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Microwave interference on ESPN, ESPN2, HBO HD

Discussion in 'DIRECTV Installation/MDU Discussion' started by AntAltMike, Nov 27, 2012.

  1. AntAltMike

    AntAltMike Hall Of Fame

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    I have a DirecTV Commercial Public Viewing system that is getting blasted by some kind of microwave interference. It is in a ten story Washington, DC hotel, about a mile to the north/north-northeast of National Airport and ten blocks west of the White House. I installed a SWM-5 dish there and connected two H-25s to it about two months ago.

    They have reported intermittently having the signals degraded to unwatchable on ESPN and ESPN2. Lodgenet provides the free to guest channels there from 1.2 meter, Alaska/Hawaii dishes using Pro:Idiom QAM, and they are experiencing the same HD reception symptoms on their ESPN, ESPN2 and HBO-E channels in the guestrooms. Those are the only DirecTV based HD channels in their system. We, of course, cannot access HBO in the lounge.

    I moved the dish 30 feet but am experiencing the same problem there. It is intermittent, but chronic when occurring.

    For testing, purposes, I swap the SWM-5 LNB for a SLM-5, which lets me see nearly one fourth of the transponders at one time on my Blonder Tongue, BTSA-5 spectrum analyzer. Over a testing interval of about five to ten minutes, I occasionally saw what looked like a powerful radar sweep when the spec analyzer is calling for 22 KHz, 13 volts, which should include Ku 110 (Sat C) and 119 (Sat B) odds and, if my memory of this system serves me correctly, the 103 slot odds. Would someone confirm for me the Ka satellite and polarity that is selected by 22KHz/13 volts?

    Each time I saw the severe radar sweep going through the 22KHz/13 volt spectrum, I would toggle the voltage and tone selectors but did not see that interference on any of the other three sets of waveform displays. My spec analyzer was set to show 950-2,200 MHz on the screen and I didn't bother to drop the frequency range to try to see the Ka low (250-750 MHz).

    I saw this exact same symptom over a decade ago on a DirecTV Ku dish about three blocks away on another ten story hotel owned by the same hotelier. It was first reported to me in late July or early August of 2001, and continued to about late 2001 or early 2002. Back then, it appeared on the 101 (Sat A) degree evens, and it wiped out the HBO standard definition programming, which was on either transponder 30 or 32 at the time. Visually, it was obliterating the whole 950-1,450 MHz Ku spectrum then, too, but as I recall, all the other important programming was being carried on odd numbered transponders and they were not affected, and disruptions of other even transponder programming were not reported to me, even though they were surely occurring.

    Unfortunately, it was not possible for me to simultaneously view the channels on a TV screen and view my spectrum analyzer to observe the disruption, and it isn't even possible for me to definitively say that none of the other three combined bands were similarly disrupted because I just can't make the instant comparisons that I'd like to. The interference subsided and when it didn't return during about the next five minutes, I discontinued this testing.


    Can anyone tell me the polarities of the transponders carrying those three channels? I got this transponder information from forum member gtc's "Transponder Maps:..." sticky thread in the DirecTV Tips and Resources sub-forum ( TPN_MAP_Domestic_13921_121121.xlsx ), but I can't determine the Ka band transponder polarities from it:


    Code:
    ESPN 99C TID 136 VPID 1010
    ESPN2 99C TID 136 VPID 1050
    HBO 99C TID 130 VPID 1020
    According to Lyngsat, ESPN2HD is on 103C, whereas the Transponder Maps ESPN2 table entry says it is on 99C. The Transponder Maps thread incorporates the term "New Data 11/21/2012 " in its title, whereas the ESPN2 entry in the Lyngsat table was updated by c hoffman on 120119, which I think means 01/19/12 to us American civilians.

    For what it is worth, the last time I visually checked Lodgenet's three channels in a guest room, their ESPN and HBO were horrendous but their ESPN2 was perfect, which is more consistent with ESPN2 being on a different satellite. Does the H25 menu enable me to select a single transponder test of the channel that the receiver was tuned to before entering signal test? I remember some earlier receivers that sometimes included that test feature, but I also remember that during their lifetime, DirecTV had "updated" receiver software and taken that feature out.


    I had tried to mitigate the problem back in 2001 first by moving the dish, which was on a non-pen mount, around the rooftop mechanical room, using it as a shield, but it made no difference, leading me to conclude that this interference was coming from aerial-based or look-down radar. Then, in desperation, I set up a dish in the parking lot and dropped a 150 foot coax down to it. Down there, the intensity of the interference was less severe, but still created unacceptable degradation.

    I made a couple of informal requests for assistance to the FCC but they never replied, and then, nearly six months later, the problem went away on its own.

    And for those who have not yet considered this, it began a month or so before the 9-11 attacks, leading me to suspect that it may have been part of an intensified effort to detect an airborne threat.

    Anyway, last night, I lagged a j-tube mast to the inner wall of the cinder block structure surrounding the rooftop cooling tower, so I will try using a dish there that is physically shielded by cinder block from all sides and wait and see what is subsequently reported to me. The interference had subsided by the time I got that mast installed, so I wouldn't have been able to definitively pronounce on the efficacy of that shielding even if I had connected it to their satellite SWM downlead.

    I haven't spent much time studying the operation of the H25, but I see that the HD channels are accessed using the same channel numbers that are used for those same channels in standard definition systems, meaning that ESPNHD, for example, is on 206, as is ESPNSD in standard definition receiver channel tables. That differs from how the channels were numbered back when I was installing H10s and H20s, when the HD versions of channels were numbered in the 70s and 80s and the STD versions were simultaneously accessible. Since it is possible that the standard definition Ku transponders are not being disrupted by this interference, it there any way for the users of this system to still access them? For now, it would be preferential for this customer to "downres" his viewing to standard resolution if the problem recurs during an important sporting event.

    If I am not able to remedy this problem, I will have to consider switching this customer to DISH Network if I can establish that DISH Network HDTV signals are reliable there.

    Here's an interesting thought. Since I only observed interference when I has selected 22 KHz but this customer is not using the 110 and 119 degree signals, I could cover over the 110 and 119 degree waveguide openings with tin foil and maybe that will help, and if it does, then I would replace the SWM-5 LNB with a SWM-3.
     
  2. veryoldschool

    veryoldschool Lifetime Achiever Staff Member Super Moderator DBSTalk Club

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    Lots of squirrels here.

    Yes the voltage/polarities are:

    no tone 13 volts = 101 & 99 odd, & 18 volts even
    tone is the same but for 103, 110, 119

    There isn't anything on 110 that we use and 119 is mostly for local SD spots.

    Sounds like you need to look at the no tone 250-750 band for the ESPN problem channels.

    No the new receivers don't default to the tp & SAT they were tuned to for signal levels.
    They can be tuned to a SAT & tp in the signal screen in the setup menu.

    If you're seeing a sweep, this type of RADAR is a search RADAR and the only airborne doing this is an AWACs, which I doubt it flying overhead.
    Search RADAR doesn't use the 18-20 GHz band.
    "Back in the day" search was 2-4 GHz & attack was ≈ 10 GHz.
     
  3. AntAltMike

    AntAltMike Hall Of Fame

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    I wasn't able to ascertain the transponder numbers for those channels from either of the transponder tables I looked at. Do you know what they are, or how to find out what they are?

    I did also see occasional, near instantaneous, fixed frequency radar zaps on the Ku band spectrum, which are probably part of the normal incoming flight identification and which probably disrupt no more than one video frame and go unreported.

    I'm figuring that either a harmonic or composite is being developed, or perhaps this invasive radar is in the L-band and corrupting the block-downconverted signal

    We used to pay Microwave Filter Co. $700 a pop for the filter that we installed between the wave guide and the LNB to mitigate the AWACs radar. The notch filters to mitigate the telephone company's L-band interfering carriers (1030 and 1090 MHz) were a lot cheaper and easier to implement.

    Back when I had previously addressed this problem in 2001, I was hoping that what I was seeing on my spec analyzer was a harmonic or composite of an out-of-band interfering signal, and that perhaps, if I could insert some tuned chamber between the waveguide and LNB, I could sufficiently mitigate it, but no one made a discrete LNB that had the right amount of heterodyne shift to match the DBS frequencies.


    And the remaining unanswered question: Is there a way for the customer/receiver operator to access the standard definition, Ku-based ESPN with these H25s?
     
  4. veryoldschool

    veryoldschool Lifetime Achiever Staff Member Super Moderator DBSTalk Club

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    Sure, change the guide preferences from hide SD duplicates to either show both or hide HD, and the channel numbers are the same [mapping].
     
  5. HoTat2

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    Not sure why you couldn't find the transponder numbers listed under the "TPN" column of gct's Excel sheet map. :confused:

    But anyhow ESPN HD and ESPN2 HD are both on 99c (CONUS beam from the D11 satellite) transponder 13.

    HBO HD East is on 99c (D11 CONUS beam) transponder 7.

    This places all three channels in the Ka B-band range or 250-750 MHz odd channel set of the LNB output.

    NOTE: Even though 110w is not used for CONUS channels, its nationwide beam is to be used for SD channels for Puerto Rico. So your SA should still indicate signals from 110's three even transponders 32, 30, and 28 (12, 10 and 8 in LNB translation) when the LNB control signal is 18v/22khz.
     
  6. kenglish

    kenglish Icon

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    Can you try covering all of the dish feeds with foil, and see if there is any interference showing up on your analyzer? It might be L-Band, getting in to the LNBs, or through the cables. You'd want to look at a split of the cable, down near the receiver location, with the rest of the receivers still connected, to determine if it's coming in via a bad cable...not right at the dish.
    Might even be something like TV Broadcast Auxiliary ("Live Shot") microwave, in the 2 GHz band, if it's really intermittent/rare.

    If it's 11 GHz microwave, you might try a small dish and LNB, handheld or on a camera tripod, and an analyzer. Move around the roof, and try different locations, to see if you can determine the direction it's coming from, using things like other buildings or mechanical rooms, as shields.

    You might also see if it's coming from a nearby microwave oven, using the same techniques.
     
  7. AntAltMike

    AntAltMike Hall Of Fame

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    It is occurring on two different antenna systems: mine and Lodgenet's, and theirs uses RG-11 that is protected by conduit. If the LNB cases are not shielded inside, then it is possible that the offending signal is leaking into the downconverter or amplifier circuitry directly, rather than through the wave guide.



    That's what I tried a decade ago, but to no avail.
     
  8. AntAltMike

    AntAltMike Hall Of Fame

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    Bad news in that regard. DISH Network ESPN and ESPN2 are broadcast from orbital slots 110 and 119, which is the direction where I suspect the interference is coming from, and worse, they are Ku and I saw the strongest indications of radar interference on the Ku 11950 to 1,450 spectrum, so the prospects of DISH Network HDTV being less vulnerable to this interference than DirecTV is seem nil.
     
  9. SomeRandomIdiot

    SomeRandomIdiot Godfather

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    Exactly how far from 1600 Pennsylvania is this? The RF on all frequencies out of there is insane. Drive around that block with a portable spectrum analyzer and stuff spikes with mains and harmonics everywhere. A simple radar detector has a mental breakdown right around there.
     
  10. Tisby

    Tisby AllStar

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    What about a drone? Several municipal PDs have them now, though most aren't using them... yet. I'd bet DCs PD does though. It'd suck if that's the problem because I'm not sure how you'd fix that, have to build some type of foil cover or something.
     
  11. veryoldschool

    veryoldschool Lifetime Achiever Staff Member Super Moderator DBSTalk Club

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    I very much doubt they're carrying RADAR.
    The "big ones" might, but they're not going to be that powerful and it can be used to target them, so they'll be using "other sensors" for their mission.
     
  12. speedy99

    speedy99 New Member

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    So is there any updates to this issue ? did you find your source of interference or another solution ?
     
  13. AntAltMike

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    They haven't called me back, but that could just mean that the interference has not been observed during an important sporting event since then. The Monday Night Football game was simultaneously carried on WDCA, so even if there was interference on ESPN, they might have been watching it on the local channel.

    A commercial A/V installer told me he can no longer use UHF remote controls in that area, He said they transmit at around 410 MHz. I don't know if that was the frequency of the DirecTV remotes or of some other master remote.
     
  14. kenglish

    kenglish Icon

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    You might find an FCC engineer, with a little time on his hands, who'd love to check this out. They have some really good analyzers.
     
  15. Floyd

    Floyd Legend

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    Here are some more suggestions:

    1. Try both SWM and non-SWM to see if there is any difference.

    2. I think all the LNBs are metal inside, and are thus shielded, so to see if maybe the cables running to the receivers are getting ingress, hook up a receiver right near the dish.

    3 When the problem is happening, do any of the transponder levels degrade on the receiver signal strength screen?

    4. If you can see the problem exibiting, take an aluminum window screen and use it as a shield to see if any of the suspect interferrence can be blocked. If it's like the old days the microwaves came from point sources.
     
  16. SomeRandomIdiot

    SomeRandomIdiot Godfather

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    I was on 14th Street last week a few blocks from the WH and driving by several hotels. Could not remember exactly where you said yours was (west, not east of WH). Verizon via iPhone 5 could not even hold a data or voice signal in the area. LTE had 1 bar at best but disappeared every few feet. 3G showed up much more than LTE, but dropped off within a few seconds. The unit constantly showed no signal period.

    That area is just horrible for interference.
     

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