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RF control — Parallax Forums

RF control

ArchiverArchiver Posts: 46,084
edited 2004-01-21 15:26 in General Discussion
What type of setup do you think is in simple RF communication
devices like RC cars and the like? Does the transmitter as well as
the receiver (the car) need a PIC, or does it need something more
advanced? Also, I seem to see a lot of products like these use the
27Mhz band. Can anyone use that frequency that wants to? Also, why
did Stamp settle on 900Mhz and 433.92Mhz for its RF devices?

I am obviously new to this area and would appreciate any help.


Thanks
Patrick

Comments

  • ArchiverArchiver Posts: 46,084
    edited 2004-01-21 15:26
    A short explanation of radio frequency allocation.

    The Federal Communications Commission (FCC) is responsible for allocating
    various bands of frequencies for specific purposes under agreements with
    other countries. Some of these bands are set up for commercial purposes
    such as television broadcasting, AM and FM radio broadcasts, etc. Some are
    for non-commercial licensed use such as Amateur Radio and Public service
    (fire,police,etc.) A few bands have been set aside for non licensed use
    provided the equipment used has limited range. Some bands like those you
    mentioned along with a few at 49 MHz may be used for different purposes like
    RC control. These are designated as Part 15 devices. The equipment must be
    type accepted by the FCC (tested and certified to comply) and must not cause
    harmful interference to other licensed services. Also, there is no immunity
    from interference from other devices guaranteed. Some frequencies are
    better than others as they have less range, more range, less man-made and
    atmospheric noise, more bandwidth, higher or lower equipment costs, etc. so
    the selection of bands is determined by the manufacturer within the
    limitations of the FCC. Some modes of modulation are not compatible with
    others so certain types of operation tend to be grouped in specific bands
    (networking).
    So, there are many considerations when selecting bands of operations, and
    this dialog has merely scratched the surface in very general terms.

    Hope this helped,

    jim
    http://www.geocities.com/jimforkin2003/


    Original Message
    From: rodroddy_778 [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=fgF5n79yl0_rvdtqsm6NhTsUpidLTWuDzuMX0LAkSvoQiK3iej_FkkohYrAJBEPPfj51CsiYC3s2BbtIpBs]rodroddy_778@y...[/url
    Sent: Tuesday, January 20, 2004 5:40 PM
    To: basicstamps@yahoogroups.com
    Subject: [noparse][[/noparse]basicstamps] RF control


    What type of setup do you think is in simple RF communication
    devices like RC cars and the like? Does the transmitter as well as
    the receiver (the car) need a PIC, or does it need something more
    advanced? Also, I seem to see a lot of products like these use the
    27Mhz band. Can anyone use that frequency that wants to? Also, why
    did Stamp settle on 900Mhz and 433.92Mhz for its RF devices?

    I am obviously new to this area and would appreciate any help.


    Thanks
    Patrick



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