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6.6 - Antenna Pointing & Peaking, 1.2 Meter

Creation date: 10/27/2020 1:57 PM    Updated: 3/21/2023 1:47 PM   odn field services manual service manual excerpt
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Antenna Pointing & Peaking, 1.2 Meter

(Section 6.6 in ODN Field Services Manual)

Pointing a 1.2M VSAT requires basic hand tools; for our standard Skyware Global 1.2 Meter VSAT you will need:
  1.  Ratchet Wrench with 13mm and 10mm sockets
  2.  13mm open ended wrench
  3.  Small bubble level
  4.  Clinometer or pitch finder
  5.  Compass
  6.  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.
  7.  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.
  8.  Satellite meter that is compatible with DVB-S2 signals and can identify satellites or ODN Gen2 Satellite modem for pointing.

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 6.6.1]                                                              [Figure 6.6.2]

  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 6.6.1] Note: Echostar 105 is at 105 degrees West Longitude.  105 degrees 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.  [Figure 6.6.2]  - Polarity Skew of +30.6 pointing from central Missouri
  5. Fine tuning will be accomplished later via meter or NOC assistance after the antenna is pointed.

Elevation - Initial Setting

   [Figure 6.6.3]

  1.  Use a satellite finder app to determine your target elevation angle.
  2.  Loosen elevation pivot bolts and bolts in curved slots (both sides) of AZ/EL housing approximately 1 complete turn.
  3.  Turn elevation adjustment bolt clockwise to decrease elevation and counterclockwise to increase elevation.
  4.  Align the edge of the clamp with appropriate mark on housing at the desired elevation reading. [Figure 6.6.3] This will be an approximate setting. Optimum setting achieved when fine tuning with a meter.
  5.  When properly pointed, the reflector will appear to be “looking” lower than the satellite’s position in the sky. This is because the antenna has an 18-degree offset. [Figure 6.6.4]
NOTE: Degree values shown on bracket Elevation Scale are accurate only if the mast is plumb. If the mast is not plumb, then a clinometer can be used to find the true elevation angle, but the measurement must compensate for the antenna offset angle, which is -18 degrees. With a clinometer or “pitch finder”, measure the edge of the mounting bracket that is parallel to the back if the reflector. [Figure 6.6.5] The gauge should be oriented so that it would read “0” if the antenna reflector were pointing at the horizon. Take the target elevation and subtract 18. Set the elevation by clinometer as per that new calculation. Pictured (below right) is a measurement from a pointed central Missouri antenna. The target elevation angle is 37 degrees, so the (37-18) angle measured at the bracket is approximately 19.

   
   [Figure 6.6.4]                                                                     [Figure 6.6.5]


Azimuth - Initial Setting

   [Figure 6.6.6]
  1.  Use a satellite finder app to determine your target azimuth (east<>west) heading.
  2.  Connect RF cable from LNB to sat signal strength 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. Rotate reflector/mount assembly on its mast, pointing it toward the correct compass reading. [Figure 6.6.6] Slowly sweep the antenna azimuth until a signal is found.
  4.  If the desired signal is not found, slightly increase or decrease elevation setting and repeat the azimuth sweep.
  5.  Temporarily tighten half clamp (mast) bolts and set screws at the point where the highest signal strength is achieved.

      
   [Figure 6.6.7]                                   [Figure 6.6.8]                                  [Figure 6.6.9]

Connect RF RX cable to LNB [Figure 6.6.7] & peak signal strength either by portable meter [Figure 6.6.8] or modem graphical user interface. [Figure 6.6.9] The pair of examples shown are from the same 1.2M antenna.

Fine Tuning

[Figure 6.6.10]
  1.  Using a portable satellite meter or the signal meter available in the modem GUI, alternate between elevation and azimuth fine tuning to reach maximum signal strength, until no improvement can be detected.
  2. Azimuth is fine tuned by loosening the (4) carriage head bolts and swivel nut which allows adjusting the azimuth fine tune bolt for the peak signal. [Figure 6.6.10]
  3.  When AZ/EL fine tuning is complete, tighten all AZ/EL hardware. Torque mast clamp hardware in alternating sequence. Recheck and repeat torque on four clamp bolts until they are equally torqued to 18 ft-lb.
  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. 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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