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RF (Antenna) plumbing

Discussion in 'Electronic Design' started by Don Y, Dec 31, 2011.

  1. Don Y

    Don Y Guest

    Hi,

    [hoping this is the right place to ask]

    I'm trying to organize the antenna feeds at home. There are
    two separate antenna -- TV + FM. And, two CATV feeds (one
    acting as a spare). These will, in some combination, feed up
    to ~15 drops throughout the house through a set of splitters.

    Of course, "what goes where" can change over time. So, I
    want to be able to "rewire"/replace the splitters as the
    need arises.

    My current plans are to terminate the source feeds and one
    end of *each* drop in male F-connectors at a "patch panel" (of
    sorts) consisting of double threaded (female) F-connectors.

    Then, connect the sources to splitters (i.e. for each source)
    using male-male "patch cords" and the splitters to the drops
    with similar patch cables.

    It is unlikely that every drop will ever be driven from any
    single splitter. Worst case would probably be an 8-way.
    In practice, probably 3 or 4 -ways.

    I'm using RG6 and the longest drop is probably ~70 feet.
    So, I figure roughly 5dB in the cable and ~10-12dB in the
    (8-way) splitter(s).

    I figure I can insert a small wideband, in-line amplifier
    ahead of each splitter to compensate. And, a power injector
    *immediately* downstream of that (no mains power available
    nearby).

    Schematically (fixed width font), something like this:

    _
    V (antenna, CATV, etc)
    |
    |
    |
    +-> >< <====> >AMP< <====> >INJ< <=+
    |
    |
    --> >< <==============> >-S |
    : : : P |
    --> >< <==============> >-L-< <====+
    : : : I
    --> >< <==============> >-T


    where "<===>" are patch cords terminated in male connections
    and "><" are the double female connectors.

    My questions:

    Is it *worthwhile* to use female F-connectors on each cable
    instead of a male connector screwed into the double female?
    (the male+female+path approach is a bit easier to assemble)

    Are there practical consequences of using the various (short)
    lengths of "patch-cords"? (i.e., instead of tying feeds/drops
    directly to the splitters/amps)

    I assume the double female connectors should be mounted on an
    insulated plate so that the grounding is dictated by the
    particular splitters/drops?

    If the splitter passes DC (i.e., power), I imagine it is still
    not advisable to locate the injector on one of the drops? (i.e.,
    pushing power back *through* the splitter to the amplifier)

    As the amplifier is relatively low power, I assume I can just run
    a (long... ~50 ft) length of zip cord to get power to the injector?

    What sort of bandwidth should I plan on for the CATV feed and
    its amplifier? (I figure ~1GHz for DTV+FM)


    [Apologies for any delay in my replies as end-of-the-year equipment
    upgrades have me working without full news feeds, etc]

    Thx,
    --don
     
  2. Joerg

    Joerg Guest

    Yikes! That many teenagers? How did you do that?

    :)

    That will make it expensive if you want to do it properly.

    We have a fairly large home run distribution at our house. My rule:
    Cable ends always get male F-connectors, every module in the
    distribution has female jacks. That includes filters and such.

    Out here: Every line that goes to TVs and such has its own driving amp,
    usually gain 0dB(a buffer). Ideally these are source-terminated, meaning
    a gain of 6dB plus a 75ohms series resistor at the output. You cannot
    rely on TV sets to provide clear 75ohms terminations. Usually they
    don't. Plus someone might unplug a TV and then you've got reflections
    into the other lines if there is no bufer amp to isolate the rest of the
    system.

    If you change anything on the input side make sure a 75ohm terminator
    gets plugged into any F-jack that is now open.

    Don't know about cable, we only have OTA and our amps go to 900MHz. But
    they roll off gracefully.
    Last but no least: Designers of consumer electronics generally no longer
    know what a third order IP is. They probably think it's some sort of
    patent. So if you have large signals coming in via the antenna they
    might swamp the TV set. Such signals can be out of band, for example a
    160MHz police repeater, air band, 900MHz stuff. Or in-band.
     
  3. Joerg

    Joerg Guest

    Them thar erriall fer gitten the ballgame on da teevee :)

    Neat! If that had existed 10 years ago I've have spared myself some
    busted knuckles. OTOH I needed them shielded anyhow, no plastic cases.
    We have a separate digitally controlled UHF modulator fed by the DVD/VHS
    player.

    What, you are an analog guy and you don't make your own filters? That's
    like buying pizza at the supermarket. Tsk, tsk, tsk.

    Ours routes to a vacant UHF channel.
     
  4. Your diagram depicts what I have for OTA Tvee (except I have a mast
    mounted amp). Works well in the fringe area where I am.
    But Jim is correct, you need a distribution amp for that many drops.
    FYI 100' RG6 on my Directv dish works fine too.


    Cheers
     
  5. Don Y

    Don Y Guest

    Hi Joerg,
    <grin> No (*thankfully*!). There are actually ~twice that
    number of drops. Most rooms have more than one -- to allow
    kit to be relocated ("Let's put the TV in *this* corner!
    No, on second thought, how about *that* corner??") without
    cables trapsing along floorboards, etc.

    Also, the four feeds effectively have four *drops* located in
    the equipment closet. I've been trying to move all media
    to distribution "over IP" (instead of wired antennae, cable,
    etc.). But, it will be a while before I hook up the DTV/CATV
    decoders (havent even *started* the design of the video clients
    until I sort out performance issues for the *audio* clients)

    However, I haveno intention of leaving all that kit for any
    "future owner" of the house so I want, as a fallback, to just
    be able to point to "traditional" cable drops ("You can hook
    up your TV/HiFi here. Or here. Or...")
    Not a big problem. So far I've spent $0 (had 1,000 ft of RG6
    plus a collection of splitters, F connectors, etc.). Biggest
    issue is the "mechanical" one -- figuring out what needs to
    be mounted and how to arrange it in a serviceable manner.
    OF, that's consistent with what I've drawn. The only distinction
    is that I have a "module" that does nothing more than provide wiring
    convenience: the "patch panel" -- at which almost *all* of the
    connections are made.
    Ah, OK. I have terminators on all unused "jacks" (as well as the
    unused splitter outputs). But, the buffer amp is a much nicer solution!
    Presumably I can find these for in-line (remote) deployment? Recall,
    I don't have mains power available where I want the interconnects to
    reside. Then, the question of grounding through the power source
    raises its head...? (I am *perpetually* nervous about grounds)
    The amplifier I'm currently using runs to 1000MHz with splitters
    spec'd at that (or twice that). But, I have no idea what CATV
    uses/requires.
    I tried to select a fairly directional antenna for the DTV as virtually
    all of the transmitters are colocated at the same facility. Probably
    less than 10 miles as the crow flies -- so, lots of signal (when the
    trees aren't blowing! :-/ )

    Thanks and have a Happy New Year!
    --don
     
  6. Joerg

    Joerg Guest

    Same here, but I see that differently. It hones my prototyping skills
    and I chalk it up as "continuing education". Besides, when I met my
    girlfriend who is now my wife she was always quite impressed that I
    could fix or build just about anything she threw at me. Got to keep up
    that reputation :)

    Yet an other reason is that when one sits on the keister in front of the
    computation machine all day long that will, over the years, foster a
    certain "rotundness" which ain't healthy.

    [...]
     
  7. Don Y

    Don Y Guest

    THat's the problem. No attics or basements, here. And, the house
    floorplan is very "open" so few places to hide things. The *best*
    place for a wiring closet I have set aside for all of the
    networking/automation stuff alongside the servers. Unfortunately,
    making wiring accessible (for change) uses up a lot of space!
    E.g., my current network cabling design puts the cables in a
    *drawer* so I only use ~3 inches of vertical space to support
    the full panel (48 points).

    Since (aside from inline amplifiers) the antenna/CATV wiring
    doesn't need easy access and can tolerate harsher envirnments,
    I've tucked this in the "ceiling" (i.e., flat roof) where I
    can get to it if I *really* need to (e.g., to rewire which feeds
    go to which drops) -- but don't *expect* to need access.
    I have four drops (for the four feeds) running to the equipment
    closet. One of the feeds is a spare (in case a problem develops
    with the CATV feed) and the corresponding *drop* is likewise.

    E.g., assuming no wire failures, I can run the cable feed directly
    to the wiring closet (e.g., for a cable modem) and then *back* to
    the main wiring hub (on the spare drop).

    Of course, that then reduces my ability to cope with future wire
    problems/needs :>
     
  8. Joerg

    Joerg Guest

    Easy fix: A (removable) bridge in the fist wall box and running a cable
    over to the next. And the third if there is one.

    Yeah, keep it simple. That's what I tried to do. I ran four cables to
    each location which was overkill but not expensive. Just harder to pull.
    The phone runs are not used and might never be. The LAN is, because WLAN
    is iffy and slow. Then two coaxes each, one for back-feeding.

    Hint: Leave a few feet of service loop for each. In case you screw up an
    F-connection later. Cheap insurance.

    Ah, forget it. Even if you rip all this out when moving, afterwards
    it'll sit in the new garage and collect dust. BT. Still have the PBX
    from a previous residence. Guess where it lives? Right, in a garage cabinet.

    Yeah, but to do it properly that's not going to suffice. You'll need
    buffer amps, splitters, filters and other additional hardware. Which
    either costs money or time if you roll your own.

    Just keep in mind that this is RF stuff. Everything needs to be a clean
    75ohms no matter what's connected or disconnected. A hard reflection
    roaring back into the system can blue-screen lots of digital TV channels.

    Usually they cannot be cable-fed but, of course, you can make or buy DC
    splitters. But I strongly suggest mounting everything in a central
    wiring closet. That is how I did it here.

    You'd have to call your cable company on that, an engineer there. If
    there are mandatory converter boxes in front of every TV they might use
    higher frequencies. I believe regular cable doesn't go past 1000MHz
    (that one would be channel 158).

    Or just hang a spectrum analyzer to you cable and look.

    We've got tons of signal but multipath screws it up, big time. Analog TV
    was better than DTV. Way better.


    Same to you, and lots of good health. Since they say the world will end
    in 2012 <snicker, snicker> we put this in the fridge to celebrate:

    http://en.wikipedia.org/wiki/File:Unibroue_-_La_fin_du_monde.jpg

    In English it means "The end of the world" :)
     
  9. Joerg

    Joerg Guest

    So do we, because our dogs demand that. But that is hardly enough to
    prevent rotundness :)
     
  10. Joerg

    Joerg Guest

    Attic space or cathedral layers can be a lot hotter than a garage.
     
  11. Gary

    Gary Guest

    "Don Y" wrote in message news:jdnpc1$v3s$...
    Modern digital cable plants top out at somewhere between 850MHz and 1GHz.
    Most are at 850MHz. The tricky part is the cable is bi-directional; the
    set-tops transmit signals back to the headend for interactive services
    (video on demand, for example).

    If you're with cable company such as Comcast, the return path is below
    100MHz, maybe even below 54MHz (my memory is fuzzy). Cable modems use this
    same path for the upstream data.

    If you're on FiOS, a technology called MoCA is used (Google it). MoCA
    essentially creates an Ethernet type LAN (or LANs) above 1GHz (1.1GHz isn't
    unusual, but it does change). It is used for communication between the set
    top boxes, the router, and the ONT. MoCA is able to pass through
    splitters - it can go in one "out" port and come out all the other ports.
    Of course, there is significant loss when it goes through splitters, but it
    is designed to work with typical home coax networks.

    So, if you want the return path to work, make sure you use the right
    splitters and amplifiers that match your service provider. For cable
    companies, make sure any amps have a low loss upstream path. For FiOS, be
    careful with splitter and amp selection, as they shouldn't block the high
    frequency MoCA signals.

    If you spend some time with Google and Wikipedia, you should be able to get
    a good idea of the frequencies and technologies in use by your particular
    service provider.

    -Gary
     
  12. Guest

    You're looking at the problem backwards. Use the TV as furniture anchors.
    Tell her to plan where the TVs go and that will anchor the rest of the
    furniture; no more rearranging parties ever few months. ;-)

    "Yeah, the sofa would look good over there, but then we couldn't see the
    TeeVee. Besides, the big game is on. Get me a beer."
     
  13. Don Y

    Don Y Guest

    Hi Joerg,
    When I was framing the walls in the kitchen, I thought of that
    approach. But, figured it didn't buy me much in terms of
    savings. On the downside, it would have been "puzzling"
    for a future homeowner to sort out. And, would have made
    it difficult to cram all the cables in each box (even if you
    restrict yourself to daisy-chaining -- one "in", one "out")
    as I have network and phone drops in every box as well as
    "bits of electronics" in many cases.

    As i is, I opted for *very* deep boxes and selected ones with
    built-in cable clamps (instead of the traditional ones) as that
    allows the "clamping screw" to be accessed from inside the box
    (contrast this with traditional clamps that locate the screws
    exterior to the box -- inaccessible for "new work" boxes once
    the walls are in place!). So, I could "push back" the extra
    service lop cable *outside* the box (into the wall cavity)
    instead of having to leave it coiled up inside the box
    (RG6 has a reasonably large bend radius).
    Wire is cheap. If you are at a point where you *can* pull, the cost
    (effort) to pull several is nothing compared to the cost of having to
    pull a *replacement* (or additional) later!
    I ran CAT3 for the phones - mainly because that was cheaper (free!) than
    buying a spool of "quad". But, that's there "for future owners" as the
    phones here are moving to VoIP -- like everything else!

    [The goal here is to get rid of all the "kit" lying around the house
    as well as centralize its maintenance. Let the house know what you
    want -- on demand or algorithmically -- and then let *it* get it to you,
    wherever you might be.]
    Yup. See above. I was even considerate of *how* each cable entered each
    Jbox to try to anticipate kinks, twists, etc.
    I trashed the PBX ears ago. :> But, the multimedia and automation
    aspects of the system are reusable "as is" (forget the "wire" and
    other infrastructure aspects -- they're disposable). You wouldn't
    discard your hifi/tv/{cd,dvd collection} just because your address
    changed? :>
    So far, it looks like the buffer amps are the missing ingredient.
    The bigger issue is making sure it doesn't have to be done over
    (or -- GASP -- *relocated*!)
    That's why I took the time to add the terminators, etc.
    (though I much prefer your solution! more "resilient")
    Not an option. The only available space is set aside for the media
    server and networking kit. I've already stolen damn near every
    conceivable "nook" for other things. E.g., the telco wiring sits
    in the furnace "closet"; automation system in a false ceiling in one
    of the closets; access points are currently fighting for spots in the
    skylight wells (I had wanted to put them *behind* these wells -- in
    the ceiling -- but fear the radios wouldn't tolerate the heat).

    The annoying thing s the "wasted"volume in some of the HVAC soffits
    that can't be exploited (without adding a very VISIBLE "access panel").
    We don't have cable service (there's nothing on TV that is worth
    the time that could be spent on something more interesting/productive).
    My efforts there are mainly intended as a courtesy to any future
    homeowner (or, if I ever become an old couch-potato-fart! :> )
    Agreed. We have an *almost* perfect line-of-site to the towers atop the
    (nearby) mountain. But, a neighbor's tree wreaks havoc with things in
    high winds, rain, etc. (I could *probably* work around this -- just
    barely -- if I wanted to locate the antenna on the rooftop at the other
    end of the house... but, that makes it more visible, harder to cable,
    more prone to lightning, etc.)
    Huh? You mean it didn't end as predicted LAST year??

    --don
     
  14. Joerg

    Joerg Guest

    I ran CAT-5 everywhere because it's so cheap. Got two 1000ft boxes to be
    able to do the double pull. I'll never use them up in this earthly life
    of mine. Same for the two RG6 spools.

    If you ever come across something reasonably priced that can replace
    this %#&@!! X10 stuff let me know. Right now it also won't let me put
    CFLs on the times lights because it's all triac switched in the wall
    switches.

    [...]

    I use this kind, two of them:

    http://www.homedepot.com/h_d1/N-5yc...splay?langId=-1&storeId=10051&catalogId=10053

    Mine are 0dB from input to each output when terminated.

    Just do not assume TV or VCR to be a 75ohm load.

    Make the access panel a speaker or something. Then it has a more mundane
    and acceptable primary purpose :)

    [...]

    The western method would be a chain saw :)

    No, Senor Camping did roll the rev level to rev B but that didn't pan
    out either. And the AGW crowd will keep their predictions well in the
    future so that they can try to milk some more taxes out of us first :)
     
  15. Joerg

    Joerg Guest


    But Don does.

    Sometimes I wish we had that.
     
  16. Don Y

    Don Y Guest

    Hi Joerg,
    Ah, I've run a fair bit more than that (not counting the CAT3 stuff).
    <frown> I'll be needing a third box RSN (there are ~50 CAT5 "drops",
    here). I've opted to do everything *wired* instead of "wireless".
    Even this laptop is currently tethered to the wall with ts wireless
    "off".

    However, I may want to change much of the automation kit to run a
    slower protocol (instead of 10/100BaseT) to save complexity and money
    on the network switch. Doing everything PoE -- and having to battery
    back much of that -- leads to a horrendously costly switch when
    the traffic doesn't really *need* it (and, finding PoE switches
    that let you selectively back up certain parts of the fabric makes
    this even worse!)

    Of course, the existing CAT5 cable is still *usable* -- just overkill!
    I think the way to do this (for new construction) is with switching
    at the electrical panel (one of my uncles built a home like this
    50+ years ago -- everything controlled by low voltage switching.
    Jeez, what a piece of cake *that* would be to automate!!)
    <frown> But, intended for indoor use with AC mains nearby.

    I use this on the FM antenna:

    <http://www.hollandelectronics.com/catalog/catalog.php?product_id=LA-10-Amplifier>

    So, all I have to worry about is pushing power up the wire (complicated
    by the splitter's presence)
    I already thought of that (many of the CAT5 drops feed ceiling
    speakers). But, those are in an even more hostile space than
    the location I have selected for the patch panel (i.e., the
    speakers are enclosed to give them a bit more protection).

    I had thought of the garage but there is *no* wall space, there
    (floor to ceiling industrial shelving).

    I would *like* to drop the ceiling in the laundry room and exploit a
    soffit there. That would also let me un HVAC to the store room in
    the garage and turn that into "living space". But, the wall I would
    have to open is load-bearing and I don't want to tackle that, now. :<
    And his, equally Western, response would be a Colt... (TV is just not
    worth *that* much! :> )

    --don
     
  17. Joerg

    Joerg Guest


    Fifty? Wow!

    Looks like you went pretty far with home automation. I have dismantled
    most of it because this whole X10 stuff is IMHO junk. Plain unreliable.
    And the transmission protocol isn't very good to begin with.

    I have seen a house like that, probably around 40 years old. Mains home
    runs could only be done back in those days, when copper was cheap. Also,
    those relays were freaking hot, could barely touch them.

    I don't remember if and how easily the enclosure can opened. If yes then
    one can hack them.

    Cute. But looks expensive.
    Get a DC-passthrough splitter?

    Get rid of some stuff on those shelves, maybe? :)

    A round cut for a duct that doesn't require cutting any structural
    members might be ok.

    [...]
     
  18. Don Y

    Don Y Guest

    Hi Joerg,
    But that's misleading. It actually doesn't include the "computers"
    (there are ~22 additional nodes in the office, etc.). Keep in mind, I
    intend to serve *everything* over IP. Look around your house and
    count the number of televisions, phones, HiFi's, etc. Then, think
    about where you could conceivably want to relocate each of those.
    I.e., you may not have a TV in (each) bedroom, but, if you were
    sick/bedridden, the ability to drag one in that room would be nice!
    What about the front and back *porches*? (the weather here allows
    for year round outdoor activities)

    Then, think about other "fixtures" that you would have in place:
    ceiling/wall mounted speakers (powered and driven over the network),
    surveillance cameras, etc. You may not want a TV in the *bathroom*
    but might welcome being able to hear the balance of a newscast
    while (ahem) "reading"... :>

    On top of that, imagine places where you would want to "interact"
    with your "house":
    - I have drops by the front and back doors for "control (touch) panels"
    that let you view and set things ("who is at the front door ringing the
    doorbell?", "Turn the ACbrrr down a few degrees", etc.)
    - similarly, a panel in the hallway to the bedrooms ("I'm going to
    bed, tun the house 'off'")
    - and the passageway to the garage
    - and *in* the garage, itself
    - (I even ran a drop up to the roof so I can control the swamp cooler
    *while* servicing it!)

    It is astonishing how quickly this list grows! :< (at least *I*
    was surprised!)
    I haven't worried about things like lighting. I'm more interested
    in HVAC, making sure the big freezer doesn't "thaw", ensuring the
    yard gets watered appropriately (regardless of weather), etc.
    I.e., things that aren't typically readily instrumented. ("Is the
    garage door closed?")

    And, most of all, being able to tie all the cruft together so
    relationships between them can be expoited. ("Someone rang the
    doorbell! Let me route the front_door_video to the display(s)
    nearest the current occupants...")
    Nowadays, I think the real downside risk is not being able to purchase
    replacement parts!
    But, if it is designed for indoor use, I suspect the components won't
    have been chosen with environmental extreme in mind...
    My splitters will pass DC. The problem I worry about is that now I am
    putting that "injected DC" on everything connected to that splitter!
    I.e., the downstream side of the injector is blocked or DC. But, the
    other "drops" just have cables running to them with this DC sitting
    on it -- courtesy of the splitter!

    [I have no idea what the front-ends look like but figure that the
    fact that the injector isolates what *it* thinks to be the (downstream)
    load means it might be worth considering!]
    *gasp* Shirley you jest?! :>
    Sorry< I wasn't clear. :<

    I meant turning that store room into living space would require
    opening a *doorway* through that load-bearing wall. We visited
    a nearby home with the same (basic) floorplan. On returning home,
    chuckled at the realization that the owner had removed a load-bearing
    wall in the center of the house. ("Gee, this wall breaks up the view
    through the house. Let's remove it!") I've been dying to get back in
    there and count the cracks in the ceiling, etc.! :>

    --don
     
  19. Don Y

    Don Y Guest

    Hi Michael,

    Or, install the injector further upstream -- closer to the amplifier
    (and "above" the splitter)
     
  20. Don Y

    Don Y Guest

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