SP: Development of an Interference Temperature Monitor

智能优点：无线电频率干扰(RFI)监测是分配频段和减少用户之间有害干扰的重要工具。在过去，人为干扰的一个主要来源是汽车点火。现在，人为干扰的主要来源是电子设备、数字应答机、计算机等。移动电话和无线计算机网络等通信设备是相对较新的参与者，它们使用具有功率控制的码分多址(CDMA)来有效地利用频谱，以最小的发射机功率最大化容量。这些设备产生的扩频信号在不知道解扩信号的代码的情况下很难与高斯噪声区分开来。另一个类似噪音的信号来源来自新的数字电视发射机。为了避免有害干扰，将环境中噪声水平的升高降到最低，监测这种噪声的水平是很重要的。500 MHz~20 GHz频段的自然环境噪声主要来自地面约300K，宇宙背景约3K，大气约5~30K。在射电天文频段和其他仅接收频段中，重要的是防止噪声温度的任何增加，而测量其他频段的噪声温度可能是优化频谱有效利用所需的有用信息，包括射电天文和无线通信。麻省理工学院干草堆天文台建议开发一种监视器，在30至1500 MHz的频率范围内测量干扰水平，以提供以开尔文为单位的输出度量，并具有足够的灵敏度，能够将受保护的仅接收频段(如射电天文、遥感和深空频段)中不需要的噪声量化到几个开尔文的水平。这支持了NSF和FCC之间的联合倡议。在第一阶段，建议者计划研究接收器和校准设计，以提供所需的灵敏度和准确性，而不会出现显著的内部互调、杂散响应和杂散信号。在这一阶段，他们还将利用目前可用的设备，在马萨诸塞州韦斯特福德的麻省理工学院海斯塔克天文台根据RFI环境的初步测量制定设计规范。在第二阶段，我们建议在干草堆上制作干扰温度监测器的原型并对设计进行测试。在第三阶段，我们建议在马萨诸塞州和新罕布夏州南部地区的几个地点对该系统进行测试。未来，根据结果，这样的监测系统可以在其他地方复制，以收集数据集来描述其他地点的RFI环境。广泛影响：通过这个项目，提出者旨在提高对无线电波技术的特性及其各种应用，如射电天文学和无线通信，以及无线电频率干扰环境的认识。因此，将开发一个简单的RFI监测系统，用于大学前的教育环境，以使学生和教师了解无线电波信号的测量技术和他们所在的学校和城镇周围的环境。这些数据可以通过互联网进行相互比较，干草堆天文台将开发基于网络的教育材料，介绍无线电波的研究及其各种应用。具体而言，建议者会安排在天文台附近的地区学校安装市面上出售的简易无线电接收器和天线，让学生参与射频辐射的量度工作。作为澳大利亚SEARFE项目的一部分，将促进与澳大利亚学生和教师的合作，以加强在这一主题上的国际联系。作为国家科学基金会在干草堆天文台的“教师研究经验(RET)”项目的一部分，一个与当地教师一起的项目将于2003年夏天开始，以启动这项活动。

Intellectual Merit: Radio Frequency Interference (RFI) monitoring is an important tool in theassignment of frequency bands and in the reduction of harmful interference between users. In thepast, a major source of man-made interference was from automobile ignition. Now a majorsource of man-made interference is from electronic devices, digital answering machines,computers etc. Communication devices like cellular phones, and wireless computer networks arerelative new comers and are making efficient use of the spectrum using Code Division MultipleAccess (CDMA) with power control to maximize capacity with the minimum transmitter power.These devices generate a spread spectrum which cannot be easily distinguished from Gaussiannoise without knowledge of the code to de-spread the signal. Another source of noise-like signalscomes from the new digital television transmitters. In order to avoid harmful interference andminimize the elevation of the noise level in the environment, it is important to monitor the levelof this noise. The natural environmental noise for frequencies between 500 MHz and 20 GHzconsists mainly of about 300 K from the ground, 3K from the cosmic background, and about 5 to30 K from the atmosphere. In the radio astronomy bands and other itreceive onlyle bands, it isimportant to prevent any increase in the noise temperature while measurement of the noisetemperature in other bands can be useful information needed to optimize the efficient use of thespectrum for various applications including radio astronomy and wireless communications.MIT Haystack Observatory proposes to develop a monitor to measure the interference levels inthe frequency range 30 to 1500 MHz, calibrated to provide the output metric in units of degreesKelvin, and with sufficient sensitivity to be able to quantify, to a level of a few degrees Kelvin,the unwanted noise in the protected receive-only bands like those for radio astronomy, remotesensing, and deep space bands. This supports the joint initiative between the NSF and the FCC.In phase 1, the proposers plan to study receiver and calibration designs needed to provide the sensitivityand accuracy without significant internal inter-modulation, spurious responses and spurioussignals. In this phase they will also set specifications for the design based upon preliminarymeasurements, using currently available equipment, of the RFI environment at the MIT HaystackObservatory, in Westford, MA. In phase 2 we propose to prototype the interference temperaturemonitor and test the design at Haystack. In phase 3 we propose to conduct tests of the system at afew locations in the Massachusetts and Southern New Hampshire area. In the future, dependingon the results, such a monitoring system could be replicated elsewhere to gather a data set tocharacterize the RFI environment at other locations.Broader Impact: Through this project, the proposers aim to enhance the awareness of the properties ofradio wave technology and its various applications such as radio astronomy and wirelesscommunications, as well as the radio frequency interference environment. Thus, a simple RFImonitoring system will be developed for use in pre-college educational settings to acquaintstudents and teachers with the measurement techniques of radio wave signals and theenvironment around their schools and towns. Such data could be inter-compared using theInternet, and Haystack Observatory will develop web-based educational materials to introduce thestudy of radio waves and their various applications. In particular, the proposers will arrange for thedeployment of simple radio receivers and antennas, available commercially, to local area schoolsaround the Observatory to engage students in RFI measurements. A collaboration with studentsand teachers in Australia, as part of the Australian SEARFE project will be promoted to enhanceinternational networking on this topic. A project with local area teachers as part of NSF'sprogram 'Research Experiences for Teachers (RET)' at Haystack Observatory is starting insummer 2003 to initiate this activity.