Please explain the purpose of operation: |
Propagation testing
We would like to transmit the continuous wave carrier in a small set of available TVWS channels in the Durham, New Hampshire area. Regulations of height and power limits will be followed to reduce any potential interference to other opportunistic users. Our trial of the RuralConnect Radios gives us an active antenna installed at roughly 28 meters above average ground which is below the 30 meter limit. Using the FCC HAAT calculator, it is determined that the 28 meter antenna height at this location gives a HAAT of 18 meters. The use of this antenna will allow us to test the propagation models from a real life installation setup. According to Google’s Spectrum Database, there are 14 available TVWS channels at the transmitter location. We would want to test in a range of frequencies, so choosing a low, high and some median channel has been decided. Of the available channels, we would like to test in channel 5 (center frequency of 79 MHz), 24 (center frequency of 533 MHz), and 50 (center frequency of 689 MHz). These channels each have at least one adjacent channel open for use which should help minimize potential interference. Additionally, since we are only transmitting a CW carrier, there will be no danger of side lobe energy in another channel. Since the power limitation is 4W, or 36 dBm in these channels and our antenna has a maximum gain of 10.4 dBi, we could safely transmit 24 dBm, which is the power of the active RuralConnect Radios, and stay under the limit. To further protect this limit, we will reduce our CW transmission power to 14dBm or 25mW. With antenna gains, this will effectively be an EIRP of 24.4 dBm, well below the 36dBm limit. Additionally, since this only needs to be transmitting during active measurements, the transmission will be on the order of minutes, over a couple of weeks, rather than a 24/7 transmission. This will further help prevent interference with opportunistic and licensed users alike.
Transmitting this signal will allow us to quickly and accurately measure path loss in the suburban/rural area that is the seacoast region of New Hampshire. With this information, we can make a better assessment on available propagation models to help simplify future installations of similar networks that can help achieve broadband ubiquity. |