JPH01825A - Send level automatic adjustment circuit - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention is a device that performs a line interface function, which amplifies a received signal received via a transmission line to a predetermined value and sends it out based on the amplified value. The present invention relates to an automatic transmission level adjustment circuit that can always maintain an incoming signal level at a predetermined value regardless of the length of the transmission line between both terminals by amplifying the signal 5;- and sending it out via a transmission line.

(Prior Art) Conventionally, in a slave device on the field side of a carrier telephone device, the length of the transmission path can be changed by relocating the slave device or replacing the cable.
The material of the cable may change, but in this case,
Generally, a level adjustment circuit is provided in order to compensate for fluctuations in transmission loss of the transmission path and supply a received signal of a predetermined level to the parent device n.

FIG. 2 (al and lbl are a block diagram showing the configuration of a conventional level adjustment circuit and an explanatory diagram schematically showing the configuration of the parent device and the r device group; this level adjustment circuit 50 is connected to the receiving end and It is configured such that an Ill variable lν (attenuator 502), a band amplifier 50b corresponding to a specified frequency band, and a digital terminal f50c: are connected in series between the input terminal of the receiving circuit, and For adjustment, a high impedance level meter is connected to the check terminal r of 1rj, and the modified attenuator 51 (11) is changed to i12 to set the receiving relevel of the receiving circuit input terminal Δ to a predetermined value.

In addition, if the transmission path is long and transmission loss increases, a level adjustment I'll 60 with a circuit configuration similar to that described in 1 is provided between the transmitting circuit output end and the sending end as necessary. The signal level at the receiving end to the parent device via the transmission path is adjusted.

FIG. 2 (bl) schematically shows the arrangement positional relationship of these components as a parent device 70 and a child device (group) 80, and each r station of the child device η80 is provided with a level adjustment circuit. It is being

However, with the new installation or relocation of the 11 conventional devices, it was necessary to individually set the levels at the receiving circuit input end and the sending end using a level adjustment circuit. This level adjustment requires measurement using a level meter and knowledge of understanding the decibels of measured values. In large-scale systems, a large number of level adjustments are required when newly installed, and level adjustments must be made each time the system is moved after installation.

(Object of the Invention) The present invention has been made in view of the above, and even if the transmission loss changes due to the installation or relocation of a slave device, the incoming terminal receiver 11i of the slave device is automatically signal level at all times
The object of the present invention is to provide an automatic transmission level adjustment circuit that maintains a constant output level.

(W essential of the invention) In order to achieve the object L, the automatic transmission level adjustment circuit of the present invention amplifies to a predetermined value the reception level at the receiving end from the parent device that has fluctuated due to the transmission loss caused by the fluctuation of the transmission path length. automatic gain; uses a ta control circuit (ΔGC circuit) to set the receiving circuit input end receiving LE "j level to a constant value, detects the gain control signal of the AGC circuit, and adjusts the transmit signal based on this value. The signal is amplified and sent from the 1i end to the parent device via a transmission path.

To explain this in detail, the present invention is capable of transmitting a received signal that has arrived at a child device via a transmission path to a receiving end in data communication between a device connected via a transmission path, such as a carrier telephone device. amplification is performed using an automatic gain amplifier provided between the input terminal of the automatic gain amplifier and the receiving circuit input terminal, and the amplification level of the automatic gain amplifier is detected; an open control signal 4a is generated based on the detected amplification level; and this control signal 13 is This controls the amplification degree of the amplifier 5 provided between the transmitting circuit output end and the sending end.

This automatic transmission level adjustment circuit amplifies the transmitted signal based on the level of the received signal which has been attenuated due to the loss in the transmission path, and sends it out to compensate for the transmission loss in the transmission path. The received signal level at the receiving end of the processing device is automatically kept constant in response to fluctuations in transmission loss due to relocation.

(Embodiment) Hereinafter, the automatic transmission level adjustment circuit of the present invention will be described in detail.

FIG. 1 (al and (bl) are a block diagram of a daily adjustment circuit according to the present invention, and an explanatory diagram showing six types of transmission paths and their corresponding transmission path losses.

This output level automatic adjustment circuit is used for taking out the conveyance number 41'+ in the middle of the communication path at the 1st end and the 1st end.
' l, automatic interest rl control amplifier (AI"C circuit) 2 on the receiving side, and the gain of the amplifier 2; 1.11 A detection circuit for detecting the control signal: 3, and a signal 3a from the detection circuit 3 manually a control circuit 4 for outputting control signal 111 4alIC; an amplifier 5 on the transmission Lt side that performs amplification based on the level of the :v control signal 4a from the control circuit 4; 13P in the private channel transmission (1) area
PB and I1.

The received signal level at the receiving end fluctuates when the loss changes due to changes in the transmission path, etc., but the receiving side amplifier 2
The output (,1
AGc (8 IIL Om a L, i
c G a i n c o n t, r 01
) with an amplifier. The amplification gain of this amplifier 2 varies depending on the received signal level Ia manually controlled. Detector 3
detects this amplification gain, that is, the Li signal indicating how much amplification is required to output the Lr signal at a predetermined level, and uses the control circuit 4 to control the amplification level of the curve 119 width amplifier 5 on the transmitting side. I try to control it.

Through this series of i1 actions, the received signal tj 'J- is amplified in response to the loss in the transmission path, and the level of the transmitted signal <, t<, i is also amplified in response to the amplified value. , the transmission loss is compensated for by 11-4°. In other words, in order to compensate for transmission loss, the receiving (+i) signal level and the transmitting level are amplified by 1/7, and the fluctuations in transmission loss due to changes in transmission path length due to new installation or relocation of r equipment are compensated for. Also, the (+jS7 level) at the receiving end (1-way input end and the receiving end of the processing device) is always maintained at a constant level.

Next, we will explain the amplification gain adjustment width of the amplifiers 2.6 on the receiving side, the j side, and the sending side (li side). Figure 1 (l+) shows the variation in transmission line loss depending on the type of transmission line. ,
Even if the distance between the parent device and the -r device is the same, if the device is relocated, losses may occur due to differences in the line materials used, etc.
It will be different like.

Historically, the reception (It) transmitted from the r device to the terminating end of the parent device
Nobuyumi ``I and the parent device I'? A transmitter that transmits from the sending end to the receiving end of the r device''; r 2 has the same transmission path length.
However, the transmission loss varies depending on the frequency. If the respective losses are a ci 13 and b d 11, then r
'i kll f14■ reception a, +5x and transmission a, i
'yr2 signal level fluctuation 4. ! , ; −
; The (No. 5 level fluctuation ratio of r + is a / b,
If the amplification gain adjustment width of the transmitting side amplifier is set to a/b with respect to the amplification gain adjustment width of the amplifier 2 on the receiving (51 side), the incoming signal level of the processing device will be
Becomes chemotactic.

The automatic transmission level adjustment circuit of the present invention as shown below is as follows:
Correspondence (1-i) is installed in the carrier telephone communication equipment.

(Effects of Plan -15) As described above, according to the automatic transmission level adjustment circuit of the present invention, there is no need to adjust the level setting of the receiving circuit input terminal even when the r device is newly installed or relocated. This eliminates the need to install or add a transmission level adjustment circuit, which is required when the transmission path is long, and simplifies work for new installation or relocation.

Historically, since the reception and transmission signals are amplified to an appropriate IL level, the relative value of the noise generated from the transmission path etc. can be reduced and high quality signal transmission can be achieved.

[Brief explanation of the drawing]

Fig. 1 (fat and (bl) is a block diagram of the automatic adjustment circuit of the present invention and an explanatory diagram showing various transmission paths and corresponding transmission line losses, and Fig. 2 (a) and (bl) are conventionally used・Explanatory diagram of the configuration of the bell adjustment circuit and a diagram schematically showing the connection relationship between the parent device and the r device group. 1...+3 +'l-' 2... Amplifier on the receiving side... Detection circuit 4...Control circuit 5...Amplifier 6...131)

Claims (1)

[Claims] An automatic transmission level adjustment circuit provided at an interface of a device that transmits and receives signals via a transmission path, the automatic transmission level adjustment circuit having an automatic gain control circuit that amplifies an incoming signal to a certain set value. A control circuit (AGC) and the AGC
An automatic transmission level adjustment circuit comprising: a transmission side amplifier that amplifies a transmission signal based on a control signal.