First project - Auto rotate my HDTV antenna

Projects General Guidance
1

Hello -- this is a first post for me. I'm an application Programmer, comfortable
with C/C++, IDE's and software. No real hardware or electronics knowledge or
experiance. This is my first project.

I have a Windows PC running XP with a Hauppage TV card, connected to LCD TV
for viewing (tuner in the TV is unused). The antenna direction is controled via
an IR capble control box (the IR is expected to come from a handheld remote).

The project I have in mind is to auto position my directional HDTV antenna
according to the channel being viewed on my PC. I'd like to schedule unattended
recordings of different stations, so positioning the antenna to match the
station must be able to be humanless. Also, the distance of the TV antenna to
the TV exceeds the maximum specified by the manufacturer. If the control box was
placed at the TV, it would take about 75 feet of coax to reach the antenna on
the top of the mast. The manufacturer says it can not exceed 50 feet.

The coax cable between the control box and the antenna reads broadcast signal
from the antenna, and provides power to the motor that turns the antenna. There
is no indication of which way the antenna is pointing. The control to move
the antenna is boolean -- while the button on the control box is pushed, the
motor turns the antenna, either clockwise or counter-clockwise. Directional
rotation can be reversed if the button is pushed twice, quickly. The control box
accepts the same one button function over IR from a handheld remote.

I do not want to mess with the motor control on the antenna, that's out of
scope. I do want to control the antenna via the existing IR interface on the
control box, that is, I want the Arduino to replace the hand held remote.

Here's what I see:

** I need to interface the PC with an Arduino, giving the Arduino the desired
compass heading

** I need to mount a compass sensor to the antenna, giving the Arduino the
actual compass heading

** I need to write some code to make the desired and actual heading the same
(this is the easy part to me)

** I need to place the Arduino near the antenna mast and pass the PC info over
long distance (75 feet)

** I need to determine the IR control frequency of the motor control box and use
an IR sheild to output to it

I've yet to purchase any microcontroller or shields. My concern is the distance
issue. Can I do this with one Arduino? Can the PC/Arduino interface (whatever
that is...??) be made to function at a distance of 75 feet? Is XBee a better
idea? Could I leverage the homes Wi-Fi (802.11g)?

2

There's no access to the existing motor control, so getting into it requires that I break the (otherwise intact) weatherized housing -- and of course, voids any warranty (of course, that's the lesser of the reasons XD ). I'm sure I could run power and control to it, but that part of this is already working -- why mess with it. I figured the IR to be a simpler approach.. not too much more than the "blink" example, with 1 added input and 1 added output. It's just that my output is an IR module, rather than a motor control.

As to the need for humans to "close the loop" -- I figure these are well defined relationships -- I can give the exact compass heading for each station (see: http://www.antennaweb.org/aw/Address.aspx ).

The biggest part of my concern is the distance... I see only 3 possibilities:

  1. The Arduino sits next to the TV antenna/control box and the PC/Filesystem data travels the 75 foot distance
  2. The Arduino sits next to the PC and the IR and compass sensor data travels the distance
  3. Use 2 Arduinos, one at each endpoint, and somehow make then communicate and cooperate.

Anybody have any experience with sensors over this kind of distance? Can sensors or Ardunio interfaces (like to the PC) tolerate voltage drops, or whatever, based on wiring at this length?

3

The antenna and PC are not line-of-sight.

The rotor controller is dual-purpose. It is also the broadcast signal amplifier. The manufacturer indicates that the signal from the antenna must not exceed 50 feet of cabling before it's amplified AND that nothing is between the rotor controller and the motor, or rotational control is lost. Rotor control, rotor power and broadcast signal are carried over the one (coax) connection to the antenna. So the rotor controller will need to be placed closer to the antenna than the PC. If the Arduino is also next to rotor controler, and uses an IR shield to control it, then the only question/issue is distances that the other two interfaces can travel.

  1. The compass sensor (or whatever) is up the mast, at least 20 ft from the indoors -- can this happen over cat3 for instance? I can't reduce this distance unless the rotor control/Arduino are outside...
  2. The filesystem info indicating current channel needs to get to the Arduino. If wired, it's likely also minimum 30 ft from PC to logical location of rotor controller/amplifier. If not wired, then the question is XBee or WiFi or Enternet or ???

Thanks for taking the time to even consider this question -- your input, time and experience are appreciated. Hopefully this make the goals clearer....

4

Thanks --- clarity is creeping in... Sorry for not asking the right questions! If I were to have asked "Can a remote sensor (Compass or whatever) be connected to an Arduino over 75 feet of wire?" then I'm hearing the answer would be "yes". That was the fundamental question. Maybe a better problem statement would have been "An antenna wire from mast to PC, that must pass first through the control box/amplifier within the first 50 feet".

I think I got hung up on trying too hard to not have sensors wired at a distance from the Arduino. I think I've settled on this...

  1. Compass module at the antenna end (stating the obvious)
  2. Run a cat3 wire along the required, existing coax --- weatherized as appropriate (thanks for the tubing tip)
  3. Arduino at the control box, within the first 50 feet, with an IR LED (no "shield"?? :slight_smile: -- who knew!)
  4. From the Arduino to the PC over WiFi - exposes the XP filesystem and reduces the wiring clutter on a media PC

Thanks for your advice and time.... Any other thoughts?

Otherwise, I'll let this thread know how it turns out.