JPH01289349A - Dc recovery changeover timing system for tele-terminal system - Google Patents

Abstract

PURPOSE:To recover a data packet received through burst communication with excellent reliability accurately by controlling the operating timing of a DC recovery circuit based on the transmission timing of a polling packet. CONSTITUTION:Since the terminal equipment starts burst communication of a data packet after a prescribed time after the reception of a polling packet, a control section 3 of a tele-terminal controls the operating timing of the DC recovery circuit 23 based on the transmission timing of the polling packet. That is, the detection of a DC component of the received data packet and the operating timing of the storage of the detected DC component are controlled in the DC recovery circuit 23 so as to specify the operating timing accurately. Then the data packet received through burst communication from the terminal equipment is always received and recovered accurately with excellent reliability.

Description

Detailed Description of the Invention [Objective of the Invention (Field of Industrial Application)] The present invention provides a teleterminal system that uses boring packets to control burst communication between a teleterminal and a terminal device. The present invention relates to a DC regeneration switching timing method for a teleterminal system that can effectively control the operation timing of a DC regeneration circuit in a teleterminal system.

(Prior Art) The signal receiving section of the teleterminal in the teleterminal building system that controls burst communication between the teleterminal and the terminal device using boring packets is configured as shown in FIG. 3, for example. . That is, the signal receiving section of the teleterminal generally consists of a radio section 1 that receives data contention packets transmitted in burst communication from a terminal device, a modem 2 that reproduces data received by this radio section 1, and a signal that is reproduced by this modem 2. The control unit 3 inputs received data (playback data) and controls burst communication with the terminal device.

The modem 2 includes a low-pass filter 21, a comparator 22, and a DC regeneration circuit 23 in order to compensate for DC fluctuations caused by frequency deviations of data packets received through burst communication and to accurately reproduce the communication data. , a retiming circuit 24, a digital PLL circuit 25, and the like.

The DC regeneration circuit 23 detects the DC component of data received and input via the low-pass filter 21, and supplies the detected DC component to the comparator 22 as a reference voltage for comparison. The comparator 22 compensates for DC fluctuations caused by frequency deviation of the received input data using the comparison reference voltage supplied from the DC regeneration circuit 23, and performs data regeneration (discrimination).

The digital PLL circuit 25 is phase-synchronized with the output of the comparator 22 and regenerates the clock of the received data. The retiming circuit 24 is the digital PLL circuit 2.
sampling the output data of the comparator 22 at the timing (regenerated clock) synchronized by 5;
The received and reproduced data is obtained.

By the way, in the reception section of the teleterminal configured in this way, it is necessary to quickly detect the DC component when receiving data packets transmitted in burst communication from the terminal device, and the DC regeneration circuit 23 is a CR circuit with a small time constant. It consists of

In addition, in a teleterminal system, especially at a teleterminal base station, ■ Since data comes from unspecified terminals, the frequency differs slightly for each packet, and its DC level fluctuates.

■ There is no limit to the number of consecutive "1" or "0" bits in the data, and the DC level changes depending on how they are arranged.

For this reason, a DC regeneration circuit with a small time constant is required in the case of (2), and a DC regeneration circuit with a large time constant is required in the case of (2), which could not be handled by a CR circuit with a constant time constant.

(Problem to be solved by the invention) When reproducing DC in a teleterminal in this way,
Although a CR circuit with a small time constant can compensate for DC level fluctuations caused by frequency deviations for each packet, it cannot compensate for fluctuations caused by bits in data.

The present invention has been made in consideration of the above circumstances, and its purpose is to provide appropriate timing for switching the operating time constant of the DC regeneration circuit of the teleterminal, and to improve data packets received through burst communication. reliable,
Another object of the present invention is to provide a DC regeneration switching timing method for a teleterminal system that allows accurate regeneration.

[Configuration of the Invention (Means for Solving the Problems) The present invention provides a system in which data packets transmitted in burst communication between a teleterminal and a terminal device specify a transmitting terminal device by a polling packet given from the teleterminal. Focusing on the fact that the communication terminal starts burst communication of data packets after receiving this polling packet, it detects the DC component of the data packet transmitted in burst communication from the terminal device, and uses this detected DC component. The operation timing of the DC regeneration circuit of the teleterminal that holds the component is switched and controlled based on the transmission timing of the polling packet, for example, after a certain period of time from the transmission timing of the polling packet. be.

(Operation) According to the present invention, since the terminal device starts burst communication of data packets after a predetermined time after receiving the polling packet, the terminal device starts the burst communication of data packets after a predetermined time after receiving the polling packet.
By controlling the operation timing of the DC regeneration circuit based on the packet transmission timing, that is, detecting the DC component of the received data packet in the DC regeneration circuit,
By controlling the operation timing of storing the detected DC component, the operation timing can be accurately defined. As a result, it becomes possible to always reliably and accurately receive and reproduce data packets received through burst communication from a terminal device.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 is a diagram showing an example of the configuration of a receiving section of a teleterminal in an embodiment system, and FIG. 2 is a diagram for explaining its operation control timing.

The receiving section of the teleterminal in this system is basically constructed in the same way as the conventional device shown in Fig. 3, but
It is characterized in that the operation of the DC regeneration circuit 23 provided in the modem 2 is controlled by a switching timing signal determined by the control section 3.

That is, the DC regeneration circuit 23 has a CR open circuit with a small time constant and a hold circuit, and normally follows the DC component of the output signal of the low-pass filter 21 to the DC level fluctuation, and converts it to a high-speed CR open circuit with a small time constant. When a switching timing signal is received from the control section 3, the DC component detected immediately before is held in a hold circuit. In other words, the DC regeneration circuit 23 is normally small (it detects the DC component of the received data with good responsiveness under the set time constant, and when the switching timing signal is given from the control unit 3, the time constant is set to switch for a sufficiently long period of time, and the DC component detected just before that time is saved.

The comparator 22 inputs the output (detected DC component) of the DC regeneration circuit 23 whose time constant is switched and controlled in this way as a reference voltage for comparison, and discriminates the received data packet given through the low-pass filter 21 to determine the frequency. It compensates for fluctuations in the DC component caused by deviations, etc., and regenerates the DC component.

Now, the control section 3 generates the switching timing signal in the following manner.

That is, this control unit 3 transmits a polling packet via the downlink channel as shown in FIG. The modem 1 receives, via the modem 2, data packets that are burst-communicated via an uplink channel from a received terminal device.

Thus, the terminal device starts burst communication of data packets when a certain period of time T has elapsed after receiving the designation of transmission permission by the polling packet. Therefore, the teleterminal cannot receive a data packet from the designated terminal device until the predetermined time T has elapsed from the timing at which the polling packet was sent. In other words, the timing at which the teleterminal starts receiving data packets that are burst-communicated from the terminal device specified by the polling packet is stipulated to be a certain period of time T away from the transmission timing of the polling packet. I can do it.

The system 88B is based on this viewpoint, and as shown in FIG. The above-mentioned switching timing signal is generated at a timing (↑+t) that takes into account the DC component detection time t.

Thus, according to the present system in which the @'411 section 3 controls the operation of the DC regeneration circuit 23 by the switching timing signal generated based on the polling packet transmission timing, the signal is detected at the start of data packet reception. The DC component of the data packet can be effectively retained until reception of the data packet is completed.

Under this maintained DC component, fluctuations in the DC component of the data packet can be compensated for and the DC regeneration can be effectively performed. Therefore, it is possible to always reliably and stably reproduce the DC level of the received data packet.

Note that the present invention is not limited to the embodiments described above. For example, the generation timing of the switching timing signal based on the polling packet transmission timing can be set in consideration of the burst communication propagation time of the data packet from the terminal device to the teleterminal.
In short, the operation of the DC regeneration circuit may be controlled based on the polling packet transmission timing.

In addition, the present invention can be implemented with various modifications without departing from the gist thereof.

[Effects of the Invention] As explained above, according to the present invention, since the operation timing of the DC regeneration circuit is controlled based on the polling packet transmission timing, the operation can be accurately defined and the received data can be stabilized. DC regeneration can be ensured under very simple control. Furthermore, since a synchronization detection circuit or the like for operation control is not required, great practical effects such as the ability to easily configure the receiving section of the teleterminal can be achieved.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a schematic configuration of a main part of a receiving section of a teleterminal in a system according to an embodiment of the present invention, and FIG. 2 is a diagram showing control timing in the system according to the embodiment. ff13 is a diagram showing a schematic configuration of the main parts of a receiving section of a teleterminal in a conventional system. l...Radio section, 2...Modem, 3...1tll
I n, 21...Low-pass filter, 22...Comparator, 23...DC regeneration circuit, 24-Retiming circuit, 25...Digital PLL0 Applicant's agent Patent attorney Takehiko Suzue

Claims (2)

[Claims] (1) In a teleterminal system that controls burst communication between a teleterminal and a terminal device using boring packets, the teleterminal detects a DC component of a data packet transmitted in burst communication from the terminal device, A DC regeneration switching timing method for a teleterminal system, characterized in that the operating timing of a DC regeneration circuit that holds the detected DC component is switched and controlled based on the transmission timing of a boring packet specifying a transmitting terminal device. (2) The DC regeneration circuit is installed in a modem that receives and regenerates data packets, and detects the DC component of the data and packets after a certain period of time from the transmission timing of the boring packet, and converts the detected DC component into the data for a specified period of time. 2. A direct current regeneration switching timing method for a teleterminal system according to claim 1, wherein the operating timing is switched and controlled so as to be maintained throughout the period.