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Forum Index : Microcontroller and PC projects : TV tracking antenna
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| Talbit Senior Member  Joined: 07/06/2011 Location: AustraliaPosts: 210 |
I thought I'd run this idea past the forum before I started implementing my plan... The idea came to me when my brother in law complained that his TV signal keeps dropping out. The problem he has is that he lives on a house boat at the Gold Coast and as the boat swings around the anchor, the antenna loses the TV signal. The boaties say that the omni directional TV antennas are not all that good. So my idea is to design a rotating Yagi antenna that will keep pointing in the same direction as the boat moves. The plan is to keep it simple and cheap and most of all it needs to be easy to set up and be "Set and Forget". So the user would press a button until the the antenna rotates to the correct position ie pointing at the TV transmitter. Then he would press a button and the system would keep it pointing in the set direction as the boat rotates. It could use a 28 pin Micromite, a digital compass (Jaycar XC4496) mounted above the Yagi, a motor drive board (Jaycar XC4492) 12 volts and not much else. It doesn't need fancy displays to show where the antenna is pointing. There are motorised antenna rotators on the market at reasonable prices. So my question is... Has this been done before. I've searched and can't find a tracking system. Cheers Trevor Talbit |
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OA47 Guru  Joined: 11/04/2012 Location: AustraliaPosts: 1013 |
Talbit, thinking a bit about your project, would you be better using a bow tie style antenna over the yagi as it would give you better acceptance angle and not have too much leverage on your rotating base? OA47 |
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palcal Guru Joined: 12/10/2011 Location: AustraliaPosts: 2006 |
I told a friend to buy one of these Antenna . I installed on his caravan that was under an awning at the time 60Km. from the transmitter and was amazed at the reception. "It is better to be ignorant and ask a stupid question than to be plain Stupid and not ask at all" |
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| VK2MCT Senior Member Joined: 30/03/2012 Location: AustraliaPosts: 120 |
I used to have a rotator on my house! It used a pot to sense the antenna direction via some gears. The wiper voltage was compared to the wiper voltage of a 'direction to go to' pot on a control panel. A wiper comparator in the panel had a dc amp feeding an analogue 12v motor. The rotator needed a lube change every few years. It spun a little over 360deg, much more and the antenna feed cable would resist anyway. Which transmitter is to be aimed at ? John. VK2MCT. |
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| Paul_L Guru Joined: 03/03/2016 Location: United StatesPosts: 769 |
@John -- the pot servo mechanism works because your house doesn't change its heading! @Trevor -- you're on the right tack. I don't think it has been done before but it sounds workable. Google jaycar xc4496. At LINK David Such used this gadget which is really a Honeywell HMC5883L 12 bit magnetomer plus a breakout board to give a robot directional information. Apparently a few guys have written libraries to enable the arduino to talk to this gadget in C. Sparkfun makes a similar breakout board. It should be easier to use MMBasic to talk to it. Have fun. Paul in NY |
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Turbo46 Guru Joined: 24/12/2017 Location: AustraliaPosts: 1646 |
Silicon Chip November 2018 has an article on Electronic Compasses and interfacing them to the Arduino and the Micromite. It would be worth a read, some of the work has been done for you. One of the modules used does feature the HMC5883L IC. Don't forget that if the boat's location is changed then the angle to the transmitter antenna will change and have to be reset. You could incorporate a GPS and, knowing your location and the transmitter's location, recalculate the angle required. Bill Keep safe. Live long and prosper. |
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| Talbit Senior Member Joined: 07/06/2011 Location: AustraliaPosts: 210 |
Thanks for all the responses so far. OA47. Good point and I have thought of that. As long as it's got the gain. palcal - The Omni from Jaycar would be the first thing I'd try but the word is the boaties are not all that happy with them. But you're right, the first thing to do would be to try it first then advance to a better solution if it's unsatisfactory. John - To point at the general direction of the TV transmitters. Paul - I'm geared up to use the Maximite/Micromite so will stick with them. Bill - The November Silicon Chip article by Jim Rowe is what started me off. I've got the Jaycar compass module and will try it out with Jim's code first. Driving the rotating motor isn't a problem. The houseboat and yachty guys don't move their location very often but when they do it should be a quick job to re point the yagi. I wanted to avoid the idea of adding a GPS. That would make it too complicated. I wanted to keep it super simple. The idea would be for the operator to know the general direction of the transmitting station and operate the switch until it's in the general direction and then set and forget. Thanks again for your input. Trevor Talbit |
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| Malibu Senior Member Joined: 07/07/2018 Location: AustraliaPosts: 260 |
An interesting project... I wonder if it's possible to just slew the antenna until the signal is at it's highest strength? A couple of degrees each way initially to measure a rise or fall in signal strength. Once the signal begins to rise, keep slewing slowly until the strength begins to fall, reverse the slew again to the previous high point and that way it should be optimal position for best signal (well, close enough to it anyway) The antenna will just hunt for the best position, no matter which way/direction the boat drifts. Maybe the initial direction could be set manually with a CW/CCW buttons to give a rough starting point. Just a thought  John |
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| PeterB Guru Joined: 05/02/2015 Location: AustraliaPosts: 655 |
G'Day all Many years ago a mate of mine wanted to watch TV while he drove his tractor round and round his paddocks. It is now fairly common but this was early days. I decided to use two loopsticks tuned to the AM band and set at a slight angle to each other. Once the system is set up, it should be possible to keep it pointing the right way by keeping the two signals equal. I never did get to try it out. I think an omnidirectional antenna became available. Or he found a coat hanger worked just as well. Peter |
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| Talbit Senior Member Joined: 07/06/2011 Location: AustraliaPosts: 210 |
John - Interesting idea, but how would you measure the signal strength? Sounds like you'd need a fancy signal detector, then you'd have to analyse it and respond accordingly. Peter - Watching the telly while driving a tractor? Sounds dangerous, but I guess they'll have fully autonomous systems soon. Cheers Trevor Talbit |
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| PeterB Guru Joined: 05/02/2015 Location: AustraliaPosts: 655 |
G'Day Trevor. Farmers now use GPS to steer the tractor to within about 20mm. They only need to put the book down or stop watching the TV in order to turn a corner but I suspect that is now being taken care of. |
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