JPH0918461A - Data receiver - Google Patents

Abstract

PURPOSE: To automatically discriminate transmission rate by detecting the edges of the signal for a prescribed period in a preamplifier by a controller and measuring the time interval of the edges. CONSTITUTION: A controller 2 detects the edges of the signal for a prescribed period in a preamplifier and measures the time interval of the edge. In the case, when it is judged that the measured time is corresponding to a high rate transmission, a transmission rate is temporarily determined as high rate and the determination is notified to a decoding part 3. In the same way, when the measured time is corresponding to a low rate transmission, the transmission rate is temporarily determined as low rate and the determination is notified to the decoding part 3. The number of 1 is added to the value of an interval register and increment is performed. In this cases, the controller 2 decides each of the high rate transmission and the low rate transmission and notifies it to the decoding part 3. When the measured time is not corresponding to the high rate transmission and is not corresponding to the low rate transmission, the controller 2 finally determines the transmission rate and notifies the rate to the decoding part 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data receiving device, and more particularly to a data receiving device capable of automatically determining the transmission rate of digital data.

[0002]

2. Description of the Related Art Transmission of digital data (hereinafter, simply referred to as data) is widely used in various fields, and it is also known that the transmission speed can be switched.

If data can be transmitted at a plurality of transmission rates in this way, for example, when transmitting a large amount of data, it can be transmitted at a high speed, and at a low speed such as when transmitting distantly. If it is desired to transmit, it can be transmitted at a suitable rate.

Further, it is possible to ensure safety and reliability by retransmitting data transmitted at a certain speed at a different speed.

Further, depending on the state of noise on the communication line, it is possible to transmit at low speed when the noise is small and at high speed when the noise is large.

That is, it is possible to adaptively select the transmission rate according to the situation, and it is also possible to make the meaning of the same data different depending on the difference in the transmission rate.

[0007]

It is conventionally known that a plurality of types of data transmission rates can be switched in this way. However, in the conventional type of this type,
There is a problem in that it is necessary for the transmitter and the receiver to match the transmission rates in advance before data transmission, which is troublesome.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a data receiving apparatus capable of automatically determining the data transmission rate from the received pulse train.

[0009]

In order to achieve the above object, the data receiving apparatus of the present invention determines the transmission rate of the received data based on the time interval at which the signal level of a predetermined portion of the received data changes. It is characterized in that a means for discriminating is provided.

[0010]

In this data receiving apparatus, the time interval at which the signal level of the received data changes at a predetermined position is measured, and the transmission rate is determined based on the time interval.

As described above, according to the present invention, since the data transmission rate is automatically determined, it is possible to save the labor of the operation of matching the transmission rate on the transmitter side and the receiver side as in the prior art. Thus, the burden on the operator is reduced and the usability is improved.

Further, since the transmitter side can freely select the transmission rate, the degree of freedom in selection on the transmitter side is improved.

Further, since the present invention has a simple structure of measuring the time interval at which the signal level changes, it can be constructed at low cost.

[0014]

Embodiments will be described below with reference to the drawings.
FIG. 1 is a diagram showing the configuration of an embodiment of a data receiving apparatus according to the present invention. In the figure, 1 is a modem, 2 is a control device, and 3 is a decoding unit.

Before explaining the operation of the data receiving apparatus shown in FIG. 1, the encoding system handled by this data receiving apparatus will be explained first.

The signal whose transmission rate can be discriminated by this data receiving apparatus is a signal encoded by an encoding method in which the pulse train of data itself contains information on the transmission rate. An example thereof is shown in FIGS. 2A and 2B.

FIG. 2A shows an example of a signal waveform coded by a coding method called a bi-phase coding method or a Manchester coding method (hereinafter referred to as a bi-phase coding method). It is a figure shown, and the case where 8 bits of "00000100" are coded is shown in the figure. In this coding system as can be seen from the figure, "0" is converted into a signal to maintain a constant level over the entire period of the predetermined time period T _0, "1" is a predetermined period of time T ₀
Is converted to a signal whose level changes to.

Further, in the coding system shown in FIG. 2B, "0" is set.
And "1" have different pulse duty ratios.
That is, in FIG. 2B, “0” has a duty ratio of 50%.
Is converted into a pulse having a duty ratio of 25%.

In this embodiment, it is assumed that the data encoded by the bi-phase encoding method is received. Further, it is assumed that there are two types of transmission speeds, high speed and low speed. In high speed transmission, the predetermined period is T ₀ as shown in FIG. 3A, and in low speed transmission, the predetermined period is 3 T _{0 as} shown in FIG. 3B. And 3A and 3B show the case where the bit string of "0010" is encoded.

Further, the transmitter encodes the data to be transmitted, adds a preamble to the beginning of the data at the time of transmission, and determines the transmission rate at a predetermined portion of the preamble, for example, the beginning of the preamble. A specific code (hereinafter, referred to as a specific code) for doing so is attached. Here, this specific code is assumed to be a bit string of "00000000".

In FIG. 1, the signal demodulated by the modem 1 is input to the control device 2 and the decoding unit 3. Decoding section 3
Is to decode the data encoded by the bi-phase encoding method. Whether it is synchronized and decoded as being transmitted at high speed or synchronized and decoded as being transmitted at low speed. Is set by a control signal from the control device 2.

The control device 2 is composed of a CPU and its peripheral circuits, and detects the specific code in the preamble and performs the processing shown in FIG.

First, when the control device 2 takes in a signal of a specific code, it detects the edge of the signal (S1) and measures the time between the detected edges (S2). For example, assuming that the data transmitted by high-speed transmission is received satisfactorily without noise, the edge of the signal of the specific code is detected as shown in FIG. 4A, but the time of the adjacent edge signal is detected in step S2. Measure it.

Next, the control device 2 determines the speed based on the time measured in step S2 (S3). That is, if it is determined that the time measured in step S2 corresponds to high-speed transmission, the transmission speed is temporarily determined to be high and the decoding unit 3 is notified of the determination (S4). As a result, the decoding unit 3 operates in accordance with high speed transmission. Then, after that, 1 is added to the value of the high-speed transmission register which is an internal register and incremented (S5), and the process proceeds to step S8.

Similarly, when it is determined that the time measured in step S2 corresponds to low-speed transmission, the transmission speed is temporarily determined to be low, and the determination is made by the decoding unit 3
(S6). As a result, the decoding unit 3 operates in accordance with low speed transmission. Then, after that, 1 is added to the value of the low-speed transmission register which is an internal register and incremented (S7), and the process proceeds to step S8.
For example, if the edges indicated by P ₁ and P ₂ are not detected for some reason as shown in FIG. 4B even if the edge is indicated by t ₀ in FIG.
In 3, the low speed transmission is determined, and in step S7, the low speed transmission register is incremented.

However, if the time measured in step S2 does not correspond to high-speed transmission and does not correspond to low-speed transmission, the control device 2 ignores this and shifts to the processing of step S8. .

In the process of step S8, it is determined whether or not the specific code is completed, and if it is not completed, the process returns to step S1. That is, the control device 2 performs the processes of steps S1 to S7 during the period of the specific code. However, step S
If the specific code ends in the determination process of 8, the transmission rate is finally determined, the determination is notified to the decoding unit 3 (S9), and this process ends. As a result, the decoding unit 3 performs decoding in synchronization with the speed determined in step S9.

When determining the transmission speed in step S9, the control device 2 compares the value of the high speed transmission register with the value of the low speed transmission register, and if the value of the high speed transmission register is larger, the transmission speed is higher. If the value of the low speed transmission register is larger, the transmission speed is determined to be low. If the value of the high-speed transmission register and the value of the low-speed transmission register are equal, it is determined as the speed that has been incremented last.

As described above, it is obvious that the data receiving device can automatically determine the transmission rate.

Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment and various modifications can be made. For example, in the above embodiment, the case of bi-phase coding was taken up, but when coded by the coding method shown in FIG. 2B, the transmission rate can be determined by measuring the high level time of the pulse. it can.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of an embodiment of a data receiving apparatus according to the present invention.

[Fig. 2] Fig. 2 is a diagram for explaining an encoding method handled by the data receiving apparatus according to the present invention.

FIG. 3 is a diagram for explaining signal waveforms of high-speed transmission and low-speed transmission according to a bi-phase encoding method.

FIG. 4 is a diagram for explaining the operation of the data receiving device shown in FIG.

5 is a flowchart for explaining an operation of the control device 2 of the data receiving device shown in FIG.

[Explanation of symbols]

 1 ... Modem, 2 ... Control device, 3 ... Decoding unit.

Claims (1)

[Claims] 1. A data receiving apparatus, comprising means for determining a transmission rate of the received data based on a time interval at which a signal level of a predetermined portion of the received data changes.