Selective Radiation Meter

Transcription

1 Selective Radiation Meter Make selective, non-directional measurements of RF & microwave fields by hand, and evaluate and document the results from anywhere. Precision test equipment for safety in electromagnetic fields.

2 There s telecommunications all around. Selective measurements help to cut through the waves. You can go pretty much anywhere these days and still have radio, TV and cell phone service. That also means it s basically impossible to avoid exposure to electromagnetic radiation. To avoid detrimental influences on people and the environment, industrial nations have adopted limits for electro- magnetic radiation. These limits are mostly based on the recommendations of the International Commission on Non-Ionizing Radiation Protection (ICNIRP). ICNIRP is the formally recognized non-governmental organization in non-ionizing radiation protection for the World Health Organization (WHO). The Institute of Electrical and Electronic Engineering (IEEE) and the European Committee on Electrotechnical Standardisation (CENELEC) have also adopted their own limits in some cases. The trouble is that limits are useful only if they are upheld. Public authorities are required to check for compliance. They frequently subcontract this work to a testing service. Nowadays, it is also common for local communities, environmental groups, company boards or even private parties to hire a testing service or a specially trained inspector to investigate the electromagnetic radiation at a given site. The results can be confusing, however, due to the many different services using the radio waves. They include broadcast radio, TV, pagers, police & fire departments, public transport companies, cellular radio systems and the new 3rd generation highcapacity mobile data transmission systems. A broad measurement can give you a picture of the overall radiation level, but it cannot single out the component produced by an individual service, e.g. GSM-900 or GSM In addition, most broad test sets are not sensitive enough to measure the individual components, which can be fairly low in magnitude. An unknown radiation source, such as a hidden video camera, would go undetected. Real-world investigations require a highly sensitive selective measuring device. In the past, there were only two choices for measurement and evaluation: Fast and broad, or slow and selective. But Narda has now developed a solution that delivers fast selective measurements. Selective You can t hear electromagnetic radiation. If you could, there would be music wherever you went. But if you take the time to look, you will see huge orchestras and choirs of antennas on roofs everywhere. Since they are inaudible, you have to wonder how loud they are. Or how loud the individual soloists are. Some test sets record the whole frequency spectrum and show the sum total of the radiation. That s good enough as long as the permissible limits are met. But what if they are not? Then you have to attack the source. This requires a selective measuring device.you can then separate the GSM choir from the FM orchestra and determine their field strengths. You can recognize individual players, and if the measuring device provides sufficient sensitivity, you can even tell who s humming in the background. Narda s SRM delivers selective measurements with great sensitivity. A typical field strength situation in an urban environment Radio Television Private mobile services 800/900 MHz 1800/1900 MHz 3rd generation of mobile radio systems 2 Frequency 3

3 On a roof filled with antennas, non-directional measurements give you the big picture. If you visit your local rooftop, you might find a No Vacancy sign these days. This is true of the room for antennas and also the tolerance for more electromagnetic radiation. Even if just a single building employee has the key to the roof, the limits applicable for the general public must be upheld. If these limits are exceeded, the unpopular question is: Who has to reduce transmitting power? And by how much? Operators and public authorities all need to know who is generating the different components of the electromagnetic radiation. Unfortunately, sometimes you can t see the forest for the trees. Why? There can be more parties involved than just the known antenna users. Distant broadcast antennas and/or local (but hidden) sources can all contribute to the local electromagnetic picture. A broad orientation measurement allows the testing service to locate the hot spots with the highest field strengths. It helps if the measurement probe is isotropic (equally sensitive to radiation emanating from any direction). Shaped probes automatically evaluate the radiation by frequency so that the results reflect the totality of the radiation weighted according to the applicable regulations. If the imissions limits are violated, then the testing service needs to individually analyze the known sources at the hot spots, e.g. FM radio and certain mobile radio services. The only way to do this is through selective measurements in the appropriate frequency s. Selective measurements in other frequency s can shed light on unknown field sources. It is highly beneficial if the selective measurements can be performed using an isotropic antenna. Costly specialized scanning techniques are eliminated, and the user can just read off the relevant results. Based on selective measurements, a list of the individual sources can be compiled by frequency or field strength. This is just a starting point, however. What really matters is not the field strength for a channel in use, but the overall field strength produced by its service, rated according to the relevant legal regulations and given as a percentage of the total exposure. For instance, you might like to display the field strength for each of the services contributing more than 5% of the total radiation. Narda technology allows you to do this. Isotropic [V/m] ,1 occupational general public 100k 1M 10M 100M 1G 10G 100G [Hz] Electric field strength limits for areas accessible to the general public and for (higher) occupational exposure as stipulated by the ICNIRP, 1998 You can t see electromagnetic radiation, even though it does behave to some extent like visible light. Vertical antennas radiate in a circular pattern, sectored antennas transmit across a certain angular range, and dish antennas send a concentrated beam. Measurement probes are similar. A uniaxial probe has just two eyes (one on each side). But what happens if the transmitting antenna is in your blind spot? You need an isotropic (non-directional) probe to sense things all around. Just don t let anybody stand in your light! Narda s SRM allows non-directional measurements by hand. 4 5

4 Selective measurements let you get down to business with services & channels, right onsite. You re not alone in your exposure. Operators tend to share common systems, or at least they share common sites for supplying their customers. When a conflict occurs, everybody wants to verify their share of the total field exposure. But you need more than just a simple broad measurement to do this. Broad techniques work if there s no one else on the site or if all the other services are negligible. You also need to operate your system with all channels at full power to determine the maximum possible electromagnetic radiation. What is very useful here is a selective measurement to individually check each frequency and channel in use and display the field strength. Intelligent devices offer another capability: Integration over the service s frequency with display of the result as an absolute value or referred to the respective limit. In radio systems such as GSM which have fixed control channels that continuously transmit at full power, the testing service has another very elegant option: It can make a selective measurement on the control channel(s) and compute the field strength which would arise if all of the voice channels were at full power. This technique is also useful in radio systems using WCDMA modulation (wide code division multiple access): A selective measurement is made in a given frequency block during a low traffic period and the total exposure is then computed as if only the pilot channel was in operation. To do this, the measuring device needs to have the right widths, adjustable to the individual transmit frequencies, channel spacings or entire frequency blocks. Narda technology allows you to do this. Long-term monitoring What if you need to know how the field strength of your service (or the spurious radiation from a nearby mediumwave transmitter) varies over the course of the day? You can carry out long-term measurements by recording all measured values (or all values above a given threshold) with a timestamp. Immune to spurious radiation You can t feel electromagnetic radiation. You can tell how tough a device is in mechanical terms by just picking it up. But the only way to verify electromagnetic ruggedness is through measurements. The field strength produced by a broadcast antenna can be 10,000X greater than that of a mobile radio channel. This represents a tremendous challenge for a measuring device. Naturally, it has to be very sensitive. But, it cannot allow high power levels at the probe to reach the electronic circuitry and falsify the result (or destroy the circuitry). Narda s SRM measures wherever you go, providing superior interference immunity BCCH Even when surrounded by a multitude of transmitters, a selective measuring device can analyze individual mobile radio channels. Here is a typical GSM scenario with a 200 khz channel spacing. BCCH is the control channel, and TCH are the voice channels for up to eight conversations. TCH TCH TCH Channel 6 7

5 SRM Selective Radiation Meter. Get a grip on radiation. Slow and selective or fast and broad? You no longer have to make this choice. The SRM makes selective measurements and immediately produces reliable results, without additional cables and without an external PC. The folks at Narda designed the SRM to meet your needs when it comes to safety in electromagnetic fields. In other words, we ve built a device which is handy, batterypowered and immune to interference so you can carry it into any environment. It has an isotropic probe so you no longer need to worry about the direction of the radiation. It covers the frequency range of main interest from FM radio to UMTS. The most common measurements in the GSM range are particularly easy. It evaluates the field strengths it measures in accordance with the applicable regulations and immediately presents the results in a format which telecom and mobile radio operators, testing services and public authorities will all appreciate: level or percentage of permissible limit Single source or single channel List of sources or channels Contribution by a given telecom service Contribution by all services and their percentage of the total exposure The SRM is your basis for comprehensive safety analysis of electromagnetic fields. As a sophisticated spectrum analyzer, you can also use the device for field strength measurements unrelated to personal safety applications. The SRM s isotropic probe simultaneously measures the electric field strength in all directions. As an alternative, you can use the uniaxial probe from Narda or your own measurement antenna. Revolution The SRM is the world s first selective measuring device designed especially for safety in electromagnetic fields. The SRM handles evaluation of results immediately, wherever you are, and without a computer or any special cables. Of course, you can transfer the results to your PC via an RS-232 interface (electrical or optical). Narda s SRM performs selective, non-directional measurements by hand wherever you go. 8 9

6 SRM Selective Radiation Meter Get your work done onsite. Narda s SRM represents significant innovation by our developers in creating a selective precision measuring device that can be operated like a conventional broad handheld meter. The result will save you time and money. The SRM is designed for applications involving safety in electromagnetic fields. In other words, you can take the device into any environment without additional cables, power supplies or PCs and without worrying about radiation overloading the device. Since it is designed for safety in electromagnetic fields, no specialized training is required to operate the device. If you want to guarantee safety in electromagnetic fields, you need reliable measurement results. As a precision measuring device, the SRM will normally deliver results you can count on. As a specialized device for safety measurements, the SRM takes care of two frequently underestimated problems: Improper operation and faulty evaluation. Safety in electromagnetic fields: The SRM will immediately display your results, right where you are. Now you don t have to return to the office to evaluate your work. These same benefits will come in handy even if you use the device just as a spectrum analyzer for field strength measurements. Application: Analysis from FM radio to UMTS With its isotropic probe, the SRM works in the frequency range from 80 MHz to 3 GHz, so it covers all services from FM radio to UMTS. When fitted with other probes, it can measure down to 100 khz to include the entire radio down to longwave. The resolution width (RBW) can be set depending on the service, e.g. 1 khz for longwave, 200 khz for the GSM channel spacing or 5 MHz for an entire UMTS frequency block. Technology: Extremely sensitive, but immune to interference The SRM has enough sensitivity to measure individual GSM channels inside of buildings and reliably verify limits as low as a few volts per meter in sensitive areas. On the other hand, if you need to measure field strengths of services in the immediate vicinity of a powerful mediumwave transmitter or an FM radio repeater, the SRM provides immunity up to 500 V/m. Operation: Simple and consistently reliable SRM is easy to get along with. Take it with you in heat (up to 50 C), cold (down to -10 C) or humid climes (up to 95% humidity). The device is splashproof and will briefly tolerate condensation. The carrying strap makes it easy to operate with a single hand, and you can call up test setups with a single keypress. When you re high up on an antenna tower, you don t want to struggle to make complicated settings! This is critical when you need reliable results. Future-oriented design: Ready for new applications The SRM has an open design concept that allows you to load new standards and tolerance curves for safety measurements. You will also find that the advanced spectrum analysis features come in handy for future applications. Reinvent the wheel? Never. Exploit it to the max? Naturally. The rotary switch lets you easily select different resolutions and frequencies, instead of typing them in. Scroll your way through result lists instead of positioning the cursor. You ll get things done fast. SRM Summary of technical specifications for the device. For probes, see page 14. Frequency range Resolution widths (RBW) Intrinsic noise Sweep time Memory capacity Battery life Weight 100 khz to 3 GHz 1 khz to 5 MHz, depending on the selected span, spectrum analysis mode -125 dbm for 1 khz resolution width (RBW) < 500 ms for a span of 100 khz to 3 GHz and 5 MHz resolution width (RBW) More than 500 spectra 3 to 4 hours on one charge Approx. 1.9 kg including rechargeable cells Evolution There s no denying the origin of the Narda family of testers. The SRM represents precision measurement technology, packaged for everyday use: High-tech on the inside, and simple and rugged on the outside. Just power up and measure You can count on the results. Narda s SRM performs selective, non-directional measurements by hand wherever you go

7 Test modes designed for everyday use Since safety in electromagnetic fields is the primary objective, the first mode is called: Safety Evaluation Here, you have everything you need to make measurements and evaluate the results. Just select the service(s) to be tested and the regulations they should comply with. As an alternative, you can start with a scan of the entire frequency range. The SRM will handle the rest automatically. If you re not an expert in electromagnetic fields (and maybe you spend part of your time making gas and noise measurements), you probably don t want to worry about complex issues like the frequency span, RBW and sweep time. If you are an expert, however, you ll be interested in this mode: Spectrum Analysis Here, the SRM works like a full featured spectrum analyzer. If, however, you need to know how the field strength varies over a longer time interval, you can choose the following mode: Time Analysis Here, the SRM gathers and stores data without an operator present. The time interval can range from a few minutes to many hours. Evaluation in accordance with applicable regulations All of the common limit curves are stored in the SRM, including ICNIRP (International Commission on Non-Ionizing Radiation Protection), IEEE (Institute of Electrical and Electronic Engineering), FCC (Federal Communications Commission), the German BGV B11 (Occupational safety guideline of the employers' liability insurance association) and Federal German Pollution Control Act (26 th Implementing Ordinance). Additional limit curves are under development. Unknown (or unclear) field environment? In Safety Evaluation mode, the SRM automatically displays the total field exposure along with the contribution of the individual services. Evaluation according to applicable regulations Measured field strengths are a physical result and thus neutral. The resultant radiation exposure is obtained by referring measured field strengths to frequency-based limits, producing a weighted result. Different organizations have set different limits in some cases, including the ICNIRP (International Commission on Non-Ionizing Radiation Protection), IEEE (Institute of Electrical and Electronic Engineering) and other national organizations, most of whom base their standards on the ICNIRP. In the United States, the FCC (Federal Communications Commission) has published bulletins for the determination of the compliance of transmitting facilities with limits for human exposure to radiofrequency fields. With the SRM, just select the desired weighting in the configuration menu. Narda s SRM measures in accordance with applicable regulations, by hand wherever you go. PC-based software allows easy upgrades and customer-specific downloads. When you need to import settings or export results, you ll have no trouble doing it via the RS-232 interface (electrical or optical). The PC-based software lets you create or edit tables of services and frequencies, input data for customer-specific probes and cables, get new limit curves or software upgrades, and transfer it all to the SRM. On the other hand, you can export results from the SRM for processing with your favorite software to create customerspecific documentation. Just spectrum analysis? No problem with the SRM in Spectrum Analysis mode. Use the marker to read off all of the values. Which field sources contribute the bulk of the field exposure? In Spectrum Analysis mode, the SRM provides a tabular summary of the 20 largest field strength levels, automatically arranged by service. Need to measure a single channel? What about field strength fluctuations in a certain frequency block? In Time Analysis mode, the SRM shows the current field strength at the selected frequency or the field strength variation over a selected time interval

8 Three axes or one? We ve got the right probe for every job. The SRM s isotropic probe (measurement antenna) measures on three perpendicular axes simultaneously. Its anisotropy (= deviation from perfect sensitivity) is so good that, despite the close connection to the SRM device, most measurements at 400 MHz and higher can be made while you hold the SRM in your hand. For more precision, you can mount the probe on a tripod and connect it to the SRM via a cable. This minimizes the influence of reflections caused by the device housing or the technician. For precision measurements below 400 MHz, we recommend Narda s uniaxial probe. The SRM can also measure three axes with a uniaxial probe. To do this, a special apparatus must be used to arrange the receiving axis Narda probes Summary of technical specifications of the probe in three different perpendicular positions in succession. The SRM saves the result for each of the axes, computes the field strength and then displays the result directly. The isotropic probe can also be used to make uniaxial measurements. Just change the setting in the SRM s menu to uniaxial and select the desired receiving axis. Laboratory specimen of an isotropic probe. It measures the electric field using three perpendicular monopoles which are turned into electrical dipoles by the conducting surfaces of the cube. The series-production version uses a three-dimensional dipole array. Probe type E-field probe, isotropic E-field probe, dipole Antenna factors? The SRM knows its probes. In precise terms, the SRM does not measure the electromagnetic field. Instead, it measures the voltage caused by the field at the probe output (measurement antenna). To be able to display the corresponding field strength, the antenna factor must be known. For precision measurements, it must be individually determined for the probe at different frequencies and used in the evaluation process. This is a major benefit of probes from Narda. The antenna factors are stored on an EEPROM in the probe and automatically recognized and used by the SRM. You can also input the antenna factors for other probes using the PC-based software. In this case, it is necessary to tell the SRM what probe you are currently using. If their loss vs. frequency cannot be neglected, cables connected between the probe and SRM must be treated in the same manner for precision measurements. Data for standard cables from Narda are automatically accessible to the SRM in an EEPROM in the cable connector. Patent application filed Surfaces and bodies either reflect or absorb electromagnetic radiation. Their size determines how much they influence the electromagnetic field. Here, large and small refers to the wavelength of the radiation. In general, probes should be small to avoid influencing the field. But they need to be large to provide better sensitivity. Since RF radiation has very small wavelengths (e.g. about 10 cm at 3 GHz), the dimensions are quite manageable. Everything else in the surroundings is large by comparison and produces interference, including the connecting cable, the measuring device and the person making the measurement. Thanks to a highly innovative design of the probe and SRM housing, Narda has managed to minimize interference so much that it is now possible to make measurements while holding the measuring device. The company has filed a patent application for this concept. Narda s SRM performs selective, non-directional measurements by hand wherever you go. Frequency range 80 MHz to 3 GHz 30 MHz to 3 GHz (on tripod, connected to SRM (on tripod, connected to SRM via special ferrite cable) via special ferrite cable) 400 MHz to 3 GHz (mounted directly on SRM) Sensitivity 5 mv/m at 900 MHz with 10 mv/m at 900 MHz with in conjunction with 100 khz resolution width 100 khz resolution width SRM device (suitable for GSM measurements) (suitable for GSM measurements) 35 mv/m at 2.1 GHz with 70 mv/m at 2.1 GHz with 5 MHz resolution width 5 MHz resolution width (suitable for UMTS measurements) (suitable for UMTS measurements) Preferred application Fast, non-directional measurements Precision measurements in the on mobile radio systems VHF The output of the probe is connected to the SRM device via an N connector. The device reads the probe data from an EEPROM via an auxiliary cable

9 Rest assured with the SRM s automatic safety evaluation Forget about long frequency tables or complicated weighting factors: Just select the services you want to test in the configuration menu and the regulations you want to use for evaluation. To avoid faulty measurements, the SRM s menu shows only those services which can actually be tested with the connected probe. Narda has prepared tables of services and their frequency s for most countries. You can edit these tables using the PC-based software or create new ones. Just name your service and specify the upper and lower frequency limits. Then transfer it to the SRM via the serial interface. Once loaded, it s there for your use at any time. Complete single-keypress procedures Welcome to single-keypress procedures. The SRM will measure the service-related s in succession and also measure what s happening between these s. The device will adjust the resolution width (RBW) to a fine enough setting to allow precise selection of all sources, but without wasting any extra sweep time. The operator doesn t have to worry about any of this. The first result displayed is a field strength value for one of the services. Prior to this, the SRM automatically integrates all of the spectral lines measured in the associated frequency. It checks by while filling the table. Once it has measured all of the s and the interlying frequencies, the SRM displays the final result: The total field exposure with the contributions of the individual services and the interlying frequencies. Many measurements, one result As a general rule, the testing service needs the results as a percentage of the permissible limit. The SRM automatically evaluates each spectral line according to the relevant standard or regulation. If you need absolute results, however, just switch over to display field strength (V/m) or power density (W/m 2 ). Weighting of results is now switched off. What about safety evaluation with a uniaxial probe? Yes, it s possible. First axis, first pass: The SRM displays the first interim result. Now rotate the probe and make the second pass: The SRM refreshes the result. The third pass then displays the final result. Safety Evaluation Narda s SRM is built for reliable safety assessment. The SRM measures the field strengths in the frequency s associated with the selected services. It automatically adjusts the resolution width (RBW) to the size of the defined frequency s. In the next step, the device evaluates the results in accordance with the selected standard or regulation. Each of the individual results is given as a percentage of the permissible limit. as % of limit Limit curve Civil air traffic 100% 800/900 MHz 800/900 MHz 1800/1900 MHz Frequency 1800/1900 MHz 3rd generation of mobile radio systems 3rd generation of mobile radio systems Frequency as % of limit Integration over the frequency range of a service is used to determine its contribution to the total exposure. The SRM groups the interlying frequencies under Others. Civil air traffic 800/900 MHz 1800/1900 MHz 3rd generation of mobile radio systems Others Service as % of limit In Safety Evaluation mode, the SRM automatically displays the total field exposure as a percentage of the permissible limit, along with the contributions of the individual services Finally, the SRM determines the overall result Total Total 16 17

10 Your single source for products relating to safety in electromagnetic fields Narda Safety Test Solutions develops and manufactures a comprehensive line of measuring devices for: Low frequency fields RF & microwave fields Personal safety applications We support our users with a practical range of services, including: Consultation on equipment and applications through our worldwide network of sales engineers Repair and calibration services Expertise transfer through standards and ongoing developments Training and testing services Low frequency test equipment Just power on and measure! Simple operation is a prerequisite for producing reliable measurement results. This requires device technologies capable of simplifying complex EMF measurements for the user. The motto for our entire product line at Narda Safety Test Solutions is: Just power on and measure! With about 95% of all patents in the area of measurement of electromagnetic fields, Narda Safety Test Solutions possesses a great body of expertise. This includes the patent for frequency response shaping, which simplifies measurements in a multifrequency environment. The groundbreaking new concept of the Selective Radiation Meter is the subject of a new Narda patent application. The measuring devices are built to stand up to extreme ambient conditions, and their housings are carefully optimized to resist all sorts of mechanical stress and electromagnetic interference. All devices from Narda carry the CE mark and are produced in our own manufacturing facilities, which are certified according to ISO 9001 guidelines. Our manufacturing facilities are located in the United States and Germany. Our RF and microwave product line All of the measuring devices from Narda Safety Test Solutions are characterized by outstanding measurement accuracy and are designed for practical operation. This is naturally true of the new Selective Radiation Meter, which enables experts to perform complex analysis work while still allowing singlekeypress execution of defined applications. For all application areas Precision measurements of RF & microwave fields are required in the following sectors: Wireless / telecommunications Satellite communications Radio & TV broadcasting Military Industrial processes involving heating, curing, smelting, plastics welding and semiconductor production Railways / transport systems with their own communications systems Medical applications such as diathermy and hyperthermy EMC laboratories We have a wide range of products to suit your needs. Whether you are an expert responsible for qualification of entire systems, or you just need to make regular tests or perform service work on individual pieces of equipment, you will find the product you require. For an overview of our products, please visit for more information. All products from Narda are calibrated and comply with standards around the globe. Rest assured that we can deliver a device to comply with your country s standard. Radiation monitors for personal safety Broad RF & microwave test equipment Area monitoring stations Selective RF & microwave test equipment 18 19

11 Services from Narda Safety Test Solutions Calibration and repair Measuring devices and probes from Narda Safety Test Solutions are calibrated prior to shipping. Calibration data are traceable to national and international standards. We can recalibrate your devices and probes either in the United States or Germany. The site in the United States offers an express calibration service within 10 days. If you need this service, please request an RMA number beforehand. Visit our site at for additional information. If you need repair work, please send the device to the nearest calibration site, or contact your sales representative for information on service facilities in your area. For a list of current seminar offerings, please visit Seminars and training courses Narda offers a wide range of RF/microwave occupational safety training courses. Here, users can learn the fundamentals of electromagnetic fields while getting acquainted with measurement techniques and guidelines for safety concepts. Visit for details. Narda Safety Test Solutions GmbH Sandwiesenstrasse Pfullingen, Germany Phone: +49 (0) Fax: +49 (0) support@narda-sts.de Narda Safety Test Solutions 435 Moreland Road Long Island, NY, USA Phone: Fax: NardaSTS@L-3COM.com We have calibration and service sites in the United States and Germany Subject to change without notice NSTS E