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15.4 TV and radio broadcast towers

TV and radio broadcast towers are a relic from the “stone
age” of information transmission. They are among the
strongest radiation sources in existence. The highest
transmitting powers are used by TV broadcast stations,
which may employ more than 1000kW! (for comparison: a
cell tower uses about 40 watts=0,04kW). Short wave radio
stations employ transmitting powers of up to approx.
600kW. FM radio broadcast, employing approx. 100 kW,
are already “more conservative” in this respect. Recently,
these are being converted to digital standards (DVB-T and
T-DAB).
Seeing the enormous transmitting powers involved, it is
not surprising that close to these stations (approx. 100m),
even the extremely high official exposure limits are excee-
ded.

15.5 Satellites

Satellites are gaining an ever-increasing importance for
information transmission nowadays. They orbit the earth at
a height of approx. 36000 km in a geostationary orbit. Even
though these satellites employ a “high” transmitting power
in the high GHz range, the radiation exposure on earth is
so extremely low due to the vast distance that you need
the well known dish antennas seen everywhere to focus
the radiation like a lens. These dish antennas and the cor-
responding LNB receivers do not(!) radiate, in contrast to
popular misconceptions. They are completely passive
reception devices. Thus, satellite technology only causes a
very low amount of radiation exposure. If at all, the recei-
ver may cause radiation as it amplifies and converts sig-
nals for later sending them to the TV. For measuring 

this

radiation, you additionally need an LF measurement devi-
ce from the SPECTRAN series.

Stone-age technology:
Thousands of these bro-
adcast towers are in
operation.

Modern and almost
exposure-free: Informati-
on transmission via
satellites.

15.0 RF exposure in practice

55

Содержание SPECTRAN HF-2025

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Страница 6: ...dle miniature tripod 5 Battery charger mains adapter 6 SMA tool 7 SPECTRAN HF xxxx device 8 SMA adapter 9 SMA rod antenna Aaronia 1300mAh Power battery already fitted Express manual This manual Regist...

Страница 7: ...ODE Status field AVG PEAK HOLD TIME MIN MAX 7 MARKER block 1 8 Graphics display Pixel display 9 MULTIPLICATOR field 10 MEMORY Status field STORE RECALL RECORD RESET 11 DISPLAY MODE Status field SPECTR...

Страница 8: ...s Move frequency range by one SPAN Up Down keys Move Reference Level by 10dB 3 In Exposure limit calculation mode Right Left key Select Exposure limits or W m Display 4 In Audio mode Right Left key In...

Страница 9: ...ing on signal strength the half circle will grow or shrink A very handy function for quickly changing levels On all SPECTRAN models with broadband detector the bargraph dis play will ALLWAYS show the...

Страница 10: ...e on the left However should the big Main display show or 120 no signal is being received and you need to change your location or align the anten na differently During every measurement a little dot m...

Страница 11: ...requency tables on pages 64 ff 5 2 The HOLD function The MODE status field displays HOLD As you have probably noticed the display constantly changes This is completely normal as the signal strength of...

Страница 12: ...dows as these often produce the hig hest readings During measurement the maximum reading will also quickly increase until it finally does not change anymore and freezes on its highest level When measu...

Страница 13: ...1 000 000 000 one billionth p 1 1 000 000 000 000 f 1 1 000 000 000 000 000 In our example the display reads 797 21nW m or 797billionth W m or in other words 0 000 000 797 21 W m As this example clear...

Страница 14: ...displayed This means overflow HINT You can download new and or updated exposure limits which con stantly change from Aaronia s homepage and keep SPECTRAN up to date at any time You should also check...

Страница 15: ...on the left ATTENTION During audio analysis the complete dis play is frozen and the pixel display is shut off to free up enough CPU power for demodulation Hence ONLY an acoustic reproduction takes pla...

Страница 16: ...tly at 1733 33Hz When one or more cellphones are active you can recognize an additional 217Hz crackling noise similar to morse code An optimal reproduction can be achieved with the 1MHz or 3MHz filter...

Страница 17: ...level display in contrast to spectrum analysis mode of the PEAK power in the complete measurable frequency rage By utilizing a high end state of the art Silicon Germanium SiGe technology detector chi...

Страница 18: ...ower meter Its high temperature stability guarantees very well reproducable results As the input impedance of the unit is standard 50 Ohms connection to other measu rement equipment is straightforward...

Страница 19: ...irst check the UMTS frequency list on page 65 UMTS uses frequencies between 1 900 1 and 2 200 0MHz As we only want to measure the cell tower and not the cell phone we only need the so called downlink...

Страница 20: ...frequency range between 2 110 and 2 121MHz is being sweeped measured thus all operation modes exposure limit calculati on spectrum display now only refer to this frequency range Now you can precisely...

Страница 21: ...nently show the following information from left to right START CENTER and STOP frequency each in full MHz Below the current values are shown for from left to right Range MrkLvl and Reflev This is very...

Страница 22: ...s are relative to the aforementio ned Center frequency of the display By changing Span the Start Stop fre quency see following description is automatically adjusted to be able to con form to the Span...

Страница 23: ...vity at once When bandwidth is set to a very high value or even to FULL the sweep will be very fast however the display becomes comparatively inaccurate and sensitivi ty is low Hence very weak signals...

Страница 24: ...set in seconds from 0 05 to 9 999 Attention Please note that special digital communication standards like e g cell phones often might not be recognized well or at all with wrong sampletimes as the hi...

Страница 25: ...especially with very strong signals to avoid overloa ding the RF input Available choices are Auto The attenuator is chosen automatically default setting 0dB No attenuator 10dB Attenuate input by 10 d...

Страница 26: ...Frequency hopping Examples of devices falling into this category include DECT phones cell phones microwave ovens etc By choosing Pulse the mode is activated and the Mode status field reads PEAK By sel...

Страница 27: ...n where HOLD mode is indispensable is the panning approach described in the following chapter Another situation where HOLD mode is very helpful is exposure limit calcu lation You can use the readings...

Страница 28: ...ilable At the 30dBm setting markers are only shown starting from a very high signal strength of 30dBm At 90dBm even the weakest signals but also other inter ference and noise are being shown as marker...

Страница 29: ...ecording Data Logger With Logger you can start a long term recording Log ger in the current frequency range HF 4040 and above Here the highest reading and the corresponding level and frequency is regu...

Страница 30: ...you can write programs and store them in SPECTRAN s program memory Also SETUPs see the following paragraph are stored as programs Every program is stored under its specific program number Program numb...

Страница 31: ...aminated again just due to a trivial mains cable To avoid this screened rooms must be equip ped with so called mains filters Especially however the utilization of usual power cables for data transmiss...

Страница 32: ...cell phones you need to know their characteristics as in practice both systems are only rarely really active to allow measurement With cell phones you should actively place a call Please also note tha...

Страница 33: ...impressive sensitivity considering their price a yet higher measurement inaccuracy than the base device itself has is assumed in practice The reason behind this are further factors which can influence...

Страница 34: ...isplay of the cursor are only updated after a complete sweep and shown in the first leftmost marker field As such the auto marker feature is principally disabled When you press the Jog dial after posi...

Страница 35: ...signals can be almost completely suppressed using certain settings As soon as you set SpTime to 1 or higher AND use an RBW setting from 300kHz 3MHz an ADDITIONAL Anti aliasing interleave sampling algo...

Страница 36: ...u can freeze readings Now simply change the unit V m mA m dBm dB V in the Unit menu and the old reading will instantly be converted after leaving the menu Correct settings for manual input measurement...

Страница 37: ...d in the Verordnung ber elektromagnetische Felder 26 BlmSchV and are mostly derived from the international recommendations As an approval for the compliance with these exposure limits radio installati...

Страница 38: ...not the cell towers that cause the strongest exposure to radiation in homes it s often portable phones so called DECT phones or microwaves ovens 10 2 Device exposure limits Contrary to the personal se...

Страница 39: ...heap and broadband frequency selective professional measurement is impossible with these Thus frequency selective architecture biological expo sure limits would simply not be measurable with these dev...

Страница 40: ...ter attaching the antenna must not wiggle around and should be seated firmly You can also turn the antenna by 45 or 90 degrees like shown in the illustration on the left Finally you can also screw the...

Страница 41: ...ttom side of the HyperLOG antenna in a way that the HyperLOG antenna points away from yourself see picture Now you can handle both the SPECTRAN and the HyperLOG antenna with one hand each Like this th...

Страница 42: ...efore While doing so slightly and continuously push the HyperLOG antenna further into the sensor pickups on the SPECTRAN As soon as the SMA adapter is screwed to the HyperLOG antenna slightly tighten...

Страница 43: ...urces from 8V to 12V max using a 3 5mm phone jack Polarization of the jack needs to be as follows The inner conductor must be the outer conductor must be Using our optional car power adapter see price...

Страница 44: ...briefly press the jog dial Like this you can e g control the complete menu system just with this prac tical little wheel However with the demodulator activated this jog dial serves as a volume control...

Страница 45: ...ds to the HyperLOG7025 etc If you do not have an antenna connected choose None as antenna type Confirm your entry by pressing the ENTER key or clicking the jog dial You are now being taken back to the...

Страница 46: ...each application conflicts between different road users can be avoided so that e g a cell phone cannot be dis rupted by a microwave oven Big differences between exposure limits Back to our motorway O...

Страница 47: ...d now You ve performed an ANALYSIS of the entire range of lanes from 0 6km Or in other words You performed a RANGE ANALYSIS As you know to analyze something means breaking it down into smaller parts w...

Страница 48: ...Hz Also the signal strength of every frequency range is exactly stored Like this we also learn what signal strength was present on which frequency range Real world examples Let s assume that we want t...

Страница 49: ...rast already uses a far higher bandwidth 2 320 2 450 130MHz and so on Well this wasn t all that difficult was it We can now see ALL information con cerning these three signal sources In practice this...

Страница 50: ...to right This procedure of con tinuous scanning is called sweeping So what kinds of information have we acquired now 1 In the entire frequency range from 0 6GHz there are 3 main signal sources 2 The...

Страница 51: ...adio transmission is done digitally and pulsed at approx 100Hz which is well audible with SPECTRAN with activated demodulation even when no call is being placed as the base station of a DECT phone alw...

Страница 52: ...void exposure to this strong radiation you should definitely use an external antenna for your car Exposure then becomes minimal and reception quality will also be significantly better Likewise your ce...

Страница 53: ...ss In most cases you will find the version with three radio cells triangular installation with 3 sectors spanning 120 degre es each see image Here you will find a transmitting antenna on every side wi...

Страница 54: ...are very inconspicuous as they are mostly mounted without any kind of mast or tower and are also of an extremely small size by themselves Thou sands of micro and pico cells can be found in most cities...

Страница 55: ...portance for information transmission nowadays They orbit the earth at a height of approx 36000 km in a geostationary orbit Even though these satellites employ a high transmitting power in the high GH...

Страница 56: ...PCs etc as well as enable communication between up to 8 devices like e g UMTS cellphones or portable PCs Just a few years ahead it will be pretty normal that the coffee maker will be able to talk to t...

Страница 57: ...ssue in the head exac tly this effect is utilized in a microwave oven The electro magnetic waves generated in the oven excite vibrations in the water molecules The energy from these vibrations in turn...

Страница 58: ...controlled alarm clocks These devices do not emit radio waves themselves they just receive them Radio controlled clocks do not emit radio waves themselves They only receive them 15 0 RF exposure in p...

Страница 59: ...e between two poles The nearer these poles are to each other and the higher the voltage the stronger the electric fields for med between them Thus electric fields are present even when no current is f...

Страница 60: ...logy is 1mW or 1 V So logarithmic level readings are expressed in dB milliwatts dBm or dB microvolts dB V 17 2 Field strength V m A m and power density W m If you don t feed signals directly and inste...

Страница 61: ...also table 1 on page 64 More rarely values in dBm m and dBW m can be found Conversion is equal ly simple 1 W cm 10dBm m 20 dBW m and 10 W cm 20dBm m 10 dBW m etc respectively However the most frequent...

Страница 62: ...as follows 18 1 Calculation of wavelength Wavelength can be calculated using the formula Here c corresponds to the speed of light in m s rounded to 300 000km s in our example f to the frequency of the...

Страница 63: ...separately However outside the close up range both field types are coupled tightly to each other so knowing the strength of one of them will be enough to derive the other 18 3 Calculating power densi...

Страница 64: ...019 0 000 000 022 0 000 000 033 We assume the following center frequencies f GSM900 f 900MHz GSM1800 DECT f 1850MHz UMTS f 2000MHz and WLan micro wave ovens f 2450MHz The conversion table demonstrate...

Страница 65: ...m 19 4 V m 0 051 5 A m Table 3 Conversion between dBm dBW and W 0 dBm 30dBW 0 001W 1mW 10dBm 40dBW 0 000 1W 100 W 20dBm 50dBW 0 000 01W 10 W 30dBm 60dBW 0 000 001W 1 W 40dBm 70dBW 0 000 000 1W 100nW 5...

Страница 66: ...rivate UL Uplink mostly means portable device mobile transmitter which transmits towards the base station e g a cellphone DL Downlink mostly means base station fixed transmitter which transmits toward...

Страница 67: ...937 4 GSM900 DL Vodafone 937 6 944 8 GSM900 DL T Mobile 945 0 951 0 GSM900 DL Vodafone 951 2 955 4 GSM900 DL T Mobile 955 6 959 2 GSM900 DL Vodafone 959 4 959 8 GSM900 DL T Mobile UL Uplink mostly mea...

Страница 68: ...To get the full luxury get our free PC analysis software directly from there 20 0 Frequency tables 68 Table 8 German GSM1800 frequencies and providers Start Stop frequency Abbreviation Provider 1 710...

Страница 69: ...h the SPECTRAN HF 4060 by just paying the difference to this model However for taking advantage of this service you need to be a registered custo mer Thus you should definitely fill the included regis...

Страница 70: ...22 0 Analyzer Antenna Frequencychart 70 Frequencychart SPECTRAN Spectrum Analyzer Frequencychart HyperLOG and BicoLOG Antennas and Probes...

Страница 71: ...23 0 For your notes 71 Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com...

Страница 72: ...23 0 For your notes 72...

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