JPH0149222B2 - - Google Patents
Info
- Publication number
- JPH0149222B2 JPH0149222B2 JP8438783A JP8438783A JPH0149222B2 JP H0149222 B2 JPH0149222 B2 JP H0149222B2 JP 8438783 A JP8438783 A JP 8438783A JP 8438783 A JP8438783 A JP 8438783A JP H0149222 B2 JPH0149222 B2 JP H0149222B2
- Authority
- JP
- Japan
- Prior art keywords
- interference
- signal
- transmission
- fsk
- signals
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 230000005540 biological transmission Effects 0.000 claims description 28
- 238000001514 detection method Methods 0.000 claims description 14
- 230000006854 communication Effects 0.000 claims description 10
- 238000004891 communication Methods 0.000 claims description 10
- 238000010586 diagram Methods 0.000 description 6
- 230000003321 amplification Effects 0.000 description 4
- 238000003199 nucleic acid amplification method Methods 0.000 description 4
- 230000000694 effects Effects 0.000 description 2
- 230000007257 malfunction Effects 0.000 description 2
- 230000002265 prevention Effects 0.000 description 2
- 230000001629 suppression Effects 0.000 description 2
- 230000007175 bidirectional communication Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 239000013307 optical fiber Substances 0.000 description 1
- 230000010355 oscillation Effects 0.000 description 1
- 230000008054 signal transmission Effects 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/10—Frequency-modulated carrier systems, i.e. using frequency-shift keying
- H04L27/14—Demodulator circuits; Receiver circuits
Landscapes
- Engineering & Computer Science (AREA)
- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
- Bidirectional Digital Transmission (AREA)
- Small-Scale Networks (AREA)
- Digital Transmission Methods That Use Modulated Carrier Waves (AREA)
Description
〔技術分野〕
本発明は、1本の信号ケーブルに接続された複
数個の端末器間で双方向通信ができるようにした
双方向通信システムに関するものである。
〔背景技術〕
最近、ホームオートメーシヨン、オフイスオー
トメーシヨンの発達に伴つて、インターホン信
号、有線テレビなどの映像信号、防犯あるいは防
災などのセキユリテイ情報などを1本の信号ケー
ブルに分岐接続されている複数個の端末器間で授
受するようにした双方向通信システムが考えられ
ている。第1図はコンテンシヨン方式の双方向通
信システムの一例を示すもので、1A〜1Dはア
ドレス信号を含むデータ信号VD(ベースバンド信
号)にて搬送波をFSK(Frequency Shift
Keying)変調した送信信号VTを送出する端末
器、2は各端末器1A〜1Dからの送信信号VT
の搬送周波数f1をf2に変換した返送信号VBを送出
するコーンバータ部2aを具備した中央制御装置
であり、各端末器1A〜1Dおよび中央制御装置
2は分岐器4を介して同軸ケーブル、光フアイバ
ーなどよりなる信号ケーブル3に接続されてい
る。一方、端末器1A〜1Dには返送信号VBを
FSK復調して自己のアドレスと一致するアドレ
スデータを含む返送信号VBが受信されたとき、
その返送信号VBのデータを取込むようにしたデ
ータ受信部が設けられており、端末器1A〜1D
間で中央制御装置2を介して双方向通信が行なわ
れるようになつている。図中、2bはデータ処理
回路、5はテレビカメラ、6はインターホン装置
であり、信号ケーブル3はテレビインターホンシ
ステムの信号伝送路にも用いられるようになつて
いる。
ところで、このような従来例において、各端末
器1A〜1Dには他の端末器1A〜1Dから送信
信号VTが送出されているかどうかを判別し、他
の端末器1A〜1Dから送信信号VTが送出され
ているとき自己の送信信号VTの送出を抑圧する
送信抑圧手段が設けられていたが、この送信抑圧
手段の応答時間以内に2個の端末器1A〜1Dか
ら送信信号VTが発生されて混信が起きることが
あつた。すなわち、略同時に送信信号VTが発生
されデータ信号の欠けや誤伝送が発生し、通信シ
ステムが混乱し、重大事態が起きる恐れがあつ
た。
〔発明の目的〕
本発明は上記の点に鑑みて為されたものであ
り、その目的とするところは、複数個の端末器か
ら送信信号が同時に送出された場合の誤動作を防
止することができる双方向通信システムを提供す
ることにある。
〔発明の開示〕
実施例
第2図は本発明一実施例の端末器2A〜2Dの
要部ブロツク回路図であり、10は局部発振回路
11と、混合回路12と、リミツタ増巾回路13
と、FM検波回路14と、比較回路15とよりな
るFSK復調器であり、このFSK復調器10は受
信された返送信号VBを増巾するとともにリミツ
タにて振巾変調成分を除去した後FM検波し、そ
の検波出力VFのレベルを比較回路15にて検出
することによりベースバンド信号よりなるデータ
信号VD′を復調するようになつている。16は
FSK復調器10にて復調されたデータ信号VD′の
うち自己のアドレスデータを含むものを適宜取込
んで負荷を制御したり、データを記憶して受信デ
ータを処理するデータ処理回路である。なお、こ
のデータ処理回路16はマイクロコンピユータを
用いて形成され、端末器1から送信するデータ信
号VDを形成してFSK変調器17に送るデータ処
理回路をも兼用している。18はFSK復調器1
0のFM検波回路14の検波出力VFに含まれる振
巾変調成分(周波数2Δf)を検出することにより
混信の有無を判別する混信判別部であり、この混
信判別部18から出力される混信検知信号VMに
て送信信号VTの送出を停止するようにしてある。
なお、19はリミツタ増巾回路13出力に含まれ
ている振巾変調成分すなわち返信信号VBに含ま
れる振巾歪のうちリミツタ増巾回路13にて除去
できなかつた振巾歪を検出することにより混信の
有無を判別する第2の混信判別部であり、両混信
判別部18,19出力がオア回路20を介してデ
ータ処理回路16に入力され、いずれかの混合判
別部18,19から混信検知信号VM′,VM′が得
られたとき、送信信号VTの送信を停止するよう
になつている。
以下、実施例の動作について説明する。いま、
端末器1Aから第4図aに示すような送信信号
VTAが送出され、略同時に端末器1Bから同図b
に示すような送信信号VTBが送出された場合、流
送信信号VTA,VTBが混信して周波数が異なる部
分T1,T2(データが異なつている部分)において
干渉によるビートが同図cに示すように振巾変調
成分として現われ、振巾変調成分の周波数は
FSK変調におけるシフト周波数Δfの2倍となり、
中央制御装置2のコンバータ部2aにて周波数変
換f1→f2された返送信号VBにも含まれる。この振
巾変調成分はリミツタ増巾回路13にて除去さ
れ、FM検波回路14にてFM検波される。第3
図はFM検波特性を示す図であり、S字カーブの
下方が検波入力、右方が検波出力VFである。と
ころで、このようにして得られたFM検波回路1
4の検波出力VFにも第5図に示すように干渉に
よるビートが現れ、そのビート成分の振巾は下表
のように両送信信号VTA,VTBのレベル差に応じ
て変化する。
[Technical Field] The present invention relates to a two-way communication system that enables two-way communication between a plurality of terminal devices connected to one signal cable. [Background technology] Recently, with the development of home automation and office automation, multiple signals such as intercom signals, video signals such as wired television, and security information such as crime prevention or disaster prevention are branched and connected to a single signal cable. A two-way communication system is being considered in which information is exchanged between two terminal devices. Figure 1 shows an example of a contention type bidirectional communication system.
Keying) A terminal device that sends out a modulated transmission signal V T , 2 is a transmission signal V T from each terminal device 1A to 1D
This is a central control device equipped with a cone converter section 2a that sends out a return signal VB obtained by converting the carrier frequency f1 into f2.Each terminal device 1A to 1D and the central control device 2 are connected via a coaxial cable via a , and is connected to a signal cable 3 made of optical fiber or the like. On the other hand, the return signal V B is sent to the terminals 1A to 1D.
When a return signal V B containing address data that matches the own address after FSK demodulation is received,
A data receiving section is provided to receive the data of the return signal VB , and terminal devices 1A to 1D
Two-way communication is carried out between the two via the central control device 2. In the figure, 2b is a data processing circuit, 5 is a television camera, and 6 is an intercom device, and the signal cable 3 is also used as a signal transmission path of the television intercom system. By the way, in such a conventional example, each terminal device 1A to 1D determines whether or not a transmission signal V T is being sent from another terminal device 1A to 1D. A transmission suppression means is provided for suppressing the transmission of the own transmission signal V T when the transmission signal V T is being transmitted. However, within the response time of this transmission suppression means, the transmission signal V was generated, causing interference. In other words, the transmission signals V T are generated almost simultaneously, resulting in missing data signals or erroneous transmission, which may confuse the communication system and cause a serious situation. [Object of the Invention] The present invention has been made in view of the above points, and its purpose is to prevent malfunctions when transmission signals are simultaneously sent from multiple terminal devices. The purpose is to provide a two-way communication system. [Disclosure of the Invention] Embodiment FIG. 2 is a block circuit diagram of main parts of terminal devices 2A to 2D according to an embodiment of the present invention, in which reference numeral 10 indicates a local oscillation circuit 11, a mixing circuit 12, and a limiter amplification circuit 13.
, an FM detection circuit 14, and a comparison circuit 15. This FSK demodulator 10 amplifies the received return signal VB , removes the amplitude modulation component with a limiter, and then outputs the FM signal. By performing detection and detecting the level of the detected output V F in a comparison circuit 15, a data signal V D ' consisting of a baseband signal is demodulated. 16 is
This is a data processing circuit that appropriately takes in the data signal V D ' demodulated by the FSK demodulator 10, including its own address data, controls the load, stores the data, and processes the received data. Note that this data processing circuit 16 is formed using a microcomputer, and also serves as a data processing circuit that forms a data signal V D to be transmitted from the terminal device 1 and sends it to the FSK modulator 17. 18 is FSK demodulator 1
This is an interference discrimination section that determines the presence or absence of interference by detecting the amplitude modulation component (frequency 2Δf) included in the detected output V F of the FM detection circuit 14 of 0. The transmission of the transmission signal VT is stopped at the signal VM .
Note that 19 detects the amplitude distortion that cannot be removed by the limiter amplification circuit 13 among the amplitude distortion contained in the amplitude modulation component contained in the output of the limiter amplification circuit 13, that is, the amplitude distortion contained in the reply signal VB . This is a second interference discriminator that determines whether or not there is interference.The outputs of both interference discriminators 18 and 19 are input to the data processing circuit 16 via an OR circuit 20, and interference is detected from either of the mixture discriminators 18 and 19. When the detection signals V M ′, V M ′ are obtained, the transmission of the transmission signal V T is stopped. The operation of the embodiment will be described below. now,
Transmission signal as shown in Figure 4a from the terminal 1A
V TA is sent out, and almost at the same time, terminal device 1B sends
When a transmission signal V TB as shown in the diagram is sent out, the current transmission signals V TA and V TB will interfere and beats due to interference will occur in the parts T 1 and T 2 (parts where the data are different) where the frequencies are different. As shown in c, it appears as an amplitude modulation component, and the frequency of the amplitude modulation component is
It is twice the shift frequency Δf in FSK modulation,
It is also included in the return signal V B subjected to frequency conversion f 1 →f 2 in the converter section 2a of the central control device 2. This amplitude modulation component is removed by the limiter amplification circuit 13 and FM detected by the FM detection circuit 14. Third
The figure shows the FM detection characteristics, where the lower side of the S-shaped curve is the detection input, and the right side is the detection output VF . By the way, the FM detection circuit 1 obtained in this way
A beat due to interference also appears in the detected output V F of No. 4 as shown in FIG. 5, and the amplitude of the beat component changes according to the level difference between the two transmission signals V TA and V TB as shown in the table below.
本発明は上述のように、搬送波をデータ信号に
てFSK変調した送信信号を送出する多数個の端
末器と、各端末器からの送信信号の搬送周波数を
変換した返送信号を送出するコンバータ部を具備
した中央制御装置とを1本の信号ケーブルに分岐
接続し、返送信号をFSK復調して適宜データ信
号を取込むようにしたデータ受信部を各端末器に
設けて成る双方向通信システムにおいて、FSK
復調器のFM検波回路出力の振巾変調成分を検出
することにより混信の有無を判別する混信判別部
を各端末器に設け、混信判別部から出力される混
信検知信号にて送信信部の送出を停止するように
したものであり、FSK復調器のFM検波回路出力
の振巾変調成分を検出することにより混信の有無
を判別しているので、回路構成が簡単で確実に混
信の有無が判別でき、複数個の端末器から送信信
号が同時に送出された場合の誤動作が防止できる
という効果がある。
As described above, the present invention includes a large number of terminal devices that send out transmission signals obtained by FSK modulating a carrier wave with a data signal, and a converter unit that sends out return signals obtained by converting the carrier frequency of the transmission signals from each terminal device. In a two-way communication system, each terminal device is provided with a data receiving section which connects a central control device equipped with a central control device to a single signal cable, demodulates the returned signal by FSK, and receives the data signal as appropriate. FSK
Each terminal device is equipped with an interference discrimination section that determines the presence or absence of interference by detecting the amplitude modulation component of the FM detection circuit output of the demodulator, and the transmission section transmits signals based on the interference detection signal output from the interference discrimination section. Since the presence or absence of interference is determined by detecting the amplitude modulation component of the FM detection circuit output of the FSK demodulator, the circuit configuration is simple and the presence or absence of interference can be determined reliably. This has the effect of preventing malfunctions when transmission signals are sent out simultaneously from a plurality of terminals.
第1図は本発明に係る双方向通信システムの概
略構成を示す図、第2図は本発明一実施例の要部
ブロツク回路図、第3図乃至第6図は同上の動作
説明図、第7図は他の実施例の要部回路図であ
る。
1A〜1Bは端末器、2は中央制御装置、2a
はコンバータ部、3は信号ケーブル、18は混信
判別部である。
FIG. 1 is a diagram showing a schematic configuration of a two-way communication system according to the present invention, FIG. 2 is a main block circuit diagram of an embodiment of the present invention, FIGS. 3 to 6 are operation explanatory diagrams, and FIG. FIG. 7 is a circuit diagram of a main part of another embodiment. 1A to 1B are terminal devices, 2 is a central control unit, 2a
1 is a converter section, 3 is a signal cable, and 18 is an interference discrimination section.
Claims (1)
信号を送出する多数個の端末器と、各端末器から
の送信信号の搬送周波を変換した返送信号を送出
するコンバータ部を具備した中央制御装置とを1
本の信号ケーブルに分岐接続し、返送信号を
FSK復調して適宜データ信号を取込むようにし
たデータ受信部を各端末器に設けて成る双方向通
信システムにおいて、FSK復調器のFM検波回路
出力の振巾変調成分を検出することにより混信の
有無を判別する混信判別部を各端末器に設け、混
信判別部から出力される混信検知信号にて送信信
号の送出を停止するようにしたことを特徴とする
双方向通信システム。1 A central control unit equipped with a large number of terminal devices that send out transmission signals obtained by FSK-modulating carrier waves with data signals, and a converter unit that sends out return signals obtained by converting the carrier frequency of the transmission signals from each terminal device. 1
Connect the branch signal cable to the main signal cable and send the return signal.
In a two-way communication system in which each terminal is equipped with a data receiving section that demodulates FSK and receives data signals as appropriate, interference can be avoided by detecting the amplitude modulation component of the FM detection circuit output of the FSK demodulator. 1. A two-way communication system characterized in that each terminal device is provided with an interference discriminating section for determining the presence or absence of interference, and transmission of a transmission signal is stopped in response to an interference detection signal output from the interference discriminating section.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP8438783A JPS59210752A (en) | 1983-05-14 | 1983-05-14 | Two-way communication system |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP8438783A JPS59210752A (en) | 1983-05-14 | 1983-05-14 | Two-way communication system |
Publications (2)
Publication Number | Publication Date |
---|---|
JPS59210752A JPS59210752A (en) | 1984-11-29 |
JPH0149222B2 true JPH0149222B2 (en) | 1989-10-24 |
Family
ID=13829148
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP8438783A Granted JPS59210752A (en) | 1983-05-14 | 1983-05-14 | Two-way communication system |
Country Status (1)
Country | Link |
---|---|
JP (1) | JPS59210752A (en) |
-
1983
- 1983-05-14 JP JP8438783A patent/JPS59210752A/en active Granted
Also Published As
Publication number | Publication date |
---|---|
JPS59210752A (en) | 1984-11-29 |
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