SRM: WHEN SAFETY COUNTS SRM-3006: SELECTIVE RADIATION METER FOR ELECTROMAGNETIC FIELDS UP TO 6 GHz

2 Radio, TV, mobile phones, wireless services: Electromagnetic fields are the medium wherever such forms of communication are used. These fields affect everything around them including the people that are moving within them. Complete coverage would otherwise be impossible. National and international authorities have fixed limit values for such fields to prevent harmful effects. The field strengths allowed in the occupational environment are usually higher than those for the general public, because people who routinely work in electromagnetic fields are trained, aware of the potential dangers,...

3 Legislators have laid the responsibility for ensuring safety upon the operators of transmitting equipment and the relevant authorities. These, in turn, can take advantage of the measurement services offered by organizations and independent providers. There is really only one way to make sure everything is safe: CHECK! Photo reproduced by kind permission of ORS – Österreichische Rundfunksender GmbH & Co KG Austrian Broadcasting Services, www.ors.at DAB TETRA GSM UMTS CDMA WIMAX

4 Wideband measuring equipment gives blanket coverage of large frequency ranges, which could range from the broadcast band to the mobile phone band and beyond, for example. When fitted with special probes, such equipment can deliver results that are expressed automatically in terms of the applicable permitted limit values. These devices are usually easy to operate. Selective devices such as spectrum analyzers break the fields down into their individual frequency components, allowing detailed analysis. They are more complex to operate and some specialist knowledge is needed to evaluate results....

5 The results can be shown in physical units, e.g. electric field strength in V/m, magnetic field strength in A/m, and power density in W/cm2, or directly as a percentage of the limit values, for example those specified by ICNIRP. Important: The SRM can also subsequently convert results to percentages, physical units or logarithmic quantities. The Selective Radiation Meter and its measuring antennas are matched. Any antenna and any instrument in the range can be combined to form a handy unit. Plug and Play. V/m A/m W/cm2 %

6 Legally airtight, trustworthy results depend on many factors: The measuring equipment must be calibrated. The measurement must comply with standards, and it must be made professionally and correctly. The SRM from Narda Safety Test Solutions is calibrated – traceable to national and international standards. It fulfills all the requirements of current human safety standards. And it makes correct, professional measurements easy, such as time-averaged measurements over the standard six-minute period or spatial averaging over several measurement points. When using the isotropic measuring antennas...

7 Impossible to falsify: Screenshot of a ‘Safety Evaluation’ result. The calibration certificate records the traceability of the calibration of the instrument and antenna to recognized standards – with accreditation if requested.

8 Electromagnetic fields always consist of an electrical and a magnetic field component. Limit values are therefore specified for both the electric as well as the magnetic field strength. The electric and magnetic field strengths at a distance from the source are in a fixed relationship, so it is sufficient to measure just one of the two components. This relationship does not apply close to the source, so both components must be determined separately. The wavelength of the radiation determines the location of the near-field and the far-field. The near-field of a long wave transmitter extends...

9 Quick and reliable because they are non-directional: The isotropic antennas detect the field strengths in three mutually perpendicular directions, and the SRM automatically calculates the resulting field strength. Nevertheless, isotropic measurements are also possible using the single-axis antennas if you use a tripod and the antenna holder, which allows you to make successive measurements in three mutually perpendicular positions. The SRM supports this procedure by saving the result for each of the three positions and then calculating the resulting field strength – without a PC. All antennas...

10 Broadcasting, mobile telephony, industrial equipment: What proportion of the overall field is from which source? The answer is of interest to the relevant authorities and safety representatives as well as to the operators themselves. There is often a need to know what field strength is emanating from which equipment, which channel or which radio cell. This determines who must reduce output power in the event that the limit values are exceeded, for example. On the other hand, the overall field strength is more important when it comes to human safety and environmental protection. The Selective...

11 Which channels are occupied? The bar graph display in ‘Safety Evaluation’ mode shows maximum, average, and minimum values simultaneously, so you can clearly see what’s going on. UMTS P-CPICH Demodulation: The SRM automatically identifies every received UMTS cell by means of its scrambling code and measures the field strength or power density of the associated pilot channel (P-CPICH) at the same time. The SRM also shows the sum of all P-CPICH levels as an overall value (Total). The analog measured value for the frequency channel is also shown for comparison. You can also set a factor that the...

12 It doesn’t take long to measure the actual field exposure level. But how does the level change over a period of seconds, minutes, hours, or even days? The SRM-3006 records individual radio channels in real time with microsecond resolution in ‘Scope’ mode; this capability is needed in order to capture radar impulses. On the other hand, the instrument can also be used for long-term measurements, such as a ‘Safety Evaluation’. The flow of data doesn’t have to become a flood, though. The start and sequence of measurements can be timer controlled or triggered when a threshold is crossed. The SRM...