Sp-461 ers-envisat Symposium

Tx Aux

Tx Main

Rx Main

Rx Aux

Radiating

Row

T/R Module

(1 of 320)

Signal BFN

Cal BFN

Cal

P3

P2

P1A

P1

Figure 2 : ASAR Internal Calibration Diagram

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Transmit Calibration Pulses P1 (representative of T/R module load)

Since T/R modules of the four adjacent rows share the same power supply, the ten

modules of the ‘wanted’ row are set to their nominal phase and amplitude settings whilst

the phase of the modules of the three ‘unwanted’ rows are set so that their combined

contribution out of the calibration network is nominally zero. Thereby minimizing their

interference to the measurement of the ‘wanted’ row.

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Transmit Calibration Pulse P1a

A second type of transmit pulse is added in order to characterize the residual parasitic

contribution of the three unwanted rows during P1. During P1a, the three unwanted rows

are set as for P1 and the previously wanted row is now switched off. Even though the

load conditions on the power supplies are not exactly representative, the small error

introduced into the estimation of P1a is negligible.

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Receive Calibration Pulse P2

The receive path of the instrument is also characterized but since no variation is expected

from power supply load variations it is possible to characterize on a row by row basis.

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Central Electronics Calibration Pulse P3

The central electronics transmit and receive paths are included in the P1/P1a and P2

characterizations. The central electronics are therefore characterized independently by

means of P3