David Braue21 April 2010, 2:20 PM
No need to call out Mr Antenna for that glitchy picture -- just whip out your iPhone, and follow our simple steps to align your antenna correctly.
If you’ve ever struggled to come up with an actual use for the compass on your iPhone, take heart: it is not totally useless. Struggling recently to dispatch the chronic static in my digital TV signal, I found the compass to be indispensable.
Those who have installed TV antennae in the past will know the cardinal rule: point the thing, short arms forward, towards the transmitter towers. This is simple enough if you can see the towers from your roof, but for many people it’s a real guessing game. In Melbourne, for example, many of the most populated areas are 25km or more away from the TV transmitters high atop the Dandenong Ranges.
This means your best bet when aligning the antenna has been to approximate whatever your neighbours have done, then hope for the best. With the iPhone putting a compass in every pocket, however, there is an easier way.
The first part of the solution involves Google Earth. Fire up the application, then find the TV transmission towers in your city (Sydney’s TCN tower is here, Melbourne’s Mt Dandenong Ranges towers are here, and the locations of others are in a document available from here (registration required).
In Google Earth, choose Tools > Ruler, which brings up a popup box that measures the distance and angle between two points. Zoom in or out so your house and the transmitter are on the same screen, then click once on your house and again on the transmitters. This will give you a heading, in degrees, between the two points: for example, Google Earth tells us Melbourne’s transmission towers are 32.86km away from our hypothetical house in Sandringham, at a heading of 66.74 degrees.
Time to get up on your roof. As with all potentially dangerous things, we must remind you that climbing onto your roof is dangerous, scary, not to be done on rainy days, and can cause death and other unpleasant consequences should you lose your footing. Wear shoes with good, non-slip soles; only go up when someone else is around; step on the top or bottom of your roof tiles, rather than the middle where they can break; and bring an adjustable spanner to loosen and tighten your antenna’s nuts.
And, of course, your iPhone.
In our case, interference from the digital signal had become headache-inducing, with loud squawks and digital snow that persisted throughout the day but seemed to get much worse on windy nights. Close inspection of the antenna revealed that the mounting bracket was slightly larger than the antenna shaft itself, so strong winds were shaking the antenna and causing snow every time the shaft collided with the edge of the bracket. It also appeared the antenna wasn’t pointed in exactly the right direction.
Unscrewing the bracket, inserting several cut-to-size melamine packers around the antenna shaft and tightening the unit again stopped it from shaking. But how to determine whether the antenna was pointed in the right direction for optimal reception?
This is where the iPhone comes in. We activated the Compass, rotated it to the compass heading taken from Google Earth, and aligned the antenna in the same direction. When doing this, be sure to hold the iPhone flat to get correct readings. You may also need to calibrate the compass, by waving the iPhone in a figure-eight pattern, to ensure accuracy.
Assuming everything is correct inside the house, your antenna should be aligned and stable – and give you a better TV signal than ever. Of course, there may be other considerations: check here for some tips if you’re having reception problems. But when it comes to important angles, this is just one place your iPhone can be a big helper.