JPS6239878B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a switching control system for telephone and telegraph lines using a time division switching switch. In a satellite communication system such as a maritime satellite communication system, in which telephone and telegraph signals are transmitted using different carriers, when it is necessary to exchange between telephone lines and telegraph lines, conventionally, an exchange switch for telephone exchange is used. A common method is to install a switch and an exchange switch for telegraph exchange at the earth station, and use these to control the exchange. However, when the number of telephone lines and telegraph lines used is relatively small, it is uneconomical to provide dedicated switching switches for each line. An object of the present invention is to provide an exchange control system that eliminates such drawbacks. The switching control method of the present invention time-division multiplexes telegraph signals.
means for transmitting sample values of a plurality of channels of a telegraph signal sampled using a clock synchronized with transmission bits of the PCM telephone signal through a particular channel of the time division multiplexed PCM telephone signal; means for converting a sample of a multiple channel telegraph signal into a time division multiplexed telegraph signal having the same timing as said time division multiplexed PCM telephone signal;
and means for exchanging the time division multiplexed PCM telephone signal and the time division multiplexed telegraph signal via the same time division switching switch. Next, the present invention will be explained in detail using the drawings. FIG. 1 is a block diagram showing one embodiment of the present invention. Reference number 1 indicates time division multiplexing of 30 channels.
A time division multiplexed PCM telephone signal indicating a PCA telephone terminal station and implemented with up to 29 channels and necessary control signals are supplied to the telegraph multiplex terminal station 2. The telegraph multiplex terminal station 2 multiplexes telegraph signals using a configuration as will be described later, synthesizes them into the time slot of one channel of the time division multiplexed PCM telephone signal, and outputs the combined signal. A 50 baud telegraph line that now accommodates the telegraph
Assuming 24 channels. This multiplexed 24
The telegraph line of the channel is No. 30 as shown in Figure 2.
It is transmitted by an 8-bit signal corresponding to one channel of the second telephone. (Of course, it can be accommodated in any telephone channel, but for convenience of explanation, it is assumed that it is accommodated in the 30th telephone channel as described above.) Thus, the above-mentioned signal, which is apparently no different from a regular 30-channel PCM signal, The output of the telegraph multiplex terminal station 2 is transmitted from the central office where the PCM telephone terminal station 1 and the telegraph multiplex terminal station 2 are installed to the earth station via a suitable transmission line 3. At the earth station, the 30 channel PCM signals containing the multiplex telegrams are input to a multiplex telegraph separation/combination terminal station 4. In this multiplex telegraph separation/synthesis terminal station 4, the 24 channels of multiplex telegraph signals transmitted on the 30th channel are processed to have the same timing as the 30 channel PCM signals using the component equipment described below. The division multiplexed signal is developed between the first channel and the 24th channel. The PCM telephone signal and this telegraph signal, which are thus time-division multiplexed in exactly the same manner, are respectively connected to the first signal line 6 of the terminal station 4.
and a second signal line 7 to the two inputs of the time division switching switch 5. The exchange switch 5 outputs the input time-division signal as a time-division signal of the same type, but it can transfer the signal of a certain time slot of the input signal to any time slot of the output signal by control. It is a split exchange switch. That is, the signals from the first signal line 6 are rearranged according to the control so that the channels included therein are outputted from the corresponding third signal line 8 as time-division signals of the same type. . Similarly, the time-division signal of the multiplex telegraph inputted from the second signal line 7 is rearranged in accordance with the control so that the channels contained therein are rearranged according to the control and correspond to the time-division signal of the same type. It is output from the fourth signal line 9. In general, the time division exchange switch 5 not only rearranges the channels as described above, but also transfers, for example, a designated arbitrary channel from the first signal line 6 to a channel from the second signal line 7 having the same number. as if to transfer to
Although it is possible to add a function to mutually exchange signals from the first signal line and signals from the second signal line, this is not necessary in this embodiment, and the addition of such a function is omitted. be able to. In this way, it becomes possible for the time division exchange switch 5 to perform exchange control on the telephone signal and the telegraph signal without distinguishing them as signals having exactly the same timing. In the satellite communication system, the third signal line 8 is connected to a PCM decoder 10, of which only a specific channel is decoded and becomes an audio output, which is a different radio frequency signal for each audio channel. It is used for telephone communication with ships via a transmitter 11 that sends out a carrier.
On the other hand, 22 channels of telegraph are time-division multiplexed.
A 1200 baud time division signal containing a synchronization signal is modulated onto one radio frequency carrier and transmitted. The time division multiplexed telegraph signal arranged in the form of a 30-channel PCM telephone signal is converted into a time division multiplexed telegraph signal as specified in the maritime satellite system, and the transmitted In section 11, the telegraphic carrier is modulated and sent out, and is used for telex communication to ships. Next, each of the above-mentioned devices will be explained in more detail. As mentioned above, the telegraph multiplex terminal station 2 multiplexes 24 channels of 50 baud telegraph signals and performs the time division multiplexing.
It accommodates one channel of PCM telephone signals. FIG. 3 is a block diagram showing an embodiment of the PCM terminal station 1 and the telegraph multiplex terminal station 2. In FIG. Reference numerals 20-1, 20-2, . . . , 20-24 indicate 24 telegraph signal input lines. Through each of these lines
A 50 baud independent telegraph signal is input. For example, a first channel telegraph signal input via input line 20-1 is sampled in a first channel sampling circuit 21-1 by a clock provided via a first channel sampling clock line 22-1; The resulting output is synthesized in a first synthesis circuit 25 with samples of other channels that have undergone similar processing. The signal is further combined with a PCM telephone signal in a second combining circuit 26 and output. The sampling clock supplied to each sampling circuit 21 mentioned above is produced as follows. First, the 30th PCM channel, which is to accommodate the telegraph signal, is
30 channel gate pulses from PCM terminal 1,
The signal is supplied to the super frame pulse generation circuit 24. This pulse is divided into four parts in the circuit 24 to generate a superframe pulse having a period four times that of the PCM frame. By making the generation time point of this super frame pulse coincide with the 30th channel gate pulse, four types of super frame pulses having different phases are obtained as shown in FIG. 4. These are defined as the 0th, 1st, 2nd and 3rd superframe pulses, respectively, as shown in FIG. 4, and each is supplied to the clock pulse distribution circuit 23. On the other hand, the clock pulse distribution circuit 23 receives a first bit clock that appears from the PCM terminal device 1 at the time of the first bit of the 30th channel, a second bit clock that also appears at the time of the second bit, and a second bit clock that similarly appears at the time of the second bit. An eighth bit clock appearing at the bit-th time is respectively provided. Clock pulse distribution circuit 23
generates a sampling clock for each telegraph channel by gating the various bit clocks thus supplied using the various superframe pulses as shown in Table 1, is supplied to the sampling circuit 21 of. The 0th superframe pulse period shown in Table 1 is used for superframe synchronization signals with all bit clocks turned off. Therefore, at the output of the second combining circuit 26, all the 30th bits of the combined PCM signal become "0" once every four frames, which means that the receiving side It is used as a superframe synchronization signal that indicates the standard for identifying each channel of a signal. As shown in Table 1, the first channel of the telegraph consists of a sampling clock gated with a first bit clock with a first superframe pulse.

[Table] Sampled in ku. Therefore, on the receiving side, by establishing superframe synchronization using the superframe synchronization signal as a reference and selecting the first bit of the 30th channel of the first superframe, the sample value of the first telegraph channel can be reproduced. be able to. Similarly, for example, a sample of the 10th telegraph channel is transmitted as the second bit of the 30th channel every second superframe. Thus, all 24 channels of telegraph signals are accommodated in the 30th time slot of the PCM signal, and the superframe synchronization signal for identifying each channel is inserted in the same time slot, along with the PCM telephone signal. It becomes possible to transmit. 30th output from time division multiplexed PCM telephone terminal station 1
The channel time slots are assumed to have all bits at a "0" logic level. If not, PCM telephone terminal 1
An inhibiting circuit (not shown) is provided between the output of the 30th combining circuit and the input of the second combining circuit 26.
This inhibition circuit is gated off using a channel gate pulse, and during the 30th channel gate pulse, the output from the PCM telephone terminal 1 is transferred to the synthesis circuit 2.
It is sufficient to prohibit it from reaching 6. The frame period of the PCM signal is 125μsec,
Therefore, the interval between each superframe pulse is 125×4=500 μsec. On the other hand, since the unit code length of a 50 baud telegraph signal is 20 msec, approximately 40 sample values are obtained for each code, and even if the superframe synchronization signal is inserted, the accuracy is sufficient to reproduce the original signal. ing. Next, the multiplex telegraph separation/combination terminal station 4 will be described in detail. FIG. 5 is a block diagram showing one embodiment of a multiplex telegraph separation/combination terminal station. The 30 channel PCM signals transmitted through the transmission line 3 are input to a multiplex telegraph separation/synthesis terminal station 4. Reference numeral 40 designates a channel gate pulse bit clock generation circuit included in said multiplex separation terminal station 4. This circuit 40 first receives the input 30 channels according to the usual method.
Establishes bit and frame synchronization for PCM signals. Channel gate pulses are then generated for channels 1 to 24 of the input PCM signal, which are different for each channel.
Guided by 9. The generation circuit 40 also generates a gate pulse for the 30th channel in which the aforementioned multiplex telegraph signal is accommodated, which is led to the reception superframe pulse generation circuit 45 via the 30th channel gate pulse output line 42. It will be destroyed. Further, the generation circuit 40 internally uses the 30th channel gate pulse to input
The 30th channel signal is selected by gating the PCM signal, and based on the superframe synchronization signal included in that signal (as mentioned above, the 30th channel A stable superframe synchronization signal (including a superframe synchronization signal whose bit becomes 0) is established, and the stable superframe synchronization signal thus obtained is sent to the receiving superframe pulse generation circuit 45 via a superframe synchronization signal output line 43. supply Furthermore, the channel gate pulse bit clock generation circuit 40
generates eight bit clock pulses for each bit from the first bit to the eighth bit of the 30th channel of the received PCM signal and sends them to the receive clock pulse distribution circuit 46 via the bit clock pulse output line 44. supply Now, the reception superframe pulse generation circuit 45 divides the frequency of the inputted 30th channel gate pulse by 4, and uses it and the inputted superframe synchronization signal to gate the 30th channel of the first superframe. Generates a first superframe pulse, a second superframe pulse for gating the 30th channel of the second superframe, and a third superframe pulse for gating the 30th channel of the third superframe, and transmits them to the receiving clock pulse distribution circuit. 46
supply to. The reception clock pulse distribution circuit 4
6 generates 24 telegraph channel gate pulses by gating the 8 input bit clock pulses using the 3 input superframe pulses in combinations shown in Table 1. It is supplied to the telegraph signal separation circuit 47. The separation circuit 47 includes a multiplex telegraph separation terminal station 4.
30 channels PCM from the first signal line 6
A signal is input, and by gating it with the input telegraph channel gate pulse, it is possible to switch from the 1st telegraph channel to the 24th telegraph channel as described above.
A sample of the telegraph signal of each channel up to the telegraph channel can be taken. The sample of the telegraph signal extracted in this way is a signal in which narrow pulses repeat at 500 μsec intervals during the period when the original telegraph signal is “1”, so a pulse width stretcher is added to each telegraph channel. A pulse width expansion circuit 48 having the following structure is inserted. This is approximately 1100 μsec from the time the narrow sample pulse is input.
This is a circuit that maintains the "1" level over a period of time, making it possible to reproduce an approximate waveform of the original telegraph signal. (The retention period was chosen to be more than twice 500μsec because the superframe synchronization signal is inserted, so the interval between telegraph signal samples is approximately
This is because the time may be 1000 μsec, and it is necessary to fill this gap. ) Thus, the original telegraph signal of each channel is reproduced at the output of the pulse width expansion circuit 48, which is further supplied to the telegraph time division multiplexing circuit 49. As mentioned above, the telegraph time division multiplexing circuit 49 receives the 30 channels via the 24 channel gate pulse output lines 41.
A channel gate pulse is provided for gating each channel from the first channel to the twenty-fourth channel of the PCM signal, and the first channel gate pulse is used to gate the restored signal of the first telegraph channel, and the second channel gate pulse is used to gate the restored signal of the first telegraph channel. A channel gate pulse is used to gate the restored signal of the second telegraph channel, and a 24th channel gate pulse is used to gate the restored signal of the 24th telegraph channel. By combining (oring) the telegraph signal samples of each gated channel, a 30-channel PCM signal (this signal is
The PCM signal input from transmission line 3 is output through a suitable buffer amplifier and regeneration circuit.
A time division multiplexed telegraph signal can be obtained that has the same timing as the original time division multiplexed PCM signal (which is essentially the same signal as the original time division multiplexed PCM signal). The time-division multiplexed telegraph signal thus obtained is transmitted from the multiplexed telegraph separation/synthesis terminal station 4 to the second signal line 7.
The signal is supplied to the time division exchange switch 5 via. As is clear from the above explanation, the time division telephone signal supplied to the time division exchange switch 5 via the first signal line 6 of the multiplex telegraph separation and combination terminal station 4 and the 2 signal line 7
Since the time division telegraph signal supplied to the time division exchange switch 5 via the time division exchange switch 5 has exactly the same timing relationship, the same time division exchange switch 5 can be used to perform the above-mentioned exchange regardless of whether it is a telephone or a telegraph signal. can perform actions. In this embodiment, the telegraph signal is the first of the 30 channel time division multiplexed PCM signals.
It is transmitted using the 30th channel, restored to the original signal at the multiplex telegraph separation/combining terminal station 4, and then converted to the original signal using the telegraph time division multiplexing circuit 49.
Although we again used a configuration in which the time division multiplexed telegraph signal has the same timing as the time division multiplexed PCM telephone signal, even if other transmission means are used for the telegraph signal,
As mentioned above, if the original signals of each telegraph channel are obtained, they are directly transmitted to the telegraph time division multiplexing circuit 4.
By adding to the input of each channel of 9,
As described above, by using the same time-division exchange switch 5, the above-mentioned exchange operation can be carried out regardless of telephone or telegraph. As described above, by using the present invention, it is possible to use the same time division switching switch to perform switching operations without distinguishing between telephone and telegraph.
This has the effect of making the device more compact and economical.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the present invention;
Fig. 2 is a diagram explaining the transmission signal waveform, Fig. 3 is a block diagram showing an embodiment of a time-division PCM telephone terminal station and a telegraph multiplex terminal station, and Fig. 4 is the 30th channel gate pulse and each superframe pulse. FIG. 5 is a block diagram showing an embodiment of a multiplex telegraph separating/combining terminal station. In FIGS. 1, 3, and 5, 1...
Time division multiplex PCM telephone terminal station, 2... Telegraph multiplex terminal station, 3... Transmission line, 4... Multiplex telegraph separation/combination terminal station, 5... Time division switching switch, 6... First signal line, 7 ...Second signal line, 8...Third
signal line, 9... fourth signal line, 10...
... PCM decoder, 11 ... Transmission unit, 12 ... Telecommunication time division terminal station, 20-1, 20-2, ..., 20
-24... Telegraph signal input line, 21-1, 21
-2,...,21-24...sampling circuit, 2
2-1, 22-2,..., 22-24...Sampling clock line, 23...Clock pulse distribution circuit, 24...Super frame pulse generation circuit, 25...First synthesis circuit, 26...Second Synthesis circuit, 40... Channel gate pulse/bit clock generation circuit, 41... Channel gate pulse output line, 42... 30th channel gate pulse output line, 43... Super frame synchronization signal output line, 44... Bit clock Pulse output line, 45... Receive super frame pulse generation circuit, 46... Receive clock pulse distribution circuit, 47... Telegraph signal separation circuit, 48... Pulse width expansion circuit, 49... Telegraph time division multiplexing circuit.

Claims (1)

[Claims] 1. Means for transmitting sample values of a plurality of channels of the telegraph signal obtained by sampling the telegraph signal using a clock synchronized with the transmission bit of the time division multiplexed PCM telephone signal via a specific channel of the time division multiplexed PCM telephone signal. and the sample values of the transmitted telegraph signals of the plurality of channels are subjected to the time division multiplexing PCM.
means for converting into a time division multiplexed telegraph signal having the same timing as a telephone signal; and said time division multiplexed PCM.
1. A telephone and telegraph line time division switching control system, comprising means for exchanging a telephone signal and the time division multiplexed telegraph signal via the same time division switching switch.