Environmental Radio Noise Generated by Cities and Towns

人类活动产生的无线电辐射可分为故意和非故意两种。前一类包括发射机、雷达和许多其他设备，是一系列法规的主题。许多其他设备，如数字计算机、电子开关以及无线电和电视接收器，作为其活动的副产品，会产生无线电辐射。还有其他设备，如无绳电话、车库门开启器或家庭警报系统，确实会故意排放，但估计排放水平相当低。这两类设备都只受到最低限度的监管。这种低水平的无线电辐射是射电天文学家和其他科学家在探测和研究自然无线电辐射时的主要干扰源，他们是频谱的被动使用者。无意的无线电发射器的综合影响是提高自然噪声下限水平。这种影响不仅会干扰频谱的被动用户，还会干扰其他一些利用低电平无线电信号的科学活动，如野生动物跟踪。在主要人口中心附近，噪音下限已经大幅提高，这一点具有重要意义。例如，航空公司的飞行员发现，当他们靠近主要的人口中心时，听指令变得越来越困难。由于若干原因，了解非故意辐射体造成的噪声水平很重要，例如规划干扰预防战略、预测未来趋势以及记录此类设备侵入分配给射电天文学的被动频段的情况。然而，测量很难进行，除了少数特殊群体感兴趣的频段外，几乎不存在测量。首席调查员将在大约30-3 000兆赫范围内，以分配给射电天文学的频率从飞机上获得这种测量结果。PI在1972年获得并发布了一套类似的、但不那么复杂的测量结果。没有其他测量来表明这一重要活动的时间演变。这项研究对于保护良好的科学环境是至关重要的。私募股权投资公司非常有经验，有良好的业绩记录。另外一个优点是，大部分工作将由研究生完成。很少有研究人员在这一重要领域工作，增加训练有素的人力是非常可取的。

Radio emission generated by human activity can be classified as intentional and unintentional. The former category includes transmitters, radars, and numerous other devices and is the subject of an extensive body of regulations. Many other devices, such as digital computers, electric switches, and radio and television receivers, generate radio emissions as a byproduct of their activity. Still other devices, such as cordless telephones, garage door openers, or home alarm systems, do emit intentionally but presumably at fairly low levels. Both of these categories of devices are only minimally regulated. Such low level radio emissions constitute a major source of interference for radio astronomers and other scientists, who are passive users of the spectrum, in detecting and studying natural radio emissions. The aggregate effect of unintentional radio emitters is to raise the natural noise floor level. This effect interferes not only with passive users of the spectrum but also with a number of other scientific activities which make use of low level radio signals, such as wildlife tracking. That the noise floor has already been raised considerably near major population centers has important implications. Airline pilots, for example, find it increasingly difficult to listen to instructions as they near major population centers. Knowledge of the noise level due to unintentional radiators is important for a number of reasons, such as the planning of interference prevention strategies, prediction of future trends, and documentation of the invasion of such devices into the passive bands allocated to radio astronomy. Measurements are difficult to carry out, however, and are practically nonexistent, except for a few frequency bands of interest to special groups. The Principal Investigator (PI) will obtain such measurements from aircraft, at frequencies allocated to radio astronomy, within the 30-3,000 MHz range, approximately. The PI obtained and published a similar, but less sophisticated, set of measurements in 1972. No other measurements exist to indicate the time evolution of this important activity. The research is of the kind that is fundamental to preserve a sound scientific environment. The PI is very experienced and has a proven track record. An additional strong point is that most work will be carried out by a graduate student. Few researchers are working in this important area and the addition of trained manpower is highly desirable.//