Pointing Ku dish using Sun, not compass

[polgyver]

Finding the satellite azimuth by turning the dish could be time consuming and frustrating. For beginners, and not pressed for time, perhaps this trick would help? First, the data from dishpointer should be written down: coordinates of the area where the dish will be used, and the azimuth and elevation of the desired satellite. Next, google the words "Sun or Moon altitude" and find the web site which calculates azimuth of Sun and Moon in any chosen day and time. Interval 1 minute can be chosen. The coordinates of the town should be converted to degree - minute format (dishpointer provides degrees with 4 digit decimal fraction) and entered into the proper space. Time zone also has to be input (for example, Toronto is in zone 5, but in summer, zone 4 works). The calculated table should be scrolled until the needed Sun azimuth is found, and the corresponding hour and minute written down. A piece of string, or shoelace, should be attached to the top of the dish and the back of the LNB. At certain time, when the Sun is (hopefully) shining, the dish should be turned until the shadow of the string is in the exact centre of the dish. This position can be marked on the mast and bracket. Pictures follow.

 

[cyberham]

I used a similar method, differing only in that I found a program (Satellite Antenna Alignment) which I can run at anytime that gives the exact position of the sun at my location at every minute of the day. So I know from this program the exact time when the sun is at its peak elevation. Using the shadow cast is more accurate than trying to use the type of compasses we usually have, including adjusting for our local magnetic declination. Using dishpointer.com is good in theory, but there isn't much that's unique for me to reference to when using dishpointer.com; all trees look about the same in the fuzzy image.

Added: I should add that dishpointer.com clearly shows me after-the-fact why I can't get 123W or 125W. The LOS runs right into my neighbour's house! I wish I knew about this website before I installed. On the first sunny warm day, I'll be picking up my mini-tower, moving it about 15 feet and start all over again. But this time I know what I'm doing. It will be fun to see if USALS will work 15W through 125W.

 

[oblio]

Added: I should add that dishpointer.com clearly shows me after-the-fact why I can't get 123W or 125W. The LOS runs right into my neighbour's house! I wish I knew about this website before I installed. On the first sunny warm day, I'll be picking up my mini-tower, moving it about 15 feet and start all over again. But this time I know what I'm doing. It will be fun to see if USALS will work 15W through 125W.

Are you looking at just the azimuth to get 123w or 125w or allowing for the impingement angle of the sat beam when looking at your LOS. I understand you may be pretty low to the horizon for both sats but while I haven't used the feature, dishpointer is supposed to be able to give you the required set back distance and/or needed dish height to clear a known obstruction. Havng seen lots of working dishes looking like they are pointed directly at walls or trees or even pointed down to the ground, apparent obstructions may only be perceptual.


I find my dish and h to h motor will swing almost a full 180 azimuth arc but as a practical matter the horizon gets in the way too far e or w. With USALS being simply a programming function of the STB it rotates the dish left-right to whatever limits it has programmed or you've set. Haven't noticed as I don't use it much but it seems like USALS tries to move to the dish to any sat you ask it to and only gvies an error for an out of range sat when the dish can't move any more or its at the limit. Doesn't seem to have any programmed sense of the horizon based on user location. So I'd think no reason it can't mechanically swing 15w or 125w if dish is aligned e-w properly but whether or not you get reception on the higher dish skew sats is another discussion.

 

[cyberham]

I am considering both azimuth and satellite elevation. To be neighbour friendly, I had to move my dish location far down a steep hill in my backyard, 200 feet from the house. Visually, you might think I couldn't receive much from there low on the western horizon. The offset dish does appear to be pointing at ground and even into the hillside. But I can receive 121W well (ERT World on Ku when it was ITC). I've learned it's best to use tools and not try to guess what you will be able to see. dishpointer.com indicates I may only be able to see about 20 feet above ground at the neighbour's 2-storey house location. If so, the house blocks me to 125W for elevation reason. However, I think the easier-to-determine problem is that the azimuth runs through his house. By moving the dish about 15 feet to the south, I should be able to avoid both issues. I know I can get 125W since I received it from a different location at this property last year. Elevation of 125W for me is 11 degrees.

I read that USALS software has a limitation of as little as 40 or 50 degrees swing on either side of due south. I know this is not correct at least for my receiver / motor combination since I can use USALS for more than 65 degrees to the west of due south. I've also used it for 58 degrees to my east of due south. You're right...USALS does not consider satellite elevation in its calculation since its purpose is only to determine azimuth. Elevation-wise, if not for objects in the near ground, I can see beyond where satellite footprints will provide a signal for me. That is, azimuths for my +5 elevation points to the west and east are 133W and 7E. So elevation is not the limiting factor, satellite footprint is.

 

[hwm]

Finding the satellite azimuth by turning the dish could be time consuming and frustrating. For beginners, and not pressed for time, perhaps this trick would help? First, the data from dishpointer should be written down: coordinates of the area where the dish will be used, and the azimuth and elevation of the desired satellite. Next, google the words "Sun or Moon altitude" and find the web site which calculates azimuth of Sun and Moon in any chosen day and time. Interval 1 minute can be chosen. The coordinates of the town should be converted to degree - minute format (dishpointer provides degrees with 4 digit decimal fraction) and entered into the proper space. Time zone also has to be input (for example, Toronto is in zone 5, but in summer, zone 4 works). The calculated table should be scrolled until the needed Sun azimuth is found, and the corresponding hour and minute written down. A piece of string, or shoelace, should be attached to the top of the dish and the back of the LNB. At certain time, when the Sun is (hopefully) shining, the dish should be turned until the shadow of the string is in the exact centre of the dish. This position can be marked on the mast and bracket. Pictures follow. View attachment 72913View attachment 72914View attachment 72915View attachment 72916View attachment 72917View attachment 72918

Thanks for sharing this. Usually I just set the elevation very carefully, and slowly sweep the area of the sky my compass indicates is correct. Your method will be useful for dishes with elevation scales of unknown accuracy. I will print it out and put it in my FTA INFO notebook, along with Iceberg's Tips, and FaTAir's C-band Manual. The original post should be a sticky in the FAQ section.

 

[cyberham]

...I've learned it's best to use tools and not try to guess what you will be able to see. dishpointer.com indicates I may only be able to see about 20 feet above ground at the neighbour's 2-storey house location...

I realize now that dishpointer's obstacle height is calculated using the dish location as its reference, not the location of the obstacle. In this case, a 20-foot house sitting on a 30-foot high hill means that the house is not the problem, the hill is the problem. I realize moving the dish in its local area will never see over that hill. I can dedicate a different fixed dish much closer to my receiver and aim it exclusively at 125W and maybe catch 123W too.

 

[polgyver]

Thanks for sharing this. Usually I just set the elevation very carefully, and slowly sweep the area of the sky my compass indicates is correct. Your method will be useful for dishes with elevation scales of unknown accuracy. I will print it out and put it in my FTA INFO notebook, along with Iceberg's Tips, and FaTAir's C-band Manual. The original post should be a sticky in the FAQ section.

Thank you for words of appreciation. I, too, used to sweep horizon with dish, and it was time consuming. Regarding the FAQ section, I hope that the site of Naval Observatory Sun or Moon Altitude/Azimuth Table: Locations Worldwide — Naval Oceanography Portal would be popularized and used much more, also with its Moon data. Cheers, Polgyver

 

[Conky]

more good stuff polgyver. any prole can use an iphone but it takes a real MacGyver to use a shoelace and the sun

maybe for your next project you could build a homemade dish using a cardboard and aluminum tape Fresnel lense

 

[polgyver]

I realize now that dishpointer's obstacle height is calculated using the dish location as its reference, not the location of the obstacle. In this case, a 20-foot house sitting on a 30-foot high hill means that the house is not the problem, the hill is the problem. I realize moving the dish in its local area will never see over that hill. I can dedicate a different fixed dish much closer to my receiver and aim it exclusively at 125W and maybe catch 123W too.

I believe,when searching for obstacles, nothing can substitute your presence under your dish and looking up towards the Moon from behind of your dish at certain day and time. This Naval site can also provide you with minute-after-minute positions of Sun and Moon. I do not know your exact location, but assumed you are in Halifax area. Coordinates of this city are 44 deg 39 min ; 63 deg 35 min. Satellite 125 has azimuth 249,1 and elevation 11.4 degree in this city. On Jan.14, 8.53 AM, the moon (70 % face) will be at azimuth 249.1 with elevation 13.1 - almost 2 degrees above your satellite 125. Moon's face, similarly like Sun's is seen at the angle of half a degree, so, to imagine location of satellite, you have to look below Moon's face 3 to 4 its diameters. Next day, Jan. 15, at 10.04 AM, the Moon (59 % face) will be at the same azimuth, but the elevation will be only 5.9 degree. If there will be no clouds (and it is big IF ...) you could estimate the best location for your tower, just looking towards the Moon at these hours. Cheers, polgyver

 

[Andrew K]

Sometimes when I look at the numbers that I get from Dishpointer, it's hard to get a real idea of what these numbers actually represent. Like if it tells me the satellite is 25 degrees above the horizon, that angle may be hard for me to eyeball. Isn't the sun's position in line with the satellite arc on the autumnal and vernal equinox?

 

[Jim S.]

Isn't the sun's position in line with the satellite arc on the autumnal and vernal equinox?

Not quite. There's a parallax effect because the satellites are only 23000 miles away vs. the sun at 93000000 miles (and the celestial equator at infinity, but 93000000 miles is far enough to ignore that for our purposes), and because you're not at the equator (unless you ARE at the equator.)

From around 40 degrees north latitude, the sun tracks the satellite arc around the first week of March and the first week of October. You can figure exact times for your location, and even for the beamwidth of your dish, at Sun Outage Calculator

 

[cyberham]

I believe,when searching for obstacles, nothing can substitute your presence under your dish and looking up towards the Moon from behind of your dish at certain day and time...

It's going to be 10 degrees F tomorrow morning...before the wind chill is added. Doubt I'll be outside looking for the Moon. Your method with the Moon would be good to use. Back in October, I was using the Sun's afternoon positions since it was closely approximating the arc's location. At certain times of the afternoon, I'd run outside and I could fairly accurately tell where each satellite was located based on the sun's position at that moment. Now with a little more experience, I'm not sure why I had so much trouble (read lack of experience then). I could probably put my dish anywhere now within reason and lock onto satellites in a fairly short time since I know the angles, azimuths, elevations and transponders to go use.

 

[polgyver]

It's going to be 10 degrees F tomorrow morning...before the wind chill is added. Doubt I'll be outside looking for the Moon. Your method with the Moon would be good to use. Back in October, I was using the Sun's afternoon positions since it was closely approximating the arc's location. At certain times of the afternoon, I'd run outside and I could fairly accurately tell where each satellite was located based on the sun's position at that moment. Now with a little more experience, I'm not sure why I had so much trouble (read lack of experience then). I could probably put my dish anywhere now within reason and lock onto satellites in a fairly short time since I know the angles, azimuths, elevations and transponders to go use.

Take heart, cyberham, the Moon will be behind satellite 125 on Saturday, January 14, not today nor tomorrow, and the temperature probably will be more friendly, 30 t0 40 F. Moon shows behind satellites sometime 10 to 15 times a year, more often that Sun (2 times a year), and does not endanger the observer's eyes.

 

[polgyver]

more good stuff polgyver. any prole can use an iphone but it takes a real MacGyver to use a shoelace and the sun

maybe for your next project you could build a homemade dish using a cardboard and aluminum tape Fresnel lense

I am not sure if Fresnel rings, made of aluminum tape (width : about 50 mm) would reflect electromagnetic waves 25 mm long - the waves would get rather dissipated, not reflected. Waves of sunlight, hundreds of microns long, could reflect OK, but I doubt the rings could be shaped properly by amateur.

 

[cyberham]

Take heart, cyberham, the Moon will be behind satellite 125 on Saturday, January 14, not today nor tomorrow, and the temperature probably will be more friendly, 30 t0 40 F...

Saturday morning: Temp: 35 deg F. Variable cloudiness.
Sunday morning: Temp: 10 deg F. Wind chill: 0 deg F. Cloudy periods. :

 

[skysurfer]

I am not sure if Fresnel rings, made of aluminum tape (width : about 50 mm) would reflect electromagnetic waves 25 mm long - the waves would get rather dissipated, not reflected. Waves of sunlight, hundreds of microns long, could reflect OK, but I doubt the rings could be shaped properly by amateur.

I don't recall the design construction elements, but I saw a fresnel lens satellite dish article from some magazine in the 1980's. I may have to try to find it and do some calculations. I know I wanted to possibly build one when I saw the article but I concluded the satellites were too weak back then to make it work (and a used 10' popped up not long after my desire for a fresnel lens dish). With the power of today's satellites, I bet the project is more likely to succeed.

 

[cyberham]

...On Jan.14, 8.53 AM, the moon (70 % face) will be at azimuth 249.1 with elevation 13.1 - almost 2 degrees above your satellite 125...

Total cloud cover this morning. No chance to view the Moon. I'll check again tomorrow morning. Not a good day...the wind storm last night snapped off the top of a 70-foot tall tree bringing down my HF wire ham antenna suspended from the top of the tree. But the antenna survived!

 

[AcWxRadar]

Not quite. There's a parallax effect because the satellites are only 23000 miles away vs. the sun at 93000000 miles (and the celestial equator at infinity, but 93000000 miles is far enough to ignore that for our purposes), and because you're not at the equator (unless you ARE at the equator.)

From around 40 degrees north latitude, the sun tracks the satellite arc around the first week of March and the first week of October. You can figure exact times for your location, and even for the beamwidth of your dish, at Sun Outage Calculator

The site that Jim provided the link for is the system/calculator that I use and recommend.

If you want to evaluate your site for the best possible location to install a dish, this is the tool that you need to use. Other methods work, but this one provides the installer (you) with direct visual feedback regarding any LOS obstructions. You can personally see first hand where the satellite is located in the sky, rather then assuming that the calculations are correct. It is a foolproof method to judge the optimum installation location.

On-line calculators do not and can not take into account your specific landscape. Trees and power poles and buildings, etc. are not considered in these calculators. Using the sun's position in the sky when the sun is in alignment with the satellite in orbit is the most effective method to locate the satellite and determine if there are any obstructions to the LOS.

The solar alignment only occurs twice a year (early March and October). That is somewhat restrictive, but there are several days each time that this occurs so you can generally have plenty of opportunities to evaluate your installation location.

I don't think that it is a particularly great tool for actually aligning the dish to pick up the satellite signal. It will only provide you with a generally good feel as to where to start aiming, but the fine tuning requires much more finesse. You must rely upon the angle calculators to set your dish and motor angles correctly from the start, then you must rely upon the signal quality registering on your IRDs signal meter and expressly the QUALITY meter. From this point forward, it is all patience and persistence.

The spring solar alignment is a couple of months off, but this is a good time to revisit the subject so that people can prepare for it properly. You need to familiarize yourself with the solar outage calculator and how to fill in the blanks. Then, you need to select the best locations on your property for your dish installations. When the solar alignment time comes, then you can evaluate each of the sites that you selected in advance and pick the best one based upon the true LOS properties.

This is a GREAT tool as it not only serves it's purpose for alignment issues, but you really get a good feel for where every satellite is located in the sky. You will be surprised where the satellites actually are (how high) in the sky. It really will open your eyes and provide you with a most valuable bit of information.

Be sure to select LOCAL PC (personal computer) time when you use the calculator, providing that your PC time is accurately set. This will eliminate the need for time corrections and calculations that may be confusing.

I had to utilize this solar calculator to determine the location of Hispasat @ 30W as this sat was low in elevation to my eastern horizon. There were tall cottonwood trees on my neighbor's property that I had to aim in between. This calculator helped me locate the best position to set my dish so that it could have a LOS through the trees and capture this satellite's signal.

I recommend getting your research on this started now so that you are prepared when the actual solar alignment occurs. Especially if you have a lot of trees or buildings to contend with. You can set your fixed point dishes or your motorized dish to get just about every satellite up there if you use this tool. Obviously, your dish or dishes may have to be further from your home to do this and sometimes there may be no place on your property that work out. But, at least you will be able to see why.

RADAR

 

[cyberham]

...Next day, Jan. 15, at 10.04 AM, the Moon (59 % face) will be at the same azimuth, but the elevation will be only 5.9 degree. If there will be no clouds (and it is big IF ...)...

Cloud cover! I did see the Moon at 9:00 a.m. local when it was 15.6 @ 237.5 azimuth. Tomorrow the Moon will be too low on horizon to see at 249 azimuth. Maybe next month! I agree this is the best way to know your elevations/azimuths. Like somebody pinning a photo of each satellite in the sky.

 

[polgyver]

Cloud cover! I did see the Moon at 9:00 a.m. local when it was 15.6 @ 237.5 azimuth. Tomorrow the Moon will be too low on horizon to see at 249 azimuth. Maybe next month! I agree this is the best way to know your elevations/azimuths. Like somebody pinning a photo of each satellite in the sky.

Well, big "IF" came up unfavourable... The Moon as a reference sign has some flaws, compared to Sun (which is rightly recommended by Radar). Moon can show up in some months at very inconvenient hours, or can have very little or no face, thus hard to locate. Another flaw is that its altitude (elevation) changes by 4 - 6 degrees from day to day and therefore one needs to imaginatively visualize satellite by allowing one or two diameters of the Moon above - or below it. But because of this big jumps in altitude, the Moon returns to given satellite area more often than Sun, maybe 15 times a year or so (this I would have to check more exactly). The Sun changes its altitude by day very slightly, probably less than half a degree, and there are 6 - 8 consecutive days to check your obstacles. Very rarely dense clouds would be an obstacle for so many days in a row. Therefore, if in February the Moon would not help again, the Sun in March will - for sure. Cheers, polgyver