Acceptable Tuner 1 - Tuner 2 signal level difference?

Discussion in 'DIRECTV HD DVR/Receiver Discussion' started by ColdCase, Jan 18, 2019.

  1. ColdCase

    ColdCase AllStar

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    I’ve done a little searching but don’t seem to find exactly what I’m looking for relevant to SWiM equipment, and I may be confused. Seems some say the receiver’s reported signal levels can be inconsistent between tuners. Just wanted to double check if I should relax or I have a potential receiver or SWM16 problem that I should be troubleshooting.

    I have a decade old HR22-100 and a newer HR24-500 both connected to a SWM-16 which is connected to a recent but legacy Slimline 3 LNB (via 4 coaxes). I think one DVR is connected to one half of the SWM16 and the other to the second half.

    I noticed a bit of pixelation sometimes on the HR24 so I tuned up the antenna pointing which improved the indicated signal levels. Not perfect but better.

    But as I was massaging the pointing I noticed HR24 tuner 1 signal levels are 3 to 12 points lower than tuner 2. The two HR22 tuners are showing the same signal level +/- 1 point on all three satellites and their transponders. HR24 tuner 2 is a couple points higher than the HR22 levels on all satellites except 99CA where its the same. On the average, tuner 1 99CA is 12 points, 99CB is 1 point, 103CA is 5 points, and 103CB is 4 points lower than tuner 2. Signals are mostly in the low 90s or high 80s. 101 provides a much higher indicated signal, in the 98-100 range, and I don't see any tuner differences.

    Its been awhile since I’ve looked at this carefully, but is this typical HR24 behavior? Could it be a poorly performing tuner (or indication) or could it be the SWM-16 or coax (but the same coax feeds both tuners)? Hmmm…. lots of possibilities.

    I think some of the flakey HR24 behavior I’ve been seeing is due to it being so busy error correcting a poor signal, hopefully tuning up the pointing will fix that enough. I’ll probably be switching to a reverse band LNB this summer, so as long as its working OK I may just let it sit.
     
  2. carl6

    carl6 Moderator Staff Member DBSTalk Club

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    It would either be in your HR24 or in your SWM16. Swap the two coax going to the HR22 and the HR24 (at the SWM16) and see if the symptoms move to the other DVR. If they do, then the problem is in the SWM16. If they don't, they remain with the original DVR, then the issue is in that DVR (or coax from DVR to SWM16).

    If it were in the dish or coax from dish to SWM16, you would expect the symptom to be the same on both units.

    If you have unused ports on your SWM16, you can also try just moving the HR24 coax from the pair of outputs it is using to another pair of unused outputs and see what happens.
     
  3. jimmie57

    jimmie57 Hall Of Fame

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    Everything I have ever read and diagrams I have seen just show 1 coax from the SWM box 8 or 16 just connects to a receiver with just 1 coax.
    ?????
     
  4. dreadlk

    dreadlk Hall Of Fame

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    There is just one coax from the splitter for each receiver so the problem cannot be the cable.

    Doing some troubleshooting some things can also be eliminated.

    Since the HR22 is showing the normal 1-2 point difference that would probably mean that the SWM 16 is good. It is possible that it has bad channels on the SWM but the likely hood that the HR24 always gets them on one tuner and not the other makes it unlikely.

    The single cable and splitter port cannot be bad as that would effect both tuners on the HR24.

    The LNB is also good since the HR22 and one tuner on the HR24 are working fine.

    The fact that 99CA is using an I.F Frequency between 1880MHZ to 2120MHZ while 99B is between 274 to 514MHZ is also a telling sign as any defects in a circuit are more likely to show up at higher frequencies.

    IMHO that means your assumption that something is wrong with tuner one on the HR24 is probably correct.
     
  5. James Long

    James Long Ready for Uplink! Staff Member Super Moderator DBSTalk Club

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    The cable could be having issues passing certain frequencies.
     
  6. slice1900

    slice1900 Well-Known Member

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    While I agree that a bad tuner in the HR24 is the most likely scenario, there are other possibilities like James Long said so I'd try a couple simple tests.

    First, swap the cables at the SWM16. If they are connected separately as indicated switch them - but remember you will have to move the power inserter to the other DVR location unless it is separately connected to the SWM PWR port in the middle.

    If the problem disappears, it is an issue with one half of the SWM16 (for all practical purposes it is two SWM8s in a single unit) If the problem remains, try swapping the location of the HR22 & HR24. If the problem follows the HR24 you know it is the HR24 that's at fault, otherwise it must be some sort of issue with the cable/connectors.
     
  7. carl6

    carl6 Moderator Staff Member DBSTalk Club

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    Oh yeah, a duh moment. Sorry.
     
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  8. dreadlk

    dreadlk Hall Of Fame

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    Then the problem would show up on both tuners.
     
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  9. James Long

    James Long Ready for Uplink! Staff Member Super Moderator DBSTalk Club

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    Not with SWM, Each tuner is using a different part of the bandwidth on the cable. This is not the 1990s legacy 500MHz band stacking arrangements. (Defective cable on legacy band stacking usually showed up as certain transponders being weaker than others. SWM frequency stacking assigns a tuner to each SWM channel on a coax where a defect could affect an individual tuner.)

    One would need to know which SWM channel was being used for each tuner. There could be cable damage that affected one SWM channel more than another SWM channel. There could also be some other source of interference that would affect one channel more than another.
     
  10. dreadlk

    dreadlk Hall Of Fame

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    I fail to understand what your trying to say. What does it matter what part of the frequency spectrum is running through the cable. It's ONE cable, if it can pass 2120Mhz through the cable to one tuner it can pass it to the other tuner. If one SWM channel was damaged or even multiple channels the chance of the same tuner picking up the same bad SWM channels on each test is very very unlikely. Maybe I am missing something in translation. I have a spectrum analyzer at work I can bring it home and take some screen captures of the various channels but I know on my system the dbm of the signal is not going to vary much channel to channel it would probably only be useful on his setup but i suspect that it will also show no variation as the HR22 he has shows none.
     
  11. James Long

    James Long Ready for Uplink! Staff Member Super Moderator DBSTalk Club

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    I assume your system is working well ... so I'd expect you to have good signals across the entire spectrum used on the coax. If you want to believe that a problem as described absolutely positively cannot ever be a problem with the cable then there really isn't much more to say.

    This would not be the first time I've heard an "it can't be" that was possible. I'll agree that it is unlikely - but I would not completely rule out the cable until it is eliminated from the equation.
     
  12. dreadlk

    dreadlk Hall Of Fame

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    Nothing is ever 100% certain but when you repair stuff you have to exclude the highly unlikely and focus on what is likely. He could try swapping receiver locations and put that HR24 onto the HR22 cable but it would be surprising if it made any significant difference.
     
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  13. P Smith

    P Smith Mr. FixAnything

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    Ditto !

    That assumption of damaged cable what affect only 50-60 MHz window from 0 to 3 GHz range have a probability close to absolute nil !
     
  14. veryoldschool

    veryoldschool Lifetime Achiever Staff Member Super Moderator DBSTalk Club

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    Ah Yes... That rat hole


    "Numbers" come from CNR,

    What hasn't been mentioned is Noise
     
  15. dreadlk

    dreadlk Hall Of Fame

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    I can measure the SNR / CNR with the same spectrum analyzer but that is also going to show the same numbers going from SWM channel to SWM channel. The logic behind Noise is going to run into the same brick wall as the signal just being lower. The actual signal reading you get from the receiver almost acts like a SNR measurement. If the OP is still reading this just switch around the receivers and lets see what happens.
     
    Last edited: Jan 21, 2019
  16. P Smith

    P Smith Mr. FixAnything

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    It's CNR (in term of DTV). I did post a graph of conversion CNR values from sat tuner to "signal strength" values on IRD setup screens.
    Sets of both values/pairs been taken from debug logs of DTV IRDs.
     
  17. dreadlk

    dreadlk Hall Of Fame

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    Thats some good stuff, where did you post it. I would love to see it.
     
  18. P Smith

    P Smith Mr. FixAnything

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    it will require use Search button here ;)
     
  19. Rich

    Rich DBSTalk Club DBSTalk Club

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    I'd like to see a link to that good stuff.

    Rich
     
  20. dreadlk

    dreadlk Hall Of Fame

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    I think he is talking about this thread and post #7
    SNR/CNR to the receiver's reported "signal strength"

    It's kind of Generic data from what I can see, but I did not look at the whole thread.

    BTW Directv does not use CNR but instead uses SNR as that is what the data from the AIM meter outputs. Not any real difference but I just thought I would clear that up.
     
    Last edited: Jan 22, 2019

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