JPH04119742A - Reception data identification device - Google Patents

Abstract

PURPOSE:To always identify a correct data by discriminating a received eye pattern to be '1' when a positive gradient of a prescribed value or over is consecutive for a prescribed time or over and to be '1' when a negative gradient of a prescribed value or over is consecutive for a prescribed time or over. CONSTITUTION:When a reception eye pattern resulting from demodulating an FSK signal is inputted to a differentiating means 1, an output of the differentiating means 1 is a voltage output in proportion to the gradient of the reception eye pattern. A 1st voltage comparison means 2 compares a reference voltage V1 slightly above zero with the output of the differentiating means 1, and a 2nd voltage comparison means 3 compares a reference voltage slightly above zero with the output of the differentiating means 1 to output a pulse. A 1st count means 4 outputs a pulse when '1s' being an output of the 1st voltage comparison means 1 are consecutive for a prescribed time to set a FLIP-FLOP 6 and a 2nd count means 5 outputs a pulse when '0s' being an output of the 2nd voltage comparison means 3 are consecutive for a prescribed time to reset the FLIP-FLOP 6. Thus, the reception eye pattern is identified and a correct reception data is outputted.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention is based on FSK (Frequency 5hif)
The present invention relates to a received data identification device for reproducing demodulated digital data from a demodulated eye pattern in a digital radio device or the like using modulation or the like.

(Prior Art) Conventionally, a received data identification device for converting a demodulated eye pattern, which is an analog signal, into a digital signal, which is received data, has been an indispensable component of a digital radio.

A conventional received data identification device will be described below. FIG. 3 is a block diagram of a conventional received data identification device.

In Fig. 3, 10 is the receiving eye pattern and the reference voltage (V
Voltage comparison means 11 and 12 are resistors for creating a reference voltage (Vth) of the voltage comparison means IO, and if the voltage of the receiving eye pattern is higher than the reference voltage (Vth) of the voltage comparison means IO, 11 l I+, if the voltage of the receiving eye pattern is lower than the reference voltage (vth) of the voltage comparing means 10, the received data is identified by determining it as 0''.The received data identifying device configured as above The operation will be described below using FSX as an example.

First, when the carrier frequency f of the received FSK signal is equal to the center value f of the channel frequency, the center of the DC voltage of the demodulated eye pattern is at the voltage comparing means 1 as shown in FIG. 4(a).
This matches the reference voltage (Vth) of 0, and the data RXD after identification becomes a normal value as shown in FIG. 4(b). Also,
The carrier frequency f of the received FSX signal is the center value f of the channel frequency. If the deviation is slightly lower than that shown in Fig. 5(a)
As shown in , the center of the DC voltage of the demodulated eye pattern no longer matches the reference voltage (vth) of the voltage comparison means lO
As shown in FIG. 5(b), the data RXD after identification can obtain a correct value, but the II II II of the data after identification
The width of II OII is narrow, and the width of II OII is wide, causing the data change point to deviate from the correct predetermined value. Furthermore, if the carrier frequency f of the received FSX signal deviates to a much lower value than the center value f of the channel frequency, the center of the DC voltage of the demodulated eye pattern is shifted to the voltage comparing means 10 as shown in FIG. 6(a).
As a result, the data RXD deviates greatly from the reference voltage (Vth) of "o" after identification, as shown in FIG. 6(b).
”, making it impossible to identify the correct data.

(Problem to be Solved by the Invention) As described above, the conventional received data identification device cannot identify overwhelming data when there is a fluctuation in the DC voltage of the demodulated eye pattern due to a shift in the carrier wave frequency of the FSK signal, etc. It had a point.

An object of the present invention is to solve the above-mentioned conventional problems and provide a received data identification device that can correctly identify data even when there is a fluctuation in the DC voltage of a demodulated eye pattern due to a shift in the carrier wave frequency of an FSX signal. .

(Means for Solving the Problems) In order to solve the above-mentioned problems, the present invention provides a differentiating means for differentiating a received eye pattern, and a first
a first voltage comparing means for comparing with a reference voltage of the first voltage comparing means; a first counting means for counting the time of the output pulse of the first voltage comparing means and outputting a pulse when the counted value reaches a predetermined value; a second voltage comparing means inputting the output of the differentiating means and comparing it with a second reference voltage different from the first reference voltage, counting the time of the output pulse of the second voltage comparing means and having a predetermined count value; The second outputs a pulse when the value is reached.
counting means, said first counting means; It is equipped with a flip-flop that is set and reset by the output of the second counting means.

(Function) Therefore, the inclination of the receiving eye pattern is detected by the differentiating means of the present invention, and the voltage comparing means determines whether the inclination of the receiving eye pattern is equal to or greater than a certain value, and furthermore, the inclination of the received eye pattern is determined to be equal to or greater than a certain value. By counting whether the received eye pattern has continued for more than a certain time using a counter, if the received eye pattern has a positive slope greater than or equal to a certain value and has continued for more than a certain value, it is determined as rr l n. If the negative slope continues for a period longer than a certain value, which is a negative slope greater than the value, it is determined to be u Ou.

(Example) An example of the present invention will be described below with reference to the drawings.

FIG. 1 shows the configuration of a received data identification device in an embodiment of the present invention.

In FIG. 1, ■ is a differentiating means for differentiating the receiving eye pattern; 2 and 3 are 1° and 2nd voltage comparing means for comparing the output of the differentiating means 1 with reference voltages Vl and V2, respectively;
4 is a first counting means that counts 1''' of the output of the first voltage comparison means 2 and outputs a pulse when the counted value exceeds a certain value; 5 is the output of the second voltage comparison means 3; 0''' and outputs a pulse when the counted value exceeds a certain value; 6 is set by the output pulse of the first counting means 4 and is set by the output pulse of the second counting means 5; Resetting flip-flop, 7.8.9 is the first
and resistors for providing reference voltages Vl and V2 of the second voltage comparison means.

Regarding the received data identification device configured as above,
The operation will be explained below, taking as an example the case of demodulating an FSX signal. When the receiving eye pattern obtained by demodulating the FSX signal is input to the differentiating means 1 as shown in Fig. 2(a), the output of the differentiating means 1 is proportional to the slope of the receiving eye pattern as shown in Fig. 2(b). It becomes voltage specific force. The first voltage comparing means 2 compares the reference voltage 1 slightly higher than zero with the output of the differentiating means 1 and outputs a pulse as shown in FIG.
The voltage comparing means 3 compares the reference voltage v2 slightly lower than zero with the output of the differentiating means 1, and outputs a pulse as shown in FIG. 2(d). The first counting means 4 outputs a pulse when the output 1n of the first voltage comparing means 2 continues for a certain period of time as shown in FIG. becomes "1'". Conversely, the second counting means 5 outputs a pulse when the output 1101+ of the second voltage comparing means 3 continues for a certain period of time, as shown in FIG. The output, that is, RXD becomes '0''.As described above, the receiving eye pattern is identified and correct received data is output.

If the DC component of the receiving eye pattern fluctuates, such as when the carrier frequency of the FSX signal deviates from the center frequency of the channel, the receiving eye pattern in Figure 2 (a) will show that the DC level increases upward or downward. shift. However, the output of the differentiator l depends only on the slope of the receiving eye pattern,
Correct received data can always be identified without being affected by fluctuations in the DC component of the received eye pattern.

(Effects of the Invention) As described above, the received data identification device of the present invention detects the slope of the received eye pattern using the differentiating means, and determines whether the slope of the received eye pattern is greater than or equal to a certain value using the voltage comparing means. Furthermore, by counting with a counter whether the slope of a certain value or more has continued for a certain period of time or not, if the received eye pattern has a positive slope of a certain value or more and has continued for a certain period of time or more, it is determined as "l ++". If the reception eye pattern has a negative slope of a certain value or more and continues for a certain period of time or more, it is determined as rr O++, so the DC component of the reception eye pattern due to fluctuations in the carrier frequency of the FSX signal etc. This method is useful in practice because it can always identify the correct data even when fluctuations occur.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a received data identification device according to an embodiment of the present invention, FIG. 2 is a time chart, and FIG. 3 is a block diagram of a conventional received data identification device.
FIGS. 5 and 6 are time charts as well. l...Differentiating means, 2,3.10...Voltage comparing means, 4,5...Counting means, 6...Flip-flop, 7. 8. 9.11.12...Resistance. Patent applicant: Matsushita Electric Industrial Co., Ltd. Agent: Hisashi Hoshino

Claims (1)

[Claims] a differentiating means for differentiating a received eye pattern; a first voltage comparing means for inputting the output of the differentiating means and comparing it with a first reference voltage; a first counting means that outputs a pulse when a predetermined value is reached;
a second voltage comparison means for comparing with a second reference voltage different from the reference voltage of the second voltage comparison means, the second voltage comparison means counts the time of the output pulse and outputs the pulse when the counted value reaches a predetermined value; 1. A received data identification device comprising: a second counting means, and a flip-flop that is set and reset by the outputs of the first and second counting means.