For any of the transfer functions, to define a new coefficient click Add. Enter the coefficient value in the new field that appears in the table. Numbers entered are automatically converted to scientific notation. Click Remove to delete an entry from the table. Changes to existing values can be made directly in the table. You can add a coefficient in the middle of the table by selecting the table entry that you want to precede the new coefficient and clicking Add. You can adjust the order of a coefficient by selecting it in the table and clicking the up or down buttons.
The input-output characteristics of a re-transmitter are controlled by transfer functions for the input/output backoff characteristics, the carrier to intermod ratio, and the transmit frequency. The transfer functions are modeled as Nth order polynomials by default.
Frequency
Frequency coefficients specify the transmitted frequency as a function of the received frequency. They can only be entered in polynomial form. The coefficient order is displayed in the left column of the table and updates automatically as coefficients are added or removed. Input and output units are in Hz. The default coefficients of -7.0e8 and 1.0 are used to model a 700 MHz down conversion.
Power Back Off
Power Backoff coefficients can be entered in polynomial or table data form. Select Table Data as the Input Type to enter the coefficients in table data form. The table will then define coefficients by the Index, Input Backoff, and Output backoff fields. Select Linear Scale if your coefficients are in linear scale rather than dB. STK will calculate based on the linear scale, and then convert the finished values to dB. If you enter coefficients in polynomial form, then the table is same as for the Frequency coefficients.
C/Im
Carrier to Intermod ratio coefficients can be entered in polynomial or table value form. Select Table Data as the Input Type to enter the coefficients in table value form. The table will then define coefficients by the Index, Input Backoff, and Output backoff fields. Select Linear Scale if your coefficients are in linear scale rather than dB. STK will calculate based on the linear scale, and then convert the finished values to dB. If you enter coefficients in polynomial form, then the table is same as for the Frequency coefficients.
When using polynomial coefficients, the polynomial is defined as:
y = a0x0 + a1x1 + a2x2 + ... + anxn,where x is the input and y is the output.
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