JPS63114431A - Pcm transmission concealing system - Google Patents

Abstract

PURPOSE:To conceal a PCM signal with a simple constitution by changing the initial values of scramble and frame patterns for concealment on the transmission side and the reception side. CONSTITUTION:On the transmission side, the initial values of a scramble pattern generator 6 and a frame pattern generator 8 are optionally changed to change their random sequences. Simultaneously, the initial value data are multiplexly transmitted by a DSC. On the reception side, the initial value data are separated from the DSC, the same initial values as that of the transmission side are set up as the initial values of the pattern generators 6, 8 and the same random sequences are generated so as to reproduce the data. When the number of steps of the pattern generators 6, B is set up to (n), 2n patterns of different sequences can be generated and optionally specified. Thus, the PCM transmission equipment itself can be processed as a concealing device.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a PCM transmission concealment method, and particularly to a method for converting an existing general PCM transmission device into a concealment device, or to easily and sufficiently put it into practical use at low cost. The present invention relates to a PCM transmission concealment method suitable for obtaining secure transmission.

[Prior Art] Conventionally, this type of PCM transmission concealment system has a configuration as shown in FIGS. 3 and 4. In FIGS. 3 and 4, the case where a dedicated DATA anonymizing device is not installed at the front stage (first method) and the case where it is installed (second method) will be explained separately.

As a first method, consider a case where a concealing device is not attached.

This is equivalent to the conventional wireless PCM transmission method, but also inherently has the effect of concealing transmission. As shown in FIG. 3, on the transmitting side, the input PCM signal is
Stuffing is performed by the stuffing circuit 1 to match e. Then, it is mixed with a scramble pattern, which is a pseudo-random pattern generated by the n-stage random pattern generator 6, and scrambled by performing an exclusive OR operation in the scramble circuit 2.

FIG. 5 shows the circuit configuration of a general n-stage random pattern generator 6, which generates a pseudo-random pattern with 21-1 bit synchronization. If n is sufficiently large, the synchronicity will be long and the randomness will be strong. However, in this case, the initial value of the pattern in FIG. 5 is fixed. Through this operation, the input PCM signal is subjected to DSC multiplexing in the 0-order DSC multiplexing circuit 3, which is temporarily concealed, and the frame pattern generator 8 is used in the frame synchronization pulse inserter 4 to enable frame synchronization on the receiving side. Insert frame synchronization Hals by. This frame pattern generator 8 is also similar to the n-stage random pattern generator (scramble pattern generator) 6, but the value of n is generally small.

Finally, the signal is phase modulated by a phase modulator 5 and sent to a transmission path.

Next, as shown in FIG. 4, on the receiving side, the PCM signal is phase demodulated by a phase demodulator 12, and then combined with a pattern from a frame pattern generator 6, which generates the same pattern as that on the transmitting side, and a frame synchronization circuit 13. Then, the DSC is separated by the DSC separation circuit 14, and the scramble pattern from the scramble pattern generator 8, which also has the same pseudo-random sequence as the transmitting side, and the descrambling circuit 15 are compared and frame synchronized. is reproduced by taking the exclusive OR in the destuffing circuit 16.
He was destuffed and released.

On the other hand, as a second method, as shown in Figs. 3 and 4,
There is a method of adding DATA anonymization devices 18 and 19 before and after the first method described above. The input PCM signal is concealed by this DATA concealment device ff118.19. The subsequent configuration is the same as the first method. In this case, the DATA anonymization strength is this DATA anonymization device fi.
18.19.

[Problems to be Solved] The above-mentioned PCM transmission concealment method has the following problems. That is, as a problem with the first method.

■Since the scramble pattern and frame pattern are fixed, the concealment effect is weak.

■If a third party owns the same device, it is completely DA.
TA will be played.

■ As mentioned above, the reason for this is that n
Since the duplex pattern generator 6 has a periodicity of 2n-1 bits, it is relatively easy to decode (1), but the concealment effect is weak, and if the value of n is increased, it becomes 2'-1 bits.
This increases the periodicity and improves the effect, but the frame period time also increases, making it impractical.Originally, the meaning of scrambling in this configuration is to smooth the DATA signal spectrum, so the effect of secrecy is secondary. It is a secondary element.

Problems with the second method include: (1) Although the anonymization strength can be increased, separate DATA anonymization devices 18 and 19 are required, which increases the cost.

■, DATA anonymization device! 18.19 control pulses and frame pulses need to be inserted, so the old tR
ate increase becomes a problem. Examples include.

Accordingly, one object of the present invention is to provide a PCM transmission concealment method that can simplify the configuration and perform highly effective concealment without adding a dedicated DATA concealment device in PCB transmission. .

[Means for Solving the Problems] The present invention has the following configuration in order to solve the above problems and achieve the objectives. That is, the stuffed PCM signal is scrambled using a scramble pattern, and then DSC (Data 5 service channel
In a PCM transmission transmission system that performs multiplexing and performs phase modulation after inserting a frame synchronization pulse, the scramble pattern and initial values of the frame synchronization pulse can be arbitrarily set, and the phase demodulated PCM
In a PCM transmission/reception system that performs frame synchronization on a signal using a frame pattern, then performs DSC separation, descrambles it using a scramble pattern, and then destuffs the signal, the scramble pattern and frame pattern are used in correspondence with the transmission system. This configuration allows initial values to be set arbitrarily.

[Embodiment 1] Next, an embodiment of the present invention will be described with reference to the drawings.

1 and 2 are block diagrams of an embodiment of the present invention, with FIG. 1 being a block diagram of the transmitting side and FIG. 2 being a block diagram of the receiving side.

In Figure 1, the PCM signal input on the transmitting side is
Similarly to the first method described above, the zero order is stuffed in the stuffing circuit 1 to match the transmission rate, and then the n-stage undam pattern generator (scramble pattern generator) 6 shown in FIG. The scrambling pattern generated by the scrambling circuit 2 is mixed in the scrambling circuit 2, but the difference is that the initial value of the pattern can be set by the n-bit scrambling pattern initial value storage memory 9. The generator 6 shown in FIG. 5 has a series periodicity of 2'-1 bit, but its D type Fli
Since all the random sequences are different depending on the initial value of p-Flop, there are over 20 cases of the random sequence with n-stage configuration. Further, the initial value can be automatically or manually controlled by the initial value setting controller 10. Furthermore, if a microcomputer is used, it is also possible to perform software processing. This operation allows mixing with arbitrary different random series patterns. At the same time, the n-bit pattern initial value DATA is converted from parallel to serial by a parallel-serial converter 7, and then DSC multiplexed by a DSC multiplexing circuit 3 and transmitted.

Next, a frame periodic pulse generated by a frame pattern generator 8 is inserted by a frame synchronization Hals inserter 4 to enable frame synchronization.

This frame pattern generator 8 also has the same configuration as the scramble pattern generator 6, and the frame pattern initial value store memory 11 and initial value setting controller 10 allow the sequence to be arbitrarily converted. And as expected, the initial value DATA is the parallel serial converter 7
Parallel → serial conversion is performed at DSC multiplex circuit 13
The signals are DSC-multiplexed and transmitted. Finally, as in the conventional case, the signal is phase modulated by the phase modulator 5 and sent to the transmission path.

Further, as shown in FIG. 2, on the receiving side, the PCM signal is phase demodulated by a phase demodulator 12, and then combined with a pattern from a frame pattern generator 6 that generates the same pattern as that on the transmitting side and a frame synchronization circuit 13. However, since the pattern sequence is arbitrarily changed on the transmitting side, it is not possible to always synchronize with the same sequence of patterns.Therefore, the frame pattern initial value DATA multiplexed by DSC from the transmitting side is separated by the DOS separation circuit 14, and the serial-to-parallel converter 17 stores the same initial value as that on the transmitting side in the serial-to-parallel converter turn initial value store memory 9. At the same time, the initial value DATA is sent to the initial value setting control circuit IO.

Next, similarly, the DSC multiplexed scramble pattern initial value is separated by the DSC separation circuit 14 and stored in the serial-to-parallel converter 17 and the scramble pattern initial value store memory 11. As a result, a pattern of the same series as that on the transmitting side is always generated, and can be descrambled by the descrambling circuit 15. Finally, the signal is destuffed by a destuffing circuit 16 and output.

As explained above, in this embodiment, the scramble pattern and the initial value of the frame pattern generator 6.8 are arbitrarily changed on the sending side, and the random sequence is changed. At the same time, the initial value DATA is multiplexed by DSC and transmitted. On the receiving side, this initial value DATA is separated from the DSC and the same initial value as on the sending side is set as the initial value of the pattern generators 6 and 8, thereby generating the same random sequence and making it possible to reproduce the DATA. As a result, if the number of stages of the pattern generator 6.8 is n, it is possible to generate 2n different series of patterns, and it has become possible to specify them arbitrarily. As a result, this example has the following effects.

■The PCM transmission device itself can be made a secret device.

■There is no increase in Bit Rate due to the insertion of a concealing device.

(2) It has a much stronger concealment effect than the first conventional method described above.

■Can be processed using software.

■Even if a third party owns the same device, it cannot be reproduced because the device itself can be configured with any pattern according to the user's ideas.

■Much lower cost than the conventional second method.

[Effects of the Invention] As described above, in the present invention, by changing the initial values of scrambling and frame patterns for ciphering on the transmitting side and the receiving side, a dedicated DATA ciphering device is not added. The advantage is that the configuration is simple and the PCM signal can be concealed with great effect.

[Brief explanation of the drawing]

1 and 2 are block diagrams of a PCM transmission concealment method according to an embodiment of the present invention, FIGS. 3 and 4 are block diagrams of a conventional PCM transmission concealment method, and FIG. 5 is a block diagram of an n-stage PCM transmission concealment method. FIG. 2 is a circuit diagram of a random pattern generator. 1: Stuff circuit 2 Niscrumple circuit 3:
DSC multiplex circuit 4: Frame synchronization pulse insertion circuit 5: Phase modulator 6: Scramble pattern generator 7: Parallel to serial converter 8: Frame pattern generator 9 Scramble pattern initial value store memory 10: Initial value setting Controller 11: Frame pattern initial value store memory 12 Two-phase demodulator 13: Frame synchronization circuit 14: DSC separation circuit 15: Descrambling circuit 16: Destuffing circuit 17: Serial to parallel converter Agent Patent attorney Kihei Watanabe 11 Figure 2 Figure 3

Claims (1)

[Claims] The stuffed PCM signal is scrambled using a scramble pattern, and then DSC (Data S
Service Channel) A PC that performs multiplexing and performs phase modulation after inserting a frame synchronization pulse.
In the M transmission transmission system, the initial values of the scramble pattern and frame synchronization pulse can be set arbitrarily, the phase demodulated PCM signal is frame synchronized using the frame pattern, and then DSC separation is performed, and the scramble pattern is used to perform frame synchronization. A PC in a PCM transmission/reception system that descrambles and then destuffs, wherein the initial values of the scrambling pattern and frame pattern can be arbitrarily set corresponding to the transmission system.
M transmission secrecy method.