【正文】 如風(fēng)穩(wěn)和地面保持精度等因素。大型天線(xiàn)發(fā)射窄波束時(shí)會(huì)相對(duì)于小天線(xiàn)更加不穩(wěn)定。.LNB Noise Figure (LNB Noise Temperature)The default interpretation of this input parameter is Noise Figure. However, if you prefix the input value with a 39。+39。 character it will be automatically interpreted as a Noise Temperature instead.It is conventional to quote the noise figure of an LNB in dB for Ku and Ka bands and the equivalent noise temperature in Kelvin for S and C bands. It is usually more difficult and expensive to achieve low noise figures the higher the frequency. For Kuband low cost LNB39。s are in the range to or 30K for C band.Note: We use the term LNB in the generic sense here, LNA, LNC etc is equally valid.LNB噪聲默認(rèn)的解讀法是讀為噪聲因數(shù)，但如果在數(shù)值前加上“+”號(hào)則程序?qū)⑵渥x為噪聲溫度。通常使用噪聲因數(shù)表示Ku和Ka波段的LNB噪聲，噪聲溫度表示。頻率越高，通常來(lái)講就越難以達(dá)到很低的噪聲。，C波段的通常為30K。Antenna noise temperatureA value for the antenna noise temperature is often quoted in manufacturer39。s specifications. The total noise temperature of the antenna depends mainly on the following factors:1) Sky Noise The total antenna noise, Tant = Tsky+Tgnd. The sky noise, Tsky, consists of two main ponents, absorption and the background 39。big bang39。 radiation (). Since the atmosphere is an absorbing medium it must be a noise source so sky noise increases with decreasing elevation due to the longer path through the atmosphere.2) Ground Noise The dominant contribution to antenna noise at low elevations is ground noise pick up through side lobes. Noise temperature increases as the elevation angle decreases since the antenna will pick up more ground noise due to side lobes intercepting the ground (diffraction effects at the antenna rim). This may be reduced by various methods of feed illumination and the dish design itself. A deep dish picks up less ground noise at lower elevations than do shallow ones also prime focus mounted head units will add to noise since it is seen at the same temperature as the Earth. Estimating Antenna Noise TemperatureSince antenna noise temperature has so many variable factors, an estimate is perhaps the best we can hope for. In the absence of a specific manufacturer supplied figure, a reasonable estimate may be obtained by selecting Calculate|Estimate Antenna Noise Temperature from the menu.天線(xiàn)噪聲溫度天線(xiàn)的噪聲溫度通常標(biāo)注在廠家的說(shuō)明書(shū)中。天線(xiàn)的總噪聲主要受以下幾個(gè)方面影響：1） 天電噪聲。天線(xiàn)的總噪聲=天電噪聲+地電噪聲。天天電噪聲，Tsky，包含兩部分，空氣吸收和大爆炸背景輻射。因?yàn)榇髿馐且环N（電磁波）吸收媒介所以肯定會(huì)有噪聲。所以海拔降低大氣噪聲就會(huì)增加，因?yàn)樵陔姶挪ㄔ诖髿庵袀鞑サ母h(yuǎn)。2） 大地噪聲。在低仰角的情況下對(duì)天線(xiàn)噪聲影響最大的是旁瓣吸收的大地噪聲。天線(xiàn)仰角降低，大地噪聲就升高（天線(xiàn)的衍射效果）。它有可能通過(guò)饋源和反射面的特殊設(shè)計(jì)而減小。比較凹的天線(xiàn)反射面會(huì)減少大地噪聲，而天線(xiàn)頭部分也會(huì)增加噪聲，因?yàn)樗部梢钥醋骱痛蟮赜幸粯拥脑肼?。估算天線(xiàn)噪聲溫度因?yàn)樘炀€(xiàn)噪聲溫度受很多因素影響，我們只好算出一個(gè)估計(jì)值。如果沒(méi)有廠家提供的參數(shù)，使用CalculateEstimate Antenna Noise Temperature進(jìn)行計(jì)算。Adjacent Channel Interference C/ACI相鄰信道干擾Enter a value for the carrier to adjacentcarrier interference noise ratio C/ACI in dB. This parameter specifies the expected interference level with respect to the wanted carrier. A typical value to enter for either uplink or downlink is between 24 and 30dB. Some link programs do not use this parameter so if you wish to void it enter 60dB or more. Note that the higher this value is in dB, the lower the interference. 輸入一個(gè)相鄰信道干擾噪聲C/ACI，以dB為單位。這個(gè)參數(shù)指定一個(gè)所需載波的干擾程度。上行和下行的典型值在2430dB之間。很多工程不需要這些參數(shù)，如果不希望考慮它，輸入60dB以上的值。注意這個(gè)值越高表示干擾越小。Adjacent Satellite Interference C/ASI相鄰衛(wèi)星干擾Enter a value for the carrier to adjacent satellite interference noise ratio due to interfering signals to/from adjacent satellites in dB. This parameter specifies the expected interference noise with respect to the wanted carrier..A typical value to enter here for either uplink or downlink is between 18 and 30dB. Note that the higher this value is in dB, the lower the interference.輸入一個(gè)相鄰衛(wèi)星干擾噪聲C/ASI，以dB為單位。這個(gè)參數(shù)指定一個(gè)所需載波的干擾程度。上行和下行的典型值在1830dB之間。注意這個(gè)值越高表示干擾越小。Cross Polarization Interference C/XPI極化干擾Enter a value for the carrier to cross polarization interference noise ratio C/XPI in dB. This parameter specifies the expected interference level with respect to the wanted carrier. A typical value to enter here for either uplink or downlink is between 24 and 30dB. Note that the higher this value is in dB, the lower the interference.輸入一個(gè)交叉極化干擾噪聲C/XPI，以dB為單位。這個(gè)參數(shù)指定一個(gè)所需載波的干擾程度。上行和下行的典型值在2430dB之間。注意這個(gè)值越高表示干擾越小。Earth Station HPA Output BackOff地球站高功放輸出回退To reduce uplink interference it is customary to back off the output of the earth station HPA. This tradeoff leads to a higher HPA power capability being required. Typical values range from 1 to 7dB.為了防止上行的噪聲一般要對(duì)地球站的高功放進(jìn)行回退。這種權(quán)衡的做法會(huì)導(dǎo)致需求功放的功率變大。典型值在17dB之間。Number of HPA Carriers高功率放大器載波數(shù)量Enter the number of carriers simultaneously transmitted by the uplink earth station HPA. Normally this is set to 1 unless you need to size the HPA for multiple carriers. This has no effect other than to increase the HPA power requirement.輸入地球上行功率放大器同時(shí)傳輸?shù)妮d波數(shù)量。如果不需要同時(shí)傳多個(gè)載波的話(huà)就輸入1。這個(gè)數(shù)值只會(huì)影響功率放大器的功率需求。HPA Intermodulation Interference C/IM功放交調(diào)干擾Enter a value for the intermodulation interference expected from the uplink earth station HPA. This parameter is sometimes neglected in many programs. If you wish to make this parameter effectively void enter 60dB or more.. Note that the higher this value is in dB, the lower the interference level.輸入一個(gè)上行功放交調(diào)干擾值，以dB為單位。很多工程不需要這些參數(shù)，如果不希望考慮它，輸入60dB以上的值。注意這個(gè)值越高表示干擾越小。Uplink Power Control / Manual Power Boost上行功率控制/手動(dòng)功率控制Uplink Power Control (UPC) also known as Dynamic Carrier Control is used to pensate for instantaneous rain attenuation on the uplink. Enter the dynamic range of the system here. If UPC is not used or site diversity plans are in operation you can enter zero here. UPC systems usually require a high HPA power capability.上行功率控制（UPC）又叫動(dòng)態(tài)載波控制，是用來(lái)抵消上行偶爾的雨衰。輸入動(dòng)態(tài)的系統(tǒng)變化值。UPC系統(tǒng)需要更大的功放功率。雨衰Rain modelsHere you can select the rain model to use. Check the checkbox relevant to the model you wish to use.The ITU/DAH rain model is remended since it is probably the most accurate model to date. The Crane models are also provided if you prefer them. You do no