Motorola CDM1250, Basic Service Manual

Page: 59 / 92

Radio Programming and Tuning Procedures 4-17
Manual Squelch Tuning:
1. Under the Rx Align menu, select Squelch Atten . Select either Squelch Atten 12.5 kHz ,
Squelch Atten 20 kHz or Squelch Atten 25 kHz channel spacing variations.
2. Apply an RF signal modulated with a 1 kHz tone at 60% rated deviation listed in Table 4-16 for
current frequency point (F1 being the first) of 10dB SINAD. That is, adjust the reference signal
level until 10dB SINAD is obtained at the SINAD meter. Squelch tuning can either be done
manually (see page 17 for procedure) or by auto squelch (see page 17 for procedure). To obtain
10dB, unmute the radio first by dragging the corresponding slider value to 1.
3. Set softpot to its maximum value to mute the radio.
4. Adjust the softpot value by using the slider, keying in the edit box or using the spin controls. Press
ENTER to confirm the selection. Do this until the radio is totally unmuted. Verify the squelch
closing by inputting a signal level of 4dB lower than that of the 10dB SINAD level.
5. Repeat Step 2 and Steps 3-4 of Manual Squelch Tuning, for frequency points F2-F7.
6. Press Program to commit the softpot values into the radio.
7. Exit the squelch tuning function.
Auto Tune:
When you press the Auto Tune button, the radio automatically returns an optimum squelch value.
After you press the button, the radio may need time to produce an optimal setting for the squelch
attenuation. The following steps describe the auto tune process:
Auto Tuning:
1. Under the Rx Align menu, select Squelch Atten . Select either Squelch Atten 12.5 kHz ,
Squelch Atten 20 kHz or Squelch Atten 25 kHz channel spacing variations.
2. Apply an RF signal modulated with a 1 kHz tone at 60% rated deviation listed in Table 4-16 for
current frequency point (F1 being the first) of 10dB SINAD. That is, adjust the reference signal
level until 10dB SINAD is obtained at the SINAD meter. Squelch tuning can either be done
manually (see page 17 for procedure) or by auto squelch (see page 17 for procedure). To obtain
10dB, unmute the radio first by dragging the corresponding slider value to 1.
3. Select current frequency point (F1 being the first), then press Auto Tune .
4. Repeat Steps 2 and 3 of the Auto Tune section for frequency points F2-F7.
Note: Proceed with caution since this procedure automatically programs the softpot value
into your radio.