Digital communications modulation method and apparatus

A method and apparatus for single signal, multiple channel digital information transfer through waves with time slot allocation. The apparatus consists of one or more transmitting devices and one or more receiving devices. Multiple source signals are each allocated a unique time slot between successive synchronization waves. Digital signals from each source are converted to analog information waves having a positive wave segment and a negative wave segment. The ratio of the amplitude of the positive wave segment to the amplitude of the negative wave segment, the positive-to-negative ratio, for each signal source, is a function of the magnitude of the source digital. The sum of the amplitude of the positive wave segment and the absolute value of the amplitude of the negative wave segment, the positive-to-negative offset, is maintained at a pre-set value at transmission. The total signal, which consists of successive synchronization waves interspersed with information waves for each signal source, each within its allocated time slot, is transmitted to the receivers which extract the positive-to-negative ratio and positive-to-negative offset for each signal source, calibrate the received signals and generate output signals which reproduce the transmitted inputs.

FIELD OF THE INVENTION 
This invention relates to methods and apparatuses for modulation of 
electromagnetic waves for information transfer and more particularly to 
methods and apparatuses for modulating electromagnetic waves for digital 
information transfer. 
BACKGROUND OF THE INVENTION 
There are several principal modulation methods for electromagnetic signals 
used in communications. The ones that are most widely used are frequency 
modulation (FM), amplitude modulation (AM), pulse width modulation (PWM) 
and phase modulation (PM). There have also been some other less widely 
used methods for transmitting and receiving information by means of 
electromagnetic signals. The demands of modern information transfer, in 
particular computer networking and multi-media communications, have 
increased the need to transmit more and more information on limited 
channels of communication. With the ever increasing capacity of digital 
computers, there is an ever increasing demand for modulation methods to 
enhance the volume of digital data that can be transmitted and received. 
Methods have been developed for increasing the amount of information that 
can be transmitted and received. One such method is described in U.S. Pat. 
No. 4,387,455 to Schwartz. This method utilizes several different 
modulation systems at the same time over the same channel. However, this 
method uses FM and AM modulation and requires several cycles for each 
digital bit. Similarly the device disclosed in U.S. Pat. No. 4,103,238 to 
Deming, provides for three modulation patterns to be transmitted 
simultaneously on a single carrier wave. Again, multiple cycles are 
required for each digital bit. The deficiencies of these methods are 
typical of efforts to increase the amount of information transmitted. 
The method disclosed in U.S. Pat. No. 4,584,692 to Yazuka relies on the 
same common modulation methods but introduces polarity modulations as a 
means of enhancing the amount of information that can be transmitted. The 
polarity of the waves is modulated to encode information and then the 
original wave and the modulated wave are compared to allow decoding of the 
information. This results in a modest increase in the amount of 
information that can be transmitted over a single signal. 
Various methods designed specifically for digital information transfer 
provide some enhancement of the data transfer capabilities. The method 
disclosed in U.S. Pat. No. 4,001,728 to Schneider is a method of 
transmitting digital signals through the use of pulse width modulation on 
an incremental ramp wave. A method of transmitting multiple digital 
signals on a single carrier wave is disclosed in U.S. Pat. No. 4,347,616 
to Murakami. Another method providing for the simultaneous transmission of 
multiple digital signals independently modulated is disclosed in U.S. Pat. 
No. 3,805,191 to Kawai. 
The method disclosed in U.S. Pat. No. 3,890,620 to Toman provides for the 
modulation of a carrier wave at prescribed time intervals with digital 
information. This method, however, points up the limitations of attempts 
to enhance existing methods of digital information transfer. Incoming 
digital data must first be stored and then it is recalled for transmission 
at a rate compatible with the carrier wave modulation. The receiver then 
extracts the digital information from the signal by synchronization with 
the transmitter. The resultant signal is subject to interference at both 
the carrier frequency and the modulation frequency. 
U.S. Pat. No. 5,364,536 to Tsujimoto discloses a means of modulating a 
"data burst" on a carrier signal. Tsujimoto uses a modulation scheme to 
add a sync burst to the modulated carrier signal. This is accomplished by 
taking a delayed version of the data burst and the non-delayed data burst 
and taking the difference. This creates an artificial null in the 
frequency spectrum of the signal. This null spectrum sync burst is added 
to the signal before signal transmission. Thus for Tsujimoto, the sync 
burst becomes a signature burst for identifying the data burst. This 
method, as with the other known methods, relies upon the modulation of a 
carrier signal. It also does not provide for allocating time slots to 
multiple information signals. Also, for Tsujimoto the output digital 
signal is not calibrated. Instead, the signal strength of the carrier wave 
is calibrated. The null spectrum sync burst is not used for calibrating 
the received signal. 
The present invention is a method and apparatus for transmitting digital 
communications. The present invention's primary advantage over traditional 
modulation techniques is the quantity of digital information that can be 
transmitted and received. Both FM and AM modulation were developed for 
transmitting analog signals and, for that reason, are cumbersome in 
transmitting digital signals. The present invention is designed 
specifically for transmitting digital signals. 
This method does not require a carrier wave to transmit the information. 
Depending upon the information signal sources and the frequencies 
utilized, thousands of times more information can be transmitted. In FM 
systems hundreds and even thousands of cycles are required for just one 
bit of information. This is also true for AM modulation systems. The 
present invention provides for the placement of two bytes or more of 
information in each and every cycle. Another advantage of the present 
invention is the enhanced signal to noise ratio. 
One objective of the present invention is to provide a digital information 
transfer method which does not require a carrier wave. 
Another objective of the present invention is to provide a method and 
apparatus which substantially increases the amount of digital information 
that can be transmitted on a single signal. 
A further objective is to provide a method and apparatus for transmitting 
and receiving multiple channels of information on a single communication 
signal. 
A still further objective of the present invention is to provide a method 
and apparatus for continuously synchronizing a transmitter and receiver so 
that multiple channels of information can be reliably transmitted on a 
single communication signal by allocation of time slots to each channel. 
A still further objective is to provide a method and apparatus for received 
signals to be calibrated by the receiver to compensate for signal 
attenuation, losses, noise, distortion and interference, and thereby to 
provide for very accurate read out of the digital information transmitted. 
A still further objective is to provide a method and apparatus for digital 
information transfer which can utilize either a common synchronized 
transmitter or a plurality of remote synchronized transmitters and can 
utilize either a common receiver or a plurality of receivers. 
A still further objective is to provide a method and apparatus for digital 
information transfer which will increase the signal to noise ratio of the 
received signals in comparison to other known methods. 
SUMMARY OF THE INVENTION 
The present invention provides a method and apparatus for increasing the 
amount of digital information that can be transmitted over an 
electromagnetic signal. The apparatus of a preferred embodiment of the 
present invention includes computer circuits and transmission and 
receiving devices. Embodiments of the apparatus can include multiple 
transmitters at multiple locations or a single transmitter which is 
accessed by each signal source. Under either embodiment, each signal 
source is allocated a time slot for each successive cycle between 
synchronization pulses. If multiple transmission locations and 
transmission apparatuses are utilized, each such transmission apparatus is 
equipped with an analog receiver for receiving synchronization pulse 
transmissions from a master synchronization pulse transmitter. Each remote 
signal source is allocated a unique time slot between successive 
synchronization pulses for transmission of information simultaneously with 
other remote signal sources which are each allocated a different time slot 
between the successive synchronization pulses. Likewise, if a common 
transmission location and transmission apparatus is utilized, each signal 
source that accesses the system is allocated a unique time slot between 
successive synchronization pulses which are generated by the master 
synchronization pulse transmitter. 
For each signal source, the digital value of the source signal during its 
allocated time slot, is converted, under a preferred embodiment, to an 
analog pulse, called an information pulse, which is comprised of a 
positive wave segment and a negative wave segment, with the sum of the 
amplitude of the positive wave segment and the absolute value of the 
amplitude of the negative wave segment of the information pulse, hereafter 
referred to as the information pulse positive-to-negative offset, being a 
pre-selected value, and the ratio of the amplitude of the positive wave 
segment to the amplitude of the negative wave segment of the information 
pulse being a function of the value of the digital input. In other words, 
under a preferred embodiment, the positive-to-negative offset is held 
constant, and the value of the digital input determines the ratio of the 
amplitudes of the positive and negative wave segments. 
Under other embodiments, the reference value for the measurement of the 
amplitudes of the positive and negative segments can be any positive or 
negative value. 
Within the allocated time slot for the information pulse, the transmission 
apparatus generates the information pulse with its positive and negative 
components. The positive-to-negative offset is the calibration control for 
the signal and is set at a constant value. Whether the embodiment utilizes 
remote transmission locations and apparatuses or a common transmission 
location and apparatus, an information pulse is generated for each signal 
source for each cycle of its allocated time slot. 
The information pulse generated for each signal source is transmitted in 
that time slot for each successive cycle of the synchronization pulses. 
These transmissions may be from remote locations or from a common location 
and may be wireless or may be transmitted via any of the well known media. 
The period of each information pulse is determined by the ability of the 
receiving circuits to handle them, but will generally be as small as 
possible to reduce the effects of noise and distortion. 
The receiving apparatus calibrates each information signal for each channel 
respectively by using the information pulse positive-to-negative offset 
for the information signal as measured by the receiving apparatus, 
adjusting the positive-to-negative offset to the known value at 
transmission, and then computing the ratio of the amplitude of the 
positive wave segment to the amplitude of the negative wave segment. This 
ensures that the effects of signal attenuation, losses, noise, distortion 
and interference are minimized. The calibrated amplitudes ratio is then 
used with the known function that was used to generate the amplitudes 
ratio at the transmission location, to generate an output digital signal. 
The receiving apparatus also preferably performs a zero crossing reference 
check to enhance calibration. This is best accomplished if a brief zero 
wave segment is placed in each information pulse between the positive and 
negative wave segments. Then preferably the initial step in calibration is 
a zero correction for the zero wave segment. After the zero wave segment 
in the received information pulse is corrected to zero, the rest of the 
calibration process is completed. This zero correction enhances the 
effectiveness of the subsequent proportional calibration. 
The synchronization pulses provide for continuous synchronization of the 
transmitting apparatus and the receiving apparatus so that channel 
tracking integrity is maintained at all times. A common receiver can be 
utilized from which the various channels of information are disseminated 
to users or a plurality of receivers can be utilized at various points of 
use or dissemination.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring first to FIG. 1, there is indicated generally therein a schematic 
of a preferred embodiment of a transmission apparatus 1 of the invention. 
This embodiment of the transmission apparatus is utilized for remote, 
simultaneous transmission of digital signals. Under this embodiment, the 
transmission apparatus comprises a digital to analog signal generator 2, a 
composite signal generator 4, a master control circuit 15, a control 
receiver 14, a remote master synchronization pulse generator 8, a 
synchronization pulse receiver 5, and a transmitter 10. 
Under this embodiment, a digital input 3, for each signal source, is input 
to its respective transmission apparatus 1. Synchronization pulses 7 of a 
selected uniform wave form and frequency are generated by the master 
synchronization pulse transmitter 8 and are transmitted to each of the 
remote transmission apparatuses 1 where it is received by the analog 
synchronization pulse receiver 5. The synchronization pulses can be either 
voltage pulses or power pulses. Each of the signal sources is allocated a 
time slot between the successive synchronization pulses by the remote 
master control circuit 15 and the digital value of each signal source at 
each of its successive allocated time slots is converted to an analog 
information pulse 9, the positive-to-negative offset 6 of which, under a 
preferred embodiment, is a pre-set value and the ratio of the amplitude 41 
of the positive segment 39 and the amplitude 42 of the negative segment 40 
of the information pulse 9 is a function of the digital value of the 
source signal 3. For some embodiments the ratio of the amplitudes is 
simply proportional to the value of the input digital signal. For other 
embodiments, the ratio of the amplitudes of the positive and negative 
segments of the information pulse is determined through the use of an 
algorithm based upon the digital input value. 
In preferred embodiments, the output signal from the digital to analog 
signal generator 2 is an analog information pulse 9 which has a pre-set 
positive-to-negative offset 6 and for which the ratio of the amplitude 41 
of the positive segment 39 and the amplitude 42 of the negative segment 40 
is a function of the digital value of the input signal. Under preferred 
embodiments, the information pulse is a voltage pulse, but under other 
embodiments the information pulse may be a power pulse. 
Under a preferred embodiment for a remote transmission apparatus 1 as shown 
in FIG. 1, the composite signal circuit 4 may receive continuous 
transmissions or discrete transmissions of the information pulse, and, by 
monitoring the synchronization pulses 7 and the control signal from the 
control receiver 14, passes the information pulse to the transmitter 10 
only during its allocated time slot. 
Referring now to FIG. 3 which shows another preferred embodiment of the 
transmission apparatus, a common transmission apparatus 12 simultaneously 
accepts digital signals 3 from one or more sources. A synchronization 
pulse circuit 13 generates synchronization pulses 7 of a pre-set 
magnitude, wave form and frequency. The master control circuit 15 
allocates each signal source a time slot between successive 
synchronization pulses. For each cycle of the synchronization pulse, an 
information pulse 9 is generated for each input signal within its 
allocated time slot by the digital to analog signal generator 2. The 
composite signal circuit 4 may receive continuous transmissions or 
discrete transmissions of the information pulse, and, by monitoring the 
synchronization pulses 7 and the control signal from the control receiver 
14, passes the information pulse to the transmitter 10 only during its 
allocated time slot. The information pulse for each signal source is 
transmitted by the common transmission apparatus 12 to the receiving 
apparatus 16 shown on FIG. 2. 
Whether an embodiment of the transmission apparatus providing for the 
remote and separate transmission of analog information pulses 11 for 
signal sources as shown in FIG. 1 or an embodiment providing for the 
transmission of information pulses for signal sources from a common 
transmission apparatus as shown in FIG. 3, is used, the total signal 17 as 
illustrated in FIG. 4, is the same for the same source signals. Under the 
embodiment shown in FIG. 1, the synchronization pulses are transmitted by 
the master synchronization pulse generator 8, and each of the time slotted 
information pulses 11 are transmitted from the various remote transmission 
apparatuses 1. The total signal received by a receiver 16 then consists of 
successive synchronization pulses 7 coming from the master synchronization 
pulse generator 8 interspersed with the time slotted information pulses 
coming from the various remote transmitters 10. Under the embodiment shown 
in FIG. 3, the total signal received by a receiving apparatus 16 is 
comprised of the successive synchronization pulses interspersed with the 
time slotted information pulses coming from the common transmitter 10. 
Under a preferred embodiment, the synchronization pulses are of a uniform, 
rectangular and positive voltage wave form, with a uniform frequency 
selected as desired. The synchronization pulses allow a receiving 
apparatus 16 to continuously verify the time slots of the incoming signal 
17 so that the respective information pulses can be extracted from the 
correct assigned time slots or channels. The minimum frequency of the 
synchronization pulse will be dependent upon the nature of the information 
being transmitted over the various channels. For example, approximately 
1,000 television channels can be transmitted with a single signal with 
this invention as it is limited only by minimum frequency at which 
successive audio and video signals must be received to produce the desired 
resolution for video and audio reproduction. Other types of media or 
signal types have different requirements which will affect the minimum 
frequency of the synchronization pulse. The frequency of the 
synchronization pulse, therefore, would be adjusted depending upon the 
application. 
Under a preferred embodiment, the information pulse has a sinusoidal 
waveform. This allows the signal to be transmitted with a narrow 
bandwidth. However, other embodiments may utilize a variety of waveforms 
for the information pulse. 
Under preferred embodiments, both for the remote transmission apparatus as 
shown in FIG. 1 and the common transmission apparatus as shown in FIG. 3, 
the information pulse generated by the digital to analog signal generator 
has a zero crossing reference 43 between the positive and the negative 
segments. Under preferred embodiments, this zero crossing reference is a 
brief zero wave segment between the positive and negative segments, which 
is used by the receiving apparatus to check the zero point of the received 
information pulse at this interim segment. The brief zero wave segment 
makes it easier for the receiver calibration circuit 29 to find the exact 
zero crossing. This enhances the signal to noise ratio because even if 
there was some non-symmetrical noise added to the signal, the effect on 
the zero crossing would be less than for the other wave segments. A zero 
correction at this interim segment then enhances the effectiveness of the 
other calibration techniques, which, under preferred embodiments, involve 
proportional calibration using the information pulse positive-to-negative 
offset. 
For the common transmission apparatus shown in FIG. 3, the master control 
circuit 15 monitors and tracks all of the incoming signals and allocates 
time slots or channels for the respective information pulses for each of 
the accepted incoming signals. Referring to FIG. 4, the total signal 17 
that is transmitted by the transmission apparatus is comprised of 
synchronization pulses 7 of a selected uniform wave form and frequency and 
information pulses 11 for each information channel. The time between the 
respective synchronization pulses 38 is determined by the nature of the 
signals being transmitted and the total number of channels being 
transmitted. For the remote transmission apparatus shown in FIG. 1, one 
master control circuit 15 monitors and tracks all the source signals and 
allocates time slots or channels for each of the accepted signals and 
transmits this control information to a control receiver 14 for each 
remote transmission location and transmission apparatus 1. 
Other embodiments of the invention, whether for remote transmission as 
shown in FIG. 5 or for common transmission as shown in FIG. 6, provide for 
further enhancement of the amount of information that can be transmitted 
by incorporating a first digital to analog convertor 18, a second digital 
to analog convertor 19, and an added signal generator 20, which allows a 
first digital byte input 21 and a second digital byte input 22, such as 
the video and audio signals for a television transmission, to be converted 
from digital to analog and then added and converted into a single 
information pulse by the added signal generator 20. The total signal for a 
given time slot or channel is then a combined signal that can be 
transmitted as one. 
The embodiments shown in FIG. 5 and FIG. 6 could also be used to combine 
two input signals with one being converted to a positive analog signal and 
the other to a negative analog signal by the digital to analog convertors 
18 & 19. 
While for preferred embodiments, the synchronization pulses and the 
information pulses are voltage pulses, other embodiments may utilize power 
pulses. Also, while for preferred embodiments the ratio of the amplitude 
of the positive wave segment to the amplitude of the negative wave segment 
of an information pulse is directly proportional to its corresponding 
digital input value, other embodiments may provide for the ratio to be 
determined by an algorithm based on the digital input value. 
FIG. 4 illustrates the total signal 17 transmitted and received, whether 
remote transmission (FIG. 1) or common transmission (FIG. 3) is utilized. 
The total signal 17 consists of one or more information pulses 11 within 
their respective time slots 36, interspersed between successive 
synchronization pulses 7. The period, magnitude and wave form of the 
synchronization pulses 7 is uniform and adjustable. Each signal source is 
admitted to the network by the master control circuit 15 and allocated a 
time slot 36. Unallocated time space 37 between synchronization pulses is 
available for subsequent allocation to other signal sources. 
Other embodiments may provide for interaction between the master control 
circuit 15 and the synchronization pulse generator 8 (FIG. 1) or 13 (FIG. 
3) so that the frequency of the synchronization pulses is adjusted, based 
upon the number of channels being transmitted. 
Referring now to FIG. 2, there is indicated generally therein a preferred 
embodiment of a receiving apparatus 16. This embodiment comprises a 
receiving circuit 23, a control circuit 24, a positive-to-negative ratio 
sample hold circuit 25, positive-to-negative offset sample hold circuit 
26, a positive-to-negative ratio analog to digital convertor 27, a 
positive-to-negative offset analog to digital convertor 28, and a 
calibration circuit 29. For embodiments of the transmission apparatus as 
shown in FIG. 1, which provide for the remote transmission of time slotted 
signals, the receiving apparatus 16 receives the incoming total signal 17. 
The receiver control circuit 24 uses the synchronization pulses to 
allocate and maintain channel separation. The receiver control circuit 24 
may also control which signals are allowed to pass through the receiving 
circuit 23. The receiving circuit 23 first makes a zero check for the zero 
crossing reference 46 of the received information pulse 30 and makes a 
zero correction of the received information pulse. The receiving circuit 
23 then determines the positive-to-negative offset 35 of the information 
pulse and the ratio of the amplitude 44 of the positive wave segment 31 to 
the amplitude 45 of the negative wave segment 32 for each time slot or 
channel. The positive-to-negative offset sample hold circuit 25 extracts 
the maximum positive-to-negative offset value for each time slot or 
channel for each cycle of the received channel signal. Likewise, the 
positive-to-negative ratio sample hold circuit 26 extracts the maximum 
positive-to-negative ratio value for each channel. The receiver control 
circuit 24 establishes the channel time slots for the positive-to-negative 
offset sample hold circuit 25 and the positive-to-negative ratio sample 
hold circuit 26. 
The positive-to-negative offset analog to digital converter 27 converts the 
values obtained by the positive-to-negative offset sample hold circuit 25 
for each channel to digital. The positive-to-negative ratio analog to 
digital converter 28 converts the values obtained by the 
positive-to-negative sample hold circuit 26 for each channel to digital. 
Under a preferred embodiment, the analog to digital converters 27 and 28 
are special flash analog to digital converters. 
Other embodiments of the invention may use the analog value of the 
positive-to-negative offset to calibrate the received analog signal. For 
those embodiments this will preferably occur after the zero check and 
correction is made. The calibration is made to the wave before the analog 
positive-to-negative ratio is extracted and converted to digital. For 
those embodiments only one analog to digital converter is required in the 
receiver. 
A preferred embodiment uses a special flash analog to digital circuit 
developed for the present invention. The circuit consists of several sets 
of flash analog digital circuits. The flash consists of two arrays. The 
first array consists of ten flash circuits vertically and six horizontal 
for sixty circuits in all. The first set of ten is the most significant 
number, with six being the least significant. This allows it to measure a 
number as large as 999,999, but, however, larger arrays can be used for 
any size number. 
A calibration circuit 29 compares the digital values from the 
positive-to-negative offset analog to digital convertor 28 for each 
channel with the transmission digital value for the positive-to-negative 
offset and a calibration factor is determined which accounts for losses or 
noise. The positive-to-negative ratio values from the positive-to-negative 
ratio analog to digital convertor 27 for each channel are then calibrated 
through the use of this calibration factor and the digital output signals 
47 are generated. In this way the original digital signals input to the 
transmission apparatus are obtained for each channel. The reproduced 
signals 47 for each signal source are then available for use or 
dissemination by the intended users. 
Under a preferred embodiment of the invention, a master control circuit 15 
monitors a multi-media network to determine the time slot to be allocated 
to the various incoming signals. A signal source wanting to use the 
network would first address the master control circuit 15 to request 
access to the network. The main control circuit then allocates a time slot 
that is not being used. 
Referring again to FIG. 1, under a preferred embodiment of the invention, 
if an acceptable initiating signal is received by the master control 
circuit 15, the incoming signal is allocated an unused time slot channel. 
Successive cycles of the time slot then carry the latest information pulse 
for the source. The converted analog signals for each channel are updated 
with each synchronization cycle. 
The receiving apparatus 16 can be deployed at a single location with 
information dissemination occurring from the single location or can be 
deployed at a plurality of locations with users tuning in to the desired 
signals. 
Under a preferred embodiment, depending upon the type of signal source of 
the respective channels, the minimum frequency of the synchronization 
pulse is the minimum frequency that will permit an acceptably accurate 
reproduction of the input digital signal. For data transmission 
applications which require precise reproduction of transmitted data, the 
frequency of the synchronization pulse must be at least as high as the 
frequency of the change of the digital source signal. 
An embodiment of the invention provides an apparatus and method that would 
allow substantially faster computer networks. Substantially more computers 
could be added to any given network without degrading the network's speed. 
In computer networking the present invention will speed up the data 
transfer rates and make computer networking more efficient. It will allow 
for more computers to be used on a network without degrading the network. 
It will also allow monitors, hard drives, printers and other devices at 
separate addresses all to be connected together by a single link. This 
link could be wire, fiber optics, or wireless communication, with each 
component allocated a time slot channel. 
Another embodiment of the invention provides for enhancement of interactive 
robotics. Each component of a robotics device would be controlled by a 
single signal with each component accessing a time slot channel. This 
would make it possible for work to be accomplished in a hazardous area 
without exposing the operator to physical risk associated with the 
environment and wearing a suit as designed with sensors to detect 
movement, touch and sight, and then transmit these movements or essential 
perceptions to the robot. The robot would then transmit back what it was 
doing, and what it was sensing. The operator in the suit would then feel 
what the robot was feeling, what it was seeing and what it was doing 
instantaneously. 
Another embodiment of the apparatus and method provides for the 
transmission of voice data to specific addresses based upon the time slot 
channel allocated. 
Another embodiment of the invention provides for the simultaneous 
transmission of a large number of video recordings. Thousands of video 
recordings can be transmitted simultaneously allowing users to make a 
selection of any of the videos at any time. 
Another embodiment provides for radio and television signal transmission. 
The present invention greatly increases the channel capacity for the band 
width allowed. Furthermore, this embodiment of the invention allows the 
routing of specific channels to specific locations. This allows users to 
access a tremendous video library from their homes. It, likewise, allows 
users to access books at public and private libraries. It allows students 
to complete school work at home and to interact with their instructors as 
well as other students. This allows more channels for radio, televisions 
and cellular telephones. Furthermore, not only would the number of 
channels be increased, but channels would be of digital quality. 
An embodiment of the invention enhances the operation of video recorders by 
allowing them to operate on a digital format. This embodiment also allows 
the replacement of the revolving head with a fixed head, which makes them 
more reliable and more compact. Likewise, embodiments of the invention as 
applied to audio recorders allow audio recorders to be made digital. 
Another embodiment of the invention provides for the expansion of the 
capacity of cellular phone networks by assigning each call to an 
unallocated time slot for simultaneous transmission and then deleting the 
call from the network upon completion of the call, making the channel 
available for other users and other callers. 
Under preferred embodiments of the invention, neither the 
positive-to-negative offset nor the positive-to-negative ratio would be 
modulated onto a carrier wave. However, the present invention could be 
used to modulate a carrier wave. In fact, under other embodiments of the 
invention, the positive-to-negative offset and the positive-to-negative 
ratio could be modulated onto an FM, PM, or PWM carrier wave. For example, 
the positive and negative information pulse segments could be superimposed 
upon the peak for the carrier wave. This would allow the information 
pulses to be removed and the information recovered without affecting the 
information being transmitted by the other modulation methods. After the 
pulses are recovered, the positive-to-negative offset and the 
positive-to-negative ratio would then be analyzed in the same manner as is 
provided for the preferred embodiments described above. The process of 
adding the pulses to the respective carriers uses the process of finding 
the high or the low points of each cycle and superimposing the information 
pulses, if desired, to the selected points. Under such embodiments, a 
synchronization pulse would not ordinarily be used as the channel 
identification would arise from carrier wave identification. 
An embodiment of the present invention provides for the substantial 
increase in the capacity of existing telephone systems. The simultaneous 
transmission of numerous calls from a single signal could greatly increase 
the capacity of existing facilities. Alternatively switching circuits 
could be much smaller and would be able to provide more reliable service. 
Another embodiment of the invention provides for home stereos to transmit 
specific information to specific speakers. For example, one speaker could 
be for drums, one for the piano, one for brass instruments, one for 
strings. One could have the whole orchestra in the living room. 
Furthermore, the components could be connected by a single wire or the 
central unit could be entirely wireless. 
Another embodiment of the present invention provides for shelf tags in 
grocery stores. Each electronic grocery store shelf price tag has its own 
address for each item allowing for instantaneous update of item and price 
changes. Each product has its own time slot and the transmission can be 
wireless, allowing complete freedom of location for the shelf tags. 
Other embodiments of the invention and other variations and modifications 
of the embodiments described above will be obvious to a person skilled in 
the art. Therefore, the foregoing is intended to be merely illustrative of 
the invention and the invention is limited only by the following claims.