JPH0244932A - Optical space transmission communication equipment - Google Patents

Abstract

PURPOSE:To reduce the power consumption by devising the equipment in which the intensity of an optical signal sent from one communication equipment is decreased only when the reception intensity of an optical signal sent from one communication equipment is larger when other communication equipment receives the signal and the transmission state between the two communication equipments is excellent. CONSTITUTION:A photodiode 38 of a receiver RB of a base unit BU receives an optical signal sent from an LED 20 of a transmitter TP of a portable unit PU. A signal demodulated by a demodulator 41 includes a voice signal and a reference signal for checking the transmission state and the propriety of the transmission state is discriminated from the state of the reference signal sent from a control signal generator 37. When the transmission state is excellent, a transmission intensity control signal in response to the intensity of the signal detected by a signal intensity detector 42 is outputted from the control signal generator 37. That is, when the signal intensity in this case is large, the transmission intensity control signal to control the radiated intensity of the LED 20 of the transmitter TP of the portable unit PU to a small value is outputted. Thus, the power consumption over a required value is suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is an optical system that converts signals such as audio into optical signals and uses free space as a transmission path for the optical signals to communicate between two communication devices. The present invention relates to a space transmission communication device.

BACKGROUND ART FIG. 2 is a block diagram showing a schematic configuration of an example of a conventional optical space transmission communication device, of which FIG. 2(A) shows a transmitter T, and FIG. 2(B) shows a receiver. Machine R is shown.

In the transmitter T shown in FIG. 2(A), a microphone 1 that inputs an audio signal is connected to an amplifier 2, and the amplifier 2 frequency-modulates its output.
ulaLion: P (hereinafter referred to as FM modulation)
It is connected to the M modulator 3. The FM modulator 3 uses a light emitting diode (LigI+tE+IIi) according to its output.
I + i n g D i o de : Hereinafter, LE
(referred to as D) 5 is connected to the LED driver 4 which drives the LED driver 5.

On the other hand, in the receiver R shown in FIG. 2(B), the L of the transmitter T is
A photodiode 6 that receives an optical signal (FM-modulated infrared light) sent from the EDS into free space and converts it into electricity.
It is connected to a preamplifier 7 that amplifies the photocurrent obtained by the photoelectric conversion, and the preamplifier 7 is connected to a bandpass filter 8 that removes noise from its output. The bandpass filter 8 is connected to a demodulator 9 which demodulates its output, and the demodulator 9 is connected to a filter 10 which passes only the audio signal band of its output. Filter 1
0 is connected to a speaker 12 via an amplifier]1.

In the optical space transmission communication device having the above configuration, FIG.
On the side of the transmitter 'F shown in FIG. The LED driver 4 drives the LED 5 in response to the FM modulated signal, and the LED 5 sends out FM modulated infrared light or an optical signal into free space.

On the other hand, on the receiver R side shown in FIG. 2(B), the optical signal transmitted from the LED 5 on the transmitter T side is received by the diode 6 through the diode 6 through the free space. The photocurrent photoelectrically converted by this port 1-tie auto 6 is amplified by a preamplifier 7 and then passed through a bandpass filter 8.
The noise outside the band is removed by the demodulator 9, and the signal before F-M modulation is modulated ('A). After being amplified, it is made into sound by a speaker]2.

When the above-mentioned transmitter T and receiver R are used as a set to form one transceiver, bidirectional communication can be performed between the transceivers in 2-).

Problems to be Solved by the Invention In the above-described conventional optical space transmission communication device, even if the distance between the transmitter T and the receiver R may be shortened depending on the usage situation, the communication distance can be increased. In order to increase the length of the light, LED 5 of the transmitter T must always emit high output light. This consumes more power than necessary, and especially for lifting devices such as portable transceivers (hereinafter referred to as portable units) that use batteries as a power source, their power capacity is limited. There was a problem that it could not be used for a long time.

Therefore, an object of the present invention is to provide an optical space transmission communication device that can reduce power consumption without deteriorating reception conditions.

Means for Solving the Problems The present invention provides optical space transmission in which a voice signal is converted into an optical signal, and two-way communication is performed between two communication devices using free space as a transmission path for the optical signal. The communication device includes a reference signal output means installed in one communication device to create a reference signal for inspecting the optical signal power transmission state and transmit it as part of the optical signal, and to the other communication device. a reception strength detection means provided in the other communication device for detecting the reception strength of the optical signal transmitted from one communication device; and a reception strength detection means provided in the other communication device for determining the quality of the transmission condition from the reference signal transmitted from one communication device. a control signal output means (control signal output means for transmitting the wholesale signal as part of the optical signal), which is provided in the other communication device and is responsive to the reception strength and the quality of the transmission condition; is,
The strength of the optical signal transmitted from one communication device when it is a transmission strength control signal sent from the other communication device or a signal indicating that the reception strength at the other communication device is high and the transmission status is good. This is an optical space transmission communication device characterized by comprising a transmission intensity control means for reducing the transmission intensity.

According to the present invention, the reception strength detected by the reception strength detection means of the other communication device is large, and the determination means of the other communication device determines whether the reception strength is high based on the reference signal transmitted from one communication device.
When it is determined that the transmission status is good, the transmission strength control means of one communication device controls the optical signal transmitted from the communication device based on the transmission strength control signal transmitted by the control signal output means of the other communication device. It is possible to reduce the intensity and reduce unnecessary power consumption.

Embodiment FIG. 1 is a schematic diagram showing a schematic configuration of an optical space transmission communication device which is an embodiment of the present invention. Of these, the 11th
71(A) shows the portable transceivers BOTAFURUUNITS 1 to PU, and FIG.
Indicates U.

In the transmitter TP of the portable unit (PU) shown in FIG.
is connected to an amplifier 14, and the amplifier 1-4 passes only the components included in a predetermined audio band out of its output, and passes through the filter 1.
5. This filter]5 is connected to the mixed circuit f\817 together with the reference signal generator 16. The reference signal generator 16 is a circuit that generates a reference signal for testing the quality of the optical signal transmission between the full unit L-PU and the base unit Y1-BU, and the mixing circuit 17 includes a filter. This is a circuit for mixing the output of the reference signal generator 15 and the output of the reference signal generator 16. mixed 6 circuit 1
7 is connected to an FM modulator 18 which performs FM modulation on its output. The FM modulator 18 lights up the LED according to its output.
It is connected to a T-ED driver 19 that drives the T-ED 20.

In addition, in the receiver RP of the portable unit L-P U, the bottom optical signals 1 and 21, which receive optical signals transmitted from the base unit BU and perform photoelectric conversion, are connected to the preamplifier 22. 22 is connected to a band pass filter 2B which removes noise outside a predetermined band from its output. The bandpass filter 23 is connected to a demodulator 24 that demodulates its output, and the demodulator 24 includes a filter 25 that extracts only the audio signal from the demodulated signal, and a filter 2 that extracts only the transmission strength control signal (described later) from the demodulated signal.
8. One filter 25 is the amplifier 2
6 to the speaker 27, and the other filter 28 outputs the LED + of the transmitter TF' according to its output.
- Connected to two control circuits that control the driver 19 to speed up.

On the other hand, the transmission F! of l\-suunits l-B U shown in FIG. 1(B)! The TB also has a microphone 3o, an amplifier 31, a filter 32, a mixing circuit 33, an FM modulator 34, and a L E
A D driver 35 and an LED 36 are connected in this order, and a control signal generator 37 different from the reference signal generator 16 for lifting the portable unit (PU) is connected to the mixed circuit 33.

The control signal generator 37 is a circuit that generates a transmission intensity control signal that controls the light emission output of the LED 20 of the Votaful Uni y 1-PU. This is a slanted circuit that mixes the output with the output. Each of the other circuits has the same function as the corresponding circuit in the transmitter TP of the portable unit l-F'U.

In addition, the receivers R and B of the unit BU receive the light No. 13 transmitted from the vertical unit PU and convert it photoelectrically.The diode 38 includes three preamplifiers, Bandpass filter 1° 10,'(W.

A modulator 41, a filter 43 (which extracts only the audio signal from the Hara Choshinkan), an amplifier 44, and a speaker 45 are connected in this order, while a bandpass filter 4.0 separately extracts the signal strength (received optical signal) from its output. A signal strength detector 42 is connected to detect the signal strength.

A separate filter 46 is connected to the demodulator 11,
This filter 46 is different from the filter 28 in the receiver RP of the balk full unit F'U (which extracts only the transmission strength control signal from the demodulated signal), and is different from the filter 28 (which extracts only the transmission strength control signal from the demodulated signal). It is something. Based on these outputs, the signal strength detector 11.2 and the filter 46 perform the above-mentioned system for creating a transmission strength control signal for controlling the luminous output of the I-E D 20 of the plural unit PU. It is connected to the Shinyumi optical stop device 37.Other circuits are connected to the receiving Ill of the portable unit PU.
It has the same function as the corresponding circuit in RP.

Next, the operation of the above-described optical space transmission communication device will be explained.

In the transmitter TP of the portable unit PU, an audio signal inputted from a microphone 13 is amplified by an amplifier 4, and a filter 15 removes noise in unnecessary bands other than the frequency of the audio signal. The output of this filter 15 and the reference signal for transmission state inspection (having a frequency other than the frequency of the audio signal) output from the reference signal generator 16 are mixed by a mixing circuit i\817,
The next FM modulator 18 performs FM modulation. The FM modulated signal is sent to the L E D l-driver 19,
The ED driver 19 drives the LED 20 in response to the ED signal, and an optical signal is sent out from the LED 20 into free space.

On the other hand, in the receiver RB of the base unit I-B U, the port 38 receives the optical signal sent from the LED 20 of the transmitter TP of the portable unit PU.

The signal photoelectrically converted by the photodiode 38 is amplified by a preamplifier 39 and then passed through a bandpass filter 40.
Noises outside a predetermined band are removed by a demodulator 41, and the signal is demodulated into a signal before FM modulation.

Separately, the signal from which noise has been removed by the bandpass filter 40 is also sent to a signal strength detector 42, where the strength of the signal is detected. The detection signal from the signal strength detector 42 is sent to the control signal generator 37 of the transmitter TB of the l\-s unit BU. The strength of this signal corresponds to the received strength of the optical signal received by the phototype autograph 38 from the VOKUFURU UNITS I-PU.

The signal demodulated by the demodulator 41 includes an audio signal and a reference signal for testing the transmission state, and these two types [No. 3] are separated by a filter 43.4.6. The audio signal extracted by one of the filters 4B is amplified by 4 amplifiers and then sent to the speaker 15.)
is played back as audio. The reference signal extracted by the other filter 46 is sent to the control signal generator 37. The control signal generator 37 determines whether the transmission state is good or bad based on the state of the sent reference signal.

(When the transmission condition is good (j, 1st intensity detector 42
A transmission strength control signal corresponding to the signal strength detected by the control signal generator 37 is output. That is, if the signal strength at this time is high, a transmission strength control signal is outputted to reduce the emission strength of the I-E D 20 of the transmitter 'FP of the portable unit PU. In addition, even if the signal strength detected by the signal strength detector 42 is high in the field 6 where the transmission condition is not good, the portable unit I-F'
A transmission intensity control signal for controlling the light emission intensity of the LED 20 of the transmitter TP of U is outputted.

]] The mixing circuit 33 provided in the transmitters R and B of the unit BU uses the transmission strength control signal sent from the control signal generator 37 described in "-", the microphone 30, the amplifier 31, and the filter 32. The mixed signal is mixed with the audio signal sent through the FM modulator 34 and subjected to FM modulation. The FM modulated signal is transmitted from the LED 36 via the LED driver 835 into free space as an optical signal.

Nose unit BU Transmitter TB L E D 3
The optical signal sent out from
The light is received by the phototype autograph 21 of the receiver RP of the base unit L-B.The light is received by the phototype autograph 21 of the receiver RP of the base unit L-BU.
It is demodulated into the pre-modulated signal at M7. The demodulated signal includes a voice signal and a transmission strength control signal, which signals are separated by filters 25, 28. The audio signal extracted by one filter 25 is amplified by an amplifier 26 and then turned into sound by a speaker 27. The transmission strength control signal extracted by the other filter 28 is sent to two control circuits that control the I-ED driver 19 of the transmitter TF'.

In the two control circuits, the light emission intensity of the LED 20 is changed according to the transmitted transmission intensity control signal (this L
E I) Control (wholesale) F lime 19, i.e.
Portable unit F
While reducing the light emission intensity of 20, if the receiving light intensity is high but the transmission condition is not good due to disturbance light, set L.
Two control circuits or one LED driver are controlled so as not to reduce the light emission intensity of the ED 20. Therefore, the optical signal transmitted from the portable unit PU to the base unit (BU) always changes depending on the change in the transmission state.
The intensity is adjusted to be just the right amount for receiving all BUs.

Effects of the Invention As described in Section 2, according to the optical space transmission communication device of the present invention, the reception strength when receiving an optical signal transmitted from one communication device is large, and two The structure is configured so that the intensity of the optical signal transmitted from one communication device is reduced only when the transmission condition between the communication devices is good, so that communication in 2-) as in case 6 of short-distance communication is possible. When the transmission status between the communication devices is good, power consumption is not more than necessary, and even if a battery is used as a power source for the communication device, it can be used for a long time.

[Brief explanation of the drawing]

Reference numeral 1121 is a block diagram showing a schematic configuration of an optical space transmission communication device according to an embodiment of the present invention, and FIG. 2 is a block diagram showing a schematic structure of a conventional optical space transmission communication device. PU... Portable unit (communication device), [(I-1
... Base unit (communication device), TP - Portable unit transmitter, R, P - Portable unit receiver, TB - Base unit transmitter, RB Base unit receiver, 16... Standard Signal generator standard (S
number output means), 28. - Filters, 2 control circuits (
transmission strength control means), 37... - control signal generator (judgment means, control signal output means), 42... signal strength detector (
Reception strength detection means), 46-Filter agent Patent attorney Number of strokes Keiichi Ou

Claims (1)

[Claims] An optical space transmission communication device that converts signals such as voice into optical signals and performs bidirectional communication between two communication devices using free space as a transmission path for the optical signals. A reference signal output means, which is provided in a communication device, generates a reference signal for inspecting the transmission state of the optical signal and transmits it as part of the optical signal; a reception strength detection means for detecting the reception strength of the optical signal transmitted from the other communication device; a determination means provided in the other communication device for determining the quality of the transmission state from a reference signal transmitted from the one communication device; control signal output means that is provided in one communication device and transmits a transmission intensity control signal as part of the optical signal depending on the receiving intensity and the quality of the transmission condition; Transmission intensity control means for reducing the intensity of the optical signal transmitted from one communication device when the control signal is a signal indicating that the reception intensity at the other communication device is high and the transmission condition is good. An optical space transmission communication device characterized by: