CN1236588C

CN1236588C - Digital signal base-band modem

Info

Publication number: CN1236588C
Application number: CN 01105258
Authority: CN
Inventors: 詹喻平
Original assignee: ZTE Corp
Current assignee: ZTE Corp
Priority date: 2001-01-16
Filing date: 2001-01-16
Publication date: 2006-01-11
Anticipated expiration: 2021-01-16
Also published as: CN1366403A

Abstract

The present invention discloses a digital signal base-band modem in the field of communication, which comprises a U interface controller, a serial port 1, a serial port 2, a CPU, a B-channel data processing module, a D-channel data processing module, a U interface maintenance module and a clock processing module, wherein the B-channel data processing module sends data of two B channels to the serial port 1 in a mode of 128K, and the data of the two B channels are respectively sent to the two serial ports in a mode of 64K; the two serial ports receive user clocks and keep the synchronism of the system clocks and two serial ports, and thereby, the present invention can achieve the aims of flexible set, enough band width and low cost. The present invention can make the system clocks remain synchronization with user serial devices.

Description

A kind of digital signal base-band modem

Technical field:

The present invention relates to data communication field, relate in particular to the modulation-demodulation device of digital signal.

Background technology:

The application of digital signal base-band modulation at present more and more widely, wherein, on conventional twisted pair telephone line road, be modal a kind of with the digital baseband modulator-demodulator of full duplex mode synchronous transmitting data, it provides the communication port of 2B+D bandwidth, so claim the 2B+D baseband modem again.Wherein B is the data channel of 64kbps speed, and D is the control channel (or claiming signalling path) of 16kbps speed, is used for control (or claiming to safeguard) B passage.Digital signal base-band modem is a short haul modem, the u interface of this modulator-demodulator adopts 2B1Q coding (the 2B1Q coding is the coding that 2 dual codes is changed into 1 four-unit code), realizes synchronous data transmission with full duplex mode and outside on conventional twisted pair telephone line road.User data inserts by serial ports (with 64kbps or 128kbps speed), inserts the B passage in modulator-demodulator, and through the transmission of u interface access communications network, its spacing is from reaching 5 kilometers.The total volume of business of user data interface (being serial ports) is 2 B passages, generally is configured to two serial ports structures (each serial ports is a 64kbps speed).The 2B data-signal that the communication network that receives from u interface is come sends two users to by 2 serial ports respectively, and the D channel data is given the CPU (transmitting the maintenance information between communication network and baseband modem) of baseband modem or by serial ports and telex network.Existing digital signal base-band modem generally adopts the u interface chip that the u interface conversion of signals of 2B1Q coding is become digital interface (hereinafter to be referred as the IDL interface) bus signals between universal circuit interface (hereinafter to be referred as the GCI) bus of 2B+D coding or sheet, wins D channel data in the GCI/IDL bus by modulator-demodulator CPU (or serial ports user) by special chip such as ST5451; Utilize in the programmable logic device " dividing the multiple connection module " that the data in the B passage are passed to the user by serial ports again.Conversely, serial data inserted in the B passage of modulator-demodulator by " dividing the multiple connection module ", and the communication data of CPU inserts in the D passage by special chip such as ST5451, and modulator-demodulator carries out the 2B+D data 2B1Q coding again and sends into communication network by u interface.Along with the requirement of business to bandwidth improves, the single user of some business need occupies 2 B passages (128kbps speed), the data that are about to 2B are monopolized by a serial ports, and existing baseband modem can only receive a B channel data respectively with two serial ports, does not satisfy the demand of this kind business; And, under some particular case, need baseband modem to extract clock from serial ports, and clock is passed to the u interface opposite equip. by u interface, like this can be with user's serial equipment of whole system clock synchronization in baseband modem, and existing baseband modem can't make system clock keep and user's serial equipment is synchronous, simultaneously, because the D passage is handled and is adopted special chip in the existing baseband modem, has increased cost greatly.

Summary of the invention:

The purpose of this invention is to provide a kind of that can be provided with flexibly, can provide enough bandwidth, system clock is kept and user's serial equipment is synchronous, digital signal base-band modem cheaply, to solve existing baseband modem bandwidth deficiency, cost height and system clock is kept and the synchronous defective of user's serial equipment.

In order to finish above-mentioned purpose, the present invention has constructed a kind of digital signal base-band modem, comprise u interface controller, serial ports one, serial ports two and CPU, it is characterized in that, also comprise B channel data processing module, D channel data processing module, u interface maintenance module and clock processing module;

Described u interface controller sends the GCI frame data by the GCI bus to described u interface maintenance module, and described u interface maintenance module is sent into described B channel data processing module from the 2B passage extraction user data of GCI frame; Described B channel data processing module is delivered to described serial ports one with the 2B channel data under the 128K pattern, under the 64K pattern 2 B channel datas are delivered to described serial ports one and serial ports two respectively; Signal after described serial ports one and serial ports two will be handled sends to the user; Described serial ports one and serial ports two send to described B channel data processing module with user data simultaneously, and described B channel data processing module is delivered to described u interface controller by the GCI bus with data; Described u interface controller is connected with u interface equipment;

Described D channel data processing module receives the D channel data that described u interface maintenance module sends, and converts system's control and maintenance information to, is read by bus by described CPU; Described CPU sends information into described u interface maintenance module by described D channel data processing module simultaneously, delivers to described u interface controller by the GCI bus again, and described u interface controller is sent into u interface equipment after handling;

Described serial ports one and serial ports two receive the clock signal that the user sends, and send to described clock processing module after the processing, and described clock processing module sends to described u interface controller and described B channel data processing module with clock signal.

With respect to existing baseband modem, the digital signal base-band modem that the present invention constructed can satisfy the demand of user to broadband data transmission, the speed that makes the user insert reaches 128kbps, the present invention simultaneously also can realize extracting clock from user's serial ports, keep the synchronous of system clock and user's serial equipment clock, satisfy specific engineering demand;

In addition, D channel data processing module, u interface maintenance module are realized in programmable logic device in the digital signal base-band modem of the present invention, thereby have reduced product cost.

Description of drawings:

Below in conjunction with accompanying drawing the present invention is further described:

Fig. 1 is the application schematic diagram of 2B+D baseband modem;

Fig. 2 is the structured flowchart of existing 2B+D baseband modem;

Fig. 3 is the structured flowchart of digital signal base-band modem of the present invention.

Embodiment:

Fig. 1 shows the general application of digital signal base-band modem.In this was used, the messaging device of band u interface (as the digital subscriber board of band u interface) was by u interface and baseband modem swap data.Baseband modem passes through V.35/V.24 serial line interface and user's swap data.In fact, baseband modem be with the user data on the serial ports by the 2B data channel in the GCI frame, be encoded into the u interface signal of easy transmission (transmission range reaches 5 kilometers) through 2B1Q.Finish the transparent transmission of user data; Simultaneously, utilize the D passage in the GCI frame, the network management system communication of CPU and communication network in the realization baseband modem is to reach the monitoring purposes of network management system to baseband modem.

Fig. 2 shows the structured flowchart of existing digital signal base-band modem, divides the multiple connection module with 2B data in the GCI frame and serial data exchange, is generally realized by programmable logic device; D passage processing module and u interface maintenance module (claiming D/M passage processing module again) are finished by special chip.Serial ports one is 64kbps with serial ports two speed.CPU finishes the initialization of each chip and the maintenance management functions such as activation of u interface.But this system can only offer the 2B channel data in the GCI frame respectively two serial ports users, can't realize the 2B channel data is offered a serial ports user fully, can not satisfy a lot of users' needs; This baseband modem can only extract clock (being finished automatically by the u interface controller) from u interface, generate the required various clock signals of baseband modem after the clock processing module is handled in baseband modem, and can not extract clock from serial ports, make system clock be synchronized with the serial ports connected equipment, so just can not satisfy some specific environment; Simultaneously, a lot of parts in the general baseband modem all adopt programmable logic device, and existing baseband modem then is not placed on D passage processing module in the programmable logic device and realizes, thereby can't reduce system cost.

Fig. 3 is depicted as digital signal base-band modem of the present invention, and B channel data processing module, D channel data processing module, u interface maintenance module and clock processing module realize in programmable logic device FPGA.The u interface controller is finished conversion of signals between 2B1Q line signal and the GCI bus signals; B channel data processing module is temporary with the sampling of the 2B channel data in the GCI bus with the 512KHz clock, if with the 128KHz clock preceding 8 and back 8 bit data in the buffer are shifted respectively and export to two serial ports, then baseband modem can connect two 64kbps rate users; If with the 256KHz clock single serial ports is exported in the displacement of 16 bit data in the buffer, then baseband modem is given a user with 2B passage (128kbps speed) allocated bandwidth.Conversely, the 64kbps/128kbps serial data is multiplexed in the GCI frame (the GCI frame is the data arrangement structure on the GCI bus) by the conversion of B channel data processing module, and the u interface by the control of u interface controller converts the 2B1Q line signal to again.D channel signal in the GCI frame carries out HDLC by D channel data processing module to be handled, and the data after the processing can be read in by CPU.Conversely, CPU sends communication signaling into D channel data processing module, inserts in the D passage of GCI bus after this D channel data processing module is handled, and converts the 2B1Q line signal to through the u interface controller again and sends.The u interface maintenance module is finished the activation of u interface, the deexcitation maintenance function.Existing modulator-demodulator general work is in network terminal mode (being the NT pattern), wherein the u interface controller extracts clock (comprising 8KHz clock and 512KHz clock) from the u interface circuit, and modulator-demodulator and the user clock that links to each other with the modulator-demodulator serial ports all extract clock or its frequency division for this reason.For realizing that system synchronization is in the user clock function, this modulator-demodulator can be provided with it and work in line terminal mode (LT pattern), and then the opposite equip. of modulator-demodulator u interface (working in the NT pattern) can extract clock (this clock is synchronized with user clock) as its system clock from u interface.

U interface maintenance module 2B passage from the GCI frame extracts user data and sends into B channel data processing module.According to " 128K/64K " mode initialization value (by the toggle switch setting) of user, if the 128K pattern, then B channel data processing module is all delivered to serial ports one with the 128KHz clock that the clock processing module provides with the 2B channel data; If 64K pattern, B channel data processing module is delivered to serial ports one and serial ports two with the 64KHz clock that the clock processing module provides respectively with 2 B channel datas, every road serial ports has 64Kbps rate users data, and each serial ports is issued the user with the treated signal that is converted to V.35/V.24 of serial data again.Simultaneously, u interface maintenance module D passage from the GCI frame extracts the D channel data and sends into D channel data processing module, D channel data processing module is carried out HDLC to these data and is unpacked processing (High level data link control-High Data LinkControl), data after the processing are system's control, maintenance information, CPU can read this information by bus, finishes the communication between webmaster in CPU and the communication network.Meanwhile, CPU information is handled by the HDLC package of D channel data processing module and is connected into the u interface maintenance module, be inserted in the GCI frame D passage, deliver to the u interface controller by the GCI bus again, the u interface controller is that the u interface signal links to each other with communication network through the 2B1Q code conversion, so just the information of CPU is sent into communication network; In like manner, user 1, user's 2 data are passed to B channel data processing module by serial ports one and serial ports two with data, in B channel data processing module, user data is inserted in the GCI frame 2B passage, B channel data processing module is delivered to user data the u interface controller again by the GCI bus, and the u interface controller is converted into the u interface signal through the 2B1Q coding and sends in the communication network.8031 single-chip microcomputers that described CPU adopts Intel Company to produce.

Claims

1, a kind of digital signal base-band modem comprises u interface controller, serial ports one, serial ports two and CPU, it is characterized in that, also comprises B channel data processing module, D channel data processing module, u interface maintenance module and clock processing module;

Described u interface controller sends the GCI frame data by the GCI bus to described u interface maintenance module, and described u interface maintenance module is sent into described B channel data processing module from the 2B passage extraction user data of GCI frame; Described B channel data processing module sends to described serial ports one and serial ports two with the 2B channel data; Signal after described serial ports one and serial ports two will be handled sends to the user; Described serial ports one and serial ports two send to described B channel data processing module with user data simultaneously, and described B channel data processing module is delivered to described u interface controller by the GCI bus with data; Described u interface controller is connected with u interface equipment; The signal that transmits between described u interface controller and the u interface equipment is the 2B1Q line signal, and the signal that transmits between the u interface maintenance module is the GCI bus signals;

2, digital signal base-band modem according to claim 1 is characterized in that, described B channel data processing module, D channel data processing module, u interface maintenance module and clock processing module adopt programmable logic device FPGA to realize.

3, digital signal base-band modem according to claim 1 is characterized in that, when described digital signal base-band modem worked in network terminal mode, system clock was 8KHz clock and 512KHz clock; When described digital signal base-band modem worked in the line terminal mode, system clock received user clock by serial ports, kept synchronously with it.

4, digital signal base-band modem according to claim 1 is characterized in that, described serial ports one and described serial ports two are signal V.35/V.24 to signal that the user sent.

5, digital signal base-band modem according to claim 1 is characterized in that, described CPU adopts 8031 single-chip microcomputers.