Specifications

5-4-4 Common features shared by different monitoring

modes

Input sensitivity (AMPLITUDE)

This feature refers to the setup of the input

sensitivity level of the SDU5600 which is

adjusted by the internal amplifier of the

SDU5600. There are 4 different levels of input

sensitivity between 0dBm and -30dBm in 10dB

steps.

Press the AMPLITUDE special key to make the

reference level display appear in reverse contrast.

Enter the required sensitivity level via the

ten-keys or main dial, followed by ENT.

For example, If -20dBm is required press

AMPLITUDE 2 MHz. You can ignore trailing

zeros ‘0’ following 2 in this instance.

Any invalid entry will be alerted with the

beep, and the nearest possible value will be

automatically selected instead.

The resulting displayed signal wave on the LCD

is affected by combinations of various factors

such as input sensitivity of the SDU5600,

attenuator position and AGC setting (where

applicable) of the companion receiver. Higher

input sensitivity does not always provide the best

results. It is also possible to produce distorted

signals due to saturation to / from the companion

receiver, this may lead to a raised noise floor of

the SDU5600 or spurs.

Significance of the input sensitivity

(reference level)

The two plots shown here show the results from monitoring the same signal at 80.0MHz WFM but using different

input sensitivity settings.

The plot on top was produced with the input sensitivity of -30dBm, the input sensitivity is too high, which results in

unstable operation within the RF amplifier of the SDU5600. This has produced some ghost signals (images)

separated at regular intervals.

The bottom plot was produced with the input sensitivity of -20dBm. Optimum results are obtained due to correctly

selected input sensitivity.

It is important to select the input sensitivity most appropriately to ensure best results.

The AR5000 series receivers and RFU5600 feature AGC level adjustment, however AGC level cannot be adjusted

remotely from the SDU5600.

Effective use of the attenuator of the companion receiver will be required to prevent saturation of received

signal particularly when an external aerial is used.

Section 5-4-4