# How does a DECA work?



## mikemyers (May 19, 2010)

I've entered a discussion item here on how to get my system up and running properly. One of the most confusing things to me, was what this "DECA" device was, how it got hooked up, and how it worked. Two weeks ago I couldn't have spelled DECA; now I'm struggling to use one.

Anyway, this topic is not how to get a system up and running, but to ask how a DECA works. I'm going to write what I think I've learned so far (but please help me by correcting any mistakes), and then I'd like to ask something about how the thing works.


I know now that it's a white box with only three connections. 

One connection is where the DECA gets the power it needs to operate. Apparently it can be powered by connecting it to one of the "satellite in" connectors on a DirecTV receiver. Or, it can be powered by a "power injector" which is a device that plugs into a home AC outlet and has something that connects to the appropriate connector on the DECA. Seems pretty obvious now - the DECA just needs power so it can operate.

Another connection is for an Ethernet connection. If the system is going to be used to connect to the internet, perhaps for downloading a movie using "Video On Demand" (VOD), it needs to connect to the internet. The DECA supposedly makes this easy - it will connect to your home internet network, and then distribute the internet connection to all your receivers and DVR's using the co-ax cable from DirecTV. (I think this only works if you are using what's called a SWiM system, but that's another topic.) Anyway, this connection is basically just a way to connect to your internet network.

The last connection is labeled "Towards LNB" and apparently what it does is take the internet data from your network, and send it to your whole DirecTV system using the DirecTV co-ax cables. If you've got any number of devices, the signal goes around to all of them - meaning ANY of the devices can now download a movie using VOD for example.

I think I understand the above, but from here on I get lost - which is what I'm hoping someone here can explain to people like me, who would like to understand what's going on.


There are three lights on the DECA, one for "cLINK", one for "NTWK", and one for "Power".

Power seems obvious - if the device is connected to the Power Inserter, which is plugged into the wall (or presumably if it's connected to a receiver) it gets the needed power, and the green light glows happily. 

NTWK seemed obvious to me, but in my case it never lights up. I thought it was a means of lighting up green, to tell you that it's connected to your internet. I assumed that this was sort of like a "network switch" - plug in the cable, and you get a few lights that indicate you're connected, and maybe a few other things. I'm stuck here, as for me, even though I plug in a network CAT5 Ethernet cable that I know provides an internet network connection perfectly to a computer, my DECA never illuminates the NTWK light. (One of my questions is "why?". The only thing I can think of, is that my "Power Injector" isn't providing the right amount of power, but I doubt that's correct. Can anyone explain how this works??).

c.LINK is the third light. I'm pretty sure (but not certain) that this indicates that the DECA has found "something" to communicate with; once the communications link has been established, this light will change from a flashing yellow to a solid green. If there is more to it than that, maybe someone can elaborate here.



From what I've been reading, when you first apply power to the DECA, it "searches" for networks to connect to. The flashing yellow c.LINK light apparently means it is searching. After three minutes though, it stops searching and goes into another state, presumably where it "works" in communicating with whatever devices it found during that first three minutes. I'm not sure if this is right - I just read it somewhere.




Based on the above, I "think" the following might be correct - hopefully someone can say if these things are true:

a) If I give the DECA power, and connect it to an Ethernet network, will the green LED for NTWK light up? Will it do this regardless of whether or not the device is connected to anything? Or, is it necessary to have a connection at the other end (to some DirecTV device) before this light comes on?? I'm assuming the green light should come on as soon as you plug in a network cable, regardless of whether or not the DECA has connected to any of your receivers.

b) Does the "searching mode" time out after three minutes, or does it keep on flashing (searching) forever, or until it finds something to connect to?

c) If someone has a full system up and running, with a two or three receivers, AND an Ethernet network connection in operation, what (if anything) would or should happen if you connected a powered DECA (with or without an Ethernet cable connected to it). Would your receivers ignore the DECA, since they are already using Ethernet? Would the green light for NTWK come on, and stay on, as it's connected that way? Would the c.LINK light keep flashing, as the DECA couldn't find anything to connect to, or would something else in the existing system connect to the DECA in some way that would cause the c.LINK light to go solid green?



If I haven't asked anything that I should have please provide that information as well. There most likely are a lot of other people who would like to know what a DECA does, and how it does it.


----------



## veryoldschool (Dec 10, 2006)

The DECA is a transmitter & receiver for signals in the 525-575 MHz band.
It modulates these signals to carry the network traffic/packets.
The Power LED is fairly straight forward.
The Network & cLink LEDs aren't as straight forward.
cLink has mostly to do with the RF "link" between all DECAs. Solid yellow shows it is working but at a reduced function. Blinking means it hasn't established the link to the other DECAs on the coax.
The Network LED seems to be more related to whether the DECA is able to transfer networking traffic/packets.
So: you can have a green power LED, a green networking LED [even with the ethernet cable removed] and a [solid] yellow cLink LED.
If the cLink is blinking, then the DECA can't function.

Knowing a bit of your troubles, I noticed today, as I was doing some testing, that if the DECA to router [in yours the switch] was disconnected, and then reconnected, the cLink wouldn't sync back up. I needed to pull the PI/power and reboot the DECA, when it then only took a few sec to sync with the other DECAs. I played with this a bit and waited to see if the DECA would resync but it didn't seem to want to, and just kept blinking.

If you want to go back to your other thread, there are some steps I would like you to follow to get your cLink to sync.


----------



## JayMatt77 (Aug 25, 2009)

veryoldschool said:


> So: you can have a green power LED, a green networking LED [even with the ethernet cable removed] and a [solid] yellow cLink LED.
> If the cLink is blinking, then the DECA can't function.


All 3 of my LEDs are solid green. I'm guessing that's ideal?


----------



## veryoldschool (Dec 10, 2006)

JayMatt77 said:


> All 3 of my LEDs are solid green. I'm guessing that's ideal?


"green for go"


----------



## barryb (Aug 27, 2007)

JayMatt77 said:


> All 3 of my LEDs are solid green. I'm guessing that's ideal?


Correct.


----------



## mikemyers (May 19, 2010)

The DECA comes built-in when you get a 24 series box (DVR or receiver). Does anyone know how to access a menu to reset or re-enable a built-in DECA?

Apparently, even a full system reset doesn't always do this. Maybe this would be in some "hidden" menu that only authorized technicians would know how to access it? (I'm only asking this because as I've been told, and am now experiencing, once someone plugs a network connection into the back of a 24 series box, it "disables the built-in DECA".)



I now understand that the DECA allows DirecTV boxes to communicate with each other, and for the whole communications network (that they call a "cloud") to communicate with the outside world via an internet connection. Are there other things that it also does?


----------

