【正文】 the munication channel, and is quoted in 10 raised to the power n, where n is a negative integer. The equivalent of ITUR grade 5 in analogue link budgets is BER = 10 ^ 6. That is to say there is likely to be one error in each million bits transmitted.For convenience, only the logarithm to the base 10 need be input into this program39。Bandwidth Allocation Step Size帶寬分配塊大小Satellite operators sometimes charge for multiples of a fixed unit of allocated bandwidth. When estimating the amount of transponder bandwidth to lease or rent, the allocated bandwidth is normally rounded up to the nearest whole allocation unit. For example, a typical bandwidth charging step is 100kHz, since this program always requires input in MHz you would enter . If you do not require this rounding up process then just enter zero.天線運營商有時將頻帶分成固定帶寬的塊進行過按塊收費。如果不清楚。分子n，為受保護的包長字節(jié)。Enter the inner code rate used with forward error correction. Typical values are for BPSK and or for 4PSK (QPSK).輸入前向糾錯的內(nèi)部碼率。再按EDIT鍵就可以恢復界面。Coverage覆蓋區(qū)域Enter a literal name for the coverage of the service. . spot, hemi, conus etc.輸入服務(wù)的覆蓋區(qū)域名稱，比如點覆蓋，半球覆蓋，美國本土覆蓋等等。3）如果轉(zhuǎn)發(fā)器上只有一個載波，你應(yīng)該輸入一個相對高的值，比如30dB60dB，這樣這個值對結(jié)果幾乎沒有影響。注意：1）AUTO只是用來計算多載波轉(zhuǎn)發(fā)器在功率限定的情況下的值。通常對于單載波也是符合的，除非衛(wèi)星運營商設(shè)定了特定的IBO和OBO值來限制下行EIRP密度。它和輸入回退有關(guān)。輸入衛(wèi)星的上行ALC補償范圍。舉例：比如SFD在0dB衰減的時候為90dBW/m2。但這里需要輸入衰減為0的情況。程序會認為這個值是對應(yīng)衰減器為0dB情況。在AUTO模式下，它用來計算輸出回退的典型值和轉(zhuǎn)發(fā)器的交調(diào)干擾。雖然通常不必要。Graphs39。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.輸入一個上行功放交調(diào)干擾值，以dB為單位。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。天線仰角降低，大地噪聲就升高（天線的衍射效果）。 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.天線噪聲溫度天線的噪聲溫度通常標注在廠家的說明書中。 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。單位是dB。Antenna ApertureAntenna aperture is normally taken as the overall diameter of a parabolic dish, the major dimension if an offset focus antenna. Units are always metric (in metres) to conform to international engineering practice. The lower limit handled is metres and the highest 50 metres.天線口徑通常是拋物線天線的直徑，偏饋天線的主要直徑。Signal AvailabilityDepending on your system design requirements a choice of signal availability should be specified. For typical domestic satellite TV systems, a figure of % availability is normally sufficient. In fact most packaged fixed dish systems are designed around this figure. For SMATV you may require a higher figure of % and cable head even higher. The upper limit provided is % but this level of performance is rarely necessary or even achievable. The parameter is used in calculating an appropriate fade margin based on the rainrate statistics for the site. If you like to work with worst month statistics a conversion to average year signal availability is provided under the Calculate menu.With link budgets using uplink power control systems a higher availability is often specified for the uplink than the downlink.信號可用度（年平均）根據(jù)你的系統(tǒng)設(shè)計需求，信號可用度應(yīng)該是確定的。如果需要比較悲觀鏈路預算可以輸入0。不能輸入空格。必須以小數(shù)后跟N或S表示。這種情況下，小數(shù)部分為分的表示，不能超過59。在其他情況下，都是以度來表示的。下行的典型頻率為4Ghz和12GHz。SMATV（衛(wèi)星公共接收電視）%的可用度，電視終端機則更高。Antenna EfficiencyAntenna efficiency is the amount of incident signal actually collected by the dish and feed, expressed as a percentage. Quality of construction, signal blockage by head units, and method of feed affects this parameter. Most antennas have efficiencies of between 60% and 70%. If you do not know the efficiency of the antenna then enter 60% as a worst case value.With link budget and dual feed forms, the value entered may be prefixed with a + character so the value will be interpreted as a gain, in dBi, rather than efficiency.天線效率天線效率就是入射信號唄反射面和饋源收集到得數(shù)量，表示為一個百分比。實際中因為初始安裝誤差，很難將天線完全對準衛(wèi)星，如風穩(wěn)和地面保持精度等因素。頻率越高，通常來講就越難以達到很低的噪聲。天天電噪聲，Tsky，包含兩部分，空氣吸收和大爆炸背景輻射。估算天線噪聲溫度因為天線噪聲溫度受很多因素影響，我們只好算出一個估計值。這個參數(shù)指定一個所需載波的干擾程度。這種權(quán)衡的做法會導致需求功放的功率變大。Uplink Power Control / Manual Power Boost上行功率控制/手動功率控制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）又叫動態(tài)載波控制，是用來抵消上行偶爾的雨衰。 menus.Dual Fade Checkbox (only present on some link budget forms)Where uplink and downlink stations are separated