JP2797824B2 - Subcarrier multiplexed optical transmission device and I/O card used therein - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a subcarrier multiplexed optical transmission device and an I/O card (I/O package) used therein.

[0002]

2. Description of the Prior Art A conventional subcarrier multiplexing optical transmission device is shown in FIG.
The configuration is as shown in (A).
A plurality of multimedia signals (data, audio, video, and other information) S1 to Sn (n is a positive integer) to be transmitted are respectively transmitted to corresponding I/O terminals.
O card (a circuit for input/output interfaces, physically a circuit package consisting of a printed circuit board, etc.)
11 to n.

In each of these I/O cards 11 to 1n, the transmission input signals S1 to Sn are converted into baseband transmission signals b1 to bn, respectively, and input to the modulation-multiplexing section 1, respectively.

In this modulation-multiplexing section 1, each of the baseband transmission signals b1 to bn is modulated according to a predetermined modulation method (AM, FM, F
The signals are then modulated by a modulation method such as SK, PSK, etc., and then frequency converted to subcarrier frequencies f1 to fn, multiplexed, and output.

The frequency division multiplexed transmission signal m1 output from the modulation-multiplexing section 1 is converted into an optical output signal OPT1 in the EO conversion section 2 and then transmitted.

In the O-E conversion section 3, the received optical signal OP
This received multiplexed signal m2 is input to the separator/demodulator 4, and each subcarrier frequency f1
.fn are subjected to frequency conversion, and then demodulated to derive baseband received signals B1.about.Bn.

These baseband reception signals B1 to Bn are input to the corresponding I/O cards 21 to 2n, respectively, and are converted into multimedia reception signals J1 to Jn, respectively.

[0008] In this way, in the conventional device, the modulation-multiplexing unit 1 includes modulation and frequency conversion functions and multiplexing functions for n channels, and the separation-demodulation unit 4 includes a separation function and frequency conversion and demodulation functions for n channels.

For this reason, it is necessary to design the common sections, the modulation-multiplexing section 1 and the separation-demodulation section 4, to have the above functions in advance for the maximum number of channels that will be used. However, the number of channels actually used is not always the maximum number, and in general, a number of channels that is much smaller than the maximum number is often used. In such a case,
The common parts 1 and 4 are used inefficiently, which is uneconomical.

[0010]

SUMMARY OF THE PRESENT INVETION It is an object of the present invention to provide a subcarrier multiplexing optical transmission device which is capable of reducing the amount of hardware required for common sections such as a multiplexing section and a demultiplexing section, thereby improving utilization efficiency.

Another object of the present invention is to provide an I/O card capable of reducing the amount of hardware in the common section of a subcarrier multiplexed optical transmission device and efficiently dealing with an increase or decrease in the number of channels.

[0012]

The transmission I/O card according to the present invention modulates a plurality of transmission signals by a predetermined modulation method, converts these modulated signals to a predetermined subcarrier transmission signal frequency , and transmits the frequency converted signals to a frequency multiplexing section.
a transmission I/O card for a subcarrier multiplexing optical transmission system configured to output a signal from the transmission I/O card, the transmission I/O card including: means for receiving one of the plurality of transmission signals and modulating the transmission signal by a predetermined modulation method; and means for frequency-converting the modulated output in response to a channel setting signal from an external source to generate the subcarrier signal,
to the frequency multiplexing unit .

The receiving I/O card according to the present invention includes a separation section which modulates a plurality of transmission signals by a predetermined modulation method, converts these modulated signals to respective predetermined subcarrier signal frequencies to obtain frequency-multiplexed transmission signals, transmits these multiplexed transmission signals as optical signals, receives these optical signals, converts them into electrical signals, and separates them into a plurality of subcarrier reception signals.
a receiving I/O card for a subcarrier multiplexed optical transmission system that receives a signal supplied from a separating section and demodulates the signal from the separating section , and that includes internal means for receiving one of a plurality of subcarrier received signals from the separating section, and frequency-converting this received signal in response to an external channel setting signal to generate a received signal.

A subcarrier multiplexed optical transmission device according to the present invention comprises a plurality of transmitting I/O cards, each having modulation means for modulating an inputted transmission signal by a predetermined modulation method and frequency conversion means for converting this modulated output to a predetermined subcarrier transmission signal frequency in response to an external channel setting signal, multiplexing means for frequency multiplexing each of the subcarrier transmission signals of the transmitting I/O cards, E-O conversion means for converting this multiplexed output into an optical signal, and O-E conversion means for receiving the optical signal and converting it into an electrical signal.
The system is characterized by including a separation means for receiving this converted output and separating it into a plurality of subcarrier received signals, a frequency conversion means for receiving the corresponding subcarrier received signals after separation and converting them into a predetermined frequency in response to an external channel setting signal, and a plurality of receiving I/O cards each having a means for generating and outputting a received signal in response to this frequency converted output.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will now be described with reference to the drawings.

1 is a block diagram of an embodiment of the present invention, in which (A) is a transmitting device and (B) is a receiving device. Note that parts equivalent to those in FIG. 2 are designated by the same reference numerals.
The transmitting I/O cards 11 to 1n are respectively supplied with corresponding multimedia transmitting signals S1 to Sn.

The input transmission signals S1 to Sn of each of these I/O cards 11 to 1n are each converted to a baseband transmission signal by the baseband conversion section 100, modulated by a predetermined modulation method (FM, AM, FSK, PSK, etc.), and then frequency-converted according to each channel setting signal E1 to En from the outside to become subcarrier transmission signals C1 to Cn.

For this purpose, each of the I/O cards 11 to 1n is provided with a modulation section 100 for modulating the output of the baseband conversion section 100.
The modulation output of the local oscillator 103 is mixed with the output of the local oscillator 103. The oscillation frequency of the local oscillator 103 is set to the channel setting signals E1 to E4.
En are set and controlled so that subcarrier signals C1 to Cn of predetermined frequencies can be obtained.

The multiplexing unit 10 receives these subcarrier signals C1 to Cn, performs subcarrier multiplexing, and outputs a transmission multiplexed signal m1.
This multiplexed signal m1 is converted into an optical signal OPT1 and transmitted.

Next, at the receiving side shown in (B), the optical signal O
PT2 is received and photoelectrically converted into an electrical signal m2 by the OE converter 3. The separator 40 separates this signal m2 into frequencies f1 to fn corresponding to the respective channels, and outputs subcarrier reception signals D1 to Dn.

In each of the receiving I/O cards 21 to 2n, the corresponding subcarrier receiving signals D1 to Dn are demodulated at a frequency f
The signal is converted to an IF signal, demodulated according to the modulation method used on the transmitting side, and converted back to a baseband signal.

Therefore, each of the I/O cards 21 to 2n is provided with:
The system is provided with a mixer 104 which mixes the output with the oscillation frequency of a local oscillator 105, the oscillation frequency of which is controlled by external channel setting signals F1 to Fn, a demodulator 106 which demodulates the mixed output back to a baseband signal, and an inverse baseband converter 107 which converts the baseband signal into a received multimedia signal.

In addition, the channel setting signals F1 to
Fn is set for each of the I/O cards 21 to 2n so that it becomes fIF when the subcarrier reception signals D1 to Dn are frequency-converted. The local oscillator 103 for frequency conversion is a synthesizer type that can be changed to a desired frequency by the channel setting signals E1 to En. The same is true for the I/O cards 21 to 2n. For this reason, each I/O card (for both transmission and reception) can be used for all channels.

[0024]

According to the present invention, by storing the modulation section, demodulation section and frequency conversion section, which were previously in the common section, on the I/O card side, it is possible to significantly reduce costs when only a few channels are used.

Furthermore, since channel selection can be freely set using a synthesizer system, one I/O card can be applied to all carriers, which has the effect of facilitating rearrangement of transmission signals (multimedia signals).

[Brief description of the drawings]

FIG. 1 shows blocks of an embodiment of the present invention, where (A) is a block diagram of the transmitting side and (B) is a block diagram of the receiving side.

2A and 2B are block diagrams showing a conventional subcarrier multiplexing optical transmission device, in which FIG. 2A is a block diagram of the transmitting side and FIG. 2B is a block diagram of the receiving side.

[Explanation of symbols]

2 E-O conversion section 3 O-E conversion section 10 Multiplexing section 11 to 1n Transmission I/O card 21 to 2n Reception I/O card 40 Demultiplexing section 100 Baseband conversion section 101 Modulation section 102, 104 Mixing section 103, 105 Local oscillation section

───────────────────────────────────────────────────────────── Continued from the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H04J 1/06 H04J 14/00

Claims (3)

(57) [Claims] [Claim 1] A method for modulating a plurality of transmission signals by a predetermined modulation method, converting each of the modulated signals to a predetermined subcarrier transmission signal frequency , and transmitting the corresponding signals to a frequency multiplexing section.
A transmitting I/O card for a subcarrier multiplexing optical transmission system that outputs a frequency-converted signal , the transmitting I/O card including: means for receiving one of the plurality of transmitting signals and modulating the transmitting signal by a predetermined modulation method; and means for frequency-converting the modulated output in response to an external channel setting signal to generate the subcarrier signal ;
A configuration for deriving the frequency converted signal to the frequency multiplexing unit.
A transmitting I/O card characterized by: a first modulation scheme for modulating a plurality of transmission signals by a predetermined modulation method and converting the modulated signals to predetermined subcarrier signal frequencies to obtain frequency-multiplexed transmission signals;
This multiplexed transmission signal is transmitted as an optical signal, and this optical signal is received and converted into an electrical signal, and then a signal is supplied from a separator which separates the optical signal into a plurality of subcarrier reception signals.
A receiving I/O card in a subcarrier multiplexing optical transmission system for demodulating a signal from a splitter ,
A receiving I/O card comprising: a means for receiving one of a plurality of subcarrier receiving signals from a remote portion, and converting the frequency of this receiving signal in response to an external channel setting signal to generate a receiving signal. [Claim 3] A subcarrier multiplexed optical transmission device comprising: a plurality of transmitting I/O cards each having modulating means for modulating an inputted transmission signal by a predetermined modulation method, and frequency conversion means for converting this modulated output to a predetermined subcarrier transmission signal frequency in response to an external channel setting signal; multiplexing means for frequency multiplexing each of the subcarrier transmission signals of the transmitting I/O cards; E-O conversion means for converting this multiplexed output into an optical signal; O-E conversion means for receiving the optical signal and converting it to an electrical signal; separation means for receiving the converted output and separating it into a plurality of subcarrier received signals; frequency conversion means for receiving the corresponding subcarrier received signals after separation and converting them to a predetermined frequency in response to an external channel setting signal, and a plurality of receiving I/O cards each having means for generating and outputting a received signal in response to the frequency converted output.