Planar IT-081, Руководство по эксплуатации

Страница: 14 / 31

alphanumeric key set. To enter special channels, first press C key. After you have entered
the number, press MENU/ENTER . If the number is incorrect, the previously saved channel
number value will be restored after you pressed MENU/ENTER key. To enter the
frequency value in MHz, use the alphanumeric keypad. After you have entered the
number, press
MENU/ENTER .
NOTE Pressing ◄ and ► keys when channel plan is selected (4.4.2) will scroll the
channels of the plan. You can tune to any channel by entering its number from the
alphanumeric keypad. In this case, if the channel does not belong to the selected channel
plan, its name will not be shown, only the number of the channel will be indicated on the
screen.
Tuning to the channels and their numbering will be fulfilled in accordance with the
selected channel template (Section 4.5.2).
The measured level is shown according to the selected measurement units: in dB
related to 1 µV, 1 mV or 1 mW (Section 4.5.2). To define V/A and C/N ratios for analog
channels the IT-081 performs measurements in three frequency points. The first one is the
video carrier frequency (or the frequency your Meter is set to). The second frequency point
is the audio carrier frequency (for Secam D/K template this point is 6.5 MHz shifted up
from audio carrier frequency). The third one is the point 1.125 MHz shifted down from the
first one. The measured V/A and C/N ratio will be indicated on the screen.
While operating by channel plan, the IT-081 offers the capability of selecting the
frequency point for optimization of noise measurements (4.4.2.2).
For digital channels your Meter will perform measurement of actual channel power
within the channel frequency band.
While performing measurements for digital channels it is recommended to apply the
mode of calculating the measured value with maximum averaging: Averaging: x8
This method ensures more consistent results for wideband signals.
To reset the maximum level value, press
AUX key to open the menu with additional
set of functions, and then press F4/Reset key.
The remote cable power supply voltage is measured from 10 to 100 V. The absolute
error of the measurement is lower than ±1.5 V. The measured value and type of the
voltage at the Meter's input are indicated on the screen in VDC units for direct current,
and in VAC units for alternating current.
When sound indication is enabled and the tuning by channels is carried out, the
adjustment is performed by audio carrier frequency.
To switch to Spectrum and Scan measurement modes, use F3 and F4 keys.
4.3.3. Spectrum Measurement Mode
This mode displays the signal spectrum. See figure 4.5 for the representation of the
screen view:
Figure 4.5
You can navigate the marker by means of ◄ and ► keys, if F2 key value is
represented on the screen as Marker .
14