Archived from groups: rec.video.satellite.tvro,alt.video.satellite.mpeg-dvb (More info?)
Hello. I want to preface this by saying that I have some experience with
C-band analog but have just had my first encounter with MPEG, while trying
to set up a system for a relative (we're still in the process). So maybe
the question I'm about to ask has been discussed before, but if so I
haven't seen any references to it.
Apparently most users in the United States "slave" an MPEG receiver off of
an analog C/Ku receiver (as we are doing). The drawback to this is that
apparently the analog receiver must be left on and set to a channel of the
proper polarity. So even if you are on the right satellite, the MPEG
receiver can only pick up the signals on the same polarity that the analog
receiver is set to (horizontal or vertical).
BUT, it appears that some models of MPEG receivers (such as the Pansat
2500A) can control a feedhorn servo motor (a.k.a. "Polarizer"). So my
question is, why not let the MPEG receiver control the servo while the user
is watching that receiver, and let the analog receiver control the servo
otherwise.
To me it seems ALMOST simple. Assuming that the ground wires from the
analog and digital receivers can just be connected together (and to the
black ground wire going to the servo motor), that leaves only the red +5
volt wire and the white pulse wire that would have to be switched between
receivers. IF that is true - and I have not tested this theory - it seems
like one could use a mechanical DPDT switch and just set it to run the
servo off either the analog receiver or the MPEG receiver, by switching the
red and white wires.
But if you are the sort that doesn't like to get up and physically toggle a
switch, then it seems like a relay of some kind could be used to accomplish
the same purpose. If the MPEG receiver has a power outlet tap, you could
just use a DPDT relay with a 110 VAC coil and wire it so the presence of
110 volts closes the relay and switches the wires to the MPEG receiver
(read 220 volts instead of 110 if that's the local voltage where you live).
Otherwise I'm not sure how you'd trigger the relay remotely. To me it
would be great to have some way to do it when the MPEG receiver is actually
in use. If that +5 volt terminal puts out a constant +5 volts while the
receiver is on, but has no voltage on it when the receiver is switched off
(I do NOT know exactly how servo motors operate electrically), then you
could probably just use a relay triggered by 5 volts DC - then you could
wire it so whenever the MPEG receiver was on, it would control the servo
motor (by wiring the relay coil to +5 volts and ground), but when it was
powered down the relay would drop out and transfer control of the servo
motor back to the analog receiver.
Now, I figure someone HAS to have tried this - at least the mechanical
switch part. I can't possibly be the first one to think of something like
this. But maybe there is some reason this wouldn't work that I'm not aware
of? So I'm asking, has anyone actually tried anything like this and if so,
did it work okay? And if you used a relay, do you happen to have a source
for i? And did you have to add any circuitry to it (for example, any sort
of anti-kickback circuitry)?
Or am I the only one who feels that it's inconvenient to have to change
channels on the analog receiver just so you can see the rest of the
channels on the MPEG receiver?
One other question, does anyone know of a good source for relatively
inexpensive DiSEqC switches? I read that you have to have one to switch
between C and Ku band, and have seen them in a whole bunch of different
price ranges. We only need a two port one for now, but might get a four
port one if it's nearly the same price. Anything to watch out for when
buying one? Also, the relative in question has a good SW 21 switch but I
assume that this is NOT a DiSEqC switch and that the Pansat receiver cannot
control it? Or if I am wrong in thinking that, then how would you instruct
the Pansat to use the SW 21 switch (or is the SW 21 in fact a DiSEqC
switch)?
Sorry if this is all elementary stuff but I'm very new to MPEG. I would
much appreciate it if replies would be posted to the newsgroup - I just
changed e-mail addresses not too long ago to keep from getting buried in
spam, and really don't wish to post the new one I have now.
Hello. I want to preface this by saying that I have some experience with
C-band analog but have just had my first encounter with MPEG, while trying
to set up a system for a relative (we're still in the process). So maybe
the question I'm about to ask has been discussed before, but if so I
haven't seen any references to it.
Apparently most users in the United States "slave" an MPEG receiver off of
an analog C/Ku receiver (as we are doing). The drawback to this is that
apparently the analog receiver must be left on and set to a channel of the
proper polarity. So even if you are on the right satellite, the MPEG
receiver can only pick up the signals on the same polarity that the analog
receiver is set to (horizontal or vertical).
BUT, it appears that some models of MPEG receivers (such as the Pansat
2500A) can control a feedhorn servo motor (a.k.a. "Polarizer"). So my
question is, why not let the MPEG receiver control the servo while the user
is watching that receiver, and let the analog receiver control the servo
otherwise.
To me it seems ALMOST simple. Assuming that the ground wires from the
analog and digital receivers can just be connected together (and to the
black ground wire going to the servo motor), that leaves only the red +5
volt wire and the white pulse wire that would have to be switched between
receivers. IF that is true - and I have not tested this theory - it seems
like one could use a mechanical DPDT switch and just set it to run the
servo off either the analog receiver or the MPEG receiver, by switching the
red and white wires.
But if you are the sort that doesn't like to get up and physically toggle a
switch, then it seems like a relay of some kind could be used to accomplish
the same purpose. If the MPEG receiver has a power outlet tap, you could
just use a DPDT relay with a 110 VAC coil and wire it so the presence of
110 volts closes the relay and switches the wires to the MPEG receiver
(read 220 volts instead of 110 if that's the local voltage where you live).
Otherwise I'm not sure how you'd trigger the relay remotely. To me it
would be great to have some way to do it when the MPEG receiver is actually
in use. If that +5 volt terminal puts out a constant +5 volts while the
receiver is on, but has no voltage on it when the receiver is switched off
(I do NOT know exactly how servo motors operate electrically), then you
could probably just use a relay triggered by 5 volts DC - then you could
wire it so whenever the MPEG receiver was on, it would control the servo
motor (by wiring the relay coil to +5 volts and ground), but when it was
powered down the relay would drop out and transfer control of the servo
motor back to the analog receiver.
Now, I figure someone HAS to have tried this - at least the mechanical
switch part. I can't possibly be the first one to think of something like
this. But maybe there is some reason this wouldn't work that I'm not aware
of? So I'm asking, has anyone actually tried anything like this and if so,
did it work okay? And if you used a relay, do you happen to have a source
for i? And did you have to add any circuitry to it (for example, any sort
of anti-kickback circuitry)?
Or am I the only one who feels that it's inconvenient to have to change
channels on the analog receiver just so you can see the rest of the
channels on the MPEG receiver?
One other question, does anyone know of a good source for relatively
inexpensive DiSEqC switches? I read that you have to have one to switch
between C and Ku band, and have seen them in a whole bunch of different
price ranges. We only need a two port one for now, but might get a four
port one if it's nearly the same price. Anything to watch out for when
buying one? Also, the relative in question has a good SW 21 switch but I
assume that this is NOT a DiSEqC switch and that the Pansat receiver cannot
control it? Or if I am wrong in thinking that, then how would you instruct
the Pansat to use the SW 21 switch (or is the SW 21 in fact a DiSEqC
switch)?
Sorry if this is all elementary stuff but I'm very new to MPEG. I would
much appreciate it if replies would be posted to the newsgroup - I just
changed e-mail addresses not too long ago to keep from getting buried in
spam, and really don't wish to post the new one I have now.
/www.adventistsat.com
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