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6.7 - Antenna Pointing & Peaking, 1.8 Meter

Creation date: 10/27/2020 2:48 PM    Updated: 3/21/2023 1:43 PM   odn field services manual service manual excerpt
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Antenna Pointing & Peaking, 1.8 Meter

(Section 6.7 in ODN Field Services Manual)

Pointing a 1.8M VSAT requires basic hand tools; for our standard Skyware Global 1.8 Meter VSAT you will need:
  1.  Ratchet Wrench (1/2" Drive) with 10mm, 19mm, 24mm, & 30mm deep sockets
  2.  10mm Nut Driver
  3.  10mm Open End Wrench
  4. 1.25" Adjustable Crescent Wrench
  5.  Small Carpenter Level
  6.  Clinometer or pitch finder
  7.  Compass
  8.  Smart Phone w/ GPS capability for finding Lat/Long coordinates & calculating pointing angles. These instructions assume you have access to a GPS-based satellite locating app such as Android “Sat Finder.” The app should calculate Azimuth angle, Elevation angle and polarity angle (also called LNB skew) from the site’s location.
  9.  Laptop computer w/ RJ45 jack or w/ USB to RJ45 adaptor for accessing modem GUI & entering Lat/Long coordinates or other parameters for proper modem setup & troubleshooting.
  10.  Satellite meter that is compatible with DVB-S2 signals and can identify satellites*
*There is also a basic signal strength meter in the user interface of the modem if an external meter is not available. This requires a laptop connected to the modem via ethernet in such a way that it can be clearly viewed by the technician while at the antenna.


Pointing Procedure:
Alignment with the satellite is obtained by setting Polarization, Elevation, & Azimuth in that order, and then fine-tuning all three.

Polarization of Feed – Initial Setting = Rotate feed to Calculated Angle
Tip- Do not waste time attempting to find a satellite until the feed polarity angle is adjusted for your location! 


   
   [Figure 6.7.1]                                                              [Figure 6.7.2]

  1.  Use a Satellite Finder app to calculate your feed polarization angle (LNB skew)
  2.  Loosen feed horn clamp bolts just enough to rotate the feedhorn, but still tight enough to keep the feedhorn from sagging.
  3.  Rotate the feed toward the + range if you are east of the satellite or use the - range if you are west of the satellite. [Figure 6.7.1]   Note: Echostar 105 is @ 105.0 degrees West longitude.  105 West Longitude is roughly at Denver, Colorado.  
  4. For initial setting, align marks by sight on the horn scale to indicate your calculated + or - LNB skew. 
  5. Fine tuning will be accomplished later via meter or NOC assistance after the antenna is pointed.

Elevation - Initial Setting

   
   [Figure 6.7.3]                                                              [Figure 6.7.4]

  1. Use a satellite finder app to determine your target elevation angle.
  2.  Subtract the offset angle of the reflector (22.6) from the satellite’s elevation angle to determine the angle that should be measured on the clinometer or “pitch finder”.
  3.  Place a clinometer on the edge of the mounting bracket that is parallel to the back of the reflector. The gauge should be oriented so that it would read “0” if the antenna reflector axis were pointing at the horizon. [Figure 6.7.4]
  4.  Adjust the elevation by turning the elevation screw adjusting nuts [Figure 6.7.3] until the calculated elevation is obtained.
  5.  Optimum setting will be achieved during the fine tuning.

   [Figure 6.7.5]

[Figure 6.7.5] is a measurement from a pointed central Missouri antenna. The target elevation angle is 37 degrees, so the (EL-22.6) angle measured at the bracket is 14.4.

When properly pointed, the reflector will appear to be “looking” lower than the satellite’s position in the sky. This is because of the -22.6-degree offset. [Figure 6.7.4]

Azimuth - Initial Setting

   
   [Figure 6.7.6]                                                              [Figure 6.7.7]

  1. Use a satellite finder app to determine your target azimuth (east<>west) heading.
  2. Connect RF cable from LNB to satellite meter, or the modem RX input and setup monitoring in such a way that the meter can be seen clearly by the technician adjusting the antenna.
  3. Equally tighten the four mast bolts just until snug, so that the reflector can rotate with slight resistance.
  4. Rotate reflector/mount assembly on its mast, pointing it toward the correct compass reading. Slowly sweep the antenna azimuth until a signal is found. [Figure 6.7.6]
  5. If the desired signal is not found, slightly increase, or decrease elevation setting and repeat the azimuth sweep.
  6. Fully tighten mast bolts at the point where the highest signal strength is achieved. [Figure 6.7.7]

      
   [Figure 6.7.8]                                   [Figure 6.7.9]                                  [Figure 6.7.10]

Connect RF RX cable to LNB [Figure 6.7.8]  & peak signal strength either by portable meter [Figure 6.7.9] or modem graphical user interface. [Figure 6.7.10]

Fine Tuning

  1. Using a portable satellite meter or the signal meter available in the modem GUI, [Figure 5.7.10] alternate between elevation and azimuth fine tuning to reach maximum signal strength, until no improvement can be detected.
  2. Azimuth is fine-tuned by adjusting the two nuts on the azimuth adjustment bolt. [Figure 5.7.7] Initially, top plate bolts must be tight enough to make the assembly secure but just loose enough to allow small amount of azimuth motion.
  3. When AZ/EL fine tuning is complete, gradually but fully tighten all hardware while observing signal strength. Minor AZ/EL adjustments may need to be made again if some signal is lost when tightening the mechanics.
  4. Fine tune the polarity by making very minor rotary adjustments to the feedhorn until its orientation is at the center of its peak signal position. [Figure 5.7.2] This aspect of the tuning is more important than it seems because improper polarity skew can cause interference on other transponders of the same satellite. When finished adjusting, do not over-tighten feedhorn clamp bolts; high torque is not necessary. Assembly is made of aluminum, and any deformation will degrade the signal.

Provisioning

After the antenna is pointed, the modem is installed, and you believe the signal is peaked, call the ODN NOC to confirm and activate the site. The NOC will validate the signal quality and may request further antenna adjustments if necessary, before activating the data service at the site.

Before you call:
  • Have a computer logged into the modem GUI. The modem GUI is browsable via 192.168.222.222 if the ipv4 settings of the computer are set to 192.168.222.223 subnet mask 255.255.255.0
  • Have the modem serial number available.
  • Be ready to provide the lat/lon coordinates of the site.
  • Leave access to the antenna in place, as you may be asked to do a “push-pull” procedure or make mechanical adjustments.
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