Tracking adjustments... Part 1
The following posts will deal with the actual adjustments to make to get your dish to track the arc. Due to the length of the info this will be spread out over a few posts. It is advised to read through all the info before attempting to align the dish. Alignment of the dish will take time so plan to have an afternoon of good weather, (Maybe even a weekend,) so you can concentrait on what you are doing and take your time. Remember to make small adjustments. By small I mean only a quarter turn on bolts at a time when fine tuning. You will not actually see the dish move doing these small final adjustments, however it does move and can be the difference between a signal and no signal. Moving the dish a hair down here can be a hundred miles by the time the distance to the bird is covered. If you don't seem to get anywhere, take a break and get away from it. Come back later starting from the beginning and try again. Clear thinking and progressive adjustments will get you the best possible signal. Have a great day!
Initial adjustments and settings
Set declination/elevation.
Move the dish to the highest point in its travel arc, i.e. centering the dish at
its zenith. Do this by using the actuator; it can be done by visually looking at
the dish. It is now time to set your declination/elevation angles. I use a common carpenter's inclinometer,to set angles. First set the elevation angle, it is measured on the polar axis (sometimes the elevation angle is called the polar axis angle). By elevation, it means the angle in degrees which the dish must be tilted up from the horizon prior to addition of the declination angle. Use az/el charts to get total elevation for your latitude location then substract the declination value for your latitude location and the remainder is the elevation angle to set in this step. (NOTE: The true dish pointing angle is the angle given by all az/el calculation programs and is in fact the sum of the zenith elevation angle (when the dish is at the top of the arc) plus the declination offset angle therefore substract the declination offset angle from the zenith az/el value to get the zenith elevation angle. This is not very critical at this point because you will adjust this angle for best reception later but be as accurate as possible. Next, set the off-set angle on the polar mount, this is the declination. This is an adjustment that tilts the dish 'forwards' at an angle depending on what latitude you live. This adjustment is usually measured on one of the mounts connected directly to the dish, i.e. in the plane of the dish but on its back ring, it depends on your type mount. (In practice, use az/el charts to get total zenith elevation angle, i.e. from the ground to the dish face, for your latitude location and this will be the value to set in the declination adjustment.).
Set magnetic deviation.
Align the polar axis to the true north-south line for your site (don't forget to
adjust for magnetic deviation and to apply the deviation to the correct 'side' of the north needle on the compass) and check that the satellite dish mount cap is vertical on all sides after you tighten it. Tighten the dish on the mount, then loosen it just enough so it will turn. Sometimes, though, the weight of the front of the dish will typically cause it to drop a little so that the mount cap will not be plumb - this is especially true if the pole diameter is in centimeters and the polar cap is in inches; when this happens, Jam a screwdriver between the pole and cap until the cap is plumb then tighten the cap bolts. NOTE: Sometimes the act of tightening mount cap bolts will cause the dish/mount to rotate slightly so after tightening mount cap bolts check that the dish is still aligned to the true north-south line.In case you haven't used a compass in a while, remember it's a circle, 360 degrees. Zero is North, East is 90, South is 180 and West is 270. Put the needle on North and pick something in the distance that is in line with North. Make sure the needle moves freely as you turn the compass around and that it is not too close to the dish or anything metal. It may help you to tie a string to the mount and walk out away from the dish. Line your compass with the string and have someone hold it, or tie it to something such as a rod in the ground. When you
are behind the dish, this will give you a reference to work with. Remember, the dish will look south if you are in the northern hemisphere and will look north if you are in the southern hemisphere and will look straight up if you are on the equator
Align azimuth for azel mount satellite.
If you are using an azel mount, i.e. not a polar tracking mount, then you will
align the azimuth setting to the true heading (not the magnetic heading) of the satellite you are seeking and proceed to azel elevation setting.
Programming sats and tracking
Program first satellites.
Move your television and satellite receiver to a table near the dish, if
possible; it will save time from running in the house to look at the image then go outside to make dish adjustments. Begin with a satellite that is located as close as possible to due south of your location (if in the northern hemisphere and otherwise locate a satellite due north if you are in the southern hemisphere), this is the highest point of the arc and it is easiest to accurately adjust the polar axis angle (elevation angle) from this position. (A few degrees off will not make much difference because the dish moves almost flat in the center of arc.) It is usually best to look for a C-band satellite when you begin (if you are working with a C/Ku system), they will be easier to find than a Ku satellite; however, try a Ku satellite because the accuracy your system will have will be much greater if you tune to Ku satellites although Ku satellites are more difficult to find initially - if you have a Ku system only, of course, look for the nearest Ku satellite due south of your installation. The quickest way to track a dish, though, is to program all the C-band satellites first then put in the Ku satellites. If the elevation setting is way off or if the magnetic adjustment is way off, you might not find this first satellite. If so, while having the dish located at the highest point of the arc (due south), you have to turn the entire polar mount on the ground pole until you 'hit' the satellite.- this is where using a spectrum analyzer comes in handy. If you do not have a spectrum analyzer, then set the receiver to 'scan' mode (you will find a button, switch, on the back of the receiver to accomplish this) so it will rapidly scan the channels and you will be sure not to miss an active transponder as it flashes across your TV screen. If your first satellite is not at the top of the arc, or near to it, continue with this procedure until you locate the top of the arc satellite; always program all satellites you find into the receiver, as you find them, and do not forget to use the skew adjustment to fine tune polarity. When you find a satellite, take the receiver off scan mode and check with a current copy of your local satellite TV guide to confirm which satellite you have found. Remember to adjust the polarity to its best at each satellite and program into receiver.
Program azimuth-elevation satellite.
If you are using an azel mount, i.e. not a polar tracking mount, then you will
have aligned the azimuth setting to the true heading (not the magnetic heading) of the satellite you are seeking and in this step you will raise (lower) the elevation setting to the elevation of the satellite you are seeking and you will be finished with your installation except for fine tuning the two settings.
Fine tune north-south alignment (tracking the sides of the arc).
After you are satisfied with the elevation and declination adjustment at the top of the arc, it is time to program middle and end of the arc satellites. This is where most people fail. DO NOT adjust any elevation angles on the mount at this point! Choose the side where the satellites are lowest on the horizon and move the dish, using the actuator, to each consecutive satellite from the top of the arc to the lowest one you can find. Peak the dish on the satellite, the lowest on the arc you can locate, using the actuator. Next, push or pull upwards and downwards on the dish (remember not to stand in front of the signal so as to block incoming signal). You don't have to use much force, just a bit to see if the signal gets better or worse when you push/pull on the dish. What you are actually doing is changing the elevation angle a bit. For instance, if the dish is pointing at a satellite to the east of center and you have to push up on the dish to get a better signal, then the elevation angle must be adjusted higher. At this time, you adjust this by turning the entire mount to the east (to the west if you are in the southern hemisphere) and not by adjusting either the elevation or declination angles! Most errors in tuning a satellite system are due to improper north/south alignment. To repeat, if the dish needs to be pulled down (lowered) for a better signal, then turn the mount the opposite direction (towards the higher point on
the arc) and if the dish needs to be pushed up (lifted) to get a better signal,
then rotate the entire mount away from the top of the arc. BE SURE TO MARK, using a piece of chalk or place a strip of masking tape on the pole and mount cap, the pole and mount to know exactly where your original position is - rotate the mount only SLIGHTLY (no more than 1/16inch ). Note from the chart, a very small movement on the pole can translate to a very large amount in degrees of rotation. Best method to rotate the dish is to barely loosen the cap bolts then stand in front of the dish and grasp the lip of the dish with both hands and gently move the dish in the desired direction. Then retighten the cap bolts, checking that mount cap is still plumb, and mark the new cap position on the pole. After moving the mount, use the actuator and move the dish east/west as necessary to peak the signal on each satellite encountered. Observe the results on a satellite at each end of the arc and at the top of the arc after each mount adjustment. Repeat this procedure
until the dish has the correct north/south alignment, as you do this you should be able to locate the satellite lowest on the arc if you could not find it at first. Always go back to the top of the arc to make sure it is still in view and always check the satellites on the low ends of the arc. If you peaked the dish for center, and then for one side, and the center is still in view then the other side should be very close, of course, this will depend on the ground pole being vertical and offset angle/elevation angle settings.Remember, when you rotate the mount on the pole, each satellite will need to be reprogrammed into the receiver as rotating around the pole changes the location of the satellite in respect to the memory of actuator setting (per satellite) internal to the receiver. If, when the end of the arc satellite is in view and the top of the arc satellite is not in view, then the elevation angle adjustment is grossly wrong and you have to readjust the elevation angle and repeat the procedure until you get one side of the arc, including the top, all in view and programmed into the receiver. If you suspect your elevation adjustment is grossly wrong, go back to the first satellite, the one at the top of the arc, and adjust the elevation so that the satellite remains in view when the mount is set back to its true north-south axis then repeat procedures of this step. Ideally, what you want in this step is to be able to see the entire arc (even if the dish is not hitting center on either ends or the top); what you are looking for at this time is a compromise on the north/south setting that allows all satellites, from end to end, to be in view. After this compromise is reached then it is time to fine tune elevation/declination settings. Always, as you move the dish from side to side, stop at a couple of satellites in the middle and at the top to monitor your adjustment effects.