Digital TV without the Subscription
Pages: 1, 2
Getting guide data was reasonably straightforward, though it involved deception. I lied to my TiVo and told it that I was a satellite subscriber. The "satellite" service is a set-top box that can pick up the TV broadcast, and the TiVo will simply record what is received on the S-Video input. To find the right "satellite" service for my guide data, I needed to compare the channel lineup for satellite service to the broadcast channel lineup. TiVo purchases guide data from Tribune Media Services, which also owns Zap2it. I put my zip code into Zap2it, and looked at the lineups from both major satellite providers, DirecTV and Dish Network. Both channel lineups are identical, except that Dish Network has KCSM on channel 60, its analog broadcast channel, while DirecTV has KCSM on channel 43, its digital broadcast channel. I selected the DirecTV lineup because analog channel 60 is no more.
For the most part, the guide data was complete. There were two major exceptions. One is that my "satellite" configuration work-around implicitly assumes that the digital channel is a simulcast of the analog channel. While usually the case, there is one notable exception in the Bay Area. KQED, another PBS station, has five digital channels, none of which match the analog broadcast schedule. I retained my set-top antenna, and I have continued to watch KQED's analog broadcast through the old antenna.
The second problem was getting guide data for KBHK, the Bay Area UPN affiliate. KBHK broadcasts analog on channel 44, and digitally on channel 45. Most stations will use PSIP to remap the digital channel number back to the analog channel number. If you tune to "2-1" in the Bay Area, the PSIP data will direct your digital TV receiver to go to the frequency assigned to channel 56.
For those of us who remember the analog numbers (or have TiVos), PSIP is vital. For some reason, KBHK has decided not to use PSIP to remap their digital transmission on channel 45 to 44-1. As a result, I am recording KBHK's analog broadcast as well. However, the antenna on the HTL-HD is better at receiving a clear picture, so I told my TiVo that it should receive channel 44 on the satellite. The picture is reasonably good (and certainly better than it used to be), though I would prefer that recordings on channel 44 switched the set-top box to the digital broadcast on channel 45. In the future, it is possible that the PSIP data will be modified to perform the mapping for me; in the meantime, I live with the analog reception, and if I notice a recording being made on channel 44, I will switch the HTL-HD to channel 45-1.
To work around the two problems with the guide data, I set up my TiVo to use both an antenna for traditional analog reception, and "satellite" for a digital TV set-top box. TiVo presented me with all of the channels in the lineup, and I configured it so that most of the channels were "satellite," meaning they come in through the set-top box because they are received digitally. For local broadcast channels, I selected them through the satellite as opposed to antenna, as shown in the left picture below. TiVo presents both channel lineups simultaneously, noting the channel as either an antenna or a satellite channel. I went through the channel lineup and selected all of the local channels as satellite channels so that they would be received digitally, with the exception of KQED. I left KQED as an antenna channel because digital 9-1 is not a simulcast of analog channel 9. The final lineup can be seen in the Favorite Channels display.
I ultimately decided to make channel 44 a satellite channel because the antenna hooked to the set-top box is better at receiving UHF signals than the old set-top antenna. There is a TiVo channel remap hack available, which I may try at some point on channel 44 and 45, but I set it aside in the interest of getting something running faster.
As the old saying goes, everything old becomes new again. In the case of television, it's certainly true. Digital TV signals are available at no charge over the air, and are only now coming to cable and satellite systems at an extra charge. Powerful external antennas are available for less than $100, and can deliver high-definition programming with no monthly charge. Many people have opted for a TV antenna for local channels because the quality is as good as a subscription service, but at no charge.
There are different types of antennas based on the frequencies that they are designed to receive. All an antenna does is to pick up electromagnetic fields and pass them down to a receiver. There is no such thing as an "HDTV antenna," in spite of the impression you might get from reading boxes. Different styles of antenna are required for VHF (55.25 to 211.25 MHz) and UHF (471.25 to 801.25 MHz). In most cases, the digital broadcast occurs on a UHF channel, and it is possible to get a UHF-only antenna to reduce weight, size, and cost.
The first step in selecting an antenna is to find out where you are relative to TV transmission towers in your area. The Consumer Electronics Association runs an antenna selection web site, which will give you a table of nearby TV stations based on your address, including distance and compass headings. Using antennaweb.org, I found that most of the digital stations near me were on Sutro Tower, though there were two transmitters about 35 miles south on a mountain near San Jose. Antennaweb can give you distance and compass heading to TV transmitters; an example is shown below for O'Reilly's headquarters in Sebastopol, California. Each line points at a transmission tower, and shows the channels available on it, while the corresponding table shows the distance to the tower.
In my case, my distance to the tower is less than five miles. A large antenna would certainly work, but I was hoping to use a small indoor antenna rather than undertake a large antenna mounting project. Indoor antennas are not frequently reviewed; the best write-up I found was written by Peter Putman, an independent consultant.
The first antenna I attempted to use was the Terk HDTVi. Although the Web is full of stores of bad experiences with Terk, it was the only brand carried at the first store I tried. I thought that my close distance to the transmitter would perhaps make up for shortcomings in the antenna. I purchased the antenna for $40, and went home to see how well it worked. It could receive one channel when I aligned the antenna with a compass, while the $10 set-top antenna I was using could get five. I did not investigate why performance was so poor, but I did return the antenna the next day. In retrospect, I should have known better than to purchase a product that claimed that its appearance was compatible with new TV equipment.
My next try was with a RadioShack 15-1880 internal antenna. A similar-looking antenna performed well in Putman's review, so I thought it might be worth a try. I pointed the UHF reflector at Sutro Tower, and checked for a signal on the digital channels. There was no signal on any of them, though my set-top box diagnostics did show a weak signal on each of them. I tried repositioning the antenna, to no avail. When I switched on the built-in amplifier, the signal vanished completely.
On my next antenna shopping run, I decided to buy multiple antennas and return what didn't work. (After all, any network engineer worth knowing instinctively knows that a windowed protocol is more efficient than a stop-and-wait protocol.) I picked up the Silver Sensor indoor antenna, and a Channel Master 3010 StealthTenna.
The Silver Sensor lived up to its reputation. It could get all of the channels from Sutro Tower, and it was not very sensitive to position, either. It even outperformed the StealthTenna, which a much larger external antenna. The Silver Sensor is even capable of pulling in a UHF station from 35 miles away, though it does require repositioning the antenna. Even though it is advertised as a UHF-only antenna, the signal on some VHF analog stations is watchable.
The only problem I had with the Silver Sensor is that its performance is somewhat sensitive to height. Once I had stowed my set-top box in a cabinet, the antenna was a few inches lower and did not receive channel 2. I tried a variety of boxes, but finally resorted to books to prop the antenna up to the height it was at when on top of the HTL-HD. I strongly suspect that the reason for the poor performance when placed directly on the cabinet was due to multipath reception indoors, and the small height change puts the antenna in a better spot. On September 12, the digital transmitter doubled its power, but the increased power did not seem to have any effect on the quality of the signal that I receive. It still drops out or pixellates occasionally. Unfortunately, the only solution to indoor multipath is to put the antenna in an environment where the signals won't bounce around as much. Practically speaking, that means mounting an antenna outdoors. For now, the minor inconvenience of a blip every hour or two is not worth the hassle of an outdoor mount.
The first phase of my A/V system renovation is complete. The TiVo functions as it always has, but it now receives a pristine standard-definition video input from the HTL-HD. The HTL-HD was an acceptable choice, though I wish its channel handling was a bit more configurable so it didn't need so much help tuning channels. Now that I've put a stake in the ground, I've already started to think about what I can do next.
In the spring, I will build an antenna system. Right now, I have to position the antenna carefully to receive the digital signal from channel 36, and the signal is spotty. Rather than rely on manual antenna repositioning, I would like to combine my existing internal antenna for San Francisco channels with a long-range UHF antenna for channel 36's digital signal 35 miles to the south.
For some reason, my remote-control situation has gone critical. Adding the HTL-HD threw another remote into the mix, bringing the total to seven remotes to control the A/V system. A single Harmony remote looks more attractive every time I trip across one of the seven.
Matthew Gast is the director of product management at Aerohive Networks responsible for the software that powers Aerohive's networking devices.
Return to digitalmedia.oreilly.com