JP3425879B2 - Full-duplex modem - Google Patents
Full-duplex modemInfo
- Publication number
- JP3425879B2 JP3425879B2 JP02812499A JP2812499A JP3425879B2 JP 3425879 B2 JP3425879 B2 JP 3425879B2 JP 02812499 A JP02812499 A JP 02812499A JP 2812499 A JP2812499 A JP 2812499A JP 3425879 B2 JP3425879 B2 JP 3425879B2
- Authority
- JP
- Japan
- Prior art keywords
- level
- modem
- transmission
- signal
- full
- 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 - Lifetime
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- Bidirectional Digital Transmission (AREA)
- Communication Control (AREA)
- Telephonic Communication Services (AREA)
Description
【発明の詳細な説明】
【０００１】
【発明の属する技術分野】本発明は、全二重伝送方式の
モデムに関し、特に送出レベルの異なるモデムが通信回
線上に混在する場合にも、正確な送受信が行える全二重
伝送方式のモデムに関する。
【０００２】
【従来の技術】従来、モデムの送出レベルの自動設定
は、相手局側モデムの送出レベルまたは線路損失をセン
スして自局側モデムの送信レベルを最適に設定するもの
であった。
【０００３】
【発明が解決しようとする課題】しかしながら、この従
来技術には、次の問題点があった。即ち、回線のノイズ
を全く考慮していない為、回線品質によっては相手局側
モデムの信号を受信できない場合がある事である。
【０００４】このことを具体例に基づいて説明する。従
来、「端末設備等規則」により、モデムの信号の送出レ
ベルは−１５ｄＢｍ以下となる様に規定されていたが、
平成１０年郵政省令第１３号により同規則が改正され、
送出レベルは−８ｄＢｍ以下に変更となった。従って、
市場には送出レベル−１５ｄＢｍ以下の設定のモデム
と、送出レベル−８ｄＢｍ以下の設定のモデムが混在さ
れる事となった。
【０００５】この混在の結果、相手局側のモデムが−１
５ｄＢｍの送出レベルで、自局側のモデムの送出レベル
が−８ｄＢｍであった場合、自局側モデムのエコーが大
きくなり、エコーキャンセラの抑圧率が一定であれば、
受信レベルは変わらずに、エコーによるノイズだけが大
きくなり、相手局側のモデムの信号を受信できなくなる
可能性がある。
【０００６】そこで本発明の課題は、送出レベルの異な
るモデムが混在する場合であっても、正確に送受信が可
能な全二重伝送方式のモデムを提供することである。
【０００７】
【課題を解決するための手段】前記課題を解決するため
に本発明は、前記通信回線上に送出可能な最大送出レベ
ルが規定されている場合に、最初に該送出可能な最大送
出レベルで送出し、かつ、このときに、前記受信レベル
検出手段で検出した検出値（Ｓ）とノイズレベル検出手
段が検出した検出値（Ｎ）に基づいてＳ／Ｎ比を求め、
さらに、このＳ／Ｎ比を予めモデムの伝送速度に応じて
設定した判断基準値と比較し、Ｓ／Ｎ比が前記判断基準
値よりも小さいときは、Ｓ／Ｎ比が前記判断基準値を越
えるまで順次送出レベルを下げていくことにより自局側
の最適送出レベルを決定する送出レベル決定手段と、を
備えた構成としてある。
【０００８】このようにすれば、ノイズレベルと受信レ
ベルの両者に基づいて自局側の最適送出レベルを決定す
るので、相手局側と自局側との間で、正確な送受信を行
うことができる。
【０００９】
【発明の実施の形態】以下、本発明を図示の実施例に基
づいて説明する。図１を参照すると、本実施例のモデム
Ｍは、相手局側モデムＡが送出する信号の送出レベルを
センスする「受信レベル検出手段」である受信レベル検
出回路１と、回線上のノイズレベルをセンスする「ノイ
ズレベル検出手段」であるノイズレベル検出回路２と、
自局側モデムの送出する信号の送出レベルを最適な状態
にして送出する「送出レベル決定手段」である信号送出
回路３とを有している。
【００１０】また、１１はＤＴＥインタフェースを介し
て到来するＤＴＥ（データ端末装置）からの信号を変調
する変調回路、１２は回線インタフェースを介して相手
局側モデムＡに所定の信号を送出する送信フィルタ、１
３は受信信号から所定の信号を取り出す受信フィルタ、
１４は受信信号を復調する復調回路、１５は受信信号の
キャリアを検出するキャリア検出回路である。また、Ｎ
ＣＵは回線制御装置である。
【００１１】次に、信号送出回路３の詳細な構成につい
て説明する。図２は、信号送出回路３の構成例を示すブ
ロック図である。
【００１２】図１,図２に示すように、信号送出回路３
は、Ｓ／Ｎ算出回路３１と、Ｓ／Ｎ基準値設定部３２
と、送出レベル切替回路２２と、ｎ個の信号送出部４１
〜４ｎを備えて構成される。受信レベル検出回路１から
送出される受信レベル信号ａは、Ｓ／Ｎ算出回路３１に
入力される。また、ノイズレベル検出回路２から送出さ
れるノイズレベル信号ｂも同様にＳ／Ｎ算出回路３１に
入力される。
【００１３】Ｓ／Ｎ算出回路３１は、受信レベル信号ａ
（Ｓ）とノイズレベル信号ｂ（Ｎ）とのＳ／Ｎ比を求
め、Ｓ／Ｎ比が、Ｓ／Ｎ基準値設定部３２に予め設定し
た判断基準値（例えば２６ｄＢ、判断基準値の決定方法
は次に述べる）より大きくなるように、信号送出部４１
〜４ｎの中から適切な送出回路を選択する。各信号送出
部は、異なる信号増幅率を有しており、どの信号送出部
が選択されるかによって自局側モデムＡが送出する信号
の送出レベルが変化する。
【００１４】ここで、判断基準値２６ｄＢの設定につい
て説明する。現在、市場に出回っているＦＡＸ送受信機
能を有するＦＡＸモデム（Ｇ３規格）として高速のもの
は、１４４００ｂｐｓである。なお、周知の如く、高速
になるほどノイズの影響を受け易くなる。従って、本実
施例では高速な１４４００ｂｐｓの場合にＦＡＸ接続可
能なＳ／Ｎとしてシミュレーションにより２６ｄＢを算
出した。なお、判断基準値はモデムの性能および接続ス
ピード等により異なる。
【００１５】次に、本実施例の回路の動作について、図
３に示すフローチャートを参照して説明する。
【００１６】先ず、自局側モデムＭの送出レベルを−８
ｄＢｍ（従来例で説明した新規格）にセットする（ステ
ップＳ１）。
【００１７】この状態において、ノイズレベル検出回路
２は、回線上のノイズレベルをセンスし（ステップＳ
２）、ノイズレベル信号ｂを信号送出回路３に送出す
る。また、受信レベル検出回路１は、相手局側モデムＡ
が送出する信号の送出レベルをセンスし（ステップＳ
３）、信号送出回路３に受信レベル信号ａを送出する。
【００１８】信号送出回路３は、受信レベル検出回路１
から送出される受信レベル信号ａとノイズレベル検出回
路２から送出されるノイズレベル信号ｂとを比較し、Ｓ
／Ｎ＞２６ｄＢでなければ（ステップＳ４：ＮＯ）、従
来技術で説明した如くエコーによるノイズだけが大きく
なり、相手局側のモデムの信号を受信できなくなる可能
性があるので、自局側モデムＭの送出レベルを１ｄＢｍ
だけ下げ（ステップＳ５）、ステップＳ２に戻す。
【００１９】そして、ステップＳ２〜ステップＳ４の動
作を繰り返し、Ｓ／Ｎ＞２６ｄＢになったなら（ステッ
プＳ４：ＹＥＳ）、正確に相手局側モデムＡを受信でき
るので,送出レベルのセットを終了する。
【００２０】
【効果の説明】以上説明したように、本発明によれば以
下の効果を奏することができる。第１の効果は、相手局
側のモデムの送出レベルによって自局側のモデムで受信
に失敗する事がないという事である。その理由は、相手
局側のモデムの送出レベルを検出し、自局側モデムの送
信レベルを最適に設定する手段（信号送出回路）を有す
る事により、自局側モデムのエコーによるノイズレベル
を制御している為である。
【００２１】第２の効果は、回線品質により相手局側モ
デムとの接続が困難になる事がないという事である。そ
の理由は、回線上のノイズレベルを検出し、自局側モデ
ムの送信レベルを最適に設定する手段（信号送出回路）
を有する事により、回線品質に応じた自局側モデムの送
信レベルを設定できる為である。Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a full-duplex transmission type modem, and more particularly, to accurate transmission / reception even when modems having different transmission levels coexist on a communication line. The present invention relates to a full-duplex transmission type modem capable of performing the above. 2. Description of the Related Art Conventionally, the automatic setting of the transmission level of a modem has been to optimally set the transmission level of a local station modem by sensing the transmission level or line loss of a partner station modem. [0003] However, this prior art has the following problems. That is, since the noise of the line is not considered at all, the signal of the modem on the partner station side may not be received depending on the line quality. [0004] This will be described based on a specific example. Conventionally, according to the “Rules for Terminal Equipment, etc.”, the transmission level of a modem signal has been defined to be -15 dBm or less.
The rules were revised in 1998 by Ordinance No. 13 of the Ministry of Posts and Telecommunications,
The transmission level has been changed to -8 dBm or less. Therefore,
In the market, a modem having a transmission level of -15 dBm or less and a modem having a transmission level of -8 dBm or less are mixed. As a result of this mixing, the modem on the partner station side becomes -1.
If the transmission level of the local station modem is -8 dBm at the transmission level of 5 dBm, the echo of the local station modem becomes large, and if the suppression rate of the echo canceller is constant,
There is a possibility that the reception level does not change, and only noise due to the echo increases, making it impossible to receive the signal of the modem on the partner station side. SUMMARY OF THE INVENTION It is an object of the present invention to provide a full-duplex transmission modem capable of transmitting and receiving data accurately even when modems having different transmission levels are mixed. [0007] In order to solve the above-mentioned problems, the present invention provides a maximum transmission level which can be transmitted over the communication line.
If the maximum transmission is possible,
Outgoing level, and at this time, the receiving level
The detection value (S) detected by the detection means and the noise level detection method
The S / N ratio is determined based on the detection value (N) detected by the stage,
Further, the S / N ratio is determined in advance according to the transmission speed of the modem.
The S / N ratio is compared with the set criterion value.
When the value is smaller than the value, the S / N ratio exceeds the judgment reference value.
The local station side by sequentially lowering the transmission level until
Transmission level determination means for determining an optimum transmission level of
There is a configuration provided. With this configuration, the optimum transmission level of the own station is determined based on both the noise level and the reception level, so that accurate transmission and reception can be performed between the partner station and the own station. it can. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the illustrated embodiments. Referring to FIG. 1, a modem M according to the present embodiment includes a reception level detection circuit 1 which is a "reception level detection means" for sensing a transmission level of a signal transmitted by a modem A on a partner station side, and a noise level on a line. A noise level detection circuit 2 which is a "noise level detection means" for sensing;
A signal transmission circuit 3 which is "transmission level determination means" for transmitting a signal transmitted from the local station modem to an optimum state and transmitting the signal. Reference numeral 11 denotes a modulation circuit for modulating a signal from a DTE (data terminal equipment) arriving via a DTE interface, and 12 denotes a transmission filter for sending a predetermined signal to a modem A on the opposite station side via a line interface. , 1
3 is a reception filter for extracting a predetermined signal from the reception signal,
Reference numeral 14 denotes a demodulation circuit that demodulates a received signal, and 15 denotes a carrier detection circuit that detects a carrier of the received signal. Also, N
CU is a line control device. Next, a detailed configuration of the signal transmission circuit 3 will be described. FIG. 2 is a block diagram illustrating a configuration example of the signal transmission circuit 3. As shown in FIGS. 1 and 2, the signal transmission circuit 3
Is an S / N calculation circuit 31 and an S / N reference value setting unit 32
, A transmission level switching circuit 22, and n signal transmission units 41
To 4n. The reception level signal a sent from the reception level detection circuit 1 is input to the S / N calculation circuit 31. The noise level signal b sent from the noise level detection circuit 2 is also input to the S / N calculation circuit 31 in the same manner. The S / N calculation circuit 31 receives a reception level signal a
An S / N ratio between (S) and the noise level signal b (N) is obtained, and the S / N ratio is determined by a reference value (for example, 26 dB, which is determined in advance) in the S / N reference value setting unit 32. The method will be described next).
4n to select an appropriate sending circuit. Each signal transmission unit has a different signal amplification factor, and the transmission level of the signal transmitted by the local station side modem A changes depending on which signal transmission unit is selected. Here, the setting of the judgment reference value 26 dB will be described. At present, a high-speed FAX modem (G3 standard) having a FAX transmission / reception function on the market is 14400 bps. As is well known, the higher the speed is, the more likely it is to be affected by noise. Therefore, in this embodiment, 26 dB was calculated by simulation as the S / N that can be connected by FAX at a high speed of 14400 bps. Note that the criterion value differs depending on the performance and connection speed of the modem. Next, the operation of the circuit of this embodiment will be described with reference to the flowchart shown in FIG. First, the transmission level of the local station side modem M is set to -8.
It is set to dBm (the new standard described in the conventional example) (step S1). In this state, the noise level detection circuit 2 senses the noise level on the line (step S).
2) Send the noise level signal b to the signal sending circuit 3. Further, the reception level detection circuit 1
Senses the transmission level of the signal to be transmitted (step S
3) Send the reception level signal a to the signal sending circuit 3. The signal transmission circuit 3 includes a reception level detection circuit 1
Is compared with the noise level signal b sent from the noise level detection circuit 2 and
If / N> 26 dB (step S4: NO), only the noise due to the echo increases as described in the related art, and there is a possibility that the signal of the modem on the partner station side cannot be received. Transmission level of 1 dBm
Only (Step S5) and return to Step S2. Then, the operation of steps S2 to S4 is repeated, and if S / N> 26 dB (step S4: YES), since the other party's modem A can be accurately received, the setting of the transmission level ends. . Description of Effects As described above, according to the present invention, the following effects can be obtained. The first effect is that the modem on the local station side does not fail in reception depending on the transmission level of the modem on the partner station side. The reason is that the transmission level of the modem on the partner station side is detected, and the noise level due to the echo of the modem on the local station side is controlled by providing a means (signal transmission circuit) for optimally setting the transmission level of the modem on the local station side. It is because. The second effect is that the connection with the partner station modem does not become difficult due to the line quality. The reason is that means for detecting the noise level on the line and optimally setting the transmission level of the local station side modem (signal transmission circuit)
The reason for this is that the transmission level of the local station side modem can be set according to the line quality.
【図面の簡単な説明】
【図１】本発明の実施例のブロック図である。
【図２】同実施例における信号送出回路の詳細ブロック
図である。
【図３】同実施例の動作フローチャートである。
【符号の説明】
Ａ 相手局側モデム
Ｍ 自局側モデム
１ 受信レベル検出回路
２ ノイズレベル検出回路
３ 信号送出回路
３１ Ｓ／Ｎ算出回路
３２ Ｓ／Ｎ基準値設定部
４１〜４ｎ 第一の信号送出部から第ｎの信号送出部BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of an embodiment of the present invention. FIG. 2 is a detailed block diagram of a signal transmission circuit in the embodiment. FIG. 3 is an operation flowchart of the embodiment. [Description of Code] A partner station side modem M own station side modem 1 reception level detection circuit 2 noise level detection circuit 3 signal transmission circuit 31 S / N calculation circuit 32 S / N reference value setting sections 41 to 4n first signal From the sending unit to the n-th signal sending unit
───────────────────────────────────────────────────── フロントページの続き (58)調査した分野(Int.Cl.7，ＤＢ名) H04L 29/10 ──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. 7 , DB name) H04L 29/10
Claims (1)
側モデムとの間で全二重伝送方式によりアナログ信号の
送受を行う全二重伝送方式のモデムにおいて、 前記通信回線上のノイズレベルを検出するノイズレベル
検出手段と、 前記相手局側モデムから到来する信号のレベルを検出す
る受信レベル検出手段と、 前記通信回線上に送出可能な最大送出レベルが規定され
ている場合に、最初に該送出可能な最大送出レベルで送
出し、かつ、このときに、前記受信レベル検出手段で検
出した検出値（Ｓ）とノイズレベル検出手段が検出した
検出値（Ｎ）に基づいてＳ／Ｎ比を求め、さらに、この
Ｓ／Ｎ比を予めモデムの伝送速度に応じて設定した判断
基準値と比較し、Ｓ／Ｎ比が前記判断基準値よりも小さ
いときは、Ｓ／Ｎ比が前記判断基準値を越えるまで順次
送出レベルを下げていくことにより自局側の最適送出レ
ベルを決定する送出レベル決定手段と、 を備えたことを特徴とする全二重伝送方式のモデム。(57) [Claims 1] A full-duplex transmission method for transmitting and receiving analog signals between a local station modem and a remote station modem by a full-duplex transmission method via a communication line. A modem, a noise level detecting means for detecting a noise level on the communication line, a reception level detecting means for detecting a level of a signal coming from the partner station modem, and a maximum transmission level transmittable on the communication line. Is specified, the signal is first transmitted at the maximum transmittable level, and at this time, the detection value (S) detected by the reception level detection means and the detection value detected by the noise level detection means are detected. The S / N ratio is determined based on (N), and the S / N ratio is compared with a criterion value set in advance according to the transmission speed of the modem, and the S / N ratio is smaller than the criterion value. Sometimes, S / N There Modem full-duplex transmission system, characterized by comprising: a transmission level determination means for determining an optimum transmission level local station by is lowered sequentially sending level to exceed the criterion value.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP02812499A JP3425879B2 (en) | 1999-02-05 | 1999-02-05 | Full-duplex modem |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP02812499A JP3425879B2 (en) | 1999-02-05 | 1999-02-05 | Full-duplex modem |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JP2000228688A JP2000228688A (en) | 2000-08-15 |
| JP3425879B2 true JP3425879B2 (en) | 2003-07-14 |
Family
ID=12240053
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP02812499A Expired - Lifetime JP3425879B2 (en) | 1999-02-05 | 1999-02-05 | Full-duplex modem |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3425879B2 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6366055B1 (en) | 2000-03-30 | 2002-04-02 | Shin-Kobe Electric Machinery Co., Ltd. | Power supply system and state of charge estimating method |
-
1999
- 1999-02-05 JP JP02812499A patent/JP3425879B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JP2000228688A (en) | 2000-08-15 |
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