Originally Posted by holl_ands
To eliminate truck rolls every time someone moved or changed Tiers, a number of years ago, Cable systems switched from individual Tier Filter(s) installed in the individual home connection box (or Pedestal) and are now using ADDRESSABLE TAPs or SPLITTERS contained in a DIFFERENT BOX. There are usually two controls: enable/disable each house and enable/disable JUST the Analog Channel Tier (up thru about Ch70 or so):
TWC in my neighborhood never used addressable taps. I do remember premium channel traps (individual channels) and tier traps that were phased out when scrambling and set top boxes came around. There were also negative and positive traps. Remember the beep beep beep on a premium channel you didn't subscriber to? A trap stripped out the jamming signal to allow a subscriber to see the channel. Every time you changed premium channels, a truck needed to be rolled to a subscriber's individual drop to make the change.
Addressable Taps/Splitter Utility Boxes may also contain CATV Line Amplifiers and Frequency Response "Slope" Compensation Filters. They are usually found in GREEN CURB-SIDE Utility Boxes (about 2'x1.5'x1') that typically look like this one in SOCAL region (YMMV):
Each of these taps off the neighborhood CATV "Loop", sending signals to typically 16 homes via a Circular Pedestal that feeds either two adjacent or individual homes. These locked Pedestals USED TO contain Tier Filters:
The whole purpose of the digital transition is to eliminate trapping in systems.
Anything upstream of the tap is feeding multiple homes. Any trapping would have to be installed at the individual drop to the subscriber. That square green box you pictured may have just taps, it also may have amplifiers that feed a neighborhood. Could be a node where fiber connects to coax. The round pedestal probably only contains taps that feed four to six homes.
And now that the analogs are gone, and data channels are now using that portion of the bandwidth, any trap (addressable or not) are obsolete and would need to be physically (in the case of non-addressable) removed . This started happening a long time ago when the digital packages were released, and old time trapping of channels was used less and less. Here in this system, that means the old time HBO and Z channel positive and negative traps were pulled when premiums went scrambled. The last traps to be removed will be the ones that limited reception to 2-36 for the old "limited basic" tiers, and the "data only" traps now that data has spread to more of the bandwidth. The only thing left will be the locks that don't pass anything, they're just F-connector locks that supposedly can't be removed by a pair of pliers.
And as you mentioned, DTAs don't send anything upstream, so there is nothing communicated to the head end and time delay can't be measured. That only happens with two way set top boxes, and cable modems.
In my newly rebuilt system, while we were launching high speed data, we could take a cable modem anywhere in the system served by the same CTMS, which served a huge swath of area. We could hook it up to any drop, and it would fire up just fine. No one back at the office was looking at ping times to see if modems were moving around. There are a lot of reasons that timing would change, not just that the device physically moved.
And "most" digital channels on switched digital is an overstatement. Perhaps not even "many." Certainly a few, at least in my system. I can tell what I can see on my tuning adapter equipped TiVo vs. what's available on a set with a DTA. Its a "small handful."