DTV: Some finer points to be mentioned...

 There are many set top antennas claiming to be HDTV/DTV ready. They are in fact UHF only antennas. And there are a lot of outside DTV antennas that are UHF only too. (or have very minimal VHF reception.) I know in other markets some major retailers have been pushing UHF only DTV antennas claiming they're OK.

 What I'm saying here is that when using VHF DTV some antennas may not in fact be able to receive the VHF DTV signal on a UHF only DTV antenna. This issue is a real and continuing issue for both WIBW and KTWU. WIBW, in an effort to counteract this, has applied for and been granted a license to reactivate their DTV transmitter assignment on UHF channel 44.

 I know this antenna mis-marketing was the driving force behind KMBC in K.C. choosing to abandon their DTV channel 7 and go to DTV 29. They were swamped with reception issue calls during the transition period. I also know in other markets, where VHF high band DTV signals are being used as their primary DTV assignment (as in the case of WIBW-TV and KTWU) this has also been a major issue..... Some of these stations are taking the action of either reactivating their temporary UHF DTV (as WIBW did) or are completely rebuilding their operations to be UHF only on a new channel.

  So in any particular case this may or may not be an issue. But be aware that just cause an antenna says its HDTV ready, doesn't necessarily mean you will be able to receive VHF DTV signals reliably.

The remaining of this page was first written to cover older analog TV reception, and has been update for the new world of DTV. But all the concepts, as well as the station's locations, are the same. Consequently much of the information is still relevant. 

Some details: 

For those who wish to know more.....

DTV relies on converting the picture to numbers, lots of zeros and ones. This is the same process in many ways as is used in digital cell phones or WiFi connections. And to clarify, HDTV (high definition TV) and SDTV (standard definition TV) also known at DTV use the same transmission scheme. The only difference is how many bits of information are shoved into the pipe. This digital technique means the power used to carry the signal is spaced out equally all across the band.

To put a picture to this, below is a spectrum analyzer photograph, shot during the transition period, showing KSNT and KSNT-DT. This is really a graph with the horizontal line showing frequency whereas the vertical scale shows power. The left is the lowest frequency whereas the right is the highest frequency. The photo clearly shows the visual and aural carriers of the analog signal whereas the digital channel is the large rectangular bump on the left with energy shared equally all across the 6MHz channel band. 

So now on to specific channels…. 

  For those of you wanting more information here is a table showing the channels, affiliation, whether they’re digital or analog and some other pertinent facts. 

East side, west side, outside of town…. 

Now that the DTV transition has taken place all the Kansas City DTV stations are in the UHF band. According to their coverage charts the best of them just reach the east Shawnee County line. But hope springs eternal in the heart of the TV viewer and it is possible to get these stations in parts of Topeka. Generally speaking, a viewer east of Indiana St. with a good UHF deep fringe antenna at least 30 feet up, with a preamp, on high ground can receive these stations most of time. There are some exceptions I’ll mention later. Anywhere west of this line it becomes more and more difficult where by Fairlawn St. the odds of reception dwindles…Remember the earth curves and there is some pretty decent high ground between Topeka and Lawrence, this works against the signal. Viewers North of the Kansas River are a bit luckier. In their geographic location the signals from the K.C. stations skim down the Kansas River bottom and as such can go a bit further west. But Much west of US 75 and the signal is gone. 

Your Mileage may vary…. 

Now for the exceptions, Channel 42, the DTV signal from KSHB, is parked next to channel 43 KTMJ and as such the receiver’s tuner just can’t lock to the distant signal reliably. Now that being said, there may be areas, on the Eastern edge of Topeka where these signals may be viewable on a case-by-case basis.

There’s no place like home….The Topeka Stations: 

Well here it’s a bit easier you would think, but this is not always the case either. To start with here is a map showing the location of the Topeka stations. 

 Channel 11’s tower at the North end of Wanamaker is the home of  both KTWU's DTV transmitter as well as the KTMJ transmitter.  The KSNT tower North of the river on highway 24 holds their DTV transmitter. The KTKA tower west of Topeka at 23^rd and West Union Road, holds the KTKA DTV antenna as well as the K33 LPTV antenna. Finally, WIBW is located several miles South of the Maple Hill exit on I-70 in Wabaunsee Co. It holds both the WIBW digital antennas.

So, depending in where you live in or around the city the various transmitters may not be in the same direction. This is a bad thing. As any viewer knows so well, the placement of the antenna is what gets rid of ghosts. Remember playing with rabbit ears to find the best picture? This is not so much an issue of signal strength but more one of minimizing the unwanted reflecting signals that show up as ghosts. This same thing happens with outside antennas not pointed toward the transmitting tower, ghost signals, also called multipath, can tear up an otherwise strong signal. As a side note here, don’t be fooled by folks who say DTV doesn’t have ghosts, well no, not that you can see BUT these multipath signals can and do strongly affect the reception. These multipath signals can cancel out parts of the received signal and make it very hard for DTV receivers to detect the data properly. So these digital ghosts show up as unreliable signal and will cause the DTV receiver to show a “blue screen of death” right in the middle of that all-important game. When DTV is good it’s great, when the digital signal is marginal, it simply goes away. This by the way is known as the “cliff effect” referring to the fact the signal is either there or not, rather than the cliff a viewer wants to jump off when the all important show is missed.

So in Topeka proper, it may work to have just one antenna for 11 and 13 and one antenna for the UHF channels. Or, if you live on the west side of town, a couple of antennas to get each set of signals cleanly, remember ghosts kill DTV too. 

The FCC’s “gift” to Topeka’s viewers…. 

Ok now on to the real bailiwick in Topeka TV viewing. Something the FCC didn’t think about. The idea of adjacent channels was addressed by the FCC making some assumptions, that the stations were co-owned and co-located. This would allow one, common engineering staff to make sure the proper equipment and techniques are used so the typical viewer gets both stations cleanly. Then, the FCC promptly overlooked the low power class A stations, of which KTMJ is one. So all the safeguards went right out the window….. KTMJ is a class A station and as such is limited on the amount of power they can broadcast. It’s not their fault; this is the way the FCC set up the rules. And WIBW is required by the FCC to cover their entire viewing audience with their DTV signal on channel 44. This makes their signal strong. Again it’s the FCC rules it’s not their fault. BUT what this means is there’s a big old DTV transmitter putting out what looks like snow right next to lower power KTMJ on channel 43. So neither station wins this battle. KTMJ has a strong signal over Topeka but typical TV tuners also see the digital snow from WIBW DT on channel 44 and the picture looks bad. And before you think WIBW DT channel 44 is all bad, the analog signal from KTMJ affects their digital signal too. The analog signal makes it harder for DTV receivers to lock on to the proper signal and the consequence is the viewers at home get the dreaded “blue screen of death”  out of their DTV sets….. 

Remember, it’s NOT either of the station’s fault, they are controlled by FCC regulations. This situation will solve itself in some way when KTMJ eventually converts to DTV. Remember this before you pick up the phone or sent them email..…. Stay tuned for further developments.   

Just a quick reminder…. 

Remember the Topeka TV stations didn’t create the problem, they know it’s there, and are reticent to talk about it. It’s an FCC thing. And out of their hands.  

Now before you throw up your hands and just get a satellite dish. This won’t necessarily fix your HDTV reception problems either. 

A short side trip: 

How DTV signals get on satellites and cable....

I thought a short side trip into the world of how DirecTV, Dish Network and cable providers actually get their signals from local stations might be useful here. 

Firstly for cable. WIBW, KTWU and KTKA provide a separate signal, via fiber, to Cox in Topeka. Cox takes those signals, again via fiber, to Manhattan and Junction City cable systems. I'm not sure how KSNT and KTMJ signals make it to cable currently. So it's possible for those station's transmitters to be off and still have programming on Cox. 

Other, non Cox, cable providers receive the signals over the air and just repeat it thru their systems. So a transmitter failure wipes them out too. In some cases these providers also down convert over the air signals to standard definition also. You can now see that in some cases having cable may not give you any better signal than a simple antenna system would provide.

I've worked on both the satellite local ingestion sites but won't disclose their locations. But I can explain how this all works. Hopefully this will explain to viewers why sometimes the satellite providers can have signal issues..

Back in the days of analog TV the FCC required that local stations be available as signals on the satellite from the big two providers. To meet these needs each provider built a "local ingestion" point where all the over the air signals could be received. These signals were then shipped on a high speed fiber optic link back to their broadcast centers, where they're uplinked to the satellites. 

Some of these sites were provided signals directly from the TV stations (pre transmitter) while others were received over the air, just like the folks at home. So for example if WIBW was off the air so was the signal on Dish Network and DirecTV. Whereas if KTWU was off the air it may not be off on DirecTV.

When DTV was implemented both Dish Network and DirecTV got agreements to carry only the standard definition DTV signals from local TV stations, and in some cases don't pass it as high definition or secondary channels. This is changing but slowly. But it also means that a viewer may not get an HD signal off of satellite.

What I'm saying here is that, depending on the provider and the channel being viewed, a failure may or may not wipe out a signal. And a signal may or may not be available in HD.... This means that, at least for local HDTV, just switching to cable or satellite may not necessarily be the best answer....

Where to start….   

Now that you know the gory details you can see that to get the most out of your New HDTV set, receiving the local over the air DTV signal is a must. “So what do I DO!” You ask yourself. Do not despair. It is possible to get local TV all that is needed is a plan. 

Firstly, a little pre planning goes a long way. Figure out where each TV tower is relative to where you live. It may be possible to get all the stations with two or three antennas. It may even be worth buying one antenna, which you plan to use, and try pointing it around at each of the stations from ground level while hooked up to some sort of portable TV. This is a pretty good indicator if you’re going to have problems with the final installation. If the signals look good on the ground, they should be even better from the attic or on the roof.

OK picking an antenna, in this case bigger is better. Antennas get their gain by eliminating signals from other directions. This makes the wanted signal better and off angle signals, the multipath mentioned earlier, weaker. Amplifiers amplify both the signal and the noise but an antenna selects just the wanted signal. It you have the luxury of being able to mount the antennas outside by all means do so. No need to loose most of the signal going through roofing if you don’t have to. Even for local stations a small mast outside could mean the difference between a great signal or a mediocre one. One other point here, if the antennas are outside it should be grounded properly as the directions with the antenna recommend. This is to protect against lightning damage.

Attic installs….

Well as you may have guessed the higher the antenna the better, at least for getting distant signals, but it some cases this can’t be done. Antennas placed in attics loose 60% to 80% of their signal going through the roofing material. This loss is greater on UHF signals. But in some cases, where there are home association covenants, this can’t be helped, the attic is the only place for an antenna. In these cases it’s important to make sure the antenna is still aimed properly to the station of interest.

Make it louder….

Amplifiers boost the signal but can cause problems all their own. Firstly there are actually two types of amplifiers, preamplifiers also known as preamps and line or distribution amplifiers. Preamps are used to boost the signal from the antenna to the distribution amplifier. These are sensitive but not meant to produce lots of power. Here bigger isn’t necessarily better. In fact, using the highest gain preamps can cause more problems than they solve. They can overload from stronger local signals and make the weaker, distant signals unwatchable. Use them only as needed. Distribution amplifiers serve a different function they take the combined signals,  amplify them split them to several TV sets. They have less gain and are meant to get the signal to each set adding only enough gain to make up for the loss in signal in the cable and the splitting process…They also accept high signal level without overloading. Using the proper amplifier type for the proper use can improve quality, while misuse will certainly cause reception problems.

Filters and combining the signals….

There are filters available to pass only one of the TV bands or to block only one channel. These filters can be helpful in allowing only the wanted signal into the system while blocking unwanted signals. An example here is if you live on the western edge of the city. KSNT would be due North whereas KTKA is due West. Pointing the antenna North would give a great picture for KSNT but have digital ghosts on KTKA and visa versa. The solution is to put up two smaller UHF antennas one pointed to KSNT the other pointed to KTKA. Then two UHF band pass type filters are used, one in the line from the KSNT antenna which would pass that signal and a similar filter on the West antenna to allow only the KTKA signal thru. Then both signals would be combined to get two great signals. So the trick here is to let the good signal pass and block the bad ones with filters.

These TV bands can also be combined with a band splitter/combiner filter. This device has three ports (inputs), one for each band, and one combined output. These are good for keeping any UHF stray signal from a VHF antenna from passing a poor UHF signal or visa versa……These devices are available at the same store where you get the antennas……

Don’t scrimp on the basics……

Make an effort to use good RG-6 type 75-ohm coax. Coax comes in all types but RG-6 is shielded properly and has less signal loss than other types. Using this will insure the signal you do get makes it to the TV set cleanly and with the strongest signal possible.

For the advanced hobbyist……

There are other, fancier devices that can improve the signal further, but a good understanding of TV is needed to use these.

One device is called an XUV channel converter. They only convert UHF channels to VHF channels hence the name. These would let you move any of the UHF DTV channels to open VHF channels (rather than using channel band pass filters I mentioned above)

Another device that comes in handy is called a modulator. This device takes the video and audio from a satellite receiver, VCR, or DVD, or video game, or even a home security camera and converts it to an open TV channel. With this device you can add you own channels to your TV system, allowing the source to be viewed all over the house.

Lastly, if you plan on getting this deep into a home TV system it’s worth it to get some sort of signal meter to both check levels at each set or to check for any possible interference of antennas.

Good luck….

You now have a good start on knowing how to get all the Topeka DTV stations cleanly. And have a pretty good feel if you can possibly get the K.C. stations where you live also. Depending on your need for TV you can make your TV watching choices as grand or as limited as you desire. I hope you find this useful. Happy viewing.

Other links to more info….

Lastly, if you want to learn more here are some helpful web sites.

http://www.fcc.gov

http://www.antennaweb.org

http://www.picomacom.com/macom/home/

http://www.winegard.com/

http://www.blondertongue.com/

http://www.channelmaster.com/

http://starkelectronic.com/

http://www.radioshack.com/