EP1019837A1

EP1019837A1 - Universal inter-device data transfer using radio frequency communication

Info

Publication number: EP1019837A1
Application number: EP98952005A
Authority: EP
Inventors: Stanley A. White; Kenneth S. Walley; James W. Johnston; P. Michael Henderson; Kelly H. Hale; Warner B. Andrews, Jr.; Jonathan I. Siann
Original assignee: Conexant Systems LLC
Current assignee: Conexant Systems LLC
Priority date: 1997-09-30
Filing date: 1998-09-30
Publication date: 2000-07-19
Also published as: WO1999017213A1

Abstract

A system for communicating information among a plurality of electronic devices using a plurality of radio frequency communication channels is described. The system includes a plurality of electronic appliances or devices. Each electronic device includes one or more receiver ports, and one or more transmitter ports. Each receiver port includes a radio receiver for receiving information communicated on an RF communication channel. Each transmitter port includes a radio transmitter for transmitting information on any of two or more RF communication channels to other of the appliances in the system. In particular embodiments, each receiver port in the system is tuned to a unique RF communication channel. Each transmitter port of each device in the system may be tuned to any of the unique RF communication channels to which the receiver ports of the other devices in the system are tuned. Each RF communication channel may be an RF carrier modulated at a predetermined modulation frequency, or a spread spectrum RF signal encoded with a predetermined code.

Description

Universal Inter-Device Data Transfer

Using Radio Frequency Communication

Background of the invention.

The present invention relates to a system for communicating or transferring information among electronic devices or appliances. The present invention is particularly directed to communication among devices in a defined environment, such as an office, a factory, or a home.

Many households, offices, and factories have an abundance of electronic devices or appliances. Often, the resident or occupant of the household, office, or factory wishes to have several of these devices communicate with one another.

For example, a household may have one or more computers. Each computer may need to be connected to one or more printers. In addition, the household may include entertainment electronics, such as compact disc players, televisions, and video cassette or video disc players. Furthermore, other items may be connected either to one another, or to a central control computer. Such additional items may include an irrigation system, a security system, lighting systems, etc.

In an office environment, multiple computers may each need to communicate with several printers. For example, each computer may, at different times, need to print documents on a low volume black and white convenience printer, a high speed black and white printer, a low volume color printer, and a high volume color printer. In addition, some of the computers may need to exchange information with, or to transfer information to, telephone systems, climate control systems, door or lock controls, and security systems. In a manufacturing environment, different assembly or manufacturing machines may need to transfer information among themselves. In addition, the different manufacturing machines may receive control information from a control computer. Prior to the present invention, a physical wire connection between electronic devices was generally required for the devices to communicate with one another. Certain appliances have been designed to communicate with one another wirelessly, generally using infrared signals. One example is the infrared link provided between specific computers and specific printers. However, such systems for infrared wireless communications typically require that each individual device to device link be specifically set up. Each infrared port is generally dedicated to a single communication link. Thus, each port provides communication with only a single other device. Infrared communications between devices requires that the communication ports maintain a line-of-sight relationship.

Some specialized devices provide for wireless communication of information over radio links. Such devices and their radio links are special purpose, and may require that a communication port be specially dedicated to that particular link. Present wireless communications schemes, and most hard-wired communications links, do not address the issue of multiple demands upon a particular device. Certain of the appliances may be called upon by more than one of the other appliances at the same time. In such instances, the appliance should include a mechanism to detect and prioritize such conflicts. Wireless systems have typically not been required to address this issue because each wireless port typically was dedicated to a single communication link with a single other device. In hard-wired systems, a separate device has often been provided to prioritize usage conflicts. For example, multiple computers connected to a single printer typically required that a separate device be connected to the printer to assure that when both computers simultaneously activate the printer, the printer does not receive such information until after it is prioritized

Summary of Invention

The present invention provides for communicating information among a plurality of electronic devices using a plurality of radio frequency communication channels The system includes a plurality of electronic devices Each appliance includes one or more input ports, and one or more output ports Each input port includes a radio receiver for receiving information communicated on an RF communication channel Each output port includes a radio transmitter for transmitting information on any of two or more RF communication channels to at least one other device in the system

In particular embodiments, each input port in the system is tuned to a unique RF communication channel Each output port of each device in the system may be tuned to any of the unique RF communication channels to which the input ports of the other devices in the system are tuned.

Each RF communication channel may be an RF carrier modulated at a predetermined modulation frequency, or a spread spectrum RF signal encoded with a predetermined code.

The electronic device of the present invention includes an RF receiver tuned to receive, on a first predetermined RF communications channel, information for controlling the device. The device also includes an RF transmitter tuned to transmit, on any of a plurality of RF communications channels different from the first RF communications channel, information for controlling a different electronic device The device additionally includes a controller for tuning the RF transmitter to a particular RF communications channel, and for determining if another electronic device is transmitting information on that particular RF communications channel In particular embodiments, the electronic device includes one or more additional RF receivers, each of which is tuned to receive information on an RF communications channel other than the first predetermined RF communications channel The electronic device may include one or more additional RF transmitters, each of which may be tuned to transmit on any of the plurality of RF communications channels

It is an object of the present invention to provide a system that permits wireless communication among a number of electronic devices

It is an object of the present invention to provide a system for communication among electronic devices or appliances that permits an additional device to be easily and immediately integrated into the system

It is an object of the present invention to provide a system for communication among electronic devices that does not require that each communication link between devices be separately established It is an object of the present invention to provide a system whereby multiple electronic devices wirelessly communicate with one another, regardless of the relative positions of the devices

It is object of the present invention to permit a number of electronic devices to communicate with one another while automatically insuring that conflicts in the communication channel do not occur

Brief Description of the Drawings

Figure 1 is a system diagram illustrating an exemplary system of electronic devices incorporating the present invention.

Figure 2 is a simplified illustration of panels of some of the electronic devices in the system of Figure 1.

Figure 3 is a simplified illustration of a portion of the transmitter that may be used in conjunction with the present invention Figure 4 is a flow chart illustrating a portion of the conflict avoidance mechanism provided in an embodiment of the present invention.

Detailed Description of a Preferred Embodiment

Figure 1 shows a simplified diagram of an exemplary system of electronic devices or appliances incorporating a wireless communication system in accordance with the present invention. Any combination of electronic devices or appliances may be included in the system However, for the purposes of the present example, the elements shown in Figure 1 will be described In addition, only some of the many possible communication links between the elements of the system shown in Figure 1 will be discussed

The exemplary system of Figure 1 may include two computers 1 10,120 The first computer 1 10 may include a central processing unit (CPU) 1 12, a display 1 14, and an input device, such as a keyboard 1 16

Similarly, the second computer 120 may include a central processing unit 122, a display 124, and a keyboard 126.

In accordance with the present indention, each of these computers 110, 120 communicates with each of two printers 130, 132 over radio frequency ( RF) communication links or channels. These RF communication links or channels are illustrated in Figures 1 and 2 symbolically using arrows

Information is transferred from the CPU 1 12 of the first computer 1 10 to the first printer 130 over a first RF link 239. Information from the first printer 130 to the first CPU 1 12 travels on a second RF link 229. Information is passed from the first CPU 1 12 to the second printer 132 on a first RF link 259. The flow of information from the second printer 132 to the first CPU 1 12 is on a second RF link 249.

Similarly, the CPU 122 of the second computer 120 communicates with the first printer 130 over RF links 289, 299. The second CPU 122 communicates with the second printer 132 over RF links 249, 259. In addition to communicating with the printers 130, 132, the second computer 120 may also communicate with a climate control system 150 and with an entertainment device, such as a video disc player 140. The video disc player 140 may in turn communicate with a television set 144. In some applications, one of the computers 1 10, 120 may communicate with the television set 144. For example, the television set 144 may display the same information displayed on either of the computer displays 1 14, 124. Such capability may be useful in such applications as using a large television display while exploring the internet. Radio frequency communication between the various devices or appliances in a particular system eliminates the need to attach cables or wires among the various devices. In addition, the use of radio frequency communication between the appliances allows appliances to communicate information even when they are not within a single line of sight, such as if the appliances are in different rooms.

In accordance with the present invention, each electronic device in the system has one or more RF transmitter ports and one or more RF receiver ports. Each RF transmitter port includes an RF transmitter configured or set to transmit information on any of several RF communication channels. Each RF receiver port includes an RF receiver that is set to receive information on one and only one of the RF communication channels used in the system.

By setting the receivers in the system so that each receives information on one, and only one, RF communication channel, a unique, one-to-one relationship is thereby established between each receiver port and each RF communication channel. Just as each receiver port receives information on only one channel, each channel is used only to communicate information to that receiver port.

Permitting only one RF channel for each receiver port in the system provides a mechanism by which conflicts in transmitting information to each device are avoided. If one device wishes to communicate information to a second device or to a particular receiver port of the second device, the first device initially verifies that no other device is communicating on the RF channel assigned to that receiver port. If another device is transmitting information on_. that RF communication channel, the first device waits until the channel is clear. If, however, the transmitting device determines that there is no other transmitter operating on the desired RF communication channel of the desired receiver port, the transmitter may begin communicating information over that RF communication channel. Referring now to Figure 2, a few specific communication connections are illustrated. Shown in Figure 2 is a panel of the CPU 122 of the second computer 120. A multi-purpose device such as a personal computer may have reason to communicate with several other devices simultaneously. To do that, the computer may have several transmitter ports and several receiver ports. The exemplary embodiment illustrated in Figure 2 includes four transmitter ports 128a-d. Each transmitter port 128a-d includes an RF transmitter capable of transmitting on any of the RF communication channels that are used in the system.

An apparatus such as a personal computer may be capable of receiving and processing information from multiple sources simultaneously. Therefore, it may have multiple receiver ports, each set to its own receive channel. For simplicity of the following description, each RF communication channel will be considered as a particular RF frequency.

The exemplary personal computer shown in Figure 2 includes three receiver ports 129a-c. Each receiver port 129a-c includes a radio frequency receiver. Each receiver is configured, set, or tuned to receive one and only one RF frequency. Thus, the first receiver port 129a may be set to receive a first frequency f1. The second receiver port 129b may be set to receive a second RF frequency f2. The third receiver port 129c may be set to receive a third RF frequency f3. Any or all of the receiver ports 129a-c may be active simultaneously.

A panel from the first printer 130 is also shown. It may be desirable that only one computer at a time instruct the printer 130 to print. Thus, the printer_^ may be capable of communicating with only one other device (such as the computer 120) at a time. The printer may therefore have only a single transmitter port 138 and a single receiver port 139.

The receiver port 139 of the first printer 130 is set to receive information on a fourth RF communication channel, different from the RF communication channels of the three receiver ports 129a-c of the computer CPU 122. The receiver port 139 of the printer may, for example, be set to receive information on a fourth RF frequency f4.

Another device, such as the climate control system 150, may also have a single transmitter port 158 and a single receiver port 159. The receiver port 159 of the climate control system is tuned to receive information on an RF communication channel that is different τrom any of the other receiver ports.

Thus, the receiver port 159 may be tuned to receive information on a fifth frequency f5. The transmitter port 158 of the climate control system has the capability of being tuned to any of the frequencies of any of the receiver ports to which it may send data or information. This tunability gives the transmitter port

158 of the climate control the capability of being tuned to any of the receiver frequencies l , f2, f3 used by the receiver ports 129a-c of the computer CPU 122 with which the climate control 150 communicates. Preferably, the transmitter port 158 also has the capability of communicating over any of the RF frequencies used by any of the devices in the system. Such capability provides the flexibility for the systems to be reconfigured at a future date if necessary or beneficial.

As noted previously, each receiver port, such as the computer receiver ports 129a-c, the printer receiver port 139, and the climate control system receiver port 159 are each tuned to receive a unique frequency within the entire system. By using a unique RF frequency to communicate with each specific receiver port, it is easy for devices that wish to transmit information to that selected receiver port to determine whether that port is already busy receiving information from another device in the system. Consequently, whenever another device in the system desires to communicate with that particular receiver port of that particular device, the transmitting device first verifies that no other device is communication on that frequency. If no other device is communicating on that frequency, the transmitting device can transmit knowing that there is no conflict with the receiving device.

In the example described above in connection with the partial system shown in Figure 2, any device in the system uses the first RF communication frequency f1 only to communicate information to the first receiver port 129a of the personal computer CPU 122. Similarly, the fourth RF communication frequency f4 is used only to communicate information to the receiver port 139 of the printer 130. Thus, any device that detects "traffic" on the fourth frequency f4 may assume that another device is communicating information to the printer receiver port 139. Similarly, any device in the system that wishes to transmit information to the receiver port 159 of the climate control system 150 can monitor the RF frequency f5 to which the climate control system receiver port 159 is tuned. If the device detects radio signals on that frequency, the device determines that some other device is transmitting information to the receiver port 159 of the climate control system 150.

Using a single unique RF communication channel for each receiver port in the system provides the ability to manage potential conflicts over use of different devices in the system.

Each transmitter port 128a-d, 138, 158 includes a protocol receiver and a controller. The protocol receiver 125 and the controller 127 of the first computer transmitter port 128a are shown in Figure 3 as representative. Before the transmitter 123 of the transmitter port 128a transmits on a predetermined frequency, it first monitors that frequency through the protocol receiver 125 to ascertain that there is no other traffic on that frequency. The controller 127 connected to the protocol receiver 125 determines whether there are signals on the selected frequency. If there is no traffic or other signals on that frequency, controller 127 instructs the transmitter 123 can then transmit. If however, there is traffic (other signals) on the particular frequency, the transmitter must wait and try again later. The process followed within the transmitter port 128a is illustrated in the flow chart of Figure 4. For example, the CPU 122 may direct the first printer 130 to print a document. As noted above, the receiver port 139 of the first printer 130 may be tuned to receive information on the fourth frequency f4. The first transmitter port 128a of the CPU is set to transmit the print information on the fourth frequency f4, to establish the communication link 239. The CPU 122 may then transfer the print information to the printer 130.

If another device, such as another computer, is prepared to direct the first printer 130 to print a different document while that printer is receiving the first document from the CPU 122, the other device will first monitor the fourth frequency f4 of the printer's receiver port 139. Upon doing so, the other device will discover that the fourth frequency f4 is already in use. Upon discovering such prior use of the communication channel designated for the printer receiver port 139, the other device waits until its protocol receiver determines that there is no more traffic on the fourth frequency f4. Once the other device determines that the fourth frequency is clear, the other device may then proceed to transmit information to the printer 130.

A variety of small RF transmitters and receivers are available for use in the transmitter and receiver ports. These miniature RF transmitters and receivers are well understood by those skilled in the art. Such RF transmitters are widely used in cordless telephones, and in particular in digital cordless telephones. Many such radio transmitters and receivers Communicate on radio signals having carrier frequencies in the 900 MHz range. Other communications methods may be employed, such as digitally pulsed signals, and different types of encoded signals. Each RF communication channel may be a particular modulation of a given carrier frequency. However, in a system containing a large number of electronic devices, there may not be a adequate number of modulations available to provide a desired unique RF channel for each receiver port.

Spread-spectrum signals may be used to provide a large number of RF communication channels. The spread spectrum signals operate within an assigned bandwidth, each having unique code defining each unique RF channel for each intended receiver port. Using a spread-spectrum signal, a single RF receiver configuration and a single RF transmitter configuration may be used with all the devices in the system. Each transmitter and receiver decodes the spread spectrum signal to extract the information. This decoding is done digitally. The digital decoding may be done in any of a number of conventional manners, including hardware, firmware, or software control. RF transmitters and receivers for such encoded spread-spectrum signals are well known and commonly available. Using digitally encoded spread-spectrum signals also reduces the probability of interference among different systems that may be near one another. For example, such a configuration or embodiment may reduce the likelihood that a system in one residence may interfere with a similar system in an adjacent residence.

Each RF transmitter modulates information from the appliance or device onto the RF channel for transmission. Various modulation techniques may be used by the RF transmitters, and are well understood in the art. Similarly, each RF receiver receives the radio signal and demodulates the information from that radio signal. The RF frequency to which each receiver port is responsive may be set at the factory. This configuration is best served with an industry convention concerning the RF communication frequencies used by various devices. For example, all printers of a particular class (such as low volume black and white laser printers) may be set to receive information on the fourth specified frequency f4. All printers of a different class (such as high volume black and white laser printers) may be set to receive information on a different RF channel, such as a sixth frequency f6.

A preferable option is to manufacture each device with the receiver port capable of receiving signals of any of the RF communication channels that could be used in the system. Each receiver port has an adjustment so the user can set the specific channel for that device upon the device being brought into a particular system. In one embodiment, the receiver port is provided with a switch or series of switches to permit the user to manually set the radio channel over which the port is to receive information. Those skilled in the art will recognize that a variety of alternative arrangements may be provided. For example, the port may include a series of toggle switches, a rotating knob, software configuration, or other frequency selection mechanisms.

The printer 130 shown in Figure 2 includes a dial 137 as the frequency selection mechanism for the receiver port 139. The dial 137 may be rotated to change the frequency to which the RF receiver port 139 is tuned. In many embodiments it is desirable to provide a detent (not shown) at each channel or frequency setting on the dial 137.

The system described above allows, for example, the multiple computers 1 10, 120 to use multiple printers 130, 132. This use can be made without requiring physical wire connections amongst the various appliances.

Data signals are communicated over each communication link in the same manner that they are over a hard wire connection. Each transmitter and receiver port may be configured to process information either in parallel or serially, just as physical ports for use with wires .

Many device communication links require a two way transmission of information. For example, referring to the partial system illustrated in Figure 2, the CPU 122 transmits information to the printer 130 using the transmitter port 128a to the printer receiver port 139 over the communication link 238. This communication link 238 is established on the fourth communication frequency f4 of the printer receiver port 139. Information transmitted from the printer 130 to the CPU 122 is transmitted from the transmitter port 138 of the printer to the receiver port 129a of the CPU 122. This printer-to-CPU communication link

238 is established on the first frequency f1 , which is the communication channel designated for the receiver port 129a of the CPU 122.

Similarly, information is transmitted over the communication link 359 from the CPU transmitter port 128b to the climate control receiver port 159. This communication link 359 is established on the fifth RF communication frequency f5 to which the receiver port 159 is tuned. Any information transmitted from the climate control device 150 to the CPU is transmitted on a communication link 329 from the climate control system transmitter port 158 to the CPU receiver port 129b. This communication link 329 is established on the second RF frequency f2, which is the designated channel of the second CPU receiver port 129b. The second frequency f2 is different from the first frequency f1 of the first CPU receiver port 129a.

Thus, the CPU 122 may simultaneously communicate in both directions with both the first printer 130 and the climate control unit 150. If it is not necessary for a particular device to return information to the CPU 122, only a unidirectional communication link needs to be established. For example, if the climate control unit 150 need not communicate any information back to the CPU 122, the communication link 329 need not be established. The second receiver port 129b of the CPU 122 may then be used for receiving information from a different device

Other than the transmitter and receiver ports, each device in the system incorporates conventional device design Information received through the receiver ports, after being demodulated or decoded in the receiver, is directed and processed in the same manner as information received through a conventional data port Information is also processed conventionally within the device until the information is provided to the RF transmitter for transmitting to a different device in the system Specifically, conventional design techniques are used within the CPU 122 for directing the information from each receiver port 129a-c to the appropriate internal location Conventional design techniques are also used for directing information within the CPU 122 to the different transmitter ports 128a-d

Conventional designs are also used for the internal circuitry of the printer 130, including directing the information received at the receiver port 139 to the appropriate place within the printer. Besides the receiver and transmitter ports 138, 139 the printer 130 includes conventional printing mechanisms and circuitry Any number of different devices may be incorporated into the system For example, in a household environment, climate control, lighting, entertainment, irrigation, drapes, blinds, and cooking devices may be interconnected The system ideally includes at least as many RF communication channels for transmitting information as there are receiver ports on all of the devices connected within the entire system. As noted above, it is preferred that each receiver port be capable of receiving information on one of these RF frequencies, and that the user sets a particular receiver port to a particular frequency or channel In addition, each transmitter port is capable of transmitting on any of the RF frequencies used in the system Some are controlled within the device The device sets the frequency of the transmitter upon a particular use to the frequency to which the receiver port with which the transmitter is to communicate

In certain embodiments, it may be advantageous to limit the number of transmit frequencies available to a particular transmitter The transmission capability may be limited to the frequencies of the receiver ports with which it is most likely to communicate For example, in many installations it is highly unlikely that the climate control unit 150 would ever need to communicate directly with either of the printers 130, 132 Therefore, it may be beneficial not to provide the transmitter port 1 58 of the climate control unit 150 with the ability to transmit on any of the frequencies used by the receiver ports of either printer 130, 132 Similarly, there would be no need to provide the transmitter ports of printers with the frequencies used by the receiver port 159 of the climate control

However, overall costs may be reduced by manufacturing a universal receive unit and a universal transmitter unit that may be used in all devices

Such a universal receiver and universal transmitter may permit an economy of manufacture by allowing a large number of identical RF receivers to be manufactured

Those familiar with the art will recognize that the above description represents an exemplary description, and that numerous variations and alternatives are available and will be apparent to those skilled in the art upon reading the above description Therefore, the above description is intended to be exemplary only, and not limiting

Claims

CL IMS WE CLAIM: 1 . A system of electronic devices, the system comprising a plurality of devices, wherein each of said devices comprises:

one or more receiver ports, each of which includes a radio receiver for receiving information communicated on an RF communication channel; and one or more transmitter ports, each of which includes a radio transmitter for transmitting information on any of two or more RF communication channels to other of said devices.

2. The system of Claim 1 , wherein each of said devices additionally comprises a controller, wherein, when said device is to transmit information to another of said devices in said system, said controller:

tunes one of said transmitter ports of said device to the RF communication channel to which a receiver port of said other device is tuned; and verifies that no other device in said system is transmitting information on said RF communication channel.

3. The system of Claim 2, wherein each receiver port in said system is tuned to a unique RF communication channel.

4. The system of Claim 3, wherein each transmitter port of each device in the system may be tuned to any of the unique RF communication channels to which the receiver ports of the other devices in the system are tuned.

5. The system of Claim 4, wherein one or more of said receiver ports additionally includes an adjustment to permit said receiver port to be tuned to receive information on a different RF communication channel.

6. The system of Claim 5, wherein each receiver port in said system may be tuned to a different RF communication channel.

7. The system of Claim 1 , wherein each RF communication channel comprises an RF carrier modulated at a predetermined modulation frequency.

8 The system of Claim 1 , wherein each RF communication channel comprises a spread spectrum RF signal encoded with a predetermined code.

9. A system for communicating information among a plurality of electronic devices, the system comprising:

a plurality of RF communication channels; a plurality of electronic devices, wherein each of said devices comprises:

one or more radio transmitters for transmitting information to other of said devices, wherein each of said radio transmitters may be tuned to transmit information any one of a plurality of RF communication channels; and

one or more radio receivers, wherein each of said radio receivers is tuned to receive information communicated on one and only one of said RF communication channels; and a controller, wherein, when a radio transmitter of said device is to transmit information to another of said devices in said system, said controller: tunes said radio transmitter to the RF communication channel to which a radio receiver of said other device is tuned; and verifies that no other radio transmitter in said system is transmitting information on said RF communication channel 10. The system of Claim 9, wherein each of said receivers may be tuned to receive information on a particular one of said RF communication channels. 1 1 . The system of Claim 10, wherein each of said RF communication channels comprises a predetermined modulation frequency 12 The system of Claim 10, wherein each of said RF communication channels comprises a uniquely encoded spread spectrum radio signal

13 An electronic device, comprising

an RF receiver tuned to receive, on a first predetermined RF communications channel, information for controlling said appliance,

an RF transmitter tuned to transmit, on any of a plurality of RF communications channels different from said first RF communications channel, information for controlling a different electronic device; and

a controller for tuning said RF transmitter to a particular RF communications channel, and for determining if another electronic device is transmitting information on said particular RF communications channel

14. The electronic device of Claim 13, additionally comprising one or more additional RF receivers, each of which is tuned to receive information on an RF communications channel other than said first predetermined RF communications channel.

15 The electronic device of Claim 13, additionally comprising one or more additional RF transmitters, each of which may be tuned to transmit on any of said plurality of RF communications channels.

16. The electronic device of Claim 13, wherein said controller tunes said RF transmitter to a particular RF communications channel corresponding to an RF receiver in a different electronic device.

17. The electronic device of Claim 13, additionally comprising an adjustment for said RF receiver to permit said RF receiver to be tuned to receive, on a third predetermined RF communications channel, information for controlling said device.

18. A method of communicating information among a plurality of electronic devices in a system, the method comprising:

tuning a radio receiver in each of said devices to a single radio communication channel, wherein each radio receiver in said system is tuned to a unique one of a predetermined plurality of radio communication channels, wherein said step of tuning radio receivers includes tuning a radio receiver in a first appliance in said system to a first radio communication channel; tuning a radio transmitter in a second device in said system to said first radio communication channel; verifying that no other device in said system is transmitting information on said first radio communication channel; transmitting information on said first radio communication channel from said radio transmitter of said second device to said radio receiver of said first device.

19. The method of Claim 18, wherein said step of tuning radio receivers includes tuning a radio receiver in said second device to a second radio communication channel, and said method additionally comprises: tuning a radio transmitter in said first device to said second radio communication channel;

verifying that no other device in said system is transmitting information on said second radio communication channel; and transmitting information on said second radio communication channel from said radio transmitter of said first device to said radio receiver of said second device.

20. The method of Claim 18, wherein said information transmitted from said second device to said first device includes information for controlling said first device.

21 . The method of Claim 20, wherein each of said radio communication channels comprises a predetermined modulation frequency.

22. The method of Claim 20, wherein each of said radio communication channels comprises a uniquely encoded spread spectrum radio signal.

23. A computer system comprising: a central control unit comprising:

a central processing unit an RF receiver for receiving information on a first RF communication channel and transferring said information to said central processing unit; an RF transmitter for selectively transmitting information from said central processing unit on second or third RF communication channels; a printer comprising: a printing mechanism; an RF receiver for receiving information on said second RF communication channel and transferring said information to said printing mechanism; an RF transmitter for transmitting information on said first RF communication channel; and

a third device, comprising an RF receiver for receiving information on said third RF communication channel.

24. The computer system of Claim 23, wherein said third device is an additional printer, said additional printer comprising:

a printing mechanism; an RF receiver for receiving information on said third RF communication channel and transferring said information to said printing mechanism; and

an RF transmitter for transmitting information on said first RF communication channel.

25. The computer system of Claim 23, wherein: said computer system additionally includes an additional printer, said additional printer comprising:

a printing mechanism; an RF receiver for receiving information on a fourth RF communication channel and transferring said information to said printing mechanism; and an RF transmitter for transmitting information on said first and third RF communication channels; said third device is an additional central control unit, said additional central control unit comprising: a central processing unit; an RF receiver for receiving information on said third RF communication channel and transferring said information to said central processing unit; an RF transmitter for selectively transmitting information from said central processing unit on said first, second, or-fourth RF communication channels;

said RF transmitter of said first central control unit is additionally capable of selectively transmitting information from said central processing unit on said fourth RF communication channel;

said RF transmitter of said first printer is additionally capable of transmitting information on said third RF communication channel.