satilite tv

[Robert Stratton]

On 2006-02-07 12:40, "Alex Fraser" <beatnic at comcast.net> wrote:

> I just purchased a Pansat 2700A receiver. I'm awaiting delivery (oh boy
> a new toy!).
> I will go through my back yard dish collection, get rid of the spiders etc.
> I assume I have to make a mount of sorts, probably a tripod till the
> spring concrete season opens up. It wasn't really clear to me how power
> gets to the dish,  does the receiver inject a voltage into the coax or
> is this another component?
> I just missed a
> SG2100 DISH MOTOR with DISEQC 1.2  on Ebay (by $1.30 in last 5 seconds!)
> more are available though.  The same question on powering the motor, is
> it as simple as a  RG6  coax run to power motor and  the Dish?  You
> don't need an extra power supply?   The receiver is DISEQC 1.3  and the
> motor is DISEQC 1.2, I hope they are backwards compatible.

The compatibility is fine between that motor and receiver, from what I've
heard. I have an SG2100 and it's a fine motor, though perhaps not quite as
solid as the STAB motors.

These motors are powered by the LNBF voltage put on the coax by the
receiver. Polarity is switched by voltage changes (I think it's 14/18
Volts). 

DiSEqC is a standard for 22 kHz tone pulses on the coax. The most basic
standard is for simply pulse trains that actuate nX1 switches. The more
complex is for telling the motor to move to a stored position, or perhaps to
go to 0 degrees. The most complex variant ("1.3" or "USALS") is for telling
the motor to "Goto X" degrees, which is calculated by the receiver after the
user inputs lat/long coordinates.

The only compatibility issue likely to come up has to do with your LNBF.
There are "universal" or "wideband" LNBFs that actually span two frequency
bands and use the presence of 22kHz on the line to switch the LNBF band,
with voltage switching for polarity.

Some receivers get flaky if you try to use a DiSEqC switch while also using
a wideband LNBF. The wideband LNBF is really only useful for certain
Atlantic Ocean satellites. If you're not going East of 59 degrees West, this
will not be an issue for you. You also want to be sure to put any LNBF
switches _after_ the motor, to ensure the motor gets the signals all of the
time. 


>        How low on the horizon can you pick up the satilite?  I'd assume
> a bigger dish would help, but if they are beaming to Europe is there any
> chance you could gather enough radiation to get over the noise?  I guess
> I could pour liquid Nitrogen on the dish hi hi, but short of that  what
> is piratical?  I think when the growing season comes around I might just
> start a dish farm.

It's a function of your motor's range, line-of-sight and obstructions, along
with dish size and LNBF temp. (It's all Eb/NO in the end.) The motors also
have internal and programmable limits (the latter should be set at install
time), though some people remove the internal blocks to gain another 10
degrees on either side. I wouldn't recommend it on your first motor - some
of them are somewhat fragile plastic parts.

My SG2100 gets me things from 61.5W to 111.1W, just for a reference. If I
were getting started and wanted to be able to hear all of the Ku band
signals out there, I'd consider the Invacom QPH-031 - it combines dual
linear polarization LNBFs with dual circular polarization LNBFs. With a 2x1
switch, you would be able to receive any free-to-air circularly-polarized
signals on the DBS satellites from DISH Network and others and the
linear-polarization signals everywhere else. It's not cheap, but it saves
the need to kludge together LNBF brackets and having to aim your dish
differently for different signal types.

--Bob Stratton