单选题If the radio signal ground wave extends out for less distance than the minimum skywave distance，there is an area in which no signal is received．This is called the（）.ASkip zoneBBlackout zoneCDiffraction zoneDShadow zone
单选题
If the radio signal ground wave extends out for less distance than the minimum skywave distance，there is an area in which no signal is received．This is called the（）.
A
Skip zone
B
Blackout zone
C
Diffraction zone
D
Shadow zone
参考解析
解析：
暂无解析
相关考题：
The correction to be applied to a LoranC reading when matching a sky wave to a ground wave may be found______．A.on loran charts covering areas where sky waves are usedB.in the Radio Aids to Navigation PUB 117C.in the LoranC Correction TablesD.Sky waves cannot be matched to ground waves in LoranC to produce a usable reading
Echo sounder sends a (无线电信号)from the bottom of the ship to the seabedA.radio signalB.radio waveC.signalD.signal radio
A person on a fixed, or floating platform. engaged in oil exploration, located 10 nautical miles from nearest land MAY discharge( ).A.food wasteB.food, ground to less than 1 inchC.paper, ground to less than 1 inchD.None of the above
________is the most visible signal of distress from a lifeboat at sea in the daytime.A.Smoke signalB.Flash signalC.Fire signalD.Radio emergency transmission
A vessel to which Annex V to MARPOL 73/78 applies is located in a MARPOL designated special area，14 nautical miles from nearest land.What type of garbage is permitted to be discharged?A.Paper productsB.Glass ground to less than 1C.Metal ground to less than 1D.Food waste
If the radio signal ground wave extends out for less distance than the minimum skywave distance，there is an area in which no signal is received．This is called the ______．A.Skip zoneB.Blackout zoneC.Diffraction zoneD.Shadow zone
Loran-C uses the multiple pulse system because ______．A.Less signal energy is necessary for receiver operationB.More signal energy is available at the receiverC.It significantly increases the peak powerD.It increases the signal capacity
The loran lines drawn on navigation charts represent ______．A.Ground wavesB.SkywavesC.Either ground waves or skywaves interchangeablyD.An average between ground wave and skywave positions
Which statement concerning satellite EPIRBs is TRUE ________．A.Once activated，these EPIRBs continuously send up a signal for use in identifying the vessel and for determining the position of the beaconB.The coded signal identifies the nature of the distress situationC.The coded signal only identifies the vessel's name and port of registryD.If the GMDSS Radio Operator does not program the EPIRB，it will transmit default information such as the follow-on communications frequency and mode
In the OSNR model for EDFA amplifiers, SNR OUT = 1/(1/SNR IN + FhvB/P IN ), what does SNR IN represent?（）A、the signal to noise of the current optical amplifierB、the signal to noise of the previous amplifier or sourceC、the signal to noise introduced by the optical multiplexerD、the accumulated noise to signal ratio of the optical channel
Echo sounder sends a（） (无线电信号)from the bottom of the ship to the seabed.A、radio signalB、radio waveC、signalD、signal radio
单选题A vessel to which Annex V to MARPOL 73/78 applies is located in a MARPOL designated special area，14 nautical miles from nearest land. What type of garbage is permitted to be discharged? （）APaper productsBGlass ground to less than 1CMetal ground to less than 1DFood waste
单选题A person on a fixed, or floating platform engaged in oil exploration, located 10 nautical miles from nearest land MAY discharge （）.Afood wasteBfood, ground to less than 1Cpaper, ground to less than 1DNone of the above
单选题The generators on your rig have shut down，leaving you without navigation lights. Which emergency signal would you transmit over the VHF radio to alert vessels in the area of your predicament? （）AMayday，Mayday，MaydayBPan，Pan，PanCSecurity，Security，SecurityDLights out，Lights out，Lights out
问答题Practice 3 BBC World Service is the world's biggest radio network, with 140 million listeners across the globe, broadcasting in 44 languages, heard on short-wave, medium-wave, FM and satellite. We have an ambitious plan for the brand new technology of Digital Broadcasting by Satellite, due to start next year. The appearance of the Internet has taken us broadcasters all by surprise. The Internet has enabled any radio station anywhere to become an international broadcaster with only a minor investment. Although its sound quality is far from perfect, it excels that of short-wave. Internet radio does not only mean competition but also great opportunities. The BBC is taking the Internet very seriously, for it's a cheap way of getting a reasonable quality signal to places in the even our short-wave transmitters can't adequately reach. Very recently, we launched “BBC On-Line”, which incorporates a 24-hour news service. And the users can hear programmes in Mandarin, Arabic, Spanish and Russian.
单选题In the OSNR model for EDFA amplifiers， SNR OUT = 1/（1/SNR IN + FhvB/P IN ）， what does SNR IN represent？（）A the signal to noise of the current optical amplifierB the signal to noise of the previous amplifier or sourceC the signal to noise introduced by the optical multiplexerD the accumulated noise to signal ratio of the optical channel
单选题The loran lines drawn on navigation charts represent（）.AGround wavesBSkywavesCEither ground waves or skywaves interchangeablyDAn average between ground wave and skywave positions
单选题If you are transmitting a distress message by radiotelephone you should（）.Ause English languageBalways use the International CodeCpreface it by the word SOSDfollow the transmission with the radio alarm signal
单选题（）sends a radio signal from the bottom of the ship to the sea-bed,from which it is reflected.AThe marine sextantBThe chronometerCThe echo sounderDThe radar
单选题We（）the distress signal on our own radio before the shore station relayed it to us.Areceived alreadlyBhave receivedChad receivedDwas receiving
单选题In the OSNR model for EDFA amplifiers, SNR OUT = 1/(1/SNR IN + FhvB/P IN ), what does SNR IN represent?（）Athe signal to noise of the current optical amplifierBthe signal to noise of the previous amplifier or sourceCthe signal to noise introduced by the optical multiplexerDthe accumulated noise to signal ratio of the optical channel
单选题The correction to be applied to a Loran-C reading when matching a sky wave to a ground wave may be found（）.Aon loran charts covering areas where sky waves are usedBin the Radio Aids to Navigation，PUB 117Cin the Loran-C Correction TablesDSky waves cannot be matched to ground waves in LORAN-C to produce a usable reading
单选题For working details（）admiralty list of radio signal.AreferBseeCwatchDlook