🚀 go-pugleaf

In article <1992Nov5.123811.11033@doug.cae.wisc.edu> kolstad@cae.wisc.edu 
(Joel Kolstad) writes:
>I'm just curious... does anyone out there know the bandwidth limitations
>on the baby monitor/cordless phone/RC car/etc. non-lincensed 46 and 49MHz
>radio bands?

To start with baby monitors must operate between 49.82 and 49.90 MHz. Cordless
telephones operate in the 46.60 to 46.98 and 49.66 to 50.0 MHz bands on 10
assigned channels (actually 10 base transmitter channels at 46 MHz and 10
handset channels at 49 MHz).

>I believe I've heard that the power output is limited to producing an
>E-field of 10000uV/m at a distance of one meter from the transmitting
>antennta (correct me if I'm wrong).  But what is the frequency range
>of the "49MHz band?"  I would assume that I can't start modulating my
>49MHz carrier at 1Mhz, for instance... :-)

Actually the limits are 10,000 uV/m measured at 3 meters.  The detailed rules
are somewhat complicated as to emission bandwidths but basically all of the
energy in the carrier and modulation products must fall within 49.82 to 49.90
MHz band with emissions outside this band being severely limited.  This 
effectively limits your modulation frequencies to 4 kHz or less if you stay
in the center of the band.

The full set of rules can be found in Part 15 of the FCC Rules and Regulations.
Check your local library for the Code of Federal Regulations, Title 47, for
a copy.  There are special provisions for home-built (but not marketed)
devices for this band that are outlined in Part 15.

					Barry
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|  ___  ________  |       Dr. Barry L. Ornitz          WA4VZQ
| |  / /        | |       Eastman Kodak Company
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