Classifications

• • G—PHYSICS
  • G08—SIGNALLING
  • G08C—TRANSMISSION SYSTEMS FOR MEASURED VALUES, CONTROL OR SIMILAR SIGNALS
  • G08C17/00—Arrangements for transmitting signals characterised by the use of a wireless electrical link

Definitions

• the invention relates to an information transfer system for e.g. remote control of lighting, air conditioning, security equipment and AV equipment.
• Remote control systems are generally used in e.g. entertainment electronics. Earlier they were based on using ultrasound (US), but nowadays techique based on infrared light (IR) is more commonly used.
• IR infrared light
• the disadvantage with ultra sound was e.g. a very limited possibility to use control- and address codes.
• IR control systems that are suitable for the control of lighting are produced by e.g. Siemens AG, Germany, and Philips, the Netherlands.
• the disadvantage with the IR technology is that it requires a line of sight between transmitter and receiver.
• Radio waves pass through normal walls, which causes that the communication signal between equipment includes a sufficiently broad address code.
• the control system uses only one information transfer channel, it is however not possible to transfer many control commands simultaneously within the operating range.
• the limited number of available radio channels excludes the possibility to use an individual radio channel for each transmitter or receiver in large systems.
• the problem is solved in such a way that the telephone measures alternately the noise level of the available channels and selects the channel with the lowest noise level.
• measuring the noise level of the available channels must be performed one channel at a time, because otherwise the receiver circuits become complicated and costly. It also takes a relatively long time to measure the level of signal that is random by nature from each channel until it is possible to determine reliably wether the channel is already in use. Therefore it takes a too long time to select the channel in remote control applications also with this method.
• the information transfer system includes two or more equipment between which the information is trensferred so that in addition to transmitting the normal message signal that includes information, a second signal, "additional signal", is transmitted and the content of the additional signal depends on on which channel the message signal is transmitted.
• a second signal "additional signal”
• the equipment that transmits the message can quickly recognize, which channels are received and which channels are free for the transmission of the message signal.
• the equipment that receives the message signal is able to tune quickly to the right channel.
• These additional signals can be transmitted on a separate channel so that even from many additional signals that are trensmitted on this channel simultaneously it is possible by the receiving means of the controller or the receiver to determine, which channels are occupied.
• Another possibility is that the additional signal is transmitted on the same channel as the message signal, and in this case it is possible by a broad band receiver to follow additional signals from many channels simultaneously.
• the versatile operation possibilities of the radio signals are combined with a fast response time of the control commands even in large systems.
• LA Equipment A TA1 Transmission means of equipment A for transmission of the message signal
• TA2 Transmission means of equipment A for transmission of the additional signal
• the example system consists of equipment A and equipment B. However, there can be an arbitrary number of equipment.
• the equipment A For transferring the message DA the equipment A has transmission means TA1 and the equipment B has receiving means RBI.
• the signal SA1 that includes the message DA is transferred by using e.g. radio waves and frequency channels.
• the frequency channel is selected by logic circuit GA in the equipment A and by the logic circuit GB in the equipment B.
• the second transmission means TA2 of the equipment A transmit an additional signal SA2 in the connection to the message signal.
• the content of the additional signal depends on which frequency channel is used in the transmission of the message signal.
• the equipment A Before the transmission of the message signal and the additional signal the equipment A can check, which channel is free for the transmission of the message signal.
• the controller has receiving means RA2 which receive the additional signals.
• the logic circuit GA of the equipment A can select the free channel according to the information or strength of the received additional signals.
• the equipment B can use the information or strength of additional signals received from other equipment for selecting the reception channel of the message signals.
• the equipment B has means for receiving the additional signals.
• the means that are used for reception or transmission of message and additional signals need not be separate, but for example, when radio waves are used, it is often advantageous to have at least a common amplifier and antenna in the transmission means for transmitting the both signals. Correspondingly it may be advantageous to use common antenna and preamplifier for receiving both signals in the receiving means.
• the example system consists of controllers (C) and receivers (V), the number of which can be arbitrary.
• control means e.g. push buttons, of the controller's user interface Ul are activated.
• the control means can be activated except by the user, also by e.g. computer or sensor.
• the controller's C first transmission means TCI transmit a message signal SCI, which is transmitted on radio waves e.g. on the frequency channels around 433,92 MHz.
• the number of the available channels is e.g. N.
• a control command is coded into the message signal, and the control command could be e.g. setting the receiver's functional device P to on-state.
• the controller's other transmission means transmit an additional signal SC2, which is transmitted for example on a channel that is reserved for the additional signals.
• the additional signal's carrier is modulated by a low frequency signal Sm, which includes a frequency component fm.
• Sm low frequency signal
• the frequency of the frequency component fm in the signal Sm is fl.
• the controller Before the transmission of the message signal and the additional signal the controller can check, which channel is free for transmission.
• the controller has receiving means RC2, which are tuned to the channel on which the additional signals are transmitted.
• the controller's receiving means RC2 have a detector, after which the detected low frequency signal is led to band pass filters FC, which are set to frequencies fl...fn. After the band pass filters there are level indicators DC, which are used for comparing the strengths of signals Sm that exist on frequencies fl...fn, alternatively to a set level or to each other. Based on the aforesaid comparison results the controller's logic unit selects the channel, on which the message signal is transmitted.
• the selected channel can be the one, whose corresponding frequency component fm has the lowest measured strength level.
• the selected channel can be any channel, whose corresponding frequency component fm has a measured signal level below a set level. If none of the frequency component strengths that correspond to channels is below the set level, the transmission of the message signal can be postponed until some channel becomes free, which means that the strength level of the frequency component fm that corresponds to that channel is below the set level.
• the receiver V follows the channel that is reserved for the transmission of additional signals. After the detection the receiver has band pass filters for frequencies that correspond to signals Sm. After the band pass filters there are level indicators, by which the strength of signals Sm is compared to a set level. If on some frequency, such as fl, the set level is exceeded, the receiver's means for receiving message signals tune to the channel 1 which corresponds to the aforesaid frequency. If the set comparison level is exceeded on several channels, the receiver's means for receiving message signals tune alternately to the aforesaid channels e.g. with set time intervals. The time interval before shifting from one channel to another is so long that the receiver device has time to recognize, wether the control commands that are transmitted on that channel are addressed to it. If the control commands are addressed to the concerned receiver- device, the receiver device receives the commands before shifting to another channel.
• the receiver's control circuits that may be a part of logic circuit LV, control the functional device P according to the control command, like switching a light fixture to on-state.
• the functional device may be an integral part of the receiver device or it may be mechanically separated, like a removable spot light in a lighting rail.
• the receiving means of the additional signal can be a superregenerative receiver, which is economical and has a low power consumption.
• amplitude, phase or frequency modulation can be used in transmission of the message signal.
• phase and frequency modulation methods a better quality information transfer connection is usually achieved compared to amplitude modulation.
• the means that are used for reception or transmission of message and additional signals need not be separate, but for example, in transmission means it is often advantageous to use at least a common amplifier and antenna for transmitting the both signals. Correspondingly it may be advantageous to use common antenna and preamplifier for receiving both signals in the receiving means.
• the receiver In the remote control system according to the invention it is possible to use also a feedback message, from which the controller gets information on performance of the control command.
• the receiver must include transmitting means TV1 and TV2 for transmission of the feedback message signal SV1 and additional signal SV2.
• the controller has correspondingly receiver means RCl for receiving the feedback message signal.
• the controller's user interface Ul the received return message signal e.g. switches on a signal light that describes the performed function.
• the feedback message signal In order to use the channels efficiently and to get a quick feedback it is often advantageous to transmit the feedback message signal on the same channel as the message signal, whose control command's performance is informed with the feedback message signal.
• the system In receiving the additional signals a relatively large dynamic range is required in the receiveing means, if the system includes a large number of controllers and functional devices and if there are several channels and if additionally the mutual distances between the equipment vary much. To reduce the dynamic range requirement it may be preferrable to transmit the signals partly at different times. In practice the additional signals can be transmitted as repeated pulses, and thus the probability for transmission of many simultaneous additional signals is smaller. Then the level indicators DC and DV measure the signal level of channels for at least the time of the repetition period of pulses before selecting the transmission channel.
• the timing of message signal and additional signal can be simultaneous, but they can also be partly or totally at different times, and one of them can be longer in time than the other. It is e.g. advantageous to transmit message and additional signals alternately, so that in transmission means it is possible to use only one radiofrequency oscillator, the frequency of which is controlled alternately to the channel of the message signal and the additional signal.
• the additional signal can also be transmitted on the same channel as the message signal, and thus no separate channel is required for the additional signals.
• the additional signal can then be transmitted alternately with the message signal or, depending on the modulation technique, also at the same time with the message signal.
• the means for receiving the additional signals are preferrably of wide band type, such as superregenerative receiver, so that it is possible to receive simultaneously the existing additional signals from all channels. Another alternative is to follow the channels in the system alternately.
• the system according to the invention can be applied also in infrared control, when a complicated control system is wanted to be built into a continuous space. Samples of such spaces are open offices and factory halls, where within the infrared beam range there can be a large number of remote controlled functional devices. In the same way the system can be used in IR systems in such spaces, where the material of the partition is infrared transparent plastic or glass.
• the system according to the invention can also be used if the transfer path of the information is mains, because also then in large control systems and other information transfer systems it is required to use several frequency channels.
• the system according to the invention can be used also in information collection systems, where measurement results are transferred from e.g. sensors without wires or via mains to e.g. functional units of control systems or to an information collection device.
• the system can also be used e.g. for trensfer of messages in pager systems.

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• Engineering & Computer Science (AREA)
• Computer Networks & Wireless Communication (AREA)
• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Selective Calling Equipment (AREA)

Priority Applications (1)

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Publications (1)

Family

ID=8535675

Family Applications (1)

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Cited By (1)

Citations (4)

• 1992
  • 1992-07-31 FI FI923469A patent/FI91922C/fi not_active IP Right Cessation
• 1993
  • 1993-07-29 AU AU45727/93A patent/AU4572793A/en not_active Abandoned
  • 1993-07-29 WO PCT/FI1993/000307 patent/WO1994003883A1/en active Application Filing

Patent Citations (4)

Non-Patent Citations (1)

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