Service and Repair Notes S-0044

SERVICE AND REPAIR NOTES
Bulletin
TECHNICAL INFORMATION
COMMERCIAL, GOVERNMENT & INDUSTRIAL SOLUTIONS SECTOR
1301 E. ALGONQUIN RD.
SCHAUMBURG, IL. 60196
1-800-221-7144 

SRN # S-0044
APC # 509

DATE: JULY, 2001
EXPIRES: NA

SUBJECT: Enhanced Quantar/Quantro Base Station Transmit Deviation Procedure for ASTRO Simulcast Systems.

SYSTEMS AFFECTED: Conventional and SmartZone ASTRO Simulcast Systems

MODEL/OPTION AFFECTED: T5365A Quantar/Quantro Base Station

Symptom: Subscribers may experience missed receive audio when the ASTRO Simulcast System outbound Base Station transmit deviation has not been properly optimized. The enhanced procedure primarily affects optimizations performed with the Motorola R2670 service monitor.

RESOLUTION: The enhanced guidelines for measuring deviation, will replace the current station coarse deviation set section in the digital ASTRO system outbound optimization section of chapter 7 of the GPS Simulcast Installation Manual 68-91098E65C and earlier versions, and RSS manual 68-81085E35 chapter 6 "Performing Post-Repair Alignment".

The ASTRO simulcast system deviation for "Wide Pulse" is 3.00 kHz �5% and for "Narrow Pulse" it is 2.83 kHz �5% as measured using the standard deviation test pattern (utilized in the "ASTRO TX Align and Test" mode of the station). This is not the same as the over-the-air ASTRO signal.

Note: There is no reason to align TX deviation in the field unless the exciter or station control board has been changed. TX deviation is aligned in the factory to an accuracy of 1%.

Pre-Alignment Checklist:

• You must set the deviation utilizing the service mode of the RSS. Setting deviation using off-the-air signals may cause inaccurate system deviation which may result in missed subscriber receive audio.
• A strong signal is required to get an accurate deviation measurement. It is recommended that you have a minimum of -10 dBm signal strength input to your Communications System Analyzer.
• The Narrow Bandwidth-NB filter should be enabled on the R2670. This is done to reduce the amount of noise inherent to the wider IF of the R2670. Previous versions of Motorola service monitors did not require setting the bandwidth to narrow.
• The High Pass filter should be set to 5 Hz and the Low Pass filter set to 20 kHz in the R2670�s "Special Function Menu" post filtering section.
• The R2670 firmware version should be 5.04.xxx or newer. The newer version includes a new function which provides "Deviation Smoothing" in bar graph mode with the "expand" command enabled. This will allow a more accurate reading of deviation. (See Service Information Bulletin )
• All channels on the system need to be measured with the same R2670 service monitor to ensure accurate deviation in overlap areas. If multiple R2670s will be used, measure the difference between all pieces of test equipment and apply the appropriate correction factor to your measurements.

Interpreting Test Equipment Results

Based upon system deviation tolerance and service monitor accuracy the chart depicts what error can be allowed with the deviation measuring equipment. The chart lists the allowable tolerance necessary to achieve the 3.00 kHz � 5 % specification, using various communication analyzers.

	Lower Limit	Lower Reading Measurement	Specification	Upper Reading  Measurement	Upper Limit
System Tolerance � 5 %	2850 Hz		3000 Hz		3150 Hz
1 % Instrument Accuracy		2880 Hz	3000 Hz	3120 Hz
2 % Instrument Accuracy		2910 Hz	3000 Hz	3090 Hz
3 % Instrument Accuracy		2940 Hz	3000 Hz	3060 Hz
4 % Instrument Accuracy		2970 Hz	3000 Hz	3030 Hz
5 % Instrument Accuracy		3000 Hz	3000 Hz	3000 Hz

Due to the accuracy of the R2670 (�5%), the final value must be as close as possible to the specification of 3000 Hz (We recommend an error of no more than �20 Hz).

Procedure:

1. Verify that the "Digital Modulation Compensation" is adjusted properly using the procedure as outlined in the Quantar RSS manual "Aligning Reference Modulation Compensation, F7 "Align REF MOD2"

2. Perform "TX Deviation Gain Adjustment" in RSS Service Mode using the R2670 settings as described in the pre-alignment checklist. Input the highest of the +/- displayed deviation from the bar graph with smoothing enabled.

The goal is when step 2 is performed with the standard deviation test pattern enabled in the RSS that 3000 Hz be displayed as close as the R2670 allows.

3. Perform Check "Astro TX Align and Test" in RSS Service Mode with "Standard Deviation" enabled.

Step 2 allows you to confirm that the station "Wide Pulse" deviation is set to 3.0 kHz �5% and "Narrow Pulse" deviation set to 2.83 kHz �5% as displayed on the R2670 service monitor in "bar graph" mode with "Deviation Smoothing" enabled via the "expand" command. If the deviation is not adjusted properly, you must go back and readjust the deviation in step 1.

Note: If you lower the numbers that you entered in the TX Deviation Gain Adjust screen when you did the initial station alignment, this will cause the deviation to be higher. Lowering the entered deviation values by about 40 Hz should result in a 0.1 dB increase in deviation. Due to variations in the stations, a 40 Hz change may not always be sufficient. If no change is observed, you may need to increase the value slightly. Re-verify in the "ASTRO TX Align and Test" mode in the RSS that the desired nominal deviation has been achieved.

For additional information please contact SSC-System Support Center at 1-800-221-7144 and reference bulletin # S-0044

Information on R2670 service monitor:

Service Information Bulletin 003 February 16, 2001

Communications Test Equipment Sales Information Bulletin - "Deviation Smoothing"

In response to numerous customer requests, a new feature has been added to the R2600C, R2670A, and R2625A series of communications system analyzers. This feature makes aligning radios faster, easier, and more accurate by reducing the display fluctuations inherent in wideband deviation measurements. These fluctuations are typically caused by high frequency noise, and are most pronounced when making relatively small deviation measurements in the wideband RF mode.

The feature is automatically invoked when the analyzer is in expanded bar graph display mode. The bar graph display mode simulates an analog instrument and is useful when making equipment alignments and adjustments. It graphically presents the data contained in the RF Display meter area of the screen, including Monitor Deviation, Frequency Error, and Input Level. When in the EXPANDED screen, a special algorithm is implemented that effectively averages the readings and updates the measurement display approximately once every second.

All units manufactured after November 1st, 2000, including the new color display models has this feature as standard equipment. To verify a particular unit, check the firmware version number. You can access this information via the SPF function key. Highlight the VERSION label and select the DISPLAY TABLE softkey. The STANDARD version number should be 5.04.xxx or higher.

Units that do not have this feature can have it added during a standard calibration procedure or normal repair by the Motorola Test Equipment Service Depot. Please contact them directly at 800-323-6967.

This is an Informational Bulletin only.

No reference to warranty is implied or intended. Labor and parts warranty reference is limited to products sold in the United States. For products sold or in use Internationally this bulletin is for Informational Purposes Only.