卫星链路计算软件Satmaster帮助(4)

Carrier Spacing Factor

载波分隔系数

For shared transponders, the allocated bandwidth is often greater than the occupied bandwidth of a carrier. This is to minimize adjacent carrier interference and to allow for minor fluctuations in the carrier's centre frequency.

A typical value to enter is 1.4 for multicarriers sharing the same transponder. If you do not require any carrier spacing, enter the same value as you entered for (1+ roll-off factor).

You cannot enter a value less than that entered for (1+roll off factor) as both factors are applied to the symbol rate. Be careful here because some programs apply this factor to the occupied bandwidth and not the symbol rate.

Note: The bandwidth used by a digital carrier is proportional to the symbol rate. 共用转发器时，分配的带宽一般比载波所占的带宽要大。这是用来减小相邻载波的干扰并允许载波中心频率小幅度的偏移。

多载波共用转发器的典型载波分割系数为1.4.如果你不需要载波分隔，输入值设为“1+滚降系数”的值。

不能设小于“1+滚降系数”的值，因为两个值会影响最终的符号率。注意，有的程序中这些值会影响占用带宽而非符号率。

Bandwidth Allocation Step Size

带宽分配块大小

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 0.1MHz. If you do not require this rounding up process then just enter zero. 天线运营商有时将频带分成固定带宽的块进行过按块收费。计算转发器租用带宽数量时，非配的带宽通常向上取整于最近的分配快。比如说，典型的带宽分配块大小为100kHz，因为本程序的单位为MHz你应该输入0.1MHz。如果你不需要向上取整过程只要输入0.

System Margin

系统余量

Although the program calculates industry standard rain fade margins and includes them in the link budget, it is customary to include an overall system margin to account for uncertainty in the various input parameters and to allow for difficult to quantify non-linear effects such as AM-PM conversion and perhaps terrestrial interference, a value of about 1dB should be sufficient.

Some links may not balance if this parameter is set too high. If you are having trouble balancing a link budget, or getting negative excess margin warnings, set this value to zero. 虽然本程序按照工业标准计算雨衰并且包括在链路预算中，但是通常还是要留出一个整体的系统余量来应对各种输入的不确定性，以及各种难以计量的非线性效应如 AM-PM调幅-调

相转换或者地面干扰，1dB就足够了。

如果这个量设的过高有些链路可能就会超出预算。如果你的链路预算超出预算，或者收到余量负溢出警告，请将该值设为0.

Edit Digital Modulation Method

编辑数字调制模式。

Select one of the three radio buttons to define the modulation scheme adopted and enter the value of M for an M-ary system. Example for 8-PSK you would enter 8. For QPSK (4-PSK) you would enter 4. Set M=2 for BPSK since it is a binary signaling system.

选择三个按钮中的一个来选择调制方案或者输入M值来选择一个M相键控系统。举例,8PSK为8，QPSK为4，BPSK为2。

Edit Bit Error Rate

误比特率

The bit error rate (BER) is numerically equal to the bit error probability over the communication channel, and is quoted in 10 raised to the power n, where n is a negative integer. The equivalent of ITU-R 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 program's forms. For example with a BER of 10 ^ -6. you would enter -6. For a BER of 10 ^ -10 you would enter -10. This is used exclusively to calculate the Eb/No required without channel coding.

误比特率(BER)就是通信信道中每比特发生错误的概率，以10为底数n为指数，n是一个负整数。等效于ITU-R的5级模拟链接预算为BER=10^-6。这就是说平均1000000个比特里有一个会出错。 为了方便，只需要输入BER以10为底的对数即可。比如BER=10^-6只要输入-6，BER=10^-10输入-10.这个值用来唯一计算出所需要的信道Eb/N0。

Transponder Power Usage

转发器功率使用

The program checks if the transponder usage is either \run time. If this box is checked and the transponder usage is detected as bandwidth limited, a power iteration is performed at the maximum supported carrier limit. This essentially underuses the available transponder power and often results in a lower uplink power. This is the default setting.

On the other hand, if the transponder usage is found to be bandwidth limited and this option is unchecked, no power iteration is performed and the link budget assumes all the available transponder power is to be used. The \Margin\and consequently the resulting HPA capability could be significantly higher if this box is unchecked as there is less IBO per carrier. In a situation where large HPAs and small downlink antennas are required, as in TV broadcasting, this

option may be more appropriate.

In cases where the transponder is naturally power limited (common), this option has no effect and the budget is iterated for minimum uplink power requirements. 程序会检查转发器是“功率限定”还是“带宽限定”。如果这个选项被勾选并且转发器为带宽限定，功率计算将按照转发器支持最多的载波进行迭代计算，这实际上低估了转发器功率而且经常会导致较低的上行功率。这是默认设置。 另外如果转发器为带宽限定且这个选项未选，不会有功率叠加计算，假设所有的转发器功率都可用。当选项未勾选时，算出的HPA高功放功率可以显著增加，因为每个载波的IBO减少了。在大型上行天线和功放配合小型接收天线的情况下，比如TV广播，这种选项比较合适。

档转发器是自然功率限定的（普遍），这个选项没有作用，链路预算按照最小上行功率需求计算。

Downlink Optimization Radio Buttons

下行优化单选按钮

只有手动输入“载波数量”时才会在下行栏中出现，载波数量时“AUTO”时隐藏。它也 …… 此处隐藏：7422字，全部文档内容请下载后查看。喜欢就下载吧 ……