Abstract: The IP network telephone technology (VOIP) took one kind to synthesize the traditional telecommunication network and the computer network characteristic technology already knew very well for the people. The USB network telephone is the black eyebrow coloring helps in the computer platform, provides one kind new, the user-friendly network telephone service terminal device. It through namely inserts the USB connection which and the computer namely uses is connected, realizes in the Internet from the computer network connection the voice communication, with the aid of may talk over the telephone in the gateway equipment with the telecommunication network ordinary call, is uses the computer to work for a long time a race’s good companion. This article introduced that the USB network telephone’s software and the hardware design plan and realizes the process.
Key word: Network telephone; H.323 agreement; USB; The net defends
Along with the Internet (also said that the IP net) the technical fast development, the IP network telephone already obtained the widespread use. The so-called IP network telephone is refers to uses the Internet integrated data package of form transmission pronunciation/facsimile and so on new telecommunication service, is called VoIP (Voice over IP:IP network load bearing pronunciation service). It by the inexpensive price, the nimble application causes the tradition telecommunication service to receive the enormous challenge, until at the end of 2004, occupied nearly the long-distance business volume 50%. Certainly, this mainly refers to each big telecommunication operator to promote IP the calling card form the IP telephone trunk-line service, its characteristic is turns on the part use tradition telecommunication terminal (for example telephone, handset), by the special number form recognition (179XX), the data packet form which groups in the main skeleton line transmits the voice on the Internet.
This article introduced that (hereafter refers to as USB network telephone) based on the TIGER560B USB network telephone terminal, it uses the USB connection which and the computer namely inserts namely uses is connected, does not need to draw support from the traditional telecommunication terminal, may turn on the Internet directly. Not only may dial the long-distance telephone call, moreover may also dial the public opinion. If uses in the local area network or the virtual local area network, telephone conversation completely free. In Internet popular today, uses the USB network telephone to be able to save the massive phone bills for the large and middle scale Business and enterprise unit.
1 TIGER560B controller
The early time realizes the voice correspondence on the computer mainly to use the pure software form, with the aid of connects the Internet in the network card, the sound card realizes voice the input-output through the microphone and the sound. But the shortcoming first is answering or dials telephones to operate the computer keyboard, not only complex moreover does not conform to the people to use telephone’s custom; Next is incoming call broadcasts both the divulging privacy from the sound box and to interfere with other people work; Also, the connection quality is bad, easy to have the echo. May overcome the above shortcoming based on the TIGER560B USB network telephone terminal.
TIGER560B is Tiger Jet Network Corporation develops uses in the low cost, the high voice quality VoIP processor specially, the interior contains the USB connection. Its integration rate is very high, the internal integration has many functional modules, the outside only needs the few parts to be possible to realize the VoIP function. The TIGER560B function and periphery pin as shown in Figure 1.
The TIGER560B key component has the control logic, the audio frequency channel, the USB connection, the usual I/O connection, the peripheral device connection and the disposition control interface.
The control logic is electric circuit’s core, the content special-purpose processor, uses for to be coordinated the entire electric circuit the work; The audio frequency channel connects the exterior audio frequency codec encoder-decoder, completes the audio frequency PCM data stream the input-output; The USB connection and computer’s USB connection connection, the disposition controls the TIGER560B chip and the TIGER560B connection codec encoder-decoder, the simultaneous reception and the transmission computer side audio frequency data stream, has the bridge joint correspondence function; The general I/O connection may control the indicating lamp, the ringing, the liquid crystal display; Peripheral device connection receive keyboard number and connection codec encoder-decoder; The disposition control interface uses the hardware connection to carry on the disposition to TIGER560B in the different working pattern, with the aim of loading the different driver.
The TIGER560B function is as follows:
* support keyboard scanning, liquid crystal display actuation, telephone connection (SLIC);
* supports the H.323 agreement and the SIP agreement, realizes completely the VoIP function;
* does not need to install the actuation, because actuated already to insert to the Windows operating system in;
* can realize PC to the PC point-to-point telephone conversation, realizes in the Internet the IP telephone, realizes through the gateway with the tradition telephone relation;
* supports the USB power supply electricity saving pattern and the far-end awakens the function;
* audio frequency function
Supports the USB audio frequency class equipment pattern;
Uses Windows audio frequency USB to actuate;
Supports the 8bit μ-Law codec encoder-decoder connection;
The support volume control, shuts the sound control;
●PCM connection support
Silicon Labs Corporation’s Si3210 user interface electric circuit, Chinese Nation Company’s W681511 audio frequency codec encoder-decoder and Motorola Corporation’s MC145480 audio frequency codec encoder-decoder;
Supports TDM, IOM2, GCI;
Long frame pattern and short frame pattern;
●USB connection
Full speed 12Mb/ps, compatible USB101 agreement;
Phase-locked loop, MAC, PHY, transceiver integration on chip;
In has the 3.3V regulator;
* supports the SPI 4 interface buses;
Support peripheral device bus interface; 8bit data bus, 6 address wires, 22 general I/O lines, read-write replacement line and so on;
* list 12MHz crystal oscillator, 5V working voltage, 100 pin PQFP seal.
TIGER560B integrated the IP telephone terminal necessary all functions nearly, the outside must only connect the PCM audio frequency codec encoder-decoder and the keyboard and so on may realize the VoIP function.
2 system compositions, principle of work and H.323 agreement
2.1 USB network telephone’s structure
Figure 2 is based on TIGER560B VoIP processor’s USB network telephone module diagram.
As the core USB network telephone has 3 kind of composition forms take TIGER560B.
(1) the USB network telephone which (W681511) composes with TIGER560B and the audio frequency codec encoder-decoder is equal outside USB sets at the sound card, has not operated the keyboard, does not need to install any extra actuation software, uses the computer keyboard to operate telephone’s allocation with the connection.
(2) TIGER560B, the audio frequency codec encoder-decoder, the keyboard and the ringing circuit compose the USB network telephone is a complete network telephone, the application method and the use tradition telephone dials, answering to be completely same. This form needs the supplementary keyboard scanning actuation software and the ringing control actuation software. If has not installed the additional actuation to use the computer keyboard to operate. Moreover, if need, but may also increase the liquid crystal display.
(3) TIGER560B and the user interface electric circuit (ProSLIC:Si3210) composes USB network telephone. This form is a single connection small gateway, turns on through it a standard ordinary call the Internet, realizes the network telephone’s function, can distinguish picks machine/on-hook operation, to receive the double sound multi-frequencies (DTMF) the telephone number, provides the entire labor bidirectional telephone conversation. This form network telephone needs to install the additional actuation software. This article mainly showed to the second form.
2.2 USB network telephone’s principle of work
Because the USB connection has namely inserts namely uses the function, therefore, the USB network telephone and computer’s connection is very convenient, may also body carrying.
USB the network telephone straight insertion computer USB connection, and installs the corresponding actuation software, may “the device management” - - “the somatic anthropology input device” see “the USB somatic anthropology input device” in the computer; In “the sound, the video frequency and the game control” saw “USB Audio Device”, simultaneously presents the info window in the computer tabletop.
Dials as the calling when telephones, directly presses “picks on-hook key”, then inputs the telephone number, TIGER560B to the keyboard direct scanning, will input picks on-hook information and the telephone number transmits the computer, carries on the call, is called to pick machine enters the telephone conversation condition. This time, the calling voice by the telephone handle microphone input, the audio frequency codec encoder-decoder the simulated signal will turn the PCM form the data signal, sends in TIGER560B to carry on processing, delivers the computer again by the TIGER560B USB connection, the computer uses the H.323 protocol processing, finally connects the Internet through the network interface.
Is called is the calling counter process. If has the ringing, according to “picks on-hook key”, direct answering. This time, the voice which comes from the Internet, after computer processing delivers TIGER560B from the USB connection, then turns by TIGER560B the voice information the PCM data format to deliver the audio frequency codec encoder-decoder, again after the audio frequency codec encoder-decoder turns the PCM data format voice the simulation voice, delivers is called the telephone handle’s ear trumpet.
No matter is called as the calling, is the full-duplex, the bidirectional real-time communication. The call, the telephone conversation, on-hook and so on each condition has the instruction in the computer contact surface, the dial or answers the telephone and the use tradition telephone is completely same, does not need to operate the keyboard to carry on the intervention.
2.3 H.323 agreements realize the network telephone process
This article states the network telephone is computer’s one kind is auxiliary the external instrumentation, its network protocol and realizes network telephone’s multimedia agreement H.323 to realize on the computer.
Realizes the network telephone to be possible to use the H.323 agreement and the SIP agreement. At present our country mainly uses the former.
The H.323 agreement is the Internet multimedia real-time communication agreement bunch which ITU-T (international electricity unites) formulates, controls, series agreements and so on media code, supervisory control, network security by the call to be composed, its full title is “based on the packet switching multimedia communication department”. The H.323 agreement provides based on Internet’s sound, the video frequency and the data transfer related standard, has defined 4 kind of basic constitution units: The terminal (terminal), the gateway (gateway), the net defends (gatekeeper) and the multi-spot control unit (MCU). And the gateway and the net defend are the network telephone system’s keys. The gateway realizes the Internet and the net defends is the network telephone system’s key. The gateway realizes the Internet telephone and the traditional telecommunication network telephone’s connection, the net defends is responsible for in the Internet the telephone call, the cost and the management and so on. The USB network telephone is only the network telephone terminal one form. Its agreement software skeleton like chart 3 standard, but the network telephone only involves to the audio communication part, therefore, multi-spot control unit MCU does not take its necessary equipment.
In computer’s software design: The audio frequency arranges the decoding part to be able to receive and dispatch codes and so on G..722, G.729, G..723.1 with the USB network telephone handle through the USB connection, transmits by the network interface. Has provided the network telephone and the net defends, between the gateway and other terminals the essential control interface, uses the H.225.0 call to control, the H.245 channel control, the RTCP real-time control agreement to realize.
The net defends is the network telephone system necessary management unit, in after the terminal the electricity, first defends the registration to the net, delivers the net its IP address and the telephone number to defend (telephone number also to be possible to defend assignment by net), accepts the net to defend the management. Each time call some telephone, first defends the exchange information with the net, defends from the net obtains the IP address which calls, then with is called the direct communication. The telephone conversation ended, must defend the correspondence with the net, caused the net to defend obtains this telephone conversation conclusion information, or took the historic record symbol as the cost basis. If only uses the USB network telephone in the point-to-point telephone conversation time, then may the direct call opposite party IP address, but does not need the net to defend.
The gateway is between two kind of different network intercommunication equipment, completes the signaling form, the content to transform, the communication protocol to transform, the class media format conversion. It is the network telephone and the traditional telephone intercommunication necessary equipment. If the network telephone only uses in the local area network or the virtual local area network and so on small scope, may not need the gateway equipment, as shown in Figure 4.
3 hardware circuit design
The USB network telephone uses the TIGER560B special-purpose controller, the periphery hardware circuit are very few. Guaranteed that the electric circuit cost is low, the reliability is high. Concrete electric circuit as shown in Figure 5.
Figure 5 only gives TIGER560B the main ties, like audio frequency codec encoder-decoder, keyboard, USB connection, ringing circuit, crystal oscillator electric circuit and work instruction. Other like pattern disposition, the power line, the grounding, the resistor connection and so on actual content may refer to reference [4]. Uses the TIGER560B design the network telephone, the electric circuit is simple, does not need to establish in the telephone the software, all establishments, the actuation and the application software move on the computer, are advantageous for the volume production.
TIGER560B can have the MC14LC5480 succession, as shown in Figure 6. Uses the short frame pattern. Does not need the extra succession to produce the electric circuit. When achievement calling, MC14LC5480 the simulated signal which sends the handle turns the PCM data symbol stream (to tally G..711 code standard), then delivers TIGER560B to carry on processing, TIGER560B sends in through the USB connection the PCM symbol stream the computer, the computer carries on it the audio frequency code, the transformation is G..729, G.723.1, G..722 (may in computer use contact surface be possible establishment), delivers again it from the computer network connection the Internet; Takes when calls, MC14LC5480 the PCM code which transmits the reversion turns the simulated signal, delivers to the handle microphone.
On the keyboard has picks/on-hook pressed key, the number key, the volume controller, the number modifier key, to shut the key and so on, the dial, answers the telephone not to need to operate the computer keyboard. Is completely same as the use tradition telephone, facilitates practical. If has incoming call, the buzzer will discover that “toot toot the sound” the prompt, the computer screen also has the instruction.
4 software designs
The USB network telephone’s audio frequency actuation software already inserted in Microsoft’s WINDOWS operating system, may realize namely inserts namely uses the function. May use general network voice communication software like MSN, QQ, OPENPHONE and so on to carry on the pronunciation exchange. This time, outside USB network telephone quite sets at the sound card, each kind of operation needs to draw support in the computer keyboard and the corresponding pronunciation software completes, cannot realize the keyboard scanning and the ringing function. If must realize the complete telephone function, must other development actuation software.
This article designs the network telephone software actuates two parts including the user interface design and the keyboard scanning/ringing. Contact surface design mainly by succinct, practical, artistic primarily, does not take the key introduction.
The design keyboard scanning, the ringing actuation part uses the SDK development package which Tiger Jet Network Corporation provides, realizes through the compilation actuation software control TIGER560B interior register. Software flow diagram as shown in Figure 7. The H.323 agreement software uses the storehouse function which the SDK development package provides, the network protocol software uses in the WINDOWS operating system’s agreement.
The keyboard scanning and the ringing actuation software subroutine is as follows:
#include “stdafx.h”
#include ” TjIpApi.h “
#include ” Tj560Bhandset.h “
#ifdef _DEBUG
#define new DEBUG_NEW
#undef THIS_FILE
static char THIS_FILE[]=_FILE_;
#endif
CTj560Bhandset_Hid::CTj560Bhandset_Hid()
{
}
CTj560Bhandset_Hid::~CTj560Bhandset_Hid()
{
}
BOOL CTj560Bhandset_Hid::InitTjHardware()
{
return TRUE;
}
BOOL CTj560BhandsetKeypad_Hid::InitTjHardware()
{
tjoutp(0×0b,100); //default is 48, now set to
100 ==> period =100/2=50ms
InitBuzzer();
Return TRUE;
}
char CTj560BhandsetKeypad_Hid:: MapHardwareKeyToUserKey (WORD wHardwareKey)
{
char cNewKey=0;
switch(wHardwareKey)
{
case 0xb0;
case 0xb1;
case 0xb2;
case 0xb3;
case 0xb4;
case 0xb5;
case 0xb6;
case 0xb7;
case 0xb8;
case 0xb9;
cNewKey= (char) (wHardwareKey -0xb0) ‘ 0 ‘;
break;
case 0xba:
cNewKey=(char)VK_MULTIPLY; // ‘*’ key
break;
case 0xbb:
cNewKey=(char)VK_POUND; // ‘ * ‘ key
break;
case 0×26:
cNewKey=(char)VK_ALT_U; //hangup
break;
case 0×31: //Enter key
cNewKey=(char)VK_RETURN;
break;
case 0×2f:
cNewKey=(char)VK_ALT_TCD;
break;
case 0×51;
VK_DOWN; //down
break;
case 0×52;
cNewkey=(char)VK_UP; //up
break;
case 0×20:
cNewKey=(char)0;
break;
default:
break;
}
return cNewKey;
}
BOOL CTj560B Hand set Key pad_Hid::Ring(BOOLbOn)
{
SetBuzzerFreq(2400); //default to 2.4kHz
TurnBuzzerOn(bOn);
Return TRUE;
}
The software also includes the USB communication protocol, the computer side uses WINDOWS the support the USB actuation software, the USB network telephone side agreement software solidifies by the micro code form in TIGER560B, cannot write the software again.
5 concluding remark
This project already completed the experiment and the test the other day. The test result indicated that its voice quality is good, the work is stable, may take the computer appendix.
The entire USB network telephone take TIGER560B as the control core, the external connection pronunciation codec encoder-decoder, the hardware circuit is simple, the software movement on the computer, has used computer’s superiority fully, turned one standard the computer based on H.323 the agreement VoIP terminal. If in the operator provides based on the pure Internet’s on network telephone business, this article states the USB network telephone certainly will have the very good development prospect.
