Broadcast Microwave Services, Inc.12367 Crosthwaite Circle - Poway, California 92064 - U.S.A.

Tel: +1-858-391-3050, Toll Free (U.S.): 800-669-9667Fax: +1-858-391-3049, Website: www.bms-inc.com

E-mail: sales@bms-inc.com

Page 1 Microwave DownlinksShort, Medium, and Long Range

Microwave Downlinks Systems in the simplest term, sends real-time video from an aircraft and to the ground so the people on the ground can see what the tactical flight officer sees. Microwave Downlinks put those on the ground in the cockpit.

The aircraft carries the transmssion equipment, which transmits the video using microwave frequencies to the people on the ground who have the receive equipment. This complete system is called a Microwave Downlink System.

The old adage, a picture is worth a thousand words, really applies here when individuals on the ground are able to view real-time video. When your aircraft is used as an aerial observation platform, the use of live video on the ground is the best way to describe what you see, to those on the ground. Video is a universal language that transcends language barriers. It allows the viewer of real-time video the ability to see what you see, regardless of their language or training.

Police can send information about a fire to Firemen, without loss of detail, and to tactical units (SWAT) who can view critical situations from the air. With additional equipment an aerial view of an incident can be printout out and handed out to each officer providing them with up-to-date information of the area surrounding an incident. Real-time video contains valuable information that is often left out of verbal descriptions; there is no better way of describing what you see than to show it to someone.

Considerations:• Line of Sight Coverage - Are there obstacles that would interfere with direct line of sight?• Know your budget• Frequency Coordination - The government has set aside certain frequencies for various groups. Frequency Bands available for Law Enforcement as listed in the FCC Rules and Regulations Parts 90 and 101. • 2,450 - 2,483.5 MHz* • 4,940 - 4,990 MHz (Excludes aviation. FCC has waiver process for aviation use). • 6,425 - 6,525 MHz*

*These bands are shared with television broadcasters and requires coordination to use these frequency bands. Since these are shared bands the FCC does not grant a license for exclusive channel use. You Must Obtain a License from the FCC to downlink from an aircraft to the ground. See www.fcc.com for more information on how to obtain a license.

What are Microwave Downlinks?

How Can Microwave Downlinks Help Me?

Where Can Microwave Downlinks Be Used?• Surveillance (Border Patrol and Security)• Natural Disaster (Floods – Fires - Earthquakes)• Pursuit Management• Planned Events (Security)• Tactical Ops

Page 2

Microwave Downlinks are systems comprised of both the airborne transmit equipment and the ground based receive equipment. There are three range categories of Microwave Downlinks: Short, Medium and Long Range. The only difference between each category is the antenna used with the transmitter and receiver.

Understanding the Antenna TradeoffsTwo types of antennas used for Microwave Downlink Systems are Omnidirectional and Directional.

•Omnidirectional (Omni) antennas have a 360° pattern similar to two way radios. They do not require pointing, are easy to set up, and are the simplest antenna to use for a Microwave System. Omni antennas are low gain, and therefore are not good for long range transmissions. When Omni antennas are used with receivers the receiver is susceptible to multipath interference; this is because of their 360° pattern. When Omni directional antennas are used for transmitting from an aircraft, multiple receivers can receive the transmitted video signal simultaneously.

•Directional antennas are configured in many styles which results in various beamwidths and gains. The beamwidth and gain of a directional antenna are directly related. The wider the beamwidth the lower the gain, conversely, the narrower the beamwidth the higher the gain. An analogy can be made between the extremes of directional antennas such as a flood light would represents a low gain wide beamwidth and a spot light would represent a high gain narrow beamwidth. A low gain wide beamwidth antenna is useful for short range applications where the aircraft is operating within the beamwidth of the antenna which doesn’t require continuous manual realignment of the antenna. A high gain narrow beamwidth directional antenna would require continuous manual adjustment to maintain a ground receive signal. This is where automatic tracking “electronic” receive antenna systems are used to track the aircraft. Automatic steering directional antennas are used as an aircraft transmitting antenna. These antennas are used for long range applications along with automatic tracking “electronic” receive antenna systems. Aircraft automatic steering antennas can only transmit to one receiver location.

Microwave DownlinksShort, Medium, and Long Range

Short, Medium, Long Range Systems. What Does This Mean?

A short range system has an Omni antenna on the aircraft and an Omni antenna on the receiver and covers 1 to 5 miles depending on frequency.

A medium Range system has an Omni on the aircraft and a High Gain antenna on the receiver and covers up to 50 miles depending on frequency.

A long range system has a High Gain on the aircraft and a High Gain antenna on the receive site and covers up to 100 miles depending on frequency.

Note: Ranges are relative and depend on numerous factors such as atmospheric conditions and line of sight, fre-quency, and gain of the antennas.

Page 3 Microwave DownlinksShort, Medium, and Long Range

There are two questions you have to ask yourself when considering a Microwave Downlink System. 1. Who on the ground needs to see the video?2. Where are they located?

Typical answers to these questions are listed below. Answer: On the ground at the scene; Chasing the suspect across a field.System: Short Range - Helicopter Omni Transmit System, Hand Held ReceiverAnswer: On the ground at the scene; In a squad car at the incident. System: Short Range - Helicopter Omni Transmit System, Suitcase ReceiverAnswer: On the ground at the scene; In a Mobile Command Center.System: Short/Medium Range - Helicopter Omni Transmit System, GTA24 Mobile Tracking ReceiverAnswer: In a Headquarters Building; Located up to 50 Miles away.System: Medium Range - Helicopter Omni Transmit System, Central Receive Tracking SystemAnswer: In a Headquarters Building; Located up to 100 Miles away.System: Long Range - High Gain Tracker on Aircraft, and at Receive SiteAnswer: At the Scene, on foot AND at a squad car, AND, in a Mobile Command Center, AND, At the Headquarters building. System: Omni Actuator System on the Aircraft, and as many Hand Held, Suitcase Receivers, GTA24 Mobile Command Centers, AND a Central Receive Tracking Receive site located within 50 Miles.

There are two types of techniques used for the transmission of video signals:

•Analog -Analog has been the standard for many years and is still used today. It is the less expensive of the two types, requires line of sight and suffers from the phenomenon of multipath especially in downlink applications or moving vehicles. The major concern of using an Analog system is multipath, as described below.

•Digital - Digital COFDM is the latest technology used for the transmission of a video signal. In most applications it does not require line of sight and does not suffer from multipath as an analog system does. These benefits come with a price namely the cost of the equipment which can be up to twice that as an analog system. The superiority of a digital COFDM does outweigh the increased cost. The 4.9 GHz frequency band is restricted to the use of Digital COFDM equipment.

What System is Best for Me?

Analog vs. Digital

What is Multipath?Multipath is the phenomenon where the direct line of sight signal is received by a receiver along with multiple signals. These multiple signals are formed when the original signal is reflected off of structures (buildings, towers, etc.), bodies of water, and other large objects. When these multipath signals are received by the receiver the resultant video signal is distorted and not viewable. This can last from a few to many seconds depending on the number and strength of the multipath signals.

GTA-24 Ground Tracking Antenna

SKYLink Analog Hand Held Receiver

Carry-Viewer II Digital COFDM Hand Held Receiver

Broadcast Microwave Services, Inc.12367 Crosthwaite Circle - Poway, California 92064 - U.S.A.

Tel: +1-858-391-3050, Toll Free (U.S.): 800-669-9667Fax: +1-858-391-3049, Website: www.bms-inc.com

E-mail: sales@bms-inc.com

All Data Subject to Change Without Notice7/14/2004

Page 4 Microwave DownlinksShort, Medium, and Long Range

TAA-101 Actuator System [Omni System]

•Low Cost•Light Weight•Skid or Cross Tube Mounted•360° Azimuth Coverage•FAA Approved•Quick Installation

Transmit Systems Antenna Options

Receive Systems OptionsPortable Systems

[Omni System For Short Range Applications]

•PBR24 - Portable briefcase receiver and monitor fixed within a briefcase for rugged on the move applications.

•SKYLink - Hand Held receiver and monitor that allows a user to hold the video in the palm of their hands and weighs between 5 and 8 lbs.

Mobile-Fixed [High Gain System For Short & Medium Range Applications]

•GTA-24 - Ground Tracking Antenna that can be fixed on a tripod or on a mobile command center.

Fixed [High Gain Systems For Short,

Medium, & Long Range Applications]•Central Receive Antennas - Fixed on the top of a building or tower. These directional antennas are continuously steerable from the ground and can be controlled remotely via a telephone line, fiber, or microwave.

GCA-4 GPS Steerable[High Gain]

•For Point to Point Microwave Communications•Operates independent of aircraft instrumentation•Continuously rotates 360°

GCA-11 GPS Airborne Directional[High Gain]

•No Moving Parts•Small Size, Light Weight•Low Maintenance Costs•Electronic High Speed Directional Tracking•Ground Data Output for Receive Tracking•Directional, Manual, and Omni Operation•Driven by up to 12W Power Amplifier