User's Manual

Rev B
10
The Range function requests a beginning and ending frequency for the search and then scans
this range. This function may be used to find the frequency of an unknown transmitter or to
check for the presence of any of a known group of signals.
The Neighbourhood function searches a range of frequencies from 8KHz below to 8KHz
above the current selected frequency. This function may be used, with the frequency increment
(∆F) set to 1 kHz, to find the frequency of best reception for signal data (though not necessarily
the best audio response).
The Continue function continues a search which has been stopped by
ESC.
SEARCH is provided in SRX_400 tracking configurations but may be absent from (or have a
different function in) some advanced data collection versions.
The
SIGNAL key is used to select signal measurement and display options. Its menu is
Power Graph uses the bottom line of the LCD display to provide a graphical display of signal
strength, with the top line showing the selected frequency and numerical signal strength value
between 0 and 255.
While in this mode, the arrow keys can be used to increment and decrement gain and frequency.
Interval displays pulse intervals in milliseconds or pulse rate in beats per minute and relative
signal strength. In most software versions, received pulses are filtered using a pulse interval
window (see Boundaries, below). A pulse is considered valid if the time elapsed since the last
received pulse is within the window. Valid pulses will trigger a dynamic "strobe" character in
the lower right quadrant of the display.
Note that Interval does not exercise any automatic control of receiver gain. In a noisy
environment (e.g., in an aircraft or in the vicinity of computer equipment) it is possible to set the
gain high enough so that the receiver is saturated with noise and cannot detect even a reasonably
strong signal. Simply reducing the gain will normally correct this situation. (See also the
Optimization example in section II of this manual).
Interval and Power Graph routines pass control to a new environment, in which the
following limited set of key functions is available.
SHIFT + SIGNAL assigns the arrow keys to open and close the pulse interval window (Interval
only). This assignment is indicated by a "W" in the delta status position (see Figure 1, below) in
the lower right quadrant of the display, and changes in window size are indicated in the upper
right display quadrant. Note that if the pulse rate display format has been selected (see below)
the window boundaries will be displayed in beats per minute, rather than milliseconds.
SHIFT + TIME toggles the interval display format between time in milliseconds and rate in beats
per minute (Interval routine only). Both pulse measurements and displayed window values are
affected.
SHIFT + CODE selects digital code discrimination in software versions which support coded
transmitters (see the Code_Log user’s manual that accompanies W17 firmware). When this
function is selected a # symbol appears in the signal status position of the display. When a
transmitted code burst is recognized the code, channel number (user assigned index into the
frequency table) and signal strength are displayed.
SIGNAL
7
1)POWER GRAPH 2)INTERVAL
3)BOUNDARIES 4)CALIBRATE
149.450MHz +102
min ²²²²²²|
Deleted: , and also to enable/disable
audio noise blanking, as discussed
below under Interval and Scan
functions.