JPH0318776B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a Munciesta decoder that converts a Munciesta code into an NRZ signal.

(Prior Art) A conventional circuit for converting a Manchester code into an NRZ signal is shown in FIG. 1, and this circuit decodes by instantaneous samples of the first half or the second half of one bit. Figure 2 a-e
2 is a waveform chart showing the operation of FIG. 1. FIG. As shown in DATA in Figure 2a, this Manchiesta code changes from 1 to 0 when it is "0", and 0 when it is "1".
This is the code that becomes 1 from . This conversion circuit consists of a bit synchronization circuit 1 and a strobe signal generation circuit 3.
and a data sampler 6. Terminal 1
Manchiesta code input from (Figure 2 a)
extracts the code-synchronized bit synchronization signal c and the half-synchronized synchronization signal (Fig. 2b) using the bit synchronization signal 1, and samples them by the strobe signal generation circuit 3 that receives these signals. A data strobe (FIG. 2d) is formed. This data strobe d is supplied to the data sampler 6, and the NRZ signal (Fig. 2e) is extracted at that timing. Generally, in the case of mobile communications, the antenna of a mobile object is often located several meters or less above the ground, and deep and rapid fading always occurs due to surrounding buildings and elevations. When a Mantier code is used as a control signal under such conditions, damage A due to fading occurs at the strobe point as shown in Figure 2a.
If there is an incorrect NRZ, as shown in Figure 2e,
The signal may be converted to signal B, resulting in poor transmission reliability.

Another method for converting this Mantier code into an NRZ signal is an integral detection decoding method in which digital integration is performed over one bit and the code is converted into an NRZ signal. This method has a circuit configuration shown in FIG. 3, and FIGS. 4a to 4g show operational waveform diagrams of FIG. 3. In this case, with respect to FIG. 1, the exclusive OR circuit (EX-OR circuit) 7,
An integrating circuit 8 is added.

This circuit performs an exclusive OR (EX-OR) of the input data (Figure 4a) and the synchronization signal (Figure 4c).
(Fig. 4 d), this output is integrated by the integrating circuit 8 (Fig. 4 e), and this integrated output is read out by a data strobe (Fig. 4 f). . Note that this integrating circuit 8 is reset to zero point and dumped at each data strobe. Although this circuit can improve the error rate, the error detection information of each bit, which is a characteristic of the Manchester code, cannot be used.

If your area consists of many wireless zones,
In order to continue a call even if the call moves to an adjacent zone during a call, tracking switching is necessary. A channel switching signal for this tracking switching is sent through the call channel. At this time, the mobile device quickly determines whether it is a voice or a signal, and if it is a signal, closes the voice gate to prevent deterioration of call quality.

In the integral detection decoding method as shown in FIG. 3, since error detection information is lost, the only way to distinguish between speech and signals is by using a frame synchronization signal. but,
The number of bits in the frame synchronization signal is limited, and there is a high probability that the same pattern will occur depending on the voice, so it had the disadvantage that the voice gate would be closed even during a call, significantly deteriorating the call quality. .

Also, in order to prevent malfunctions due to audio, if you close the audio gate after receiving the frame synchronization signal at the correct position several times, the malfunctions will disappear, but if the data speed is not fast, there will be a delay before the audio gate closes. During this time, the speaker can hear the data, which has the disadvantage of deteriorating the quality of the call.

(Objective of the Invention) The object of the present invention is to eliminate these drawbacks and digitally integrate the first half and the second half of one bit of the Manchester code, thereby performing code determination while detecting errors in each bit. The object of the present invention is to provide a Manchiesta decoder that can perform the following functions.

(Structure of the Invention) The Munchiesta decoder of the present invention includes a strobe signal forming circuit that forms a bit synchronization signal from an input Munchiesta code and forms a strobe signal from this bit synchronization signal, and a first integrating circuit that integrates every half bit; an error detection circuit that detects errors based on the output of the first integrating circuit; It includes a data sample circuit that samples each bit using a strobe signal and converts it into an NRZ signal.

In this configuration, there is a case where only the first half or the second half of the output code of the first integrating circuit is used as the input integral data to the data sample circuit, and a case where only the first half or the latter half of the output code of the first integrating circuit is used as input integral data to the data sampling circuit, and a second integrating circuit which integrates the input Munchiesta code bit by bit.
In some cases, the output of an integrating circuit is used.

In the present invention, what is converted into an NRZ signal is
Since only the first half or the second half of one bit of the integrated Manchester code is used, errors can be reliably corrected if the period destroyed by fading is less than 1/4 bit of the Manchester code.
In addition, since error detection for each bit is performed using the integrated Munciesta code, it is possible to determine whether the signal is for channel switching or voice by detecting errors in the frame synchronization signal and the following Munciesta code. You can know it. This eliminates the possibility of malfunctions such as closing the voice gate during a call or delays in closing the voice gate, causing data to leak and deteriorating call quality, while detecting errors in each bit. Transmission reliability can be obtained.

Furthermore, when converting to an NRZ signal, if the Munchiesta code is digitally integrated over one bit, and the half-bit integration is used to detect errors in the Munchiesta code, it will not be destroyed by fading. If the period of time is less than 1/2 bit, errors can be reliably corrected and even better transmission reliability can be obtained.

(Example) The present invention will be explained in detail below with reference to the drawings.

FIG. 5 is a block diagram of one embodiment of the present invention, and FIG.
Figures a to g are operational waveform diagrams of Figure 5. In this embodiment, an integrating circuit 2, a frame synchronization detection circuit 4 for supplying a frame synchronization signal to the bit synchronization circuit 1, and an error detection circuit 5 are added to the circuit shown in FIG.

First, the bit synchronization circuit 1 extracts the clock information of the bit synchronization signal (Fig. 6b, c) from the input Munchiesta code (Fig. 6a), but this Munchiesta code a has noise due to fading. is also included, and is supplied to the next integrating circuit 2.
In the integrating circuit 2, the Manciesta code is shown in Fig. 6d.
As shown in FIG. 6, the integration results are digitally integrated in half-bit increments and dumped in half-bit increments when followed by strobe signals 1 and 2 shown in FIGS. 6e and 6f. This series of operations reliably corrects periods destroyed by fading of less than 1/4 bit.

The error detection circuit 5 detects error detection information of each bit, which is one of the advantages of the Manchester code, and detects the error detection information of each bit, which is one of the advantages of the Manchester code. Data integrated based on f) (Fig. 6 d)
It is determined whether or not the value changes within one bit. Conversion to the NRZ signal is performed by the data sampler 6, and in this example, the strobe signal 2 (FIG. 6f) of the integral output of the integrating circuit 2 (FIG. 6d) is converted into an NRZ signal.
, only the second half of one bit is used to convert it to an NRZ signal.

According to this circuit, even if there is a destructive operation A due to fading as shown in FIG. 6a, the integration circuit 2 outputs the integral value of the destructive operation as shown in FIG. 6d, so that As shown in Fig. 6g, the destructive operation is corrected D and there is no error.

FIG. 7 is a block diagram of a second embodiment of the present invention;
8a to 8i are operational diagrams of FIG. 7. In this embodiment, an EX-OR circuit 7 and a second integrating circuit 8 which integrates and dumps each bit are added to the embodiment shown in FIG. The error detection circuit 5 performs error detection using the data which is integrated every half bit and dumped. That is, the method for detecting errors in each bit from the Manchester code is the same as that described in FIG. The difference from the circuit in Figure 5 is that
In the method of converting to an NRZ signal, the fading Mantier code (Figure 8a) and the bit output of the bit synchronization circuit (Figure 8c) are logically ORed and output (Figure 8g). ). this
The EX-OR output is an NRZ signal with noise and spikes due to fading.
This EX-OR output is further input to the integrating circuit 8, where it is digitally integrated over one bit as shown in Fig. 8h, and the integration result is sent to the strobe signal 2 (Fig. 8f). Continue dumping.

According to this circuit, when there is a data destruction operation A due to fading as shown in FIG.
The output of the OR circuit 7 becomes the data B' changed by the destruction as shown in Figure 8g, but the outputs C and C' of the integrating circuits 2 and 8 are slightly changed as shown in Figure 8d and h. However, the data D whose destruction is corrected can be obtained as the output of the data sampler 6, as shown in FIG. 8i. That is, through this series of operations, the period destroyed by less than 1/2 fading is reliably corrected, and the data sampler 6 outputs the strobe signal (FIG. 8f) and the integration circuit 8.
The result of integration (Fig. 8h) shows a cleaner NRZ.
The signal (Fig. 8i) can be obtained.

(Effects of the Invention) As explained above, when the present invention is used, the integral detection decoding method can be used without losing the error detection information of each bit, which is the advantage of the Munchiesta code. It is possible to obtain the NRZ signal while correcting the corrupted period.
Therefore, even when used as a channel switching signal, there is a possibility that the voice gate may malfunction when the voice gate is closed while a call is in progress, or a delay in closing the voice gate may cause the sound of the data to leak, degrading the quality of the call. It disappears.

Furthermore, as shown in Figure 7, by setting an error tolerance bit number for error detection of each bit, it is possible to effectively utilize the error correction ability of integral detection decoding, and a circuit with high transmission reliability can be obtained. be able to.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a conventional mantier decoder, Fig. 2 a to e are operational waveform diagrams of Fig. 1, and Fig. 3
The figure is a block diagram showing the conventional integral detection decoding method, Figures 4a-g are operational waveform diagrams of Figure 3, Figure 5 is a block diagram of the first embodiment of the present invention, and Figures 6a-g. 7 is a block diagram of the second embodiment of the present invention, and FIGS. 8 a to 8 i are operational waveform diagrams of FIG. 7. In the figure, 1...Bit synchronization circuit, 2, 8...Integrator circuit,
3... Strobe signal generation circuit, 4... Frame synchronization signal detection circuit, 5... Error detection circuit, 6...
Data sampler 7... is an exclusive OR circuit.

Claims (1)

[Scope of Claims] 1. A strobe signal forming circuit that forms a bit synchronization signal from an input Manchester code and forms a strobe signal for every half bit or one bit from this bit synchronization signal, and a first integrating circuit that integrates the second half of the code every half bit; an error detection circuit that detects errors based on the output of the first integrating circuit; Alternatively, a mantier decoder includes a data sampling circuit that samples each bit using a strobe signal and converts it into an NRZ signal. 2. Claim 1 in which either the first half or the second half of the output code of the first integrating circuit is used as input integral data to the data sample circuit.
Manchiesta decoder described in section. 3. The Manchiesta decoder according to claim 1, wherein the output of the second integrating circuit that integrates the input Manchiestan code bit by bit is used as input integral data to the data sample circuit.