Simrad PI44 C, Руководство оператора

Страница: 60 / 322

Simrad PI44
48
850-165085 / Rev.B
(C) Frequency spectrum
This graph provides you with information about the background
noise and the signal strength of the frequency band or channel
number selected. Each vertical bar represents the background
noise for the given frequency or channel, and the level is
measured continuously.
To select spectrum display, press the ADJ button to open the
Status setup dialogue, and select Spectrum, display to show
Frequency or Channel . In most cases a Channel view will be
most useful to you.
This function is very useful if you have too much noise and this
makes the communication with the sensor unreliable. Switch off
as much electrical, mechanical and acoustic gear and equipment
as possible. Then, switch the systems on again one by one while
keeping an eye on the frequency spectrum. When the “noisy”
system is activated, it is most likely easy to see!
Note that the frequency spectrum presentation depends on the
Interference filter setting.
(D) Gain indicators
There are six gain indicators, one for each of the current
sensors. At the top of each indicator you can see sensor number
and sensor type, at the bottom you can see the sensor’s
communication channel and current update rate.Green colour
indicates that the reception of signals and noise is within normal
specifications. Red colour indicates that the received signal
exceeds the minimum level required for reception, this is
therefore not an error message.
For the technical minded: When no sensors have been deployed,
the indicators will present the mean noise level. This is the noise
in the surrounding water, caused by mechanical, electrical,
acoustic and natural disturbances. This noise level should be as
low as possible. When a sensor in the water transmits its
information back to the PI44, this is indicated as the green
indicator extends above the mean noise level. In order for the
reception circuitry to accept and recognize the signal, it must be
stronger than a predefined minimum level. The level is normally
referred to as the detection level. If the signal is stronger than
the detection level, the indicator bar will change colour to red.