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Description  |
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BACKGROUND OF THE INVENTION
The present invention relates to local television transmission and, more
particularly, to a wireless local television transmission system
comprising, a source of a video signal to be viewed at a remote location;
up converter means connected to the source for shifting the video signal
to a frequency above the normal television bands; transmitter means
connected to the up converter means for transmitting the video signal at
the shifted frequency; receiver means at the remote location for receiving
the transmitted video signal; down converter means connected to the
receiver means for shifting the video signal back to a frequency within
the normal television bands and identified with a known channel; and,
television set means connected to the down converter for processing and
displaying the video signal on the known channel.
Television (TV) is a major factor in everyday life throughout much of the
world. Unfortunately, the rapid advances in the art relative to devices
for producing the television signals that drive the TV sets has not
provided a convenient method of connecting those devices. All this is to
say that television technology quickly outstripped interconnecting
technology resulting, quite literally, in a mess. The typical home has at
least one video cassette recorder (VCR) and, probably, two TV sets. Cable
has generally replaced the old antenna on the roof; so, there is probably
a cable select box as well. All these are usually interconnected with
so-called co-axial cable or "co-ax". The co-ax is stiff and cumbersome. If
the viewer wants to have the ability to watch one station while recording
another, quite often a so-called "A-B switch" must be employed,
particularly where scrambled pay channels are being unscrambled within the
cable select box. The result is a tangled web of co-axial cable connected
between signal splitters, A-B switches, cable select boxes, VCRs and TV
sets.
Where it has been desired to have a single VCR and/or cable select box
provide signals to TV sets in separated rooms, the co-ax has been run
through the walls, attics, along baseboards, or what have you, to make the
necessary interconnections. In one recent commercial prior art attempt to
overcome the problem, fine double stranded wire has been substituted for
the unwieldy co-ax. The use of an ordinary pair of wires in place of the
co-ax is also addressed in U.S. Pat. No. 4,054,910 of Chou et al. The
Karplus U.S. Pat. No. 3,093,706 suggests transmitting the TV signal over
the power lines. Since the latter patent is over twenty years old and the
use of power lines to replace co-ax has not been adopted, it would appear
that the teaching did not produce acceptable results.
Some of the basic problems presented and some prior art attempts at their
solution are depicted in FIGS. 1-6. The basic problem is depicted in FIG.
1; that is, some one or more TV signal sources 10 (e.g. video camera 12,
TV antenna 14, cable select box 16 or VCR 18) must be connected to the TV
set 20. The typical method is co-axial cable 22 with signal splitters and
A-B switches (not shown), as necessary for the particular hook-up. Devices
such as the cable select box 16 and VCR 18 typically output their signal
at the frequency and in the manner of a normal TV signal from channel 3 or
4 (although other normal channels can be, and have been, used). The input
to the TV set 20 is at its normal signal input terminals and the tuner of
the set 20 is tuned to the appropriate channel (3, 4, etc.) to receive the
signal in the normal manner.
In an effort to eliminate the interconnecting wires, some illegal efforts
have been made to wirelessly transmit the combined video/audio signal from
the VCR 18 in the manner shown in FIG. 2. This approach is also employed
in commercially available devices in Japan (where it is not illegal)
employing UHF television channel frequencies. The audio and video signals
developed by the VCR 18 from the cassette being played (not shown) are
input to a transmitter 24 which is set up to transmit with a low power
signal from antenna 26 on a channel normally not used commercially in the
local area, such as channel 3 or 4 as mentioned above (with channels 14
and 15 sometimes being used). The TV set 20 then picks up the transmitted
signal over its normal "rabbit ears" antenna 28. This, of course, is an
illegal transmission at a licensed frequency in the United States and can,
and has, gotten the manufacturers and sellers of such devices in serious
trouble with the Federal Communications Commission.
One very common prior art arrangement for cutting down on the number of
cables and wires required is shown in FIG. 3. The typical VCR 18 has a
power outlet (not shown) on the back of the case into which the power cord
30 of the TV set can be plugged instead of having to run two power cords
to a wall outlet. Often, the power outlet of the VCR 18 is controlled by
the VCR 18 so that to turn on both the VCR 18 and TV set 20, only the VCR
18 needs to be turned on. Commonly, the VCR 18 can be controlled in all
its functions by an infra red (IR) transmitting controller 32 which also
eliminates wires and cables. The controller 32 emits a coded beam of IR
energy 34 which is detected by an IR detector 36 on the front of the VCR
18. Which brings us to the prior art improvement to such systems depicted
in FIG. 4. The transmitting controller 32 must be within a limited
distance of the detector 36 and must be able to have the IR energy 34
therefrom directed onto the detector 36. Thus, if the VCR 18 and TV set 20
are remotely located from one another, the transmitting controller 32 is
useless at the location of the TV set 20 where the viewer is located. To
solve this problem, U.S. Pat. No. 4,509,211 of Robbins teaches the use of
a transmitter 38 having an IR detector 36' therein which detects the coded
beam of IR energy 34 from the transmitting controller 32 and transmits the
signal as an electrical signal on the interconnecting co-axial cable 22
between the VCR 18 and TV set 20 to a repeater 40 which uses the
electrical signal to produce a duplicate coded beam of IR energy 34' which
is directed on the detector 36 of the VCR 18 to operate it remotely.
For the operation of multiple TV sets 20 located throughout a plurality of
rooms such as in a hotel or apartment building, the Parker U.S. Pat. No.
2,628,275 suggests the arrangement shown in simplified form in FIG. 5. A
transmitter 42 takes the received TV signals and retransmits them on an
antenna wire 44 disposed in the baseboard of the rooms throughout the
building. The antenna wire 44 is in lieu of co-axial cable 22 with
splitters at each room location and cable 22 piercing the walls at each
location to provide connection thereto. Each TV set 20 is provided with an
antenna 28' disposed along the baseboard in close spaced relationship to
the antenna wire 44 causing the signal in the wire 44 to be inductively
coupled into the antenna 28'.
Finally, as depicted in FIG. 6, it is well known to wirelessly transmit the
audio portions of the TV signal from an audio transmitter 46 to a local
speaker 48 located where the viewer sits to provide privacy in viewing
television; that is, one viewing and listening to the TV set 20 by means
of the local speaker 46 does not disturb someone else in the room or
house. Such devices are exemplified by Sienkiewicz U.S. Pat. No. 3,259,689
and Trask U.S. Pat. No. 4,021,737; the latter patent being directed more
to providing high fidelity sound than to privacy.
Wherefore, it is the object of the present invention to provide a method
and apparatus for the wireless local broadcasting of video signals in a
broad spectrum of applications which eliminates the necessity for any kind
of physical interconnections, is legal, and which provides a high quality
signal.
It is another object of the present invention to provide a method and
apparatus for the wireless local broadcasting of control signals
associated with wirelessly broadcast video signals.
It is yet another object of the present invention to provide a method and
apparatus for combining control signals for multiple associated video
devices into a single device so as to eliminate the necessity of having
multiple controllers.
Other objects and benefits of the present invention will become apparent
from the description which follows hereinafter taken in combination with
the drawing figures which accompany it.
SUMMARY
The foregoing objects have been attained in the wireless local television
transmission system of the present invention comprising, a source of a
video signal to be viewed at a remote location; up converter means
connected to the source for shifting the video signal to a frequency above
the normal television bands; transmitter means connected to the up
converter means for transmitting the video signal at the shifted
frequency; receiver means at the remote location for receiving the
transmitted video signal; down converter means connected to the receiver
means for shifting the video signal back down to a frequency within the
normal television bands and identified with a known channel; and,
television set means connected to the down converter for processing and
displaying the video signal on the known channel.
In the preferred embodiment, the up converter means shifts the video signal
to a frequency band above 900 MHz and, more particularly, to a frequency
within the band 902-928 MHz. Additionally in the preferred embodiment, the
up converter means frequency modulates the video signal on a carrier
within that band.
Further with respect to the preferred embodiment, the source of the signal
including a video portion also includes a control system responding to
coded infra red energy from a controller/transmitter striking a detector
to produce a coded electrical output and the present invention
additionally comprises supplemental detector means located at the
television monitor for detecting the coded infra red energy from the
controller/transmitter and for translating it into a coded electrical
signal; remote control transmitter means connected to receive the
electrical signal for transmitting the coded electrical signal at a
frequency allocated to the transmission of binary coded information;
remote control receiver means located at the source of the signal
including a video portion for receiving the transmitted electrical signal
and for recreating the coded electrical signal therefrom; and, means
connected to the receiver means for inputting the coded electrical signal
into the control system.
DESCRIPTION OF THE DRAWINGS
FIG. 1 is a simplified block diagram showing the various devices that are
usually connected to a television set by wire according to the prior art.
FIG. 2 is a simplified block diagram of illegal prior art attempts to
transmit television signals from a VCR, or the like, to a television set
wirelessly.
FIG. 3 is a simplified block diagram of a prior art VCR employing an infra
red control transmitter which is connected by wires to a television set
for both signal and power control.
FIG. 4 is a simplified block diagram of a prior art repeater system whereby
a local transmitter responds to the infra red signals from a control
transmitter and sends those signals over the same cable interconnecting
the television set to a remotely located VCR where they are used to drive
a repeater placed in front of the infra red detector of the VCR.
FIG. 5 is a simplified block diagram of a prior art system proposed for use
in hotels, apartment buildings, etc. wherein an antenna is run through the
baseboards in the rooms and the television sets pickup their signal
through inductive coupling to the antenna.
FIG. 6 is a simplified block diagram of a prior art technique for
wirelessly broadcasting the audio portion of a received television signal
to a local speaker placed near the viewer's chair.
FIG. 7 is a simplified block diagram of one embodiment of the present
invention without control feedback.
FIG. 8 is a simplified block diagram of a second embodiment of the present
invention without control feedback.
FIG. 9 is a simplified block diagram of a third embodiment of the present
invention without control feedback.
FIG. 10 is a simplified block diagram of one embodiment of the present
invention with control feedback.
FIG. 11 is a simplified block diagram of a second embodiment of the present
invention with control feedback.
FIG. 12 is a more detailed block diagram of one manner of preferred
operation of the present invention wherein the wireless local transmission
of the television signal is accomplished employing a frequency modulated
signal.
FIG. 13 is a more detailed block diagram of another manner of preferred
operation of the present invention wherein the wireless local transmission
of the television signal is accomplished employing a frequency modulated
signal.
FIG. 14 is a more detailed block diagram of a preferred VCR construction
according to the present invention.
FIG. 15 is a more detailed block diagram of a preferred television set
construction according to the present invention.
FIG. 16 is a drawing of a dual function infra red controller/transmitter
according to a preferred embodiment of the present invention as employed
with VCR/TV matched sets.
FIG. 17 is a cutaway side view of an adjustable directional antenna as
might be employed for preferred operation of the present invention.
FIG. 18 is a view of the antenna of FIG. 17 in the plane XVIII--XVIII.
FIG. 19 is a simplified diagram of the preferred double sideband FM
operation of the present invention which provides for "A" and "B" channels
of 12 MHz total bandwidth each.
FIG. 20 is a simplified block diagram of a video camera constructed
according to the present invention.
FIG. 21 is a simplified block diagram of a video recorder constructed
according to the present invention for operation in conjunction with the
camera of FIG. 20.
FIG. 22 is a simplified block diagram of a cable select box according to
the present invention in a first embodiment containing two tuners and
single channel wireless transmission.
FIG. 23 is a simplified block diagram of a cable select box according to
the present invention in a second embodiment containing two tuners and
dual channel wireless transmission.
FIG. 24 is a simplified block diagram of the preferred dual mode controller
of FIG. 16.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention provides its benefits across a broad spectrum of
video applications. While the description which follows hereinafter is
meant to be representative of a number of such applications, it is not
exhaustive. As those skilled in the art will recognize, the basic methods
and apparatus taught herein can be readily adapted to many uses. It is
applicants' intent that this application and the claims appended hereto be
accorded a breadth in keeping with the scope and spirit of the invention
being disclosed despite what might appear to be limiting language imposed
by the requirement of referring to the specific examples disclosed. It
should also be noted that while the audio portions of the TV signal are
addressed from time to time hereinafter with relationship to novel aspects
of the present invention, the wireless local transmission of audio
signals, per se, is known in the art and the present invention is
primarily directed to the wireless local broadcasting of video which,
until the present invention, has defied those skilled in the art despite
the long felt desire and need for such capability.
The very basic approach of the present invention with respect to the
wireless transmission of video is shown in FIG. 7. The signal from a TV
signal source 10, such as those discussed with respect to FIG. 1, is input
to an up converter 50 wherein it is shifted in frequency to a legal
frequency for the transmission of video information located outside of and
far above the normal television channels. It is presently contemplated
that such frequency will fall into the band from 902 MHz to 928 MHz. After
the frequency of the signal is shifted upwards in the up converter 50, it
is broadcast via the local transmitting antenna 26 by the power
transmitter 52. On the receiving end, there is a separate receiver 54
(instead of direct reception by the TV set 20 as in the prior art) which
receives the high frequency locally broadcast signal via receiving antenna
28 and inputs it to a down converter 56 wherein it is shifted downward in
frequency back into the normal television band and an assigned channel
frequency. The normal TV signal as reconstituted by the down converter 56
is then input to the TV set 20 for normal processing.
It is envisioned by the applicants that the above-described basic approach
to local wireless video transmission and reception will be accomplished in
two ways--which can be combined as necessary and convenient for different
applications. As shown in FIG. 8, it is contemplated that the local
transmitter, generally indicated by the dashed box 58, and the local
receiver, generally indicated by the dashed box 60, can be stand alone
units. That is, for use with existing VCRs 18, TV sets 20, and the like, a
stand alone local transmitter and/or receiver 58, 60 can be employed by
simply connecting them to the associated devices. As the technology of the
present invention is accepted and new devices are produced, it is
envisioned by the applicants that the integrated implementation depicted
in FIG. 9 will be employed wherein the local transmitter 58 and local
receiver 60 are incorporated into the devices themselves in order to take
advantage of commonly usable components such as power supplies, etc.
In the preferred method and apparatus for use with a VCR/TV set
combination, the IR transmitting controller 32 is also provided for so
that the viewer at a remote location has full wireless control of the VCR
18 in another location. As with the basic approach of FIG. 7 which had
stand alone and integrated configurations as shown in FIGS. 8 and 9, the
expanded basic approach combining the controller 32 therein is also
anticipated to be available in stand alone and integrated configurations
as shown in FIGS. 10 and 11. In the stand alone configuration of FIG. 10,
the local transmitter 58' once again contains the up converter 50 and
power transmitter 52. Additionally, however, there is a remote control
receiver 62 also connected to the antenna 26. The remote control receiver
62 is connected to drive an IR repeater 40' with an electrical signal
reflecting the IR signal 34 from the transmitting controller 32 in the
manner of the prior art repeater 40 discussed above. In similar manner,
the local receiver 60' once again contains the receiver 54 and the down
converter 56. Additionally, however, there is a remote control transmitter
64 connected to broadcast via the antenna 28. The remote control
transmitter 64 receives its input from a detector circuit 66 having an IR
detector 36' therein for detecting the IR energy 34 from the controller
32. The coded signal from the controller 32 is translated into an
electrical coded signal which is then transmitted by the remote control
transmitter 64 to the remote control receiver 62. It is anticipated by the
applicants that the transmitter/receiver 64, 62 will operate on one of the
frequencies provided for the local transmission of coded information such
as those employed with garage door openers, and the like. It is also
contemplated by applicants that the transmitter/receiver 64, 62 will, most
likely, include logic for appending additional changeable coded
information on the signal sent between them which can be employed to
prevent interference between the use of the controller 32 remotely and
garage door openers, etc. in the area which might be affected thereby, and
vice versa. It is also worthy of note that the approach of a single IR
controller/transmitter for multiple devices as is part of the present
invention could also be employed with multiple devices without wireless
transmission if unique signals were recognized in each device. In such
instance, as well as with the wireless transmission, the additional
changeable coded information would also prevent interference from other IR
operated devices in the area.
In the integrated versions of a VCR 18' and a TV set 20' as shown in FIG.
11, the VCR functions 68 and local transmitter 58' are contained within a
common case, as indicated by the dashed line 70, and share common
components as applicable. The output of the remote control receiver 62 is
connected to the preamplifier 72 of the IR detector 36 so that the VCR 18'
can be operated both locally and remotely with the same transmitting
controller 32. Similarly, the TV functions 74 and local receiver 60' share
common components and a common case as indicated by the dashed line 76.
Turning now to FIG. 12, the preferred method and mode of operation of the
present invention to reduce the chance of interference between similar
systems in an area (as from neighboring house to house) is shown. The
normal TV video signal is broadcast as an amplitude modulated (AM) signal
with the audio portions frequency modulated (FM). In the present invention
according to its preferred method of operation, pure video and audio
signals 78 and 80 are obtained by a demodulator 82. If available from the
source as in the case of some VCRs, the pure signals can be employed
directly as indicated in the figure. In either event, the video and audio
signals 78, 80 are input to a frequency modulator 84 connected to a
crystal controlled oscillator 86 providing the carrier signal in the
902-928 MHz band which is the preferred signal band for the present
invention. The FM signal from the modulator 84 containing the video and
audio information is transmitted by power amplifier 88 via the
omni-directional antenna 26'.
The user end is preferably provided with an adjustable, directional antenna
28' for maximum unwanted signal rejection capability so as to minimize the
possibility of interference from and with other signal sources in the
area. The FM signal as received is demodulated by the demodulator 90 to
reproduce the pure video and audio signals 78', 80'. The pure audio signal
80' is frequency modulated in modulator 92 with a 4.5 MHz carrier signal
from the crystal controlled oscillator 94 to reproduce the expected audio
signal portion of the resultant TV signal to be generated or use. The
output from the modulator 92 is then amplitude modulated along with the
video signal 78' in modulator 96 with a carrier signal from the crystal
controlled oscillator 98 which is operating at a selected frequency in the
normal TV band, such as channel 3 or 4 as commonly employed in such
devices. The reconstituted TV signal can then be employed with a normal
user device, generally indicated as 100, such as a VCR 18 (recording
function) or TV set 20.
A fully integrated implementation of the method and apparatus of FIG. 12 is
shown in FIG. 13. Note that the components are greatly simplified through
integration. The signal source 10' (e.g. VCR functions) need only produce
the pure video and audio signals 78, 80 which are FM modulated by
modulator 84 with the same carrier frequency in the preferred 902-928 MHz
band from the oscillator 86 as in the prior example of FIG. 12. The same
power amplifier 88 and omni-directional antenna 26' are also used. On the
receiving end, the FM signal is again received by the preferred
adjustable, directional antenna 28' and demodulated by demodulator 90 to
reproduce the video and audio signals 78', 80'. In this instance, however,
the pure signals 78', 80' are fed into a video and audio driver, 102, 104,
respectively, the outputs of which are employed to drive the user devices
100' such a monitor 106 and speakers 108 to produce a TV output or as
inputs to a VCR recorder 110 requiring only the pure video and audio
signals (i.e. without a TV tuner built in).
A preferred configuration for a fully integrated VCR 18' is shown in a more
detailed block diagram in FIG. 14. It should be noted at this point if not
already apparent, as with the rest of this specification and the appended
drawings, the individual components shown by way of block diagram are
either well known or could be easily produced by those skilled in the art
without undue experimentation and, therefore, in the interest of
simplicity and to eliminate redundancy, the descriptions contained herein
of the various circuits and apparatus are only shown to the block diagram
level. As with the more general block diagram of FIG. 11, the VCR 18' of
FIG. 14 has all its components located within a single case (not shown for
convenience). A single power supply 12 is employed for all the circuits
and electrically driven components as indicated by the dashed lines. A
cassette drive 114 is provided to releasably accept and play a video
cassette 116 to produce the pure video and audio signals 78, 80 which are
input to a video amplifier 118 and an audio amplifier 120, respectively.
The outputs from the amplifiers 118, 120 are input to modulator 84 along
with the preferred 902-928 MHz band carrier signal from the oscillator 86.
The FM signal from the modulator 84 is fed into power amplifier 88 and
from thence through a bandpass filter 122 to the omni-directional antenna
26'. The remote control receiver 62 which was discussed earlier is also
connected to the antenna 26' through trap 124 so as to receive control
signals therefrom. The trap 124 and bandpass filter 122 assure that the
video/audio FM signals being broadcast and the control signals being
received through the common antenna 26' are properly directed and filtered
of unwanted signal components. Again as previously mentioned, the remote
control receiver 62 is connected to the preamplifier 72 as one input
thereof with the IR detector 36 providing the other input thereof. The
output from the preamplifier 72 provides the control signal input to the
function control circuit 126 which, in turn, is connected to control the
power supply 12 (i.e. turn the set off and on remotely) and the cassette
drive 114 (e.g. to provide direction and speed control commands).
In like manner, a preferred configuration for a fully integrated TV set 20'
is shown in a more detailed block diagram in FIG. 15. Again, there is a
single power supply 112 and all the components are in a common case (not
shown for simplicity). The adjustable, directional antenna 28' is
connected to a first bandpass filter 128 for passing only the 902-928 MHz
band preferred local broadcasting frequency. The output of the filter 128
is connected to a selectable tuner 130. The preferred configuration for
the tuner 130 is a bi-selectable tuner having a switch 131 by means of
which a selection between an "A" channel and a "B" channel can be made.
The reason for this preferred embodiment can be seen with a brief
digression to FIG. 19. The usual television "channel" occupies a bandwidth
of 6 MHz (e.g. channel 5 occupies 76-82 MHz). Commercial television
broadcasting equipment employs complicated and expensive so-called "single
sideband" transmitting apparatus to accomplish this in order to get twice
as much broadcasting capability in the same space. For the
consumer-oriented equipment as wherein the present invention is directed,
cost is a major factor in consumer acceptability. Thus, the single
sideband approach is cost prohibitive and applicants contemplate that a
full 12 MHz will be occupied by a single transmitting/receiving pair
employing the present invention in its anticipated preferred
configurations. Therefore, it is anticipated that there will be selectable
"A" and "B" channels centered about 909 and 921 MHz, respectively. The use
of the two channels, coupled with the FM | | |
