基于网线传输的视频交换机

基于网线传输的视频交换机 郭杰、雷刚 一、 引言 随着现代电子技术的发展，视频技术越来越广泛的应用到社会生活中。各种各样的视频信号需要处理和关注，比如在居住小区、各大商场的安保视频，现代家居中的卫星电视、DVD、数字机顶盒等视频。如何在众多的视频信号中进行合理的处理和分配，成为必需要面对的问题。 本文以一个具有多输入视频的家庭为例，其中需要关注的视频有以下4路:DVD视频、卫星电视视频、数字机顶盒视频和入户监控视频;需要接收到以上视频的位置可能在客厅、主卧室、次卧室、客卧室等房间。采用视频交换机的结构如图1所示，视频交换机与各个输出之间使用一根5类非屏蔽双绞线进行连接，成本低廉。 DVD视频 客厅输出 卫星电视 主卧室输出 视频交换机 机顶盒视频 次卧室输出 监控视频 客卧输出 图1 二、 视频交换机的整体结构 视频交换机包含一下几部分组成:主控制CPU、视频切换矩阵、音频切换矩阵、遥控信号切换矩阵、视频输出驱动和电源部分(图2)。 school)], 4 4 house building as well as more than 1000 copies of books, more than 10 kinds of collection of newspapers and magazines, fires burnt down. In 1938, the Japanese learned that the national Government established in XI Tang Tomb rotten "clip" taxes, tax officers live in 8 of Yan Dong village farmers home, troops at night, Yao was burned several houses. 1938 new morning of September 18, the Japanese team went to the countryside "sweep" from the kaiyang village line to Tung Yang Jia Qiao yan Temple wall and met Yang Jia溇 Zhou Dana (male) weeks because of long-term illness and can't work in the fields, the Japanese see his face from scratch without calluses, regard him as "Shina", thrust a knife at the scene of his death. The body was stabbed 7 times, wound 13. The same day, Trang bang village heard the Japanese come to "mop-up" are hiding, mother of 9 Zhou Guanbao Zhang Aying to drill a "dry mound", was discovered by the Japanese, a shot in the end. The same day, is 7 zhouhaijiangzhi grandfather Zhou Yingbao to escape the Japanese army, was found on the road, a shot in the end. In March 1939, the Japanese army in Yan Tomb raiding, has arrested 16 people, in fengqiao cigarettes this morning bang, killing 11 people on the River, East meeting point in wood qiaotu in the afternoon killing 4 people on the Riverside. Gu Tong is a Japanese go speak the Shanghai dialect, later to be called Gu Tong as "kill left." On January 18, 1943, the elves, five thousand or six thousand, water and land go hand in hand "mop-up" jiaxing area west of the railway, Yan Tomb area fall. March 6, Niu Shan (County Government II section chief) carrying its child Niu Jun (strict Tomb seventh district Chang) and the District Assistant Yu Xuchu, and players Jin Fuqin, and Shen Baosheng, six people received Wujiang underground County Government notification 图2 主控CPU:协调控制视频矩阵、音频矩阵和遥控矩阵的正常工作;判断识别输出端反馈的切换，进行正确的切换操作。采用性价比高的51系列单片机实现。 视频切换矩阵:实现视频源和各输出点的视频切换，并可以改变信号的幅度，具体切换由主控CPU控制。为了简化电路结构、节约产品的成本，采用Fairchild公司的FMS6501视频矩阵来进行电路的设计。 音频切换矩阵:实现音频源和各输出点的音频切换，具体切换由主控CPU控制。在此采用Intersil公司的CD22M3494音频矩阵来进行电路的设计。 遥控信号切换矩阵:为了实现在各个输出节点上可以实现对自己选择的设备进行准确的遥控，在电路上还必需设计一个遥控信号却换电路。在此可以使用模拟开关或者矩阵来实现，但为了节约成本，简化电路结构，在此使用廉价的6时钟的单片机来实现。使用单片机来作为遥控信号的切换，可以大大提高电路的灵活性。 视频输出驱动:由于视频交换机的主机和各个输出点之间的距离较长(最远达到100米)，为了减小信号的衰减，需要在主机端将信号先进行差分，然后再在远端输出端，进行差分接收处理。在主机端，使用Intersil公司的EL5171差分芯片进行电路设计。 电源部分:主机使用外接12V稳压电源供电。在主机内部需要使用+5V、-5V和+3.3V的直流电源，为了提高电路的可靠性，减小电路体积和整机功耗使用，使用小型PWM开关电源芯片进行。 三、 视频交换机硬件电路 1、 主控CPU 采用飞利浦的高性能51单片机P89V51RD2作为交换机系统的控制主机(如图3)，提高了主机的运算速度和可靠性。P89V51RD2内部具有64K字节的Flash ROM程序存储器和school)], 4 4 house building as well as more than 1000 copies of books, more than 10 kinds of collection of newspapers and magazines, fires burnt down. In 1938, the Japanese learned that the national Government established in XI Tang Tomb rotten "clip" taxes, tax officers live in 8 of Yan Dong village farmers home, troops at night, Yao was burned several houses. 1938 new morning of September 18, the Japanese team went to the countryside "sweep" from the kaiyang village line to Tung Yang Jia Qiao yan Temple wall and met Yang Jia溇 Zhou Dana (male) weeks because of long-term illness and can't work in the fields, the Japanese see his face from scratch without calluses, regard him as "Shina", thrust a knife at the scene of his death. The body was stabbed 7 times, wound 13. The same day, Trang bang village heard the Japanese come to "mop-up" are hiding, mother of 9 Zhou Guanbao Zhang Aying to drill a "dry mound", was discovered by the Japanese, a shot in the end. The same day, is 7 zhouhaijiangzhi grandfather Zhou Yingbao to escape the Japanese army, was found on the road, a shot in the end. In March 1939, the Japanese army in Yan Tomb raiding, has arrested 16 people, in fengqiao cigarettes this morning bang, killing 11 people on the River, East meeting point in wood qiaotu in the afternoon killing 4 people on the Riverside. Gu Tong is a Japanese go speak the Shanghai dialect, later to be called Gu Tong as "kill left." On January 18, 1943, the elves, five thousand or six thousand, water and land go hand in hand "mop-up" jiaxing area west of the railway, Yan Tomb area fall. March 6, Niu Shan (County Government II section chief) carrying its child Niu Jun (strict Tomb seventh district Chang) and the District Assistant Yu Xuchu, and players Jin Fuqin, and Shen Baosheng, six people received Wujiang underground County Government notification 1K字节的数据存储器，可以满足复杂程序的设计。在该应用中，单片机的I/O端口分配是: 2P2端口和P1端口的低4位作为系统的当前学习按键状态指示;P3.6和P3.7最为系统的IC接口，连接外部的存储器件AT24C02和视频切换矩阵器件FMS6501;P3.4、P3.5和P0端口连接声音切换矩阵;主机和各个输出模块之间采用串口进行信号的联络。主控CPU在系统中主要完成以下几点任务: 1)当刚开机时，主机读出存储器件AT24C02中存放的各通道的选择信息，将各输出通道的视频和音频切换到相应的输入通道上，完成系统的初始化。 2)初始化完成后，主机开始利用UART和各输出端口进行定时通信，实时检测各模块的状态。如果各输出端口检测到有切换要求，各输出模块通过UART向主机发出切换要求，主机通过控制视频矩阵和音频矩阵进行切换。 VCCR136R64D4POW4.7K1K12R65D5VCCPLAYVCC341K5P0.0R66D6PAUSE6P0.1D1171KP0.2R7818P0.3R67D7P10STOP291KP0.4P11D12213P001KP0.539R79P20P12IN1224P01P0.638R68D8P21P13PRE235P021KP0.737P22P14D13246P031K36R80P23P15IN2257P0435R69D9P24P16NEXT268P051K34P25GNDU25P17D1427P061KIR133R81P261IN3D1028GND9P07IR2R7032P273RESETVOL+10VCC1KIR3RXD/P302RST1KIR4U24IN4113012TXDR115D15TXD/P31P89V51RD2ALE/PINT0/P32VOL-CAT8102913311KRXDVCCR116PSENINT1/P33EA/VP VCCP3.515181KT1/P35X2 P3.414VCCR117VCCT0/P34S2C3310KJ717IR-SETRD/P37330GND21619WR/P36X11GND红外接收头CRY111.0592MGNDC34 30VCCVCCR118R119U2310K10K24C32 18E0VCCR120R12127E1/WCGND4.7K4.7K36SCLE2SCL45 GNDSDASDA 图3 RXDTXDGND2、 视频矩阵和音频矩阵 在该应用中，分别使用FMS6501和CD22M3494作为交换机的视频和音频切换(如 图4所示)。在图4中，使用IN1-IN4作为信号源的视频输入，视频信号切换后通过 OUT1-OUT6输出到各输出端上;使用M_IN1-M_IN4作为信号源的音频输入，视频信 号切换后通过M_OUT1-M_OUT6输出到各输出端上。 视频矩阵FMS6501具有12个输入通道，9个输出通道，每个输出通道可以选择输 2出的信号强度，分别有6dB、7dB、8dB和9dB四个级别。主机和FMS6501之间使用IC 接口进行通信。在FMS6501内部，每一个输出通道对应一个8位的控制寄存器(表 一)。其中EN为使能信号，表示该通道输出允许;GAIN1和GAIN0表示输出的信号强school)], 4 4 house building as well as more than 1000 copies of books, more than 10 kinds of collection of newspapers and magazines, fires burnt down. In 1938, the Japanese learned that the national Government established in XI Tang Tomb rotten "clip" taxes, tax officers live in 8 of Yan Dong village farmers home, troops at night, Yao was burned several houses. 1938 new morning of September 18, the Japanese team went to the countryside "sweep" from the kaiyang village line to Tung Yang Jia Qiao yan Temple wall and met Yang Jia溇 Zhou Dana (male) weeks because of long-term illness and can't work in the fields, the Japanese see his face from scratch without calluses, regard him as "Shina", thrust a knife at the scene of his death. The body was stabbed 7 times, wound 13. The same day, Trang bang village heard the Japanese come to "mop-up" are hiding, mother of 9 Zhou Guanbao Zhang Aying to drill a "dry mound", was discovered by the Japanese, a shot in the end. The same day, is 7 zhouhaijiangzhi grandfather Zhou Yingbao to escape the Japanese army, was found on the road, a shot in the end. In March 1939, the Japanese army in Yan Tomb raiding, has arrested 16 people, in fengqiao cigarettes this morning bang, killing 11 people on the River, East meeting point in wood qiaotu in the afternoon killing 4 people on the Riverside. Gu Tong is a Japanese go speak the Shanghai dialect, later to be called Gu Tong as "kill left." On January 18, 1943, the elves, five thousand or six thousand, water and land go hand in hand "mop-up" jiaxing area west of the railway, Yan Tomb area fall. March 6, Niu Shan (County Government II section chief) carrying its child Niu Jun (strict Tomb seventh district Chang) and the District Assistant Yu Xuchu, and players Jin Fuqin, and Shen Baosheng, six people received Wujiang underground County Government notification 度选择，1、1表示输出9dB，1、0表示输出8dB，0、1表示输出7dB，0、0表示输出6dB;IN0~IN4用于选择该输出通道对应的输入通道号。在对视频的切换过程中，主机通过控制该寄存器实现切换控制。例如寄存器的数据为0x84，表示该输出通道以6dB强度输出矩阵的4通道输入视频信号。 D7 D6 D5 D4 D3 D2 D1 D0 EN GAIN1 GAIN0 IN4 IN3 IN2 IN1 IN0 表1 音频矩阵CD22M3494具有16个输入通道，8个输出通道。主机和CD22M3494之间通过单片机的并口P0口以及P3.4、P3.5进行连接。在音频的切换控制中，通过控制CD22M3494的编码寄存器进行控制(表2)。DATA为1，表示连接一个输入和输出通道，DATA为0，表示断开一个输入和输出通道;AX3、AX2、AX1、AX0表示输出通道号的编码(通道0~通道15);AY2、AY1、AY0表示输入通道号的编码(通道0~通道7)。例如:数据0x9C，表示连接输出通道3和输入通道4。 D7 D6 D5 D4 D3 D2 D1 D0 DATA AX3 AX2 AX1 AX0 AY2 AY1 AY0 表2 FMS6501U21U22CD22M3494MQ128R75753937IN1IN1OUT1OUT1M_IN1Y0X0M_OUT12274136R7675IN2IN2OUT2OUT2M_IN2Y1X1M_OUT2326R77754335IN3IN3OUT3OUT3M_IN3Y2X2M_OUT3425R7875134IN4IN4OUT4OUT4M_IN4Y3X3M_OUT4524752333R79IN5OUT5OUT5Y4X4M_OUT56232132R8075IN6OUT6OUT6Y5X5M_OUT6722199VCCVCCVCCOVCCY6X68211710GNDGNDOGNDY7X792011IN7OUT7X8GND1019512IN8OUT8P0.3AX0X911182413IN9OUT9P0.4AX1X1012172514IN10SDASDAP0.5AX2X111316431IN11SCLSCLP0.6AX3X12141530IN12ADDRX13267P0.0AY0X14GND278P0.1AY1X152P0.2AY2视频切换VCC4244P0.7DATAVDD20P3.5STROBE318P3.4RESETVSS4022CSVEEGND VCC-VCC音频切换 图4 3、 视频输出驱动 为了避免视频信号在双绞线的传输中信号强度的衰减，使用具有250M信号带宽的差分驱动芯片EL5171进行信号的差分驱动(图5)，在远端使用相应的差分接收器件进行信号的还原。在电路上，可以通过电阻(R58、R102和R100)的调节，改变输出信号的幅度。 GND R54GNDR58R6250OUT1+51050C18U165p-VCC18FBPOUT+R105GND27OUT1IN+VS-1k36REFVS+45FBNOUT-VCCR96C23EL5171R102R107505pOUT1-51050 GNDR100510 GND 图5 4、 电源部分 school)], 4 4 house building as well as more than 1000 copies of books, more than 10 kinds of collection of newspapers and magazines, fires burnt down. In 1938, the Japanese learned that the national Government established in XI Tang Tomb rotten "clip" taxes, tax officers live in 8 of Yan Dong village farmers home, troops at night, Yao was burned several houses. 1938 new morning of September 18, the Japanese team went to the countryside "sweep" from the kaiyang village line to Tung Yang Jia Qiao yan Temple wall and met Yang Jia溇 Zhou Dana (male) weeks because of long-term illness and can't work in the fields, the Japanese see his face from scratch without calluses, regard him as "Shina", thrust a knife at the scene of his death. The body was stabbed 7 times, wound 13. The same day, Trang bang village heard the Japanese come to "mop-up" are hiding, mother of 9 Zhou Guanbao Zhang Aying to drill a "dry mound", was discovered by the Japanese, a shot in the end. The same day, is 7 zhouhaijiangzhi grandfather Zhou Yingbao to escape the Japanese army, was found on the road, a shot in the end. In March 1939, the Japanese army in Yan Tomb raiding, has arrested 16 people, in fengqiao cigarettes this morning bang, killing 11 people on the River, East meeting point in wood qiaotu in the afternoon killing 4 people on the Riverside. Gu Tong is a Japanese go speak the Shanghai dialect, later to be called Gu Tong as "kill left." On January 18, 1943, the elves, five thousand or six thousand, water and land go hand in hand "mop-up" jiaxing area west of the railway, Yan Tomb area fall. March 6, Niu Shan (County Government II section chief) carrying its child Niu Jun (strict Tomb seventh district Chang) and the District Assistant Yu Xuchu, and players Jin Fuqin, and Shen Baosheng, six people received Wujiang underground County Government notification 视频交换机通过外置的直流12V电源进行供电(电路如图6所示)。在电路设计中使 用PWM开关电源芯片NCP3063进行电路设计。采用PWM方式可以很好的提高电源转 换的效率，减小交换机的功耗。 R20.22U181+5VL1NCSC72IpkSE63INDUCTOR2VCCTCC5C6954C3C4C2C1CIIGNDD2104GNDIN5819470/25V104104470UF/25VNCP3063GND2200PR383kR37GNDGNDJ1GND1k2L21INDUCTOR2R341U10GND81GNDNCSC72外接12V直流电源IpkSED363C76VCCTCC1254C7C8C11C10CIIGND2200PIN5819104470/25VNCP3063104470/25V104 -5V680R36R35 GNDGND2k图6 四、 视频交换机的软件设计 在该视频交换机的系统中，使用KEIL C 进行主机程序的开发。在这个软件设计中主要包含以下几个部分的内容: 、 系统的初始化。首先进行P89V51RD2中I/O端口、定时器、外中断、UART串口等初1 始化。其中定时器T0作为产生内部50毫秒定时的时间基准信号，T1作为串口的波特 2率发生器，串口设定为9600bps波特率的数据传输速率。其次进行IC总线的初始化， 从AT24C02中读出上次关机时保留在其中的通道切换数据，进行各输出通道的初始状 态选择设定。 2、 主机进入正常的监控状态。当各输出通道没有向主机发送状态变化信息时，主机维持视 频和音频矩阵的交换状态，当下位机有状态变化时，利用UART串口向主机发送需要改 变的状态。主机和各通道之间的联络需要设定固定的通信协议，保证系统的正常工作。 五、 结论 该交换机可以广泛应用于工程实际，它可以很好的管理各种视频和音频信号源，为工程应用提供了一种很好的选择。在电路的设计中，选择功能强大的交换矩阵芯片FMS6501和CD22M3494，简化了电路设计，提高了系统的可靠性，降低了系统的综合成本，为实现广泛应用提供了条件。在音视频交换机的PCB设计中，为了防止各输入通道、输出通道之间的串扰，需要很好的考虑相互之间的干扰问题和电源的退耦，提高该交换机的信号输出品质，减小信号的衰减。 六、 参考文献 [1]、马忠梅、张凯、马岩、籍顺心 《单片机的C语言应用程序设计》 北京航空航天大学出版社。 [2]、Intersil CD22M3494 Datasheet January 16,2006 FN2793.7。 [3]、Intersil EL5171 Datasheet June 29,2004 FN7307.4。 [4]、Fairchild Fms6501 Datasheet April 2007。 [5]、On Semiconductor NCP3063 Datasheet September 2006。 第一作者:郭杰(四川工程职业技术学院) 第二作者:雷刚(四川工程职业技术学院) school)], 4 4 house building as well as more than 1000 copies of books, more than 10 kinds of collection of newspapers and magazines, fires burnt down. In 1938, the Japanese learned that the national Government established in XI Tang Tomb rotten "clip" taxes, tax officers live in 8 of Yan Dong village farmers home, troops at night, Yao was burned several houses. 1938 new morning of September 18, the Japanese team went to the countryside "sweep" from the kaiyang village line to Tung Yang Jia Qiao yan Temple wall and met Yang Jia溇 Zhou Dana (male) weeks because of long-term illness and can't work in the fields, the Japanese see his face from scratch without calluses, regard him as "Shina", thrust a knife at the scene of his death. The body was stabbed 7 times, wound 13. The same day, Trang bang village heard the Japanese come to "mop-up" are hiding, mother of 9 Zhou Guanbao Zhang Aying to drill a "dry mound", was discovered by the Japanese, a shot in the end. The same day, is 7 zhouhaijiangzhi grandfather Zhou Yingbao to escape the Japanese army, was found on the road, a shot in the end. In March 1939, the Japanese army in Yan Tomb raiding, has arrested 16 people, in fengqiao cigarettes this morning bang, killing 11 people on the River, East meeting point in wood qiaotu in the afternoon killing 4 people on the Riverside. Gu Tong is a Japanese go speak the Shanghai dialect, later to be called Gu Tong as "kill left." On January 18, 1943, the elves, five thousand or six thousand, water and land go hand in hand "mop-up" jiaxing area west of the railway, Yan Tomb area fall. March 6, Niu Shan (County Government II section chief) carrying its child Niu Jun (strict Tomb seventh district Chang) and the District Assistant Yu Xuchu, and players Jin Fuqin, and Shen Baosheng, six people received Wujiang underground County Government notification 郭杰(1971-):男，四川泸县人，副教授，硕士，研究方向为自动控制。 雷刚(1980-):男，四川泸县人，讲师，大学本科，研究方向为单片机控制技术。 school)], 4 4 house building as well as more than 1000 copies of books, more than 10 kinds of collection of newspapers and magazines, fires burnt down. In 1938, the Japanese learned that the national Government established in XI Tang Tomb rotten "clip" taxes, tax officers live in 8 of Yan Dong village farmers home, troops at night, Yao was burned several houses. 1938 new morning of September 18, the Japanese team went to the countryside "sweep" from the kaiyang village line to Tung Yang Jia Qiao yan Temple wall and met Yang Jia溇 Zhou Dana (male) weeks because of long-term illness and can't work in the fields, the Japanese see his face from scratch without calluses, regard him as "Shina", thrust a knife at the scene of his death. The body was stabbed 7 times, wound 13. The same day, Trang bang village heard the Japanese come to "mop-up" are hiding, mother of 9 Zhou Guanbao Zhang Aying to drill a "dry mound", was discovered by the Japanese, a shot in the end. The same day, is 7 zhouhaijiangzhi grandfather Zhou Yingbao to escape the Japanese army, was found on the road, a shot in the end. In March 1939, the Japanese army in Yan Tomb raiding, has arrested 16 people, in fengqiao cigarettes this morning bang, killing 11 people on the River, East meeting point in wood qiaotu in the afternoon killing 4 people on the Riverside. Gu Tong is a Japanese go speak the Shanghai dialect, later to be called Gu Tong as "kill left." On January 18, 1943, the elves, five thousand or six thousand, water and land go hand in hand "mop-up" jiaxing area west of the railway, Yan Tomb area fall. March 6, Niu Shan (County Government II section chief) carrying its child Niu Jun (strict Tomb seventh district Chang) and the District Assistant Yu Xuchu, and players Jin Fuqin, and Shen Baosheng, six people received Wujiang underground County Government notification