I was a little frustrated that if the algos are freely available to any manufacturer, whether they pass compliance or not, why shouldn't STAB simply publish these in the open literature? It's possible the Moteck site that BJ found has effectively done this, because it agrees completely with the Pansat 9200HD until an obvious bug appears. I did not try to unwind their code.But, I am left with a question here. If the USALS calculations and equations are freely available to all manufacturer's of receivers, then why would a difference exist? Do you suggest that the manufacturer's are using their own modifications to the USALS algorithm?
I think the simplest explanation is the USALS calculations may use a zero declination offset, or consider the direct rotation to the satellite position. Unfortunately neither of these is a good fit for a properly adjusted dish mount. It's also possible they didn't want the added complication of having the user enter the declination angle into the receiver, or having the receiver tell the user how to adjust the declination angle. That would be a major departure from having to only enter one's lat and long.
This argues that all implementations should use the approved algorithms. In fact it would be silly not to use them and still try to get STAB's approval. One factor is that USALS was developed in a Euro-centric environment. I have no direct experience with dishes there, but my sense is they tend to be smaller and generally cover a smaller arc compared to FTA here. I don't want to over-generalize, so my apologies if this last statement is unfounded. However if there is an element of truth to it, the USALS algorithms may have been developed with this mindset and the verification would then be a natural fallout.In order for any receiver to sport the USALS official logo, they have to pass the USALS lab tests to verify the integrity of the receiver and adherence to the USALS math program.
The Winegards have a beamwidth of about 2.4 degrees, which will be more tolerant of pointing errors than the 1.2 m I used with a beamwidth of 1.4 degrees. You do have a valid question whether different receivers have different implementations. That was concern of mine and one of the reasons I brought my work to the forums. I have seen off-hand comments over time that indicate I am not the only one seeing these issues.I have both motors, a PowerTech DG-280 and a DG-380, and I am using a Coolsat 5000 receiver to control them. All my dishes are Winegard DS-2076 models. The LNBF's are Invacom QPH-031. I do not have a Pansat 9500HD receiver to compare my results with, but I do not seem to detect any discrepancies in the tracking with this receiver and setup. Just FYI.
Did you compare the results with your Pansat 9500HD with another receiver? With more than one receiver?
I only have a Pansat 9200HD as a standalone receiver. As there is no receiver that does everything I want, it was a reasonable compromise as it could do HD, H.264, DVB-S2 and blindscanning, albeit on DVB only. I only use this for hunting and playing. I also have five USB/PCI receivers for our 'operational' uses. One of the primary reasons for this research was to weed out the software applications that cannot properly send DiSEqC commands and motor positionings. Unfortunately that has proved to be every one I have tried. I am now writing code snippets on Linux to do this right. If I can find the time, I will write a full-up application.
The Pansat 9200HD has all the proper DiSEqC 1.3 and USALS logos.I find your discussion very informative and interesting as I recently tested a Sonic View 360 Premier receiver and it was not very accurate when USALS mode was implemented. I will not go into the entire details of what I found, but I will state that it was basically unusable until I had recorded several satellites using DiSEqC positioning first. Then, I was able to set other satellites to utilize USALS positioning and they appeared to be fairly accurate in locating the satellites. It seemed that the positioning algorithm in this specific receiver required more input from the user (me) in order to calculate the position of all satellites. That indicated to me that this receiver was not using a true form of USALS. It also did not display the official USALS logo.
With my Coolsat 5000, this does not appear to be the case. Once I have aligned the dish to one satellite, my true south satellite, it was able to determine (position) the motor accurately to all other satellites.
Pendragon, does the receiver in question, the Pansat 9500HD, have an official USALS logo? If it does not, I submit that they may not be utilizing an accurate positioning program. Maybe they are using a GOTO X program, as one possibility. Something that closely emulates USALS, but is not as accurate.