Why the requirement of separate dish feeds

[Autoeng]

Sorry if this is newbie in knowledge but why is there a requirement of separate dish feeds for separate TV's?

To elaborate, why do I have 2 LNB's and a line from each run to each TV? Why can't a single lead to a single LNB be split amoungst as many receivers as you wish and each receiver tune to a different station?

I got to thinking about this while running my second lead in to feed my second receiver hooked to the same TV as my 510 so that I could watch live and record live at the same time. When a cable feed comes into your home you can split it up as many times as you want and there is no need for more than one feed so whiy is there with Dish?

And another question. I am receiving from 3 sats., 61.5, 119 and (crap don't remember the other one). One receives only my local PBS station while the other receives the main satellite channels. I assume that the third receives my local broadcast channels. Is this why I have 2 LNB's and 2 seperate lines run into the house. If so, why can't I find a join connector (2 lines into 1) anywhere on the lines?

Thanks for putting up with the (anyone should know that) questions,
Autoeng

 

[ShadowEKU]

Your first question on why cant you split.

On a multi sat install (typicaly 119, 110) you have a wing bird as well (61.5) the receiver has to tell the switch which sat to look at. This is done by changing voltages and/or signals. on the standard Dish Pro 500 install there is a switch built into the LNB that the receiver tells which sat to look at and the switch makes the switch to that sat. With your wing bird I would bet you have a DP34 switch combining 2 feeds from the dish 500 dish and 1 feed from the 61.5 dish and the switch has 4 outputs (DP 34= Dish Pro 3 in 4 out).

Why cant you split. Well lets say the receiver outputs (i dont know the voltages exactly this is made up) 12 volts for lnb1, 18 volts for 2 and 24 for 3. What would happen if your receivers wanted to watch different channels. You could end up shoving 24 volts down the line telling the lnb to switch to sat 3 but you only wanted to watch something on sat 1.

that aside Dish Pro is a band stacked technology and wouldnt allow a splitter to be used as it operates well above the standard splitters 900mhz.


Your second question. As for the "Join Connector" the DP34 I mentioned above would be the equivalent. it is a multi switch though.

This goes for Dish Pro Equipment. Legacy Equipment works slightly different.




Basicly sat cant be split (D*, E* and V*) because the receivers have to send voltage and signals out to the LNB as well as receive the signals.

A TV tuner jsut has to read the right frequency coming in off the line to tune to that channel.

 

[chevyN8]

I explained it to a friend recently. "All the channels aren't on the cable at the same time" With cable they are. This is over-simplified.

 

[TuxCoder]

To add to that, cable TV connections are passive (tuner does nothing to the line when tuning any of its channels) while satellite feeds are active (tuner/receiver does stuff to the line in order to get a channel). You can't have two tuners doing stuff to the same line or they will interfere.

 

[Autoeng]

Thank you all for excellent explainations. Now I understand where the switch is and it all makes sense.

 

[Autoeng]

Oh and ShadowEKU I'm right down the road from you in Flemingsburg!

 

[ShadowEKU]

cool... howdy neighbor. glad we could be of help

 

[SimpleSimon]

Good stuff all - but Shadow - future reference - Legacy is voltage-switched for odd/even transponders. DishPro puts both sets on the cable at once - and because of that, a SINGLE BIRD system can be split using a DP Splitter - that's rarely useful, tho. One example is taking a DP Single LNB and splitting it so it looks like a DP Dual. Useful with a DP Twin and a pair of DP21's to make a cheap 2-tuner setup.

Satellite switching itself is done via actual digital commands.

But your point that different tuners would be giving conflicting commands on the same cable is right on the money.

 

[viqventeur]

I am still confused. Let's say you have a 110/119 dish, a 61.5 dish, and a 34 switch, hooked up to 3 receivers. If all three receivers are looking at programming off the 61.5 at the same time, and the channels they are looking at are on different TPs, how does this work? Could you explain this as it applies to both a legacy or DP system? Are there 3 different signals travelling from the 61.5 LNB and are they just at different frequencies? Thank you and I am sure you guys will be able to answer. I have yet to post something that even challenges "The SatelliteGuys."

 

[larrystotler]

Legacy receiver send out 2 different voltages. A 13V charge(or anything UNDER 15.6V) sent to the LNB returns the ODD transponders down the line in the 950-1450Mhz band. An 18V charge(or anything HIGHER than 15.7V) sent to the LNB returns the EVEN transponders down the line in the 950-1450Mhz band. Now, this works fine in a single sat config. When you add in more than 1 satellite location, the receiver sends out a 22khz tone to differentiate which location it needs. D* uses ONLY a 22khz tone whereas E* uses a digital component to the tone since they can access more than 2 locations.
With DP, the receiver sends out a 19.6V charge to the LNB and the LNB sends back the ODDS on the 950-1450Mhz band, and the EVENS on the 1650-2150Mhz band. Now, in this case, with ONLY 1 location, you can SPLIT it, since you are getting all the transponders at the same time. HOWEVER, when you add in more than 1 location, you get that 22khz tone with the digital component to differenciate which sat is requested. Since you have more than 1 location to deal with, you now cannot split it.

Note, D*'s triple sat LNB is a kludge. Since D* only has the 22-32 trans on the 119 and the 28/30/32 on the 110, the 110 LNB is a special unit which downconverts the 28/30/32 to the 8/10/12 and puts them on the 18V line of the 119. Due to this, the receiver only technically "sees" 2 sats.

Hope this helps.

 

[viqventeur]

Thanks Larry. Perhaps you know, is everything being transmitted from the birds at the same time( all available programming from that particular sat?) And is it the reciever telling the LNB which signals to send down the cable to the receiver? And is it just different frequencies multiplexed down the cable if all 3 recievers happen to be watching programming from the same sat, but different channels on that same sat. I am just curious of how the technology actually works. Thanks.

 

[ajohnson]

You've pretty much got it. The only other idea you need is that for more than one sat, you need a switch. In legacy equipment this was always external, but with the new DishPro stuff one is built in to the LNBF head so you can run a single line to a receiver and see two satellites.

The receiver sends the signal to the switch (legacy external or dishpro internal) telling it which satellite and transponder you've requested, and the switch (again, internal or external) sorts it out and brings down the appropriate lnbf's signal and ONLY that signal.

Theoretically you could put some kind of DC voltage blocking splitter on the line and add a 2nd receiver that could only watch half the channels on whatever satellite the main receiver was set to, but no one would want to do that.