Patent Application
20100074625
The present invention pertains to the field of telecommunications. More particularly, the present invention pertains to communication using an ordinary (non-laser) LED (light emitting diode) light source, either visible or infrared.
There are situations in which communication using radio waves is made difficult because of the use of jamming devices. For example, in a convoy of military vehicles, each vehicle may protect itself by creating a “bubble” about itself, i.e. a zone of short-range jamming signals aimed at preventing remote detonation of an IED (improvised explosive device) located within the zone. Because of such jamming signals, the vehicle is not able to communicate by radio with another vehicle within its own bubble, since the jamming signals from the vehicle extend to the location of the other vehicle.
It is known in the art to use non-coherent infrared (IR) light for communication. From the Wikipedia article on “Infrared” (i.e. on the Internet at: http://en.wikipedia.org/wiki/Infrared#Communications):
The prior art also teaches that both military vehicles and civilian vehicles are sometimes equipped with so-called lightbars, such as described by U.S. Pat. No. 7,387,414. In many applications of lightbars such as set out in the '414 patent, a vehicle is equipped with such lightbars so as to provide illumination in all directions, i.e. 360-degree illumination.
Thus, the prior art makes available a technology—communication using non-coherent IR light—that would be useable to enable vehicles located within each other's bubble to nevertheless communicate data with each other (computer/device to computer/device communication), and also makes available lightbars providing both visible and IR light. What is needed is a way to switch on and off IR light, or even visible light, so as to provide user-to-user voice communication, and in particular in case of communication between moving vehicles, possibly using light sources already used by the vehicle for illumination, such as light sources in a lightbar.
Accordingly, a communication system is provided, for communicating spoken speech, i.e. for voice communication. A communication system according to the invention typically includes, at a transmitter side, components for representing spoken speech as a series of on and off switch commands, i.e. an encoder for encoding the spoken speech in terms of switch commands, and a light, such as an infrared light LED (light emitting diode) or a visible light LED, receptive to the switch commands, for providing switched light. The light may be either a visible light or an infrared light/illuminator. Further, and preferably under some circumstances, the light may be included in a lightbar, i.e. an apparatus mounted on a vehicle for providing lighting auxiliary to driving lights/headlamps.
At a receiver side, the invention includes a photodetector to detect the switched light and thus enable determining the switch commands used to create the switched light (which determination is provided by what is here called a modulator), and a decoder for translating the switch commands back to the spoken speech. In case of a lightbar application, the photodetectors could be embedded in the lightbar. For lightbars providing 360-degree illumination (using e.g. four lightbars facing 90 degrees apart) the communication system could include photodetectors disposed so that there is one photodetector for each of four mutually more or less orthogonal directions.
A communication system according to the invention, i.e. for communicating spoken speech, can be adapted to provide data communication in addition to voice communication, since a communication system according to the invention is a digital communication system (i.e. it communicates a bit stream representing the spoken speech), which is therefore suitable for communicating data (which would also be represented by a bit stream).
The features and advantages of the invention will become apparent from a consideration of the subsequent detailed description presented in connection with accompanying drawings, in which:
The following is a list of reference labels used in the drawings to label components of different embodiments of the invention, and the names of the indicated components.
Referring now to
In an illustrative embodiment, the invention provides a communication system including, at the transmitter side 11, a microphone 11a, responsive to the spoken speech, for providing as its output an electrical signal (typically analog) corresponding to the spoken speech. The output of the microphone is fed to a speech encoder 11b, which provides as an output a digital representation of the speech, which could be binary or other. The speech encoder could be any number of prior art vocoders (i.e. voice encoders).
The output of the speech encoder 11b—a stream of digital (not necessarily binary) information—is input to what is here called a modulator 11c, which produces switch signals based on the speech encoder output.
In some embodiments of the invention the modulator 11c uses Manchester encoding to encode a bit stream representing spoken speech (produced by a vocoder), and to then provide switch commands corresponding to the encoding. Manchester encoding (also known as Phase Encoding) is a line coding in which the encoding of each data bit has at least one transition and occupies the same time. It is, therefore, self-clocking, which means that a clock signal can be recovered from the encoded data.
In some embodiments, the modulator 11c provides a switch “on” command for a bit of value “1” and a switch “off” command for a bit of value “0.” In other embodiments, the modulator provides a command to switch on and off repetitively at a first frequency for a bit of value “1,” and a command to switch on and off repetitively at a second frequency for a bit of value “0.” (In both cases in such other embodiments, the switching on and off is continued for some pre-determined period of time, sufficient to provide a reasonable compromise between throughput and reliability of the wireless link.)
In other words, the modulator maps the bit stream representing spoken speech to switch commands using Manchester encoding. The switch commands thus produced, or equivalently, the bit stream produced by the Manchester encoding, function as modulation symbols.
The output of the modulator 11c—a series of switch commands—is then input to an on/off switch 11d in order to produce the light pattern determined by the modulator.
The resulting action of the switch 11d controls a power source 11e providing power to a light source 11f. The light source could be an LED light source, either a visible light LED or an infrared light LED. For visible light, other kinds of light sources can be used, provided that they can be switched on and off quickly enough.
As a result of the action of the switch 11d, the light source 11f (which could also be any other sort of light able to be switched on and off at a rate of at least about 2 kHz) turns on and off in a way that represents the spoken speech being transmitted, according to an on/off pattern.
The switching, is, advantageously in some applications, at such a frequency as not to be discernible by the human eye, even using equipment sensitive to IR light (e.g. night vision goggles). In other words, the switching should be fast enough that the light appears to a person (using e.g. night vision goggles in case of using IR light) to be on continuously, and not switched on and off. To ensure such an apparently steady “on” state, the switching should be at least seventy times per second.
The transmission could include some basis for error checking or even forward error correction, and a protocol could be used in which a repeat request is made by the receiver side in case of an error being detected (and not being correctable). The transmission could include such error detection and/or correction capabilities because of processing by the speech encoder 11b or the modulator 11c. In other words, either the speech encoder or the modulator could be implemented to provide such error detection and/or correction capabilities. In addition, the spoken speech could be encrypted by either the speech encoder or the modulator.
At the receiver side 12 of a communication system according to the invention, a photodetector (light detector) 12a produces a detector output in response to the on/off light pattern produced by the light source 11f, i.e. the detector produces signals indicative of the on/off light pattern. The detector output is fed to a demodulator 12b that produces as an output what is substantially the encoder output produced by the speech encoder 11b at the transmitter side 11, any difference being attributable to errors in detection (as a result, typically, of errors in transmission). Thus, the demodulator output is the coded representation of the speech being transmitted (and should correspond, at least approximately, to the output of the speech encoder/vocoder 11b of the transmitter side 11).
The demodulator output is fed to a speech decoder 12c (the decoder portion of a vocoder), having as an output (analog or digital) signals for driving a speaker 12d, which uses the decoder output to reproduce the transmitted spoken speech (as received, i.e. with any errors not able to be corrected by the receiver).
In some embodiments, the communication system is integrated into a lightbar, such as a lightbar used on military vehicles or civil vehicles (e.g. police or security vehicles), e.g. a lightbar as set out in U.S. Pat. No. 7,387,414. Such embodiments can be said to provide a “talking lightbar.” In such embodiments, the lightbar includes the transmitter side 11 of the above-described communication system, and perhaps also the receiver side 12, although the receiver side may, in some embodiments, be provided outside of the housing of the lightbar.
In some talking lightbar embodiments, where the communication system is therefore mounted on a vehicle, light is transmitted in all directions in the horizontal plane (360 degrees) by one or more lightbars on the vehicle, and the communication system is advantageously provided (in such applications) so as to be able to transmit using several lights (e.g. four lights) in all directions, simultaneously or otherwise, and so as to be able to receive transmissions coming from all directions, simultaneously or otherwise.
Advantageously in such applications, a communication system according to the invention is configured to echo a received transmission that it did not itself previously transmit. Thus, for example, and now referring to
In order to achieve such echo operation without the first vehicle repeating its transmission or otherwise having repeating echoes occur, a communication system according to the invention could include in each transmission a header in turn including an identifier of the transmission, and the transmitter side 11 and the receiver side 12 could be tied together directly, as in
Thus, in some embodiments voice communication is passed from vehicle to vehicle via a relay function in order to reach all vehicles in a convoy or in a general area. The relay function, in some such embodiments, resembles a traditional Ethernet switch or Ethernet network equipment, i.e. it routes data from point to point. Each packet of voice communication in some embodiments is transmitted as a message with a header field indicative of the vehicle originating the voice packet and uniquely identifying the message (e.g. message number 2345 from vehicle number 1). Each vehicle receiving a packet of voice communication rebroadcasts the packet, provided it has not already rebroadcast the message. For this, in a typical embodiment, each vehicle would keep a rolling list of transmission identifiers for identifying transmissions the vehicle transmitted within some predetermined most recent time period, and would only retransmit a received transmission if the identifier does not appear on the rolling list.
The outputs of the photodetectors would advantageously be high-pass filtered, so as to pass only detector outputs corresponding to the rapid on/off switching of the transmitting light, corresponding to the spoken speech being communicated.
In some embodiments, and now referring to
Each IR detector is typically provided inside a frame, but to place the detectors closer to each other, the frame is removed in some embodiments, but there may still be some gaps between the detectors. However, due to the un-focused positioning of the IR detectors relative to the lens, any IR signal within the FOV will be smeared over an area larger than any of the inter-detector gaps, and so will be received by at least one (and typically at least two) detectors.
Referring still to
It should be noted that the invention can also be used to provide simulated spoken speech. In the above-described embodiments, switch commands are generated corresponding to spoken speech, and the switch commands correspond to the spoken speech itself, and a signal is created indicative of spoken speech, and the signal is indicative of the spoken speech itself, i.e. the signal conveys information about the speaker's voice, usually sufficient for a listener to identify the speaker if the listener knows the speaker, and providing intonation and other aspects of speech used to communicate meaning in case of spoken speech, as opposed to a writing conveying only the spoken words (with appropriate punctuation). For embodiments in which simulated spoken speech is provided, the switch commands corresponding to the spoken speech correspond only to the content of the spoken speech (i.e. conveying only the spoken words with appropriate punctuation), and the signal indicative of spoken speech is a signal indicative of simulated speech (i.e. artificial or computer-generated speech) and so corresponds only to the content of the spoken speech, i.e. it does not convey the information about the speaker's voice.
It is to be understood that the above-described arrangements are only illustrative of the application of the principles of the present invention. Numerous modifications and alternative arrangements may be devised by those skilled in the art without departing from the scope of the present invention.
Reference is made to and priority claimed from U.S. provisional application Ser. No. 61/190,847 filed Sep. 3, 2008.
| Number | Date | Country | |
|---|---|---|---|
| 61190847 | Sep 2008 | US |
