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Question #: 260

Question: THERE ANY STANDARD FOR A DISTANCE BETWEEN CELLULAR BASE STATION AND RESIDENTIAL AREA?

Current Solution

The two main constraints on siting cellular base stations near residential areas are government exposure limits and local zoning ordinances. Various governments have limits for human exposure to radiofrequency (RF) energy that must be complied with in the siting of cellular base stations and other transmitters. In the United States, the relevant limits are those of the Federal Communications Commission (FCC). Cellular base stations use low-powered transmitters, and RF signal levels are invariably below FCC limits at any distance more than a few feet from the antennas. Thus it is entirely feasible to locate cellular base stations on rooftops of apartment buildings and to locate communications towers within residential areas and indeed these are both common practices. Local zoning ordinances are a different story. Local governments commonly restrict the location of communications towers through zoning ordinances, and they may have provisions that restrict cellular base stations in residential districts. Local attorneys or government officials should be consulted for advice about local requirements, which vary greatly among jurisdictions. Kenneth R. Foster Professor, Department of Bioengineering University of Pennsylvania

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Other Possible Solutions to this Question

  • IT MORE DANGEROUS STAY FOR ONE HOUR AT A TEN-METER DISTANCE FROM CELLULAR ANTENNA OR TALK INTO PHONE THE SAME AMOUNT OF TIME?

    Cellular phones are designed to be safe for both the user and anyone standing nearby. Cellular phones are actually small radios that transmit signals to and from base-station antennas located on towers or buildings in the nearby neighborhood. Cellular phones use low-power radio signals, even weaker than CB, police, or fire radios.

    The American National Standards Institute (ANSI) sets safety standards for human exposure to radiofrequency (RF) electromagnetic energy in the United States. Government agencies such as the Federal Communications Commission (FCC), the Occupational Safety and Health Administration (OSHA), and many states recognize and accept the ANSI RF safety standard. Also, the United States standard for RF energy is comparable to those set in other countries.

    Cellular phones and cellular-phone base stations have been shown to meet these RF safety standards. Safety standards for RF energy are threshold standards. Threshold standards define the level of RF energy above which there may be health or safety hazards and below which there have been no reported harmful effects. Unlike ionizing radiation, which many people believe to act cumulatively even at small exposure levels, RF energy at low levels is not considered a cumulative hazard. Therefore the consensus of scientific experts in this area is that RF exposure from cellular phones, meeting the threshold levels set in safety standards, is safe for all.

    The specific answer to the question is that cellular phone technology is safe for all. There is no danger posed by either handheld phone units or by base-station antennas. In both cases, the radio signals transmitted from the antennas are required to meet the ANSI safety standard for RF safety as embodied in FCC regulations governing this technology. For more information:

    The FCC has recently revised and reissued its Bulletin 56 on Questions and Answers about Biological Effects and Potential Hazards of Radiofrequency Electromagnetic Fields.

    OSHA provides information and links to more sites on RF safety at its Web page, Radiofrequency/Microwave Radiation.

    Gary Zeman, ScD, CHP Lawrence Berkeley National Laboratory

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    IT MORE DANGEROUS STAY FOR ONE HOUR AT A TEN-METER DISTANCE FROM CELLULAR ANTENNA OR TALK INTO PHONE THE SAME AMOUNT OF TIME?

  • WHAT ARE CURRENT RECOMMENDED IEEE EMF OCCUPATIONAL EXPOSURE LEVELS AND GUIDELINES FOR RADIO BASE STATION ANTENNAS?

    The following answer assumes "radio Base Station Antennas" refers to base stations used for personal wireless communications services such as cellular telephone, Personnel Communications Services (PCS), and Enhanced Specialized Mobile radio (ESMR). In the United States, the frequency band allocated for base stations used for personal wireless communications is 869-894 MHz for cellular service, 851-866 MHz for ESMR, and 1930-1990 MHz for PCS. The IEEE exposure limits (maximum permissible exposure—MPE) for occupational exposure (controlled environments where exposures may be incurred by persons who are aware of the potential for exposure) are frequency dependent and are expressed in terms of incident power density. The appropriate value to compare with the MPE is the incident power density averaged over the vertical cross-section of the human body. The occupational exposure limits are also time-averaged over any six-minute interval. The IEEE C95.1-1991 MPE values are shown in the table below:
    IEEE C95.1-1991 Maximum Permissible Exposure (MPE) Values
    Frequency Band Power Density
    General mw/cm2 W/cm2
    851-866 MHz f/300 mW/cm2 2.84-2.88 28.4-28.8
    869-894 MHz f/300 mW/cm2 2.90-2.98 29.0-29.8
    1930-1990 MHz f/300 mW/cm2 6.43-6.63 64.3-66.3
    NOTE: f is in MHz
    As indicated above, these values are for continuous exposure (t > 6 minutes) and are to be compared with the spatial average of the incident power density. all base stations used for personal wireless telecommunications services in the United States are required to comply with the FCC limits (as mandated by the Telecommunications Act of 1996). The FCC limits are based on a hybrid of the IEEE limits and the 1986 recommendations of the National Council on Radiation Protection and Measurements. The FCC MPEs are the same as the IEEE values for frequencies below 1500 MHz but are capped at 5 mW/cm2 (50 W/cm2) for frequencies greater than 1500 MHz.

    Both the FCC and IEEE MPEs for exposure of the public (uncontrolled environments) are one-fifth of the above values. As above, the value to compare with the MPE is the incident power density averaged over the vertical cross-section of the human body. The averaging time for the general public is 30 minutes. Thus, for transient exposures lasting six minutes or less, the MPEs for occupational exposure and exposure of the general public MPEs are the same. For cases of simultaneous exposure from antennas operating in different frequency bands, the ratio of the spatially averaged incident power density in each frequency band to the corresponding MPE for that band is determined and the sum of all such ratios must be less than unity in order to comply.

    R. C. Petersen
    Manager, Wireless and Optical
    Technologies Safety Department

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    WHAT ARE CURRENT RECOMMENDED IEEE EMF OCCUPATIONAL EXPOSURE LEVELS AND GUIDELINES FOR RADIO BASE STATION ANTENNAS?

  • Are there any instructions for use the USP breakout board for a CO2 laser?

    The instructions to connect the USB CNC Interface for the blackTooth Laser Cutter and engraver can be found on instruction #18 on thispage: https://www.buildyourcnc.com/blackToothLaserCutterAndEngraver.aspx

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    Are there any instructions for use the USP breakout board for a CO2 laser?

  • HOW MUCH RADIATION GIVEN OFF BY A CELL PHONE AND THERE ANY WAY TO STOP THE FROM BEING ABSORBED INTO YOURSELF?

    Portable cell phones emit about 0.6 watts of radiofrequency energy, limited primarily by the power of the battery. As with any radiofrequency transmitter, there will be some amount of absorption in the human body; the amount depends on how close you are to the antenna. The Federal Communications Commission (FCC) limits the amount of radiofrequency energy which cell phones can deposit in the body to levels at which no health effects are to be expected. See an article on Cell Phone Safety on this website for more information.

    Gary H. Zeman, ScD, CHP

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    HOW MUCH RADIATION GIVEN OFF BY A CELL PHONE AND THERE ANY WAY TO STOP THE FROM BEING ABSORBED INTO YOURSELF?

  • What is the difference between a NEMA 23 and NEMA 24 motor? can I use either one on a machine?

    The frame size difference of the NEMA 23 and 24 is very slight and, depending on the motor mount both will most likely fit. The bigger difference between these stepping motors is the torque. Make sure that the motor that you purchase has the appropriate torque for the axis that it will move.

    Is is safe to go with the higher torque? Or if the torque is too high for what i need is that bad?

    You can use a motor with higher torque. Just make sure to select the correct driver for that motor.

    Additional Information:
    The frame size has nothing to do with torque. Nema 23 means a 2.3" frame. Nema 24 means a 2.4" frame. That's all. Either could have more or less torque depending on speed and power.

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    What is the difference between a NEMA 23 and NEMA 24 motor? can I use either one on a machine?

  • What is the difference between a NEMA 23 and NEMA 24 motor? can I use either one on a machine?

    The frame size difference of the NEMA 23 and 24 is very slight and, depending on the motor mount both will most likely fit. The bigger difference between these stepping motors is the torque. Make sure that the motor that you purchase has the appropriate torque for the axis that it will move.

    Is is safe to go with the higher torque? Or if the torque is too high for what i need is that bad?

    You can use a motor with higher torque. Just make sure to select the correct driver for that motor.

    Additional Information:
    The frame size has nothing to do with torque. Nema 23 means a 2.3" frame. Nema 24 means a 2.4" frame. That's all. Either could have more or less torque depending on speed and power.

    Click the link to add information to this solution:
    What is the difference between a NEMA 23 and NEMA 24 motor? can I use either one on a machine?

  • Are there any other manuals for the VFD that comes with the 2.2kw spindle?

    We have manuals for the VFD rather than the spindles. Can you specify what issue you may be having so we can help you better?

    Additional Information:
    I am having trouble wiring the VFD. (From the wall outlet to the VFD) I think the manual or setup guide on your website is wrong. The two diagrams show two different sets of terminals on the page.

    Also, do you have a video or other documentation on programming the VFD? Your videos and documentation looks like it only covers the 1.2kw version. Are the two different spindles from different manufacturers?

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    Are there any other manuals for the VFD that comes with the 2.2kw spindle?

  • Are there any videos detailing wiring of limit switches and stop button?

    This video may serve helpful on the homing and limit switches:
    https://www.buildyourcnc.com/PrimeronHomingandLimitSwitches.aspx

    I don't go into great detail on the wiring, however. If after you watch that video and you still need a video, please let me know and I will make a video on the wiring of limit switches and the E-stop button.

    Click the link to add information to this solution:
    Are there any videos detailing wiring of limit switches and stop button?

  • Are there contour type brushes available for leadscrews and round rails

    Yes, you can use these flexible strip brushes and create a mount for the contour that you need:

    https://www.buildyourcnc.com/item/strip-brush

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    Are there contour type brushes available for leadscrews and round rails

  • WHAT IS THE DIFFERENCE BETWEEN A PRINTER CABLE PORT AND USB MOTOR KITS

    The parallel (printer cable) port is uses the computer as its main source of pulse trains to operate the motor driver directly. Parallel ports are a direct connection from the processor commonly referred to as GPIO pins (General Purpose I/O pins) and provides a convenient and powerful way to interface with the computer. The parallel breakout board is included in those kits only to condition those signals for use with the drivers.

    The USB serves at the actual controller, sending the pulse trains, but the computer sends simple human readable instructions to the USB controller to tell the controller how to send pulses.

    The non-technical differences that may serve as the most important information to you is that the parallel configurations allow for a wider variety of industry standard software that can be used to control the cnc machine. The USB that we offer requires the operator to use a software called Planet-CNC software which is a very well made and feature full cnc control software.

    Additional Information:


    Additional Information:


    Additional Information:
    USB Motion controller breakout board work with planet cnc software?

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    WHAT IS THE DIFFERENCE BETWEEN A PRINTER CABLE PORT AND USB MOTOR KITS

  • I purchased a 220V spindle with invertor last week and the ER20-A Clamping nut appears to milled incorrectly. I installed the spindle for the first time last night and was unable to screw the nut any distance with a bit inside. Looking inside the nut, there is a machined ring that is visibly off center.

    The ring inside the nut is purposely machined in this way to allow movement for the collet. Try threading the nut counterclockwise a little bit until it seems to be flush on the spindle extension. This should ensure the collet nut will thread correctly without stripping the threads on the pipe.

    Click the link to add information to this solution:
    I purchased a 220V spindle with invertor last week and the ER20-A Clamping nut appears to milled incorrectly. I installed the spindle for the first time last night and was unable to screw the nut any distance with a bit inside. Looking inside the nut, there is a machined ring that is visibly off center.

  • WHAT IS THE DIFFERENCE BETWEEN PARALLEL AND USB ELECTRONICS COMBOS MOTOR KITS

    The parallel (printer cable) port is uses the computer as its main source of pulse trains to operate the motor driver directly. Parallel ports are a direct connection from the processor commonly referred to as GPIO pins (General Purpose I/O pins) and provides a convenient and powerful way to interface with the computer. The parallel breakout board is included in those kits only to condition those signals for use with the drivers.

    The USB serves at the actual controller, sending the pulse trains, but the computer sends simple human readable instructions to the USB controller to tell the controller how to send pulses.

    The non-technical differences that may serve as the most important information to you is that the parallel configurations allow for a wider variety of industry standard software that can be used to control the cnc machine. The USB that we offer requires the operator to use a software called Planet-CNC software which is a very well made and feature full cnc control software.

    Additional Information:


    Additional Information:


    Additional Information:
    USB Motion controller breakout board work with planet cnc software?

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    WHAT IS THE DIFFERENCE BETWEEN PARALLEL AND USB ELECTRONICS COMBOS MOTOR KITS

  • WHAT'S THE DIFFERENCE BETWEEN PARALLEL BREAKOUT BOARD AND USB ITERFACE?

    The parallel (printer cable) port is uses the computer as its main source of pulse trains to operate the motor driver directly. Parallel ports are a direct connection from the processor commonly referred to as GPIO pins (General Purpose I/O pins) and provides a convenient and powerful way to interface with the computer. The parallel breakout board is included in those kits only to condition those signals for use with the drivers.

    The USB serves at the actual controller, sending the pulse trains, but the computer sends simple human readable instructions to the USB controller to tell the controller how to send pulses.

    The non-technical differences that may serve as the most important information to you is that the parallel configurations allow for a wider variety of industry standard software that can be used to control the cnc machine. The USB that we offer requires the operator to use a software called Planet-CNC software which is a very well made and feature full cnc control software.

    Additional Information:


    Additional Information:


    Additional Information:
    USB Motion controller breakout board work with planet cnc software?

    Click the link to add information to this solution:
    WHAT'S THE DIFFERENCE BETWEEN PARALLEL BREAKOUT BOARD AND USB ITERFACE?

  • I WOULD LIKE TO KNOW IF THERE IS A STORE OR SHOP WHERE CAN SEE THE PRODUCT AND BUY IT?

    If you are located near Houston, Texas area you can stop by our shop. If you are not near us, you can check in our forums, and see if you can find someone in your area that has one of our machines, and would be willing to let you come see it in action.

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    I WOULD LIKE TO KNOW IF THERE IS A STORE OR SHOP WHERE CAN SEE THE PRODUCT AND BUY IT?

  • I have just purchased a 4x8 Greenbull system second-hand. Are there any schematics for table dimensions and rail-mounting available so that I can build a table? (previous owner disassembled)

    Actual table dimension: 4'x8' is 56.078"x 121.50" (the overhang in the illustrations should be 3/4" thick)
    To determine the frame dimensions, first consider using the frame height shown of almost 3' (2.86'). The width of the frame should be 4" narrower than the dimension from rail edge to rail edge (6X rail to rail is 80.078"). This will provide a 2" overhang on both sides (4X frame width should be 56.078").
    The length of the frame should be 4" shorter than the desired length of the rails to provide a 2" overhang on both ends. The travel length will be 20" shorter than the rail length due to the space occupied by the gantry sides.
    Two long pieces of 3/4" material will need to be placed on top of the frame with the 2" overhang on the sides and the end. These long strips of material will receive the rails and the chain mounts on the ends.


    Link:
    https://www.buildyourcnc.com/Item/cnc-machine-greenBull-v4-4X

    Click the link to add information to this solution:
    I have just purchased a 4x8 Greenbull system second-hand. Are there any schematics for table dimensions and rail-mounting available so that I can build a table? (previous owner disassembled)

  • ARE THERE PRODUCTS AVAILABLE TO THE GENERAL PUBLIC THAT CAN BE PURCHASED PROTECT CELLULAR OR PORTABLE TELEPHONE USERS FROM RADIATION? IF SO, WHERE THESE FOUND?

    There are a number of opportunistic gadgets on the market to allegedly protect the user from hazards of cellular phones. You can search the Internet to find the latest, ranging from antenna shields to whole-body shielding materials. Most experts believe that these devices take advantage of customers' misunderstanding and unfounded fears to sell products with no real value. First of all, cell phones that operate within the guidelines established by national and international safety panels have never been shown to pose a health risk to the user (see answers to other questions on cell phone safety on this website). Secondly, placing any kind of shield over the antenna of a cell phone will in most cases cause it to increase its RF output as it attempts to compensate for signal loss in the shield and maintain a quality phone call. The U.S. Food and Drug Administration published an advisory on cell phones several years ago that said if you are concerned about risks of using a cell phone, then simply use it less. That is still good advice today. Gary Zeman, ScD, CHP Lawrence Berkeley National Laboratory

    Additional Information:



    Additional Information:

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    ARE THERE PRODUCTS AVAILABLE TO THE GENERAL PUBLIC THAT CAN BE PURCHASED PROTECT CELLULAR OR PORTABLE TELEPHONE USERS FROM RADIATION? IF SO, WHERE THESE FOUND?

  • WHAT COMMON BETWEEN KUTTY, SHANKAR, LAXMAN AND SUDHIR DAR?

    Drawing Cartoons

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    WHAT COMMON BETWEEN KUTTY, SHANKAR, LAXMAN AND SUDHIR DAR?

  • I AM PUTTING TOGETHER THE BLACKFOOT AND USING A PORTER CABLE ROUTER. CONFUSED ON HOW TO RELAY ROUTETR WITH USB BOARD. IS THERE ANOTHER SWITCH THAT GOES BETWEEN BOARD ROUTER SO PLANET CNC CAN TURN PERHAPS VACUUM OFF?

    We are currently working on a relay board that will connect to USB breakout board, and the router/spindle for both the on/off function. Unfortunately we still do not have it completed or ready to be placed on our website, but it is in the final stages of testing. Please check back regularly for updated stock!

    Here is a link to a tutorial for a DIY relay circuit:



    There is no vacuum control on the Planet-CNC program, however you could use the same concept of the router/spindle on/off using the relay circuit. Although you will have to use either the flood or mist function for the vacuum.

    Click the link to add information to this solution:
    I AM PUTTING TOGETHER THE BLACKFOOT AND USING A PORTER CABLE ROUTER. CONFUSED ON HOW TO RELAY ROUTETR WITH USB BOARD. IS THERE ANOTHER SWITCH THAT GOES BETWEEN BOARD ROUTER SO PLANET CNC CAN TURN PERHAPS VACUUM OFF?

  • IS THERE A WAY TO GET RID OF THE PARALLEL CABLE AND SOMEHOW USE USB ?

    If you select the Settings Page and select or tick Auto Limit Override - this will allow you to back off the switch.

    Additional Information:
    limit and home switch

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    IS THERE A WAY TO GET RID OF THE PARALLEL CABLE AND SOMEHOW USE USB ?

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