence, microbursts, heavy rain, hail, and icing.

Regardless of the number of strikes, the TWX670 combines the data of all lightning strike activity over the preceding three minutes. This is designed to provide a meaningful dynamic map of the lightning strike rate and density without requiring the pilot to focus his or her attention exclusively on watching for individual strikes as they occur.

In “Cell” mode, the TWX670 displays up to 1,024 strikes for up to three minutes. Range, bearing, and weight (color) are shown for each transmitted strike. Activity, not age, determines the color of strike depiction, so newer, more distant strikes are not able to drown out closer, older strikes.

TWX670 data can be displayed on a variety of MFDs, and interfaces with the EX5000 MFD when equipped with Release 7 software. The product may also be used with a standalone avionics device, the Avidyne MHD300 Multi-Hazard Display. The MHD300 supports various traffic advisory systems—such as the Avidyne TAS600 series—or Honeywell’s enhanced ground proximity warning system.

Now an option on the Piper PA-46 Matrix, the TWX670 is available for retrofit in a wide range of fixed- and rotary-wing aircraft. The price is $7,995.

E-mail the author at paul.richfield@aopa.org.