Chapelrun,
It is difficult to compare signal levels and quality readings .....
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125°W AMC 21
...TP.......POL........SR.........dBm....IRD%......C/N.......AZBox Q%.....COOLSAT Q%
12140.....V........30000.....-57.6.....95.........13.0..........76...................76
12150.....H........14029.....-63.8.....80..........9.8...........59...................71
12163.....H..........4444.....-64.1.....92.........12.4..........75...................81
12169.....H..........4444.....-63.6.....87.........11.6..........70...................78
12175.....H..........4444.....-64.0.....91.........12.0..........73...................75(??)
12180.....V........30000.....-59.1.....96.........13.8..........79...................78
Please do not utilize this data for anything more than just a training excercise. ....
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I wish that all FTA receivers would adopt a meter style that displayed dBm readings and C/N ratios opposed to Q% readings. Even if they were not precisely calibrated and were just a rough reading with 10% or better accuracy, it would end a great deal of confusion for the end users.
We could then actually check each receiver's meter accuracy with a calibrated instrument and better judge the receiver's design quality from such. As it is currently, the signal level and quality level meters really mean very little unless you are comparing a Coolsat 5000 to Coolsat 5000 or an AZBox to an AZBox, etc. And then, you have to be sure that the firmware is matched as well!
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I agree that the S/Q reading comparisons between receivers are virtually meaningless. I would also suggest that the S/N or C/N figures from different meters, regardless of whether calibrated or not, would not be too meaningful either because I'm pretty sure that these readings are affected by the bandwidth of the particular receiver/instrument in question.
However, I was interested in your chart, mainly because over the past year or so, since AMC-21 became operational, I have been interested in why in general I have much more trouble with horizontal transponders than vertical, on this satellite, although it isn't always the case. Usually, there isn't too much difference, but the past two days, the 12150 transponder has been WAY down in quality relative to the vertical transponders. I noticed that it was a bit lower on your chart too, although not as much as I've been seeing, which is more like 80 for 12180, and 49 for 12150.
So I decided to do a comparison similar to yours, just for fun, but also thinking that my Twinhan results would be funny, since a STRONG signal is usually around 30 on it. Today though, the Twinhan was giving high readings for some reason. Oh well. Anyway MY CHART
Freq... Diamond ..Twinhan..Azbox.. Genpix-S/N ...TT-3200-S/N ...BL-1030-S/N
12140 .... 73 ...... 34 ........ 60 ........ 10.2 ............. 10.1 ........... 4.4
12150 .... 62 ...... 37 ........ 55 ........ 9.2 ................. 8.7 ........... 3.8
12163 .... 72 ...... 38 ........ 59 ........ 8.7 ................. 9.6 ........... 5.8
12169 .... 72 ...... 37 ........ 62 ........ 9 .................. 10.3 ........... 6.8
12175 .... 69 ...... 33 ........ 54 ........ 8.1 ................. 8.7 ........... 4.5
12180 .... 80 ...... 54 ........ 76 ........ 11.9 .............. 11.3 ........... 6.5
As you see the first three are quality readings, the last 3 are S/N readings.
But anyway, these reading are all over the place, when comparing receiver to receiver, but I'm mainly interested in the comparison between 12150, and the 2 vertical transponders. Turns out that today, it's all over the place even comparing different transponders on the same receiver. However, overall, as usual, the horizontal transponders seem to be generally worse than the vertical transponders for some reason.
I've long been confused about why horizontal just doesn't work as well on this sat for some reason. I've observed this with 4 different LNBs. I think once I even turned the LNBF 90 deg to see if it was a voltage issue (ie picking up V as H and visa-versa). Only thing I could figure is that since AMC-21 is fairly low in the sky for me, that perhaps the two polarities propagate differently when low in the sky. But now, seeing that 12150 is low for you too, perhaps it's just that 12150 is really just a bit less powerful?
But one more aspect of this. You really cannot make ANY sense out of comparisons of those 4444 SR transponders, even with the same receiver, because those 3 signals come from different places at different times. I've seen them be coming in very strong, then the signal will go off completely, then come back from a different uplink site, and be very weak, then go off, and come back up from a 3rd uplink site, and be moderately strong, then come back to the original uplink and be strong again. So you pretty much have to be looking at these 4444 signals at the same time to compare them, because even 5 minutes difference in time can mean a big difference. I'm starting to think that the same might be true of the 12150 signal as well, as I think that can be uplinked from different sites, whereas the 12140 and 12180 signals are always from the same place.
BTW, all readings are from my 3' Primestar fixed, with QPH-031 through a 4x1 diseqC switch, through an SG2100 motor, through more than 250' of RG6, with several barrel connector splices. The BL1030 values are additionally through a splitter, since it can't control a diseqC switch so I had to slave it, however I generally don't see much difference in S/N readings though a splitter, since it attenuates both.
I'm also curious relative to where your SuperBuddy readings were taken, because I've generally found that satellite meters only work well when close to the dish relative to close to the receiver. Just curious.
