Many of our viewers continue to have questions about the big switch to digital television.

You should all know by now that the existing system of analog TV transmission will end in North Texas and in most of the rest of the country on June 12, although some areas have already made the switch. Unless you already watch your local channels via cable or satellite subscription — you will need to receive digital TV off the air.

This can be accomplished by purchasing a new digital TV set (check first to see if yours isn't already digital-capable; most sets purchased in the last couple of years are), or you can adapt your analog TV to digital reception by using a simple converter box to "translate" the digital signal into something your analog set can digest.

Converter boxes are available now at most electronics retailers starting at $50, and you may be eligible to receive up to two government coupons to cover $40 of that price tag (see the link at the end of this story).

Because Channel 8 and all other local stations in Dallas-Fort Worth are already sending out their signals in the digital format, there's no need to wait. But some viewers are frustrated after making the digital connection.

"We purchased a digital converter box earlier this year and hooked it up, but we were unable to get WFAA on the television set," one viewer writes. "The man at Best Buy said the signal for WFAA was weak in our area (Wedgwood in Fort Worth)."

"I recently installed a DTV receiver and can no longer receive WFAA's signal," says another viewer. "It was my strongest analog signal, but now my DTV receiver registers no signal at all from WFAA."

After more than half a century of analog TV, we've all grown accustomed to the variety in reception patterns. There can be ghosts and snow, and sometimes you just get used to it.

Digital TV is different.

Even if you have been receiving an acceptable analog picture at your location, unless your digital signal level is above a certain threshhold, you'll either see no picture at all — or it will be "blocky" and unwatchable.

Compounding the reception problem: all local stations are sending out their digital signals on a different channel than their analog signal. Channel 8 is on digital Channel 9; Channel 5 is on digital Channel 41; etc. Some viewers have difficulty with WFAA's digital broadcast because until June 12, it is the only local station using a VHF channel. Some "digital-ready" antennas are not designed to pick up VHF channels, so be sure that your antenna is (and it doesn't have to be "digital-ready" either; if you have excellent reception with your current antenna, you should have good luck when you go digital).

On June 12, two other local stations — KTVT Channel 11 and KFWD Channel 52 — will be moving their digital broadcasts to VHF channels (11 and 9, respectively).

At the same time, WFAA will be shifting its digital transmissions to Channel 8, and the FCC has given us permission to broadcast with a 50 percent higher power than we can currently use on Channel 9, so that should help reception for many of our viewers.

If you're currently using an indoor "rabbit ear" antenna and you're having digital reception problems, extend the cable that connects it to your TV (or your converter box) and move the antenna to a higher location in the room. My son lives in an apartment in Plano and found that by doing this, he can receive digital channels that were otherwise absent.

You may need to employ an extra length of cable to get the needed positional flexibility. Use a simple coaxial "barrel" connector (available at electronics stores) to link the two cables, but don't use an extension that's longer than necessary; every foot of cable diminishes the signal strength.

Or try parking the antenna in or near a window that has the best "view" toward Cedar Hill, where local TV transmitters in North Texas are located.

Also be sure to extend the rods of an indoor antenna fully and position them horizontally for the best chance of getting all the signals.

For some viewers, an outdoor antenna is the best bet for top-quality digital reception. It offers the best possible incoming signal strength.

But there is a middle ground: using an outdoor antenna in an attic. This can be an excellent place for to pick up TV signals as long as:

• You can aim your antenna through unadulterated plywood and standard composite roofing materials. Foil-backed or aluminized insulation, tile or metallic shingles can block signals.

• Your home is within about 50 miles of the Cedar Hill transmitters.

• Your home is not at the bottom of a hill or adjacent to a large building while looking toward Cedar Hill.

I've set up sort of an antenna "lab" in my attic in Denton County, which is about 40 miles from the Channel 8 transmitter. Hanging from the rafters are two different antennas: a smaller UHF-only model (RadioShack U-75R, $30) and a larger VHF-UHF model (RadioShack VU-90 XR, $60).

The U-75R is a great size for an attic, just 40-inches long. Unfortunately, it's not designed to receive VHF signals (channels 2-13), and after the digital switch, as mentioned above, three local stations (including Channel 8) will be transmitting their digital signals on VHF.

In a test using an RCA converter box, the U-75R is powerful enough to pull in Channel 8's digital signal at my location, but I get a much better signal strength with the VU-90. Its larger physical size (80 inches long) is tailored to get the full spectrum of digital channels.

But even with a larger antenna, it's still possible for some digital channels to be missing in action. There can be several culprits.

AIM: Directional antennas (like the models specified above) must be pointed at the right spot for maximum signal strength. Most all digital TVs and digital converter boxes provide an on-screen display to indicate signal level. Some even have a menu item that also emits an audio tone that changes according to signal strength. That can help when trying to find the best spot for an indoor antenna. For an attic or an outdoor antenna, enlist a friend of family member to watch the screen and relay signal information via cell phone or walkie-talkie as you nudge the antenna back and forth toward Cedar Hill. You can plug your address into the AntennaWeb and TV Fool Web sites to get information about what stations you should be able to receive at your location and what direction to point the antenna.

SPLITTER: Many existing attic or outdoor antenna setups use a splitter to distribute the TV signal to multiple rooms. Problem is, a splitter saps signal strength. Think about what happens to the hot water when everyone in a household tries to take a shower at the same time (using different bathrooms, of course!). To determine if this is the culprit, simply take the splitter out of the equation. Unscrew the antenna cable from the splitter and connect it directly to the cable that goes to your digital TV set using a barrel connector (see above). Your reception should improve. If it does, then all you need it an RF amplifier (sometimes caled an antenna booster) installed between the antenna and the splitter. The closer the booster is to the antenna, the better your results should be. You should be able to find an antenna booser for under $50.

RESCAN: Every time you change your antenna setup, you must re-scan the channel lineup using the menu on your digital converter box or digital TV set; if you don't, your receiver won't know where to tune in any new channels that might be available.

I hope this resolves your antenna questions about digital television; if not, check the link below for our DTV Countdown page with a comprehensive guide to the switch. And if you don't find what you're looking for there, be sure to drop me an e-mail message at the address below.

We want to make sure that you can start enjoying digital television before the curtain comes down on analog in June.

• LINK: WFAA DTV 2009 Countdown
• LINK: AntennaWeb: Antenna suggestions for your location
•  LINK: TV Fool: Signal analysis
• LINK: Get up to two free $40 coupons for a digital TV converter box
•  LINK: RadioShack VU-90 XR VHF/UHF Antenna
• LINK: RadioShack U-75R UHF-only Antenna
• LINK: More from Computer Corner

Computer Corner is a feature of WFAA.com.

E-mail askwalt@wfaa.com