26
3.7.3 Calibrating of carrier frequency： In the frequency modulation, carrier
synthesizer uses controllable clock reference. Although the carrier frequency is still
the frequency of channel A, it should be calibrated in addition. Pressing the key of
【Menu】 , the indicator lights of “FM” and “Carrier” will be on. The calibrating
code of carrier frequency will be displayed on the upper row. Now the frequency of
carrier frequency is 1MHz. Use the cymometer to measure the frequency of channel
A. At the same time, modify the calibrating code by the knob. The frequency of
channel A will be changed until the accuracy is calibrated up to 10.
3.7.4 Calibrating of frequency deviation modulation ： Pressing the key of
【Menu】 , the indicator lights of “FM ” and “Devia” will be on. The calibrating
code of frequency deviation modulation will be displayed on the upper row. Now the
frequency of channel A is 2MHz and the frequency deviation modulation is 1%. Use
the modulation meter to measure the frequency deviation modulation. At the same
time, modify the calibrating code by the knob. The frequency deviation will be
changed until the accuracy is calibrated up to 1%(the frequency deviation is 20kHz)
3.7.5 Calibrating of phase shift of channel B：Press the key of 【Menu】 and
light up the indicator lights of “CHB ”and “Phase”. The calibrating code of the phase
shift of channel B will be displayed on the lower row on the screen. The frequencies
of channel A and B are 1MHz and the phase difference of the two channels is 0. the
signals of the two channels are observed by double-trace oscilloscope and the
calibrating code can be modified by the knob at one time. The phase difference of the
two channels will be changed until it gets to 0.
After the calibrating is over, press the key of 【Menu】 and “1000” will be
displayed on the upper row on the screen. Input arbitrary wrong code except 1000 by
the numeric keys and press the key of 【n】. The display on the upper row will be “-
---”, which means the calibrating is closed.，The calibrating code is stored in non-
losable memorizer so that they will not be lost even if the power is off. Unless
calibrating again will the calibrating code be renewed.
3.8 Parameter calibration（2）
The amplitude and offset cannot be calibrated via the keyboard. If the error is
too big, the following calibrating method can be adopted.
3.8.1 Calibration of amplitude of channel A： Select the function of “Frequency
of channel A”. Select sine waveform with the frequency of 1kHz and the amplitude
To Next Page
Loading...
Need help?
General
