JPH0292037A - Voice code switching system - Google Patents

Abstract

PURPOSE:To avoid the generation of noise attended with line changeover and to shorten the voice stop time by using voice transmission in the compression coding system normally, using the non-compression coding at the time of line changeover and synchronizing the compression system prior to the restoration to the compression system after the line is switched. CONSTITUTION:Switches SW1, SW2 are changed over to the position of a compression coder 11 normally, SW3, SW4 are changed over to the position of a compression decoder 16 and SW5, SW6 are changed over to the position of the active system. In this case, a non-compression coder 12 is also active through the reception of the output of a synchronizing signal generator 13. Line sections 14A, 14B are provided with a line monitoring section. When a line fault is detected in one of lines 15, it is also informed to the other of the lines 15. Then the switches SW1-SW4 are switched to the position of non-compression side, and then the SW5, SW6 are switched to the position of the standby side E. In this case, a line section 14B turns on a changeover switch SW7, and a synchronizing signal obtained by a non-compression decoder 17 receiving a reception signal and being synchronized is applied to a compression decoder 16. Then the line 15 is switched to the standby side E and after the discrimination of the absence of a fault, the SW1-SW4 are restored to the position of the compression side and the SW7 is turned off.

Description

【発明の詳細な説明】 〔発明の概要〕 音声を符号化してデジタル回線で伝送するシステムにお
ける音声圧縮符号化チャネルを別の対地や予備チャネル
等に切替える際の音声符号切替方式に関し、 回線切替時の雑音発生を軽減し、音声中断期間を短縮す
ることを目的とし、 常時は圧縮符号化系で音声を伝送し、回線切替時は一旦
非圧縮符号化系に切替え、そして圧縮符号化系の同期は
確保しておき、回線切替後、非圧縮符号化系より圧縮符
号化系へ復旧させるように構成する。[Detailed Description of the Invention] [Summary of the Invention] This invention relates to an audio code switching method when switching an audio compression encoding channel to another destination or backup channel in a system that encodes audio and transmits it over a digital line. The aim is to reduce noise generation and shorten audio interruption periods, by always transmitting audio using a compression encoding system, and when switching lines, switching to a non-compression encoding system, and then synchronizing the compression encoding system. is secured, and the configuration is configured so that after line switching, the non-compression coding system is restored to the compression coding system.

〔産業上の利用分野］ 本発明は、音声を符号化してデジタル回線で伝送するシ
ステムにおける音声圧縮符号化チャネルを別の対地や予
備チャネル等に切替える際の音声符号切替方式に関する
。[Industrial Field of Application] The present invention relates to an audio code switching method when switching an audio compression encoding channel to another destination, a backup channel, etc. in a system that encodes audio and transmits it over a digital line.

音声会議では複数の会議室を通信回線で結んで会議を行
なう。重要な会議では回線を複数用意しておき、使用中
の回線に障害が発生すると予備回線に切替えるという方
法をとる。In an audio conference, multiple conference rooms are connected via communication lines. For important meetings, multiple lines are prepared, and if a failure occurs on the line in use, the system is switched to a backup line.

またデジタル回線の普及に伴い、広帯域の音声信号を圧
縮して符号化し、狭帯域の音声チャネルで伝送する方式
が増加している。音声会議でもこの方法をとると、回線
障害時には圧縮符号化チャネルを切替えることになる。Furthermore, with the spread of digital lines, there has been an increase in the number of systems in which wideband audio signals are compressed and encoded and transmitted over narrowband audio channels. If this method is used for audio conferencing, the compression encoding channel will be switched in the event of a line failure.

アナログ回線では回線切替は格別問題なく、回線を切替
えたとき一瞬音が途切れるだけである。With analog lines, there is no particular problem when switching lines, and the sound only cuts out momentarily when switching lines.

しかし符号化したデジタル信号では、アナログ信号とは
異なり、同期外れや符号誤りが発生し、これが発生して
いる間大きな雑音が発生する。特に圧縮符号化方式では
前の値との差分を伝送するので、回線切替えで前の値が
失なわれたりすると予測値は大きくずれることになり、
これは大きな雑音となる。そこで圧縮符号化系では特に
回線切替えには注意を要する。However, in encoded digital signals, unlike analog signals, loss of synchronization and code errors occur, and large noise is generated while these occur. In particular, compression encoding systems transmit the difference from the previous value, so if the previous value is lost due to line switching, the predicted value will deviate greatly.
This results in a lot of noise. Therefore, in compression coding systems, special care must be taken when switching lines.

〔従来の技術］ 第３図（ａ）に、予備回線を持つ圧縮符号化伝送方式の
概要を示す。３１は圧縮符号化用のコーグ、３２は圧縮
復号化用のデコーダ、３３は回線制御用のライン部、３
４は回線切替部、３５は回線である。回線３５は現用Ｎ
と予備Ｅからなり、現用異常時にはＮから已に切替える
。[Prior Art] FIG. 3(a) shows an outline of a compression coding transmission system having a protection channel. 31 is a code for compression encoding, 32 is a decoder for compression and decoding, 33 is a line unit for line control, 3
4 is a line switching unit, and 35 is a line. Line 35 is currently in use N
It consists of a reserve E and a reserve E, and switches from N to E in the event of an abnormality in the current use.

回線切替は現用／予備の切替えだけでなく、対地（相手
局）切替でも生じる。第３図（ロ）はこの例を示し、Ａ
−Ｃ局の間を回線３５ＡＢ、３５ＢＣ。Line switching occurs not only when switching between working and standby lines, but also when switching to the other station. Figure 3 (b) shows this example, and A
- Lines 35AB and 35BC between stations C.

３５ＡＣで接続し、例えばＡ−Ｂ間の通話中にＡ−０間
通話に切替えることがある。この場合も同様な問題が生
じる。For example, during a call between A and B, the call may be switched to a call between A and 0. A similar problem occurs in this case as well.

〔発明が解決しようとする課題〕[Problem to be solved by the invention]

回線切替もアナログ回線であれば回線切替えによる雑音
発生は瞬間的なもの（音声の瞬断）で済むが、圧縮符号
化していると同期外れや符号誤りによって大きな雑音が
発生ずる。If line switching is an analog line, the noise caused by line switching will be instantaneous (momentary audio interruption), but if compression coding is used, large noises will be generated due to synchronization loss or code errors.

そこで、回線切替の直前にデコーダ３２の出力を止め、
切替後信号の同期が安定した時点でデコーダ３２の出力
の使用を再開する方法がある。ところが、この方法によ
ると一定期間音声が途切れることになるので、重要な音
声回線としては都合が悪い。Therefore, just before switching the line, the output of the decoder 32 is stopped,
There is a method of restarting the use of the output of the decoder 32 when the synchronization of the signals becomes stable after switching. However, this method causes audio to be interrupted for a certain period of time, which is inconvenient for important audio lines.

本発明はか〜る点を改善し、切替時に音声が停止する期
間を短縮することができる切替方式の提供を目的とする
ものである。The present invention aims to improve the above points and provide a switching method that can shorten the period during which audio stops during switching.

〔課題を解決するための手段］ 第１図は本発明の原理図で、１１は圧縮符号化用のコー
グ、１２は非圧縮符号化用のコーグ、１３は同期信号発
生器、１４はライン部、１５は回線、１６は圧縮復号化
用のデコーダ、１７は非圧縮復号化用のデコーダ、ＳＷ
１〜ＳＷ４は圧縮系／非圧縮系の切替器、ＳＷ５．ＳＷ
６は現用系Ｎと予備系Ｅの回線切替器、ＳＷ７は同期信
号に対する開閉器である。[Means for Solving the Problems] FIG. 1 is a diagram showing the principle of the present invention, in which 11 is a compression coding cog, 12 is a non-compression coding cog, 13 is a synchronization signal generator, and 14 is a line section. , 15 is a line, 16 is a decoder for compression decoding, 17 is a decoder for non-compression decoding, SW
1 to SW4 are compression system/non-compression system switch; SW5. SW
6 is a line switch for the active system N and protection system E, and SW7 is a switch for the synchronization signal.

〔作用〕[Effect]

この装置では正常時はＳＷＩ、ＳＷ２は圧縮ニーダ１１
側に、またＳＷ３．ＳＷ４は圧縮デコーダ１６側に切替
わっており、またＳＷ５．ＳＷ６は現用系に切替わって
おり、従って、音声入力は圧縮コーグ１１で圧縮符号化
され、回線１５の現用系Ｎを伝送され、圧縮デコーダ１
６で元のアナログ音声に復元される。このとき同期信号
発生器１３の出力を受けて非圧縮コーグ１２も動作して
いる。In this device, during normal operation, SWI is the compression kneader 11, and SW2 is the compression kneader 11.
On the side, there is also SW3. SW4 has been switched to the compression decoder 16 side, and SW5. SW6 has been switched to the working system, and therefore, the audio input is compressed and encoded by the compression cog 11, transmitted through the working system N of the line 15, and sent to the compression decoder 1.
6 restores the original analog audio. At this time, the uncompressed cog 12 is also operating in response to the output of the synchronization signal generator 13.

ライン部１４Ａ、１４Ｂは回線監視部を備えていて、回
線１５の状態を監視しており、一方が回線異常を検出す
るとその旨を他方へも通知する。The line units 14A and 14B are equipped with line monitoring units and monitor the state of the line 15, and when one detects a line abnormality, it also notifies the other.

そして表両ライン部１４Ａ、１４Ｂは先ず切替器ＳＷ１
〜ＳＷ４を非圧縮側に切替え、その後切替器ＳＷ５．Ｓ
Ｗ６を予備側已に切替える。このとき受信側のライン部
１４Ｂは切替器ＳＷ７をオンにして、非圧縮デコーダ１
７が受信信号を受けて同期したことにより得られる同期
信号を圧縮デコーダ１６に与える。これはＳＷ１〜ＳＷ
４が圧縮側に復旧する前に圧縮デコーダ１６を同期させ
ておくためである。Then, first, both front line parts 14A and 14B are connected to the switch SW1.
~SW4 is switched to the non-compression side, and then switch SW5. S
Switch W6 to spare sidearm. At this time, the line section 14B on the receiving side turns on the switch SW7 and decompresses the uncompressed decoder 1.
7 receives the received signal and synchronizes, and provides the compression decoder 16 with a synchronization signal. This is SW1~SW
This is in order to synchronize the compression decoder 16 before 4 is restored to the compression side.

ライン部１４Ａ、１４Ｂは回線１５を予備側已に切替え
て異常がないと判断したらＳＷＩ〜ＳＷ４を圧縮側に復
旧し、またＳＷ７をオフにする。The line units 14A and 14B switch the line 15 to the standby side, and when it is determined that there is no abnormality, restore SWI to SW4 to the compression side and turn off SW7.

これで以後は予備側已による圧縮符号化伝送が行われる
。From now on, compressed and encoded transmission will be performed using the backup sideband.

圧縮コーグ１１、非圧縮コーグ１２は同期信号発生器１
３により同期して動作しており、また非圧縮デコーダ１
７の同期信号を開閉器ＳＷ７を通して圧縮デコーダ１６
に伝えるので、切替器ＳＷ１〜ＳＷ４が復旧する以前に
圧縮コーグ１１と圧縮デコーダ１６は同期して動作して
いる。Compression Cog 11 and non-compression Cog 12 are synchronization signal generator 1
3, and the uncompressed decoder 1
7 synchronization signal is passed through the switch SW7 to the compression decoder 16.
Therefore, the compression cog 11 and the compression decoder 16 are operating synchronously before the switching devices SW1 to SW4 are restored.

このように本発明では回線切替時を含む一定期間、回線
異常時の雑音の少ない非圧縮符号化系に切替えるので、
切替時の違和感が低減される。また圧縮系も、切替後、
チャネルが圧縮系に復旧する以前に同期がとれているた
め、復旧時にノイズが発生しない。こうして本発明では
、回線切替えに伴なう雑音発生を回避し音声停止時間を
短くすることができる。In this way, the present invention switches to a non-compression coding system with less noise during a certain period of time, including the time of line switching, so that
Unnatural feeling during switching is reduced. Also, after switching the compression system,
Since synchronization is established before the channel is restored to the compression system, no noise occurs during restoration. In this manner, the present invention can avoid the noise caused by line switching and shorten the voice stop time.

〔実施例〕〔Example〕

第２図は本発明の一実施例を示す構成図で、圧縮符号化
系に７ＫＨｚ帯域のＡＤＰＣＭコーダ１コーＡＤＰＣＭ
デコーダ１６を用い、また非圧縮符号化系に３ＫＨｚ帯
域のＰＣＭコーコー２とＰＣＭデコーダ１７を用いたも
のである。FIG. 2 is a block diagram showing an embodiment of the present invention, in which the compression encoding system includes a 7 KHz band ADPCM coder and 1 code ADPCM.
A decoder 16 is used, and a 3 KHz band PCM coder 2 and a PCM decoder 17 are used for the non-compression encoding system.

送信側のライン部１４Ａにはクロック抽出部２１があり
、ここで回線より抽出された６４Ｋｂｐｓのクロックが
フレーム同期信号発生器１３へ送られ、該発生器が発生
するフレーム同期（８Ｋｂｐｓ　）でＡＤＰＣＭコーダ
１コーＰＣＭコーコー２が動作する。The line section 14A on the transmitting side has a clock extraction section 21, and the 64 Kbps clock extracted from the line is sent to the frame synchronization signal generator 13, and the ADPCM coder uses the frame synchronization (8 Kbps) generated by the generator. 1 code PCM code 2 operates.

ライン部１４Ａはまたアラーム検出回路２２Ａを備え、
これでアラームを検出するとそれを相手ライン部に送出
すると共に、モノマルチバイブレーク２４Ａで保持する
。２３Ａは、アラーム検出部２２Ａが回線異常を検出し
たとき相手側へその旨を通知するアラーム送出部である
。またモノマルチバイブレーク２４Ａは、アラーム検出
部２２Ａの出力で起動されると、一定期間切替器ｓｗ１
゜ＳＷ２をＡＤＰＣＭコーダ１コーらＰＣＭコーコー２
へ切替える。The line section 14A also includes an alarm detection circuit 22A,
When an alarm is detected, it is sent to the other party's line section and held by the mono multi-by-break 24A. 23A is an alarm sending unit that notifies the other party when the alarm detecting unit 22A detects a line abnormality. Furthermore, when the mono multi-by-break 24A is activated by the output of the alarm detection section 22A, the switch sw1 is activated for a certain period of time.
゜SW2 from ADPCM coder 1 code to PCM coder 2
Switch to

受信側のライン部１４Ｂは、同様のアラーム検出部２２
Ｂ１アラーム送出部２３Ｂ１モノマルチ２４Ｂを有する
。クロック抽出部はない。モノマルチ２４Ｂの出力は切
替器ＳＷ３．ＳＷ４をｐｃＭデコーダ１７側へ切替える
と共に、スイッチＳＷ７をオンにする。２５Ａ、２５Ｂ
はモノマルチ２４Ａ、２４Ｂの出力を記憶し、回線１５
を現用Ｎから予備Ｅへ切替えるメモリである。この切替
タイミングはＳＷ１〜ＳＷ４が圧縮側から非圧縮側へ切
替った後である。The receiving side line section 14B has a similar alarm detection section 22.
It has a B1 alarm sending section 23B1 monomulti 24B. There is no clock extraction section. The output of the monomulti 24B is output from the switch SW3. SW4 is switched to the pcM decoder 17 side, and switch SW7 is turned on. 25A, 25B
stores the outputs of monomulti 24A and 24B, and connects it to line 15.
This is the memory that switches from the current N to the backup E. This switching timing is after SW1 to SW4 switch from the compression side to the non-compression side.

切替後アラームが復旧すると、切替器ＳＷ１〜ＳＷ４も
復旧する。このときＡＤＰＣＭデコーダ１６はＰＣＭデ
コーダ１７のフレーム同期に一致しており、結果的にＡ
ＤＰＣＭコーダ１コー同期しているため、接続時のノイ
ズがなく圧縮系に切替わる。When the alarm is restored after switching, the switching devices SW1 to SW4 are also restored. At this time, the ADPCM decoder 16 matches the frame synchronization of the PCM decoder 17, and as a result, ADPCM decoder 16 matches the frame synchronization of PCM decoder 17.
Since the DPCM coder is synchronized with one code, there is no noise during connection and switching to the compression system is possible.

〔発明の効果］ 以上述べたように本発明によれば、常時は圧縮符号化系
で高品質の音声伝送を行うシステムで、回線切替時は一
時的に雑音の点で有利な非圧縮符号化系を用いるように
し、また回線切替後の圧縮系への復帰に先立って該圧縮
系を同期化させておくので、回線切替時の雑音が、非圧
縮系の場合と同一レベルに低減される。[Effects of the Invention] As described above, according to the present invention, the system normally transmits high-quality audio using compression encoding, but when switching lines, it temporarily transmits high-quality audio using non-compression encoding, which is advantageous in terms of noise. Since the compression system is synchronized before returning to the compression system after line switching, the noise at the time of line switching is reduced to the same level as in the case of a non-compression system.

【図面の簡単な説明】[Brief explanation of drawings]

第１図は本発明の原理図、 第２図は本発明の実施例の構成図、 第３図は従来の音声符号化伝送方式における回線切替え
の説明図である。 図中、１１は圧縮コーグ、１２は非圧縮コーグ、１３は
同期信号発生器、１４はライン部、１５は回線、１６は
圧縮コーグ、１７は非圧縮コーグ、５ｗｔ−３Ｗ７は切
替器である。FIG. 1 is a diagram of the principle of the present invention, FIG. 2 is a block diagram of an embodiment of the present invention, and FIG. 3 is an explanatory diagram of line switching in a conventional voice coding transmission system. In the figure, 11 is a compression coil, 12 is a non-compression coil, 13 is a synchronization signal generator, 14 is a line section, 15 is a line, 16 is a compression coil, 17 is a non-compression coil, and 5wt-3W7 is a switch.

Claims (1)

【特許請求の範囲】[Claims] １、常時は圧縮符号化系（１１、１６等）で音声を伝送
し、回線切替時は一旦非圧縮符号化系（１２、１７等）
に切替え、そして圧縮符号化系の同期は確保しておき、
回線（Ｎ、Ｅ）切替後、非圧縮符号化系より圧縮符号化
系へ復旧させることを特徴とする音声符号切替方式。1. Audio is always transmitted using a compression encoding system (11, 16, etc.), and once the line is switched, it is transmitted using a non-compression encoding system (12, 17, etc.)
Switch to , and ensure synchronization of the compression encoding system.
An audio code switching system characterized by restoring from a non-compression coding system to a compression coding system after switching lines (N, E).