Motorola Mt1500 Basic 6881094c09 B Manual

							Radio Alignment Procedures
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Transmit Power 
AlignmentThis alignment procedure adjusts the transmit power of the radio and must be performed 
for three different power levels (Low, Mid, High), at multiple frequencies for each power 
level, to allow for proper alignment across the entire RF band. The RF band is divided into 
frequency zones with a calibration point (value) in each zone.
NOTES:
The same softpot attenuation value will result in DIFFERENT radio output 
power levels at different frequencies.
All power measurements are to be made at the antenna port.
Transmit Power alignment is required after replacing (or servicing) the 
transceiver board.
1. Select the TX Power alignment screen. The screen will indicate the transmit frequencies 
to be used. See Figure 9.
2. Left-click the desired frequency field (starting with the highest frequency shown).
3. Left-click the PTT Toggle button on the screen to make the radio transmit. The screen 
indicates whether the radio is transmitting.
4. Measure the transmit power of the radio with a service monitor.
5. Adjust the softpot value until the required power, as shown in Table 12, is indicated 
on the service monitor.
6. Repeat the above process for all frequencies and all power levels.Table 12.  Transmit Power Settings
Power LevelTest Frequencies
700/800 MHz
Low (1 Watt) 1.2 - 1.4W
Mid (2 Watts) 2.5W - 2.7W
High (3 Watts) 3.2W - 3.4W 
						

							Radio Alignment Procedures
247. Left-click the Program All button on the screen to dekey the radio and save the tuned 
values.
Left-click the Close button on the screen to return to the Transmitter Alignments menu.
Figure 9.  Transmit Power Alignment Screen (Typical) 
						

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Transmit Deviation 
Balance AlignmentThis alignment procedure balances the modulation contributions of the low- and high-
frequency portions of a baseband signal. Proper alignment is critical to the operation of 
signalling schemes that have very low frequency components (for example, DPL) and 
could result in distorted waveforms if improperly adjusted.
This procedure needs to be performed at multiple frequencies to allow for proper alignment 
across the entire RF band. The RF band is divided into frequency zones with a calibration 
point (value) in each zone.
NOTE:This alignment is required after replacing (or servicing) the VOCON 
board or the transceiver board.
Proper alignment requires a modulation analyzer or meter with a frequency response to less 
than 10 Hz modulating frequency. The modulation analyzer settings during this test should 
be set for average deviation, a 15 kHz low-pass filter, no de-emphasis, and no high-pass 
filter, if these settings are supported.
This test can be done with either the R-2670 Communication Analyzer or the 8901_ Series 
Modulation Analyzer. The method of choice is the R-2670 analyzer.
1. Initial setup using the R-2670 Communication Analyzer:
-Connect a BNC cable between the “DEMOD OUT” port and the “VERT/SINAD 
DIST/DMM COUNTER IN” port on the R-2670.
-Press the SPF key on the R-2670 to display the “SPECIAL FUNCTIONS 
MENU.” Move the cursor to “High Pass,” and select 5 Hz on the soft key menu. 
Select 20 kHz for the “Low Pass” setting.
-In the “RF Control” section of the R-2670, enter the frequency displayed on the 
RSS screen. Move the cursor to the “B/W” setting and select “WIDE +/- 100 kHz” 
on the soft key menu.
-Place the R-2670 cursor in the “Display” zone. Select “AC VOLTS” on the soft 
key menu. Move the cursor to the “Range” setting and select “AUTO.”
2. Initial setup using the 8901_ Series Modulation Analyzer:
-Press the FM MEASUREMENT button. (The “Error 03-input level too low” 
indication is normal until an input signal is applied.)
-Simultaneously press the Peak – and Peak + buttons. Both LEDs on the buttons 
should light.
-Press the 15 kHz LP filter key.
3. Select the TX Deviation Balance alignment screen. The screen indicates the transmit 
frequencies to be used. See Figure 10.
4. Left-click the desired frequency field (starting with the highest frequency shown).
5. Left-click the PTT Toggle button on the screen to make the radio transmit. The screen 
indicates whether the radio is transmitting. 
						

							Radio Alignment Procedures
266. Left-click the PTT Tone: Low button.
7. Left-click the PTT Toggle button on the screen to enable transmission. The screen 
indicates whether the radio is transmitting. Wait approximately 5 seconds until the 
voltage shown on R-2670, or the deviation shown on the 8901_ analyzer, stabilizes. 
8. Measure and record the ac voltage value from the R-2670 analyzer or the deviation 
value from the 8901_ series analyzer.
9. Left-click the PTT Tone: High button.
10. Adjust the softpot value until the measured deviation/voltage, when using the high 
tone, is within +/- 1.5% of the value observed when using the low tone.
11. Repeat the above process for all frequencies.
12. Left-click the Program All button on the screen to dekey the radio and save the tuned 
values.
13. Left-click the Close button on the screen to return to the Transmitter Alignments 
menu.Figure 10.  Transmit Deviation Balance Alignment Screen 
						

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Transmit 
Deviation Limit 
AlignmentThis alignment procedure limits the modulation of a baseband signal. It is used for primary 
modulation limiting.
This procedure needs to be performed at multiple frequencies to allow for proper alignment 
across the entire RF band. The RF band is divided into frequency zones with a calibration 
point (value) in each zone.
NOTE:This alignment is required after replacing (or servicing) the VOCON 
board or the transceiver board.
1. Select the TX Deviation Limit alignment screen. The screen will indicate the 
transmit frequencies to be used. See Figure 11.
2. Left-click the desired frequency field (starting with the highest frequency shown).
3. Left-click the PTT Toggle button on the screen to make the radio transmit. The screen 
indicates whether the radio is transmitting.
4. Measure the transmitted signal deviation of the radio with a service monitor.
5. Adjust softpot value until the measured deviation is as close as possible to 2.83 kHz.
6. Repeat the above process for all frequencies.
7. Left-click the Program All button on the screen to dekey the radio and save the tuned 
values.Figure 11.  Transmit Deviation Limit Alignment Screen 
						

							Radio Alignment Procedures
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8. Left-click the Close button on the screen to return to the Transmitter Alignments 
menu.
Front End Filter 
Alignment
DefinitionThis alignment procedure adjusts the front end receiver bandpass filters for best receiver sensitivity 
and selectivity. It should be performed for all test frequencies to allow for proper software 
interpolation for frequencies in between the test frequencies in the band (see Figure 12).
NOTE:Rx Front End Filter Alignment is required after replacing (or servicing) 
the transceiver board.
Procedure for 700 
MHz Frequencies1. Left-click the desired frequency field.
2. Apply an RF signal with no modulation at -90 dBm on the current operating 
frequency.
3. Start with a softpot value (approximately 10 or 20), increase softpot in ascending 
order, and note the RSSI values. The RSSI will reach a peak value and remain stable 
and then decrease. Allow the limits of the peak range to be defined as RSSI PEAK - 3. 
Choose the middle of the peak range and program the corresponding softpot value as 
the tuned softpot value.
4. Repeat the above process for all 700MHz frequencies.
5. Click on the “Program All” button to save the tuned values in the radio.
Procedure for 800 
MHz Frequencies1. Left-click the desired frequency field.
2. Apply an RF signal with no modulation at -90 dBm on the current operating 
frequency.
3. Start with a softpot value of 50, increase softpot in ascending order, and note the RSSI 
values. The RSSI will reach a peak value and remain stable and then decrease. Allow 
the limits of the peak range to be defined as RSSI PEAK - 3. Note the upper end of 
the peak range and program the corresponding softpot value as the tuned softpot 
value.
4. Repeat the above process for all 800MHz frequencies.
5. Click on the “Program All” button to save the tuned values in the radio.
Procedure for UHF/
VHF1. Left-click the desired frequency field.
2. Apply an RF signal with no modulation at -90 dBm on the current operating 
frequency.
3. Adjust the softpot value until the maximum RSSI value is found.
4. Repeat the above process for all frequencies.Refer to your Radio Service Manual for alignment procedure details. 
This procedure should only be attempted by qualified service personnel.
!
C a u t i o n 
						

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Click on the “Program All” button to save the tuned values in the radio.
Bit Error Rate
DefinitionThis screen is used to test the Bit Error Rate (BER) of the radio’s receiver at a desired 
frequency.
Bit Error Rate FieldsThis screen contains the following fields:
Rx Frequency:
This field selects the Receive Frequency directly in MHz.
Test Pattern:
This field selects the Digital test pattern — TIA. Choices are: Standard Tone Test Pattern 
(framed 1011) and Standard Interface Test Pattern (CCITT V.52).
Modulation Type:Figure 12.  Front End Filter Alignment Screen 
						

							Radio Alignment Procedures
30This field represents the digital modulation type of the incoming signal on which BER is to 
be calculated.
Continuous Operation:
This field allows the user to make the BER test repeat indefinitely. A selection of Yes will 
cause the radio to calculate BER on a continuous basis and update the results on this screen 
after each integration time. A selection of No will cause the BER test to execute for only 
one sample of the integration time and then update the display.
Audio:
This field allows the user to select the audio output during a test. Selecting Internal will 
cause the radios built-in speaker to unmute to any signals at the desired frequency which 
are present during the test. Selecting External will route the same signal to the radios 
accessory connector audio output. Selecting Mute will disable the audio output.
Integration Time:
This field represents the amount of time over which the Bit Error Rate is to be calculated. 
The range is from 0.360 to 91.8 seconds in increments of 0.360 seconds.
NOTE:When Continuous Operation = Yes, all fields will be grayed out while 
test is in progress. They will be enabled when the STOP button is 
pressed.
When Continuous Operation = No, a wait cursor will be displayed while 
the test is in progress and return to normal when the test is done.
Figure 13.  Bit Error Rate Screen 
						

							Radio Alignment Procedures
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Transmitter Test 
Pattern
DefinitionThis screen is used to transmit specific test patterns at a desired frequency so that the user 
can perform tests on the radio’s transmitter.
Transmitter Test 
FieldsThis screen contains the following fields:
Tx Frequency:
This field selects the Transmit Frequency directly in MHz.
Channel Spacing:
This field allows the user to select the desired transmit deviation.
Te s t  P a t t e r n  Ty p e :
This field represents the type of test pattern which will be transmitted by the radio when 
“PTT TOGGLE” button is pressed.
NOTE:Channel Spacing and Test Pattern Type fields will be grayed out while 
radio is transmitting.
Figure 14.  Transmitter Test Pattern Screen 
						

							Radio Alignment Procedures
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Notes