SNV-12 信噪比选器

特点：

• Independent DSP Inputs Vote the Best Voice or Data Channel.
  独立的DSP输入信号，比选最佳话音或数据通道
• DSP Signal-to-Noise Ratio Determination for Each Site Input.
  DSP信噪比判定每一路输入
• Up to 12 Site Inputs Voted Per Chassis.
  每台主机多达12路比选信号输入
  

英文资料和技术参数

（文件为pdf格式）

• Console Interface Module Interfaces with Industry Standard Dispatch Console.
  控制台接口模块可以和工业标准的调度控制台连接Multiple Types of Repeater Control and Transmit Steering Capability.
  多种类型的转发器控制和发射控制能力
• Provides Tone Keying and Repeat Mode. 提供单音键控和重复模式
• Digital Delay Compensates for Differences in Link Paths.
  为不同链接路径提供数字延时补偿
• Local Control Plus Parallel and Serial Remote Control. 本地控制以及并行与串行遥控
• System Expansion to 36 Sites by Daisy-Chaining Multiple SNV-12s.
  "菊链"多个SNV-12可将系统扩展至36路
• 5.25'' High by 19'' Wide Rack-Mount Modular Card-Cage Package.
  机架5.25"高，19"宽，模块插件框架包装
  

　　The SNV-12 uses separate Digital Signal Processors(DSPs) to continuously select the receiver with the best Signal-Noise Ratio(SNR) from multiple remote sites. This is a vital function in two types of applications. The first is a two-way radio application in which mobiles and portables can hear a repeater, but the repeater can not always hear the mobiles and portables. By positioning remote receivers in the communications deadspots,audio from each receiver can be linked to the voter via microwave, landline, twisted pair or fiber optics. With the unit providing the "voted" (best SNR) output to the repeater for rebroadcast, all mobiles and portables can hear each other since the repeater can hear them all. The second application involves a critical message sent simultaneously via several transmission mediums, or by several transmitters on different frequencies in the same frequency band. In this "Diversity Reception" application, the message is picked up by multiple receivers while the SNV-12 always selects the signal with the best SNR at any given moment.
　　SNV-12采用独立的数字信号处理器(DSP)持续地从多个远端站点选择接收最佳信噪比的信号。在两种类型的应用中这是一项最为重要的功能。首先是双向电台应用，即移动或便携电台能收到转发器的信号，但转发器却并不总能够收到移动或便携电台的信号。将远端接收机放置于通信盲区内，将每个接收机的音频通过微波、陆上通讯[运输]线、双绞线或光纤接入比选器。由该装备提供经比选（最佳信噪比）的信号输出到转发器中对外广播，由于转发器能够收到所有的信号，因此所有移动或便携电台也能够彼此通话。第二项应用则对于一个重要的信息需要同时经由几个传输媒介发送，或是由几个在同一带宽而又不同频率的发射机发出。在这种"多样性接收"的应用中，信息在被多个接收机获取的同时并经由SNV-12在给定的时间内选择最佳信噪比的信号。

DSP Voting 比选

　　The site Voter Module uses a spectral approach to continuously measure the Signal-to-Noise Ratio(SNR) of the audio signal received from each receiver site. The signal amplitude is measured by a JPS proprietary speech detection and measurement algorithm. Noise is meased separately by the same algorithm. The SNR result is calculated by dividing the signal amplitude by that of the noise and operates from -6dB to +36dB in approximately 1.4dB steps. The SNV-12 conrinuously cheaks all inputs and ensures that the best SNR signal is voted. Thus, even if the signal is emanating from a moving vehicle, the SNV-12 will output the best signal at all times.
　　站点比选模块采用光谱方式持续性地测量各路接收机取得的话音信号的信噪比。该信号的振幅经由JPS所拥有的语音探测器和测量运算法则进行测算，噪音则采用同样的运算法则分开测算。信噪比的结果经由在-6dB至+36dB的范围内以大约1.4dB步进测算，SNV-12继续性地检查所有输入信号，并确保比选出最佳信噪比的信号。即使信号是从一辆车辆中发射出来的，SNV-12仍将随时输出最佳信号。

　　Voting voice signals allows transitions in mid-syllable without harm to the intelligibility, but when voting data, transitions from one receiver site to another causes bit errors and synchronization problems. Thus, to vote data, the Site Voter Modules make a decision initially on the best data signal and then lock onto that receiver path until the data transmission is complete. Data voting algorithms and software are special order options to the SNV-12, since the Site Voter Moduules must be equipped with software defining the data's characteristics for the spectral measurement of SNR. The DSP SNR determination makes the SNV-12 an extrmely accurate selector of the best available voice or data channel.
　　比选话音信号允许再不破坏理解性的前提下，从音节中间进行转换，但当比选数据时，从一个接收机站点转换到另一个时将造成误码和同步错误。因此，在数据比选时，站点比选模块在一开始就决定出最佳数据信号后，立即锁定该接收路径直到该数据传输完毕。SNV-12的数据比选算法和软件采用了特殊指令选项，因为站点比选模块必须配备有为信噪比的光谱测算而定义的有数字特征的软件。DSP信噪比的鉴定使SNV-12成为一台能够非常精确地判定最佳话音或数据通道的选择器。

Local and Remote Control 本地和远端遥控

　　Front pannel switches and status LEDs offer local control of the unit by allowing receiver sites to be forcibly selected, disabled and monitored. The SNV-12 provides both parallel and serial remote control, so interfacing with a PC or with any of a varity of industry-standard dispatch consoles is straightforward. Fault indicators on each of the modules provide quick warning of problems. A faulty Site Voter Module is automatically and immediately removed from voting consideration. A front panel speaker and headphone jack on the Console Interface Module allow continuous monitoring of the currently voted receiver audio.
　　前面板开关和LED状态指示提供了对接收机信道采取强制的选择、切断与监视等本地控制。SNV-12同时提供并行与串行的遥控操作，可同个人电脑或任何一种符合工业标准的调度控制台直接连接。故障显示器为每一个模块提供了故障快速警告, 一块出现故障的信道比选模块可自动而立即地被从比选考量中排除。在控制台界面模块上的前面板扬声器与耳机接口可允许对于所有在线的比选接收话音进行持续性地监听。

Repeater Control 转发器控制

　　When controlling a repeater, the SNV-12 offers three means of producing the necessary COR signal. Two of these approaches are common in public safety applications since both offer a quick method of detecting a faulty remote receiver or a faulty link. In the first, the voter produces a COR output signal for the repeater which is derived from COR inputs provided by each remote receiver. In the second case, the voter's COR output is derived from the absence of pilot tones(line proving tones) which each remote receiver produces unitl it becomes unsquelched. Pilot tone frequencies of 1950Hz,2175Hz and 2700Hz are supported; others are avialable on special order. The other approch is less common: remote receivers are squelched when not in use and the DSP uses its voice recognition algorithm to issue the COR signal.
　　在控制一台转发器时，SNV-12提供三种方式来产生所需要的COR信号。其中的两种方法普遍使用于公共安全应用中， 因为两者都提供一个探测有故障的远端接收机或故障链路的快速方式。第一种方式，比选器为转发器产生一个来自于每个远端接收机所提供的COR输入的COR输出信号。第二种方式，比选器的COR输出是来自于不存在的由每一台远端接收机产生的测试单音（线路测试单音），直至该单音成为非静噪输出。测试单音的支持频率为1950Hz, 2175Hz和2700Hz，其他频率则可根据特殊订单的要求而提供。另一种则不太常见：远端接收机在没有使用的状态下有静噪输出，DSP利用其语音识别算法来提供COR信号。

转发系统使用SNV-12和12台接收机

　　Two additional SNV-12s may be connected to the first, each expanding the number of voting sites by up to twelve additional inputs. This expasion capabilty is implemented by daisy-chaining one SNV-12 to the next via rear panel connectors, up to a practical maximum of three chassis or 36 site inputs. Signals between master and slave units include a serial data bus which allows one SNV-12 to exchange information with the next one in the chain. A Voted Audio bus transfers the best voted audio signal between units.
　　另外两台SNV-12可同第一台设备联机，可令每台比选器扩展出多达12路额外输入。这项扩展能力的实现是通过背面板接口，采用"菊链"一台SNV-12至另一台，通常最大可做三台主机或36路输入的联机应用。在主机与子机间的所有信号包括一条串行数据总线，可使一台SNV-12在链接中同相邻的设备交换信息。一条比选语音总线在设备之间传输最佳的比选话音信号。

Transmit Steering 发射机控制

　　In transmit steering applications, the transmitter associated with the current best voted receiver is used for a reply to a nearby mobile or portable radio. In this situation, the CPU Module provides for automatic routing of console transmit audio and keying information to the proper remote transmitter site. If automatic transmitter steering is enabled, this midule keeps the reply is complete and a new receiver site is voted. In manually controlled applications, the dispatcher decides which transmitter site to use for reply by issuing a Transmit Select signal to the proper Site Voter Module. The Voter can also group multiple voted receivers around separate remote transmitters. Tone Keying operation and Repeat Mode (Voted Site Talkthrough) are provided within the Transmit Steering function.
　　在发射控制应用中，发射机配合现有最佳比选接收机用来应答附近的移动或便携电台。在此状况下，CPU模块提供控制台传输话音和语音键控信息给合适的远端发射机的自动路由。若可进行自动发射机控制，该模块保持发射机的应答选择直至应答完成，并选择出一个全新的接收机信道。在人工控制应用中，发信机通过将发射机选择信号发送到适当的信道比选模块上来决定使用哪一台发射机进行应答。比选器也能够将散布在远端的发射机周围的多台比选接收机集合在一起。单音键控操作和重复模式（比选信道话音通过）也在发射控制的功能中。

Modular Packaging 模块包装

　　The SNV-12 is packaged in a 19'' wide EIA standard rack-mounted Eurocard cage equipped with a backplane board. A Power Supply Module, Console Interface Module, CPU Module, and two to twelve Site Voter Modules are plugged into the card cage backplane. Remote receiver signals are connected to the Site Voter Modules via barrier terminal strips on the backplane board for ease of hook-up. Each plug-in module has a front panel handle for removal and insertion. The unit is designed for hot plugging so that any module in the chassis may be inserted or removed with power applied without damage.
　　SNV-12包装在一个19"宽的EIA标准机架机箱内，欧洲卡(一种欧洲技术标准的印刷电路板,尺寸为100毫米×160毫米)插槽配有背面板。一块电源供应模块，控制台接口模块，CPU模块，以及2-12块信道比选模块插在底板的卡架上。远端接收信号经由在背板上的隔离终端插座条连接到比选器模块上，以便于连机。每一块插入模块都有一个前面板把手，以方便模块插拔。该设备为热插拔而设计，因此任何在机箱内的模块可以在通电情况下插拔而不会对设备造成损坏。