Please explain in the area below why an STA is necessary:
Abstract:
Institute of Marine and Coastal Science at Rutgers University would like to request a STA for the purchase and usage of two 5 Watts bi-directional amplifier in the 902-928 MHz band for the NSF funded LaGrangian Transport and Transformation Experiment (LaTTE) off the coast of NJ and Long Island, NY in early May 2004. During the experiment there will be two research vessels at sea and in constant communication with land stations. The two 5 Watts amplifiers will be deployed with low gain antennae (+3 dBd) on the two research vessels. The shore side radio will use a standard 1W transceivers with high gain antennae (+6 dBd). Our setup will give us a total output power of 36 dBd which is necessary for realtime data and video communication between land and sea at distance of up to 60 miles offshore.
Science Motivation:
Rutgers, The State University of New Jersey - New Brunswick Campus in collaboration with Lamont-Doherty Earth Observatory, University of Massachusetts-Boston, Florida Environmental Research Institute, California Polytechnic State University - San Luis Obispo, and the University of Florida - Gainsville are engaging in a study of the freshwater plume from the Hudson River in the Hudson River Bay area. The goal is to understand how contaminants and nutrients are transported from the Hudson River to the coastal ocean. We want to find out what physical, chemical and biological effects these contaminants and nutrients have on the marine environment near the coastal areas of New Jersey and New York City. A ten day cruise aboard R/V Cape Hatteras and R/V Connecticut has been arranged at the end of April and beginning of May, starting April 29th and ending May 12th of 2004.
An essential part of the experiment is to maintain realtime data and video communication between land and sea. Valuable data products such as sea-surface temperature from satellites, surface currents from coastal radars, and 3-D salinity fields from autonomous underwater vehicles are sent from the two ships at sea to shore laboratories. It is critical that we maintain reliable realtime data communication between ships at sea and the shore laboratories throughout the experiment. The collaborative effort between scientists at sea and the scientists on land is necessary for the success of the project.
Expected Communication Setup:
For our primary data and video transmission needs, we will use two pairs of wireless radio Ethernet bridges made by Freewave Technologies (model FGR-115RE). These are line of sight radios using the 902 - 928 MHz band. Each radio has power output of 1W or 30 dB per legal limit. The antennae to be used with Freewave radios are omni-directional antennae. The land station will use two 65 inch antennae each with a gain of 6 dBd. The two ships will each use a 12 inch antenna with a gain of 3 dBd.
We would like to use antenna with gain of 6 dBd on the ships as well but it is not possible because the typical vertical beam width of a large omni-directional antenna (greater than 30 inches in size) is only 8 degrees total. In rough sea conditions we expect the ships to have a pitch and roll angle of upto 40 degrees total. Only the large beam width of the 12 inch antenna allows us to maintain reliable data communication in rough sea condition.
Problems of the Expected Communication Setup:
As we just mentioned, the 12 inch antenna has a gain of only 3 dBd (versus 5 dBd for the 33 inch and 6 dBd for the 65 inch antennae). In a typical setup, we expect to run 75 feet of LMR 400 coaxial cable (this cable has a loss of around 3 dB) from the top of the mast on the ship to the Freewave radio in the deck. When we look at the energy balance (radio power + antenna gain - cable loss = output power), we get 30 dB + 3 dB - 3 dB = 30 dB of total output power. This is 6 dB lower than the legal limit of 36 dB for the total output power. Our typical setup represents a factor of 4 loss in power and a factor of 2 loss in communication distance when compared to the case when we can achieve 36 dB of total output power.
Preliminary tests show that the Freewave radio with 75 feet of LMR 400 cable and 12 inch (3 dBd) antenna when used on conjunction with the 65 inch antenna at the land station can give us a video transmission range of 7 nautical miles and a data transmission range of 15 nautical miles. Our research ships could be as much as 30 nautical miles offshore in this experiment, therefore we need to find ways to increase our communication range by a factor of 2. Increasing the total output power to 36 dB will allow us to do exactly that.
Solution to our Communication Problem:
The only effective solution to our problem is to use a 5W bi-directional amplifier with our radio on the ship. The bi-directional amplifier is offered by Freewave (model number AAA-5W, normally only offered to the military and the Federal government). The AAA-5W would allow us to achieve a total output power of 36 dB, making up for the low antenna gain and any cable loss. This amplifier offers a broadcast gain of +6.99 dB and a receiving gain of +14 dB (specification obtained from Freewave). When used with the Freewave FGR-115RE and 100 feet of LMR 400 cable (loss of 4 dB), we achieve a total output power of precisely 36 dB, as needed by our experiment while still under the legal limit for total output power (30 dB radio + 6.99 dB amplifier + 3 dB antenna - 4 dB cable = 35.99 dB total output power).
Summary:
We would like to request a an STA for the purchase of two Freewave AAA-5W bi-directional amplifiers (in the 902-928 MHz band) for two research vessels (R/V Hatteras and R/V Connecticut) to be used for the LaTTE science experiment during 4/29/04 - 5/12/04 off the coast of New Jersey and Long Island. The equipment will be used for line of sight data and video transmission needs of the LaTTE science experiment. Care will be taken to ensure that we minimize the interference we might have with other users of the 902-928 MHz band in the nearby area. Our calculation shows that we would be able to meet out goal and stay at or below 36 dB for the total output power even when the 5W amplifier is employed by. We do not intend to exceed 36 dB of total output power in our application of the 5W bi-directional amplifier.
References:
The LaTTE experiment: http://marine.rutgers.edu/cool/latte/
Freewave Technologies: http://www.freewave.com/
R/V Cape Hatteras: http://www.nicholas.duke.edu/marinelab/facilities/hatteras/
R/V Connecticut: http://vm.uconn.edu/~wwwmstc/rvct.html
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