Dissemination of information to citizens is a relevant component of governance. Expectedly, viewers tuned to broadcast stations within and outside their localities, expecting their receivers to faithfully reproduce th...Dissemination of information to citizens is a relevant component of governance. Expectedly, viewers tuned to broadcast stations within and outside their localities, expecting their receivers to faithfully reproduce the exact features of the transmitted signal. Akpabuyo is a dense forest zone near the creeks leading to the Atlantic ocean in Cross River State, Nigeria. The location has distinct environmental characteristics that made Akpabuyo Area Council, a challenging location to propagate electromagnetic waves;and therefore recipe for further investigation. Radio frequency analyzer, with 24 channels spectrum, ranging between 46 - 870 MHz (model: RO.VE.R.-“DLM3-T”) was deployed to capture signals from terrestrial television stations (TV). CATV measured signal of TV stations in dB, dBμV and dBmV. Its frequency ranged from 40 - 860 MHz;while varying from channel 1 to channel 69. Measurements taken from Akpabuyo L.G.A. showed the following results: the signal strength received from VHF Channel 11 ranged from 20 dBμV to 49 dBμV. From recorded empirical statistics from the study, 50% of the area received signal from this station above 30 dBμV, while other regions had signals below this value;representing the fringe zone of the frequency. The results obtained from the study relatively showed acceptance with Egli’s model. The study recorded a steady fluctuation between 17 dBμV and 19 dBμV from both propagating stations. However, Channel 27 signal at 519 MHz, had very weak signal coverage in Akpabuyo Local Government Area;with signal strength dropped to as low as 13 dB in many parts of the rural area. The study discovered that the state’s broadcasting stations, both at UHF and VHF channels did not transmit successfully across this densely forest (rural) location. Remedial measures such as installing Repeater stations at different locations as signal booster were recommended.展开更多
针对微纳卫星的测控数传需求,利用业务无线电及ISM(Industrial-Scientific-Medical,工业-科学-医疗)频段和设备,设计了适用微纳卫星的便携式测控站,包括ISM和VHF/UHF(Very High Frequency/Ultra High Frequency,甚高频/超高频)2个通道;...针对微纳卫星的测控数传需求,利用业务无线电及ISM(Industrial-Scientific-Medical,工业-科学-医疗)频段和设备,设计了适用微纳卫星的便携式测控站,包括ISM和VHF/UHF(Very High Frequency/Ultra High Frequency,甚高频/超高频)2个通道;优选了COTS(Commercial Off The Shelf,商用现货)ISM通信电台和VHF/UHF全模式电台、VHF/UHF八木天线、S频段花瓣式网状抛物面天线等部组件,3副天线共用1个伺服机构;并对ISM和VHF/UHF信道的上/下行链路电平进行估算。结果表明:该多频段多通道便携测控站的设计方案可行性好,效费比高,并已在相关微纳卫星的测控应用中得到验证。展开更多
通过记录物理地址扩展(Physical Address Extensions,PAE)T6T/T6R与三汇内话SVCS3000之间的IP语音(Voice over IP,VoIP)连接的互联互通性,测试在正常、网络中断、实时传输协议(Real-time Transport Protocol,RTP)打包时长不匹配、修改...通过记录物理地址扩展(Physical Address Extensions,PAE)T6T/T6R与三汇内话SVCS3000之间的IP语音(Voice over IP,VoIP)连接的互联互通性,测试在正常、网络中断、实时传输协议(Real-time Transport Protocol,RTP)打包时长不匹配、修改主备模式以及远程电台控制等情况下SVCS3000与PAE的VoIP互联互通性,解决VoIP运营商之间通信存在的协议转移问题。展开更多
文摘Dissemination of information to citizens is a relevant component of governance. Expectedly, viewers tuned to broadcast stations within and outside their localities, expecting their receivers to faithfully reproduce the exact features of the transmitted signal. Akpabuyo is a dense forest zone near the creeks leading to the Atlantic ocean in Cross River State, Nigeria. The location has distinct environmental characteristics that made Akpabuyo Area Council, a challenging location to propagate electromagnetic waves;and therefore recipe for further investigation. Radio frequency analyzer, with 24 channels spectrum, ranging between 46 - 870 MHz (model: RO.VE.R.-“DLM3-T”) was deployed to capture signals from terrestrial television stations (TV). CATV measured signal of TV stations in dB, dBμV and dBmV. Its frequency ranged from 40 - 860 MHz;while varying from channel 1 to channel 69. Measurements taken from Akpabuyo L.G.A. showed the following results: the signal strength received from VHF Channel 11 ranged from 20 dBμV to 49 dBμV. From recorded empirical statistics from the study, 50% of the area received signal from this station above 30 dBμV, while other regions had signals below this value;representing the fringe zone of the frequency. The results obtained from the study relatively showed acceptance with Egli’s model. The study recorded a steady fluctuation between 17 dBμV and 19 dBμV from both propagating stations. However, Channel 27 signal at 519 MHz, had very weak signal coverage in Akpabuyo Local Government Area;with signal strength dropped to as low as 13 dB in many parts of the rural area. The study discovered that the state’s broadcasting stations, both at UHF and VHF channels did not transmit successfully across this densely forest (rural) location. Remedial measures such as installing Repeater stations at different locations as signal booster were recommended.
文摘针对微纳卫星的测控数传需求,利用业务无线电及ISM(Industrial-Scientific-Medical,工业-科学-医疗)频段和设备,设计了适用微纳卫星的便携式测控站,包括ISM和VHF/UHF(Very High Frequency/Ultra High Frequency,甚高频/超高频)2个通道;优选了COTS(Commercial Off The Shelf,商用现货)ISM通信电台和VHF/UHF全模式电台、VHF/UHF八木天线、S频段花瓣式网状抛物面天线等部组件,3副天线共用1个伺服机构;并对ISM和VHF/UHF信道的上/下行链路电平进行估算。结果表明:该多频段多通道便携测控站的设计方案可行性好,效费比高,并已在相关微纳卫星的测控应用中得到验证。
文摘通过记录物理地址扩展(Physical Address Extensions,PAE)T6T/T6R与三汇内话SVCS3000之间的IP语音(Voice over IP,VoIP)连接的互联互通性,测试在正常、网络中断、实时传输协议(Real-time Transport Protocol,RTP)打包时长不匹配、修改主备模式以及远程电台控制等情况下SVCS3000与PAE的VoIP互联互通性,解决VoIP运营商之间通信存在的协议转移问题。
