User's Manual

Rev B

SHIFT + SET F, SHIFT + SET G assigns the arrow keys to increment/decrement frequency and

gain. The delta status position (see Figure 1) shows an "F" or a "G".

F0 (without SHIFT) toggles audio noise blanking (a new function available in SRX_400 ‘A’

receivers) which uses the automatic signal detection features of the SRX_400 to enhance audio

performance, especially in aircraft or other high-noise environments. The audio noise blanker

suppresses the receiver’s audio response except when a signal is passed by the internal phase

locked loop detector’s noise blanking mechanism, which rejects pulses that are too short to be

valid signals. (This mechanism is described in more detail in Example 2 of the Operations and

Exercises section of this manual).

In a typical tracking application, very weak signals (detected with the noise blanker off to take

advantage of the powerful frequency-domain processor in the human auditory cortex) will

quickly pass the automatic detection threshold as the aircraft (or other vehicle) is turned to

approach the target. Switching the noise blanker on at this point will make further bearing

determinations easier (using the numeric or graphic display) and will also greatly reduce

auditory saturation and fatigue.

UPARROW/DOWNARROW increments/decrements frequency or gain and opens/closes the

pulse interval window in 5 millisecond increments.

ESC exits.

Boundaries allows you to specify a time window in milliseconds for valid pulses. Enter

boundary values as 5-digit numbers, including leading zeros, if necessary. If you don't want any

time interval filtering, open the window by setting the boundary values far apart (e.g., upper

bound = 10000 and lower bound = 00001). Whatever values you set for the window will be

remembered by the receiver until you change them. Note that window values are always

entered in milliseconds, even though they may be displayed (using the

SHIFT + TIME key sequence

in Interval) in beats per minute. To specify a window value in beats per minute use the

conversion: interval(msec) = 60,000 / rate(bpm).

Calibrate refers to a specialized software feature which is not supported in any current

versions. Selecting this option should have no effect.

Figure 1: Display Status Characters (lower right display quadrant, positions 45-48)

Signal Status Delta Status Scan Status Shift Status

The

SCAN key calls a function which scans through the frequencies entered in the

current active

FTABLE partition, stops at each frequency for the time set by SET SCAN

and cycles continuously through the table.

SCAN also maintains its own

environment, which provides a number of options and control features described below:

Pulse interval and signal strength information may be displayed for any signals detected. This

feature may be toggled on and off using the

SHIFT + SIGNAL key sequence. Interval

measurements, window operations and the dynamic strobe character function exactly as in the

SCAN