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TV Is (Really) Dead, Long Live DTV

Hallo hoppy reader,

Back in April of last year, I blogged about the DTV transition and, since today is the Big Day, aka the Analog Cutoff, I thought I’d devote this Bitstream post to over–the–air reception, and some tips and tricks for better TV fun.OK, let’s talk antennas…I live in a challenging reception location so, for our family to enjoy over–the–air TV, I need an amplified antenna. After a bit of digging, I decided on Terk’s HDTVa model, a relatively small, indoor antenna. Here’s what it looks like:

 

Terk HDTVa DTV Antenna

Fig. 1: Terk HDTVa DTV Antenna

As with classic “rabbit ears,” there’s a long wavelength VHF portion, and a separate UHF portion. The UHF element is fixed and does a decent job, at least in my location. However, VHF is another matter altogether. One of my local PBS station transmits on channel 9 so, for me, that’s a very important station and after purchasing the antenna, reception was dicey. Any aircraft fly–bys or bad weather would cause the signal to frequently “drop off the cliff.” That is, signal strength would fall below the receiver’s ability to recover a usable bit stream and the result would be muted audio and a frozen or macroblocked image. What’s a geek to do?

Well, how about optimizing the antenna for my favorite channel! Because antennas are part of a tuned RF circuit, the length of the antenna is critical to optimal signal strength at the receiver.

Let’s revisit Figure 1 above…Look carefully at the area labeled “VHF elements,” and you may discern a telescoping straight element laying parallel to the body of the device. There are two of these, attached at the bottom and able pivot in a fairly wide range of orientations. OK so, what to do? First off, your receiver/converter/set–top box should have a Signal Strength mode, that lets you tweak the antenna while metering the signal strength. First, grab a tape measure or ruler, preferably one that has a decimal inch scale. Then, place your box in whatever passes for Signal Strength mode. Here’s a table that lists the needed antenna length:

 

TV Channel Band, MHz Center ƒ, MHz Quarter Wavelength, Feet Quarter Wavelength, Inches
2 54-60 57 4.11 49.3
3 60-66 63 3.71 44.6
4 66-72 69 3.39 40.7
5 76-82 79 2.96 35.5
6 82-88 85 2.75 33.0
7 174-180 177 1.32 15.9
8 180-186 183 1.28 15.3
9 186-192 189 1.24 14.9
10 192-198 195 1.20 14.4
11 198-204 201 1.16 14.0
12 204-210 207 1.13 13.6
13 210-216 213 1.10 13.2

Table 1: Suggested Television Antenna Lengths

I’ll use channel 9 as an example, and set the total length of each telescoping element to 14.9″. As to orientation, I have mine set with both elements in a straight line, parallel to the floor and ceiling, and perpendicular to the transmitting tower. Your milage will vary, so try some different configurations to see what works best for you.

 

My antenna

Fig. 2: My antenna config

 

I didn’t bother breaking out a compass to “point” the antenna, I just relied on the signal strength indication to max the signal. If you don’t know where your signal originates from, mess with the orientation and you should quickly find a good placement.

Total tweak time: about 10 minutes. And the result? Major improvement! I now have no cliff effect on that channel, the signal’s always “on,” and adjacent channels aren’t too bad either. Rockin’ good!

All for now. I don’t need no stinking cable, and frankly, with what little’s on worth watching, I’m perfectly happy with Netflix and a few choice broadcast programs. Y’all continue to geek!

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2 Responses to “TV Is (Really) Dead, Long Live DTV”

  1. Thanks for making scientific sense of my wandering about the room and bending the angle of the antenna. Now I get three PBS stations!

  2. Most excellent, I’m up to seven PBS stations here!