Technology

  IMPORTANT INFORMATION FOR VIEWERS WATCHING KPIX-TV OVER-THE-AIR

For all television viewers that are not connected to cable or satellite, construction at Sutro Tower was completed this week.

As of Tues. Oct. 21, CBS 5's antenna was officially moved up on Sutro Tower by 305 feet.

This means that you should rescan all of your television sets or converter boxes. You could now pick up KPIX and other stations you're currently not receiving. To rescan, follow these simple steps:

- Press menu on your remote and choose the channel scan function.
- Your TV set or converter box will then find all the channels now available in your area.
- Don't forget to rescan the channels on all of your TV sets.

Despite a stronger over-the-air signal for thousands of Bay Area homes, some viewers may still not be able to receive us after they rescan due to the differences between the new digital and old analogue signals, and where they live. These viewers will have to consider getting a rooftop antenna, or even cable/satellite.

 Sutro Tower Project To Bring CBS 5 To More Homes: DTV Antenna Moves to Top Position

 More Changes On The Way Following DTV Conversion: Expect Channel Disruption During Sutro Tower Construction

 Digital TV Converter Boxes May Not Always Work

 What Happens To Sutro Tower After The DTV Switch?

Digital TV Help Centers

There are some Bay Area help centers that will provide over the phone assistance, help to walk-ins, and in some cases, home visits to people who need help figuring out their converter boxes.

Self-Help for the Elderly
407 Sansome Street, Third floor
San Francisco, CA 94111
(800) 958-2999.. Leave message for Steve M-F 9-5 PM

Oakland Digital Television Assistance Center
Coordinated by Media Alliance
1431 23rd Avenue
Oakland, CA 94606
(510) 533-7266 OPEN M,W,F 11AM-5PM

Frequently Asked Questions:

Antennas
Do I need an indoor or outdoor antenna?

Viewers located in close proximity (less than 5 miles, perhaps further) to the KPIX/KBCW transmit antenna at Sutro Tower may find reliable reception using an indoor VHF/UHF antenna. Most viewers will find that an outdoor antenna will provide the best reception. While there is no set distance from the tower where one versus the other will work better/worse, the overwhelming default is an outdoor model. Since there are two stations in our area transmitting on VHF with the remainder on UHF, you will need a VHF/UHF antenna

What make/model should I purchase?

While we can't make specific product endorsements or recommendations, we can offer that there are several reputable antenna manufacturers available thru retail outlets and/or the internet. Internet sites will frequently list antennas grouped by gain or amplification factor and provide choices of antenna model grouped by how far the receiver (you) is from the transmitter (KPIX/KBCW). Larger antennas will typically provide more gain/amplification as well as be more directional; ie: tend to pick up more signal in the direction they're pointed, and less from the sides and rear of the antenna.

Is antenna placement important?

Absolutely! For outdoor antennas, the best location is one with an unobstructed line-of-sight towards Sutro Tower. Also, you should place the antenna as high off the ground as possible; bottom line with antennas, higher is better. Many viewers have opted to install a rotation device; aka: antenna rotor, on their antenna mast. This provides for precise antenna aiming which is critical in achieving the highest signal strength. An antenna rotor will also allow the viewer to re-aim the antenna towards signals transmitting from different towers or mountain tops; all by remote control.

Line-of-sight
Why is it important?

Of the digital TV transmissions in the San Francisco area, all but two are on UHF channels with KGO transmits on VHF channel 7, while KNTV-11 transmits on VHF channel 12. VHF typically provides better propagation even when there is poor line-of-sight, particularly in rough terrain such as the Bay area. UHF is typically reliant on direct line-of-sight between the transmit antenna and the receive antenna.

Signal Strength
What does it mean?

Most, if not all, digital televisions and set-top converter boxes provide some method of displaying the signal strength of the received digital signal. This is an important indication of how reliable you can expect your signal to be as well as offering insight into what may be causing poor reception. Depending on the model of receiver or STB (set-top box), you may have a button on the remote labeled 'signal' or similar, or, have a menu selection that will provide the information.

Signal strength can be displayed on-screen as one or both of the following; a number from 1-100 with higher numbers denoting higher signal strength, a color bar graph with red indicating poor signal strength, yellow indicating marginal signal strength and green indicating good signal strength. Some recent models of television offer additional signal diagnostics such as AGC (automatic gain control). For those sets equipped with it; AGC is an indication of how much amplification the receiver is supplying to the incoming antenna signal. A high AGC reading suggests that there is a relatively low signal coming from the antenna and the receiver is supplying additional amplification to try and keep the signal stable. A low AGC level; less than 50, suggests that there is ample signal strength supplied from the antenna system.

If you experience picture freeze, picture drop outs, pixilation or video tiles, or audio muting, you have; low signal strength, multipath or both. Low signal strength is usually indicated by a numeric value of 50 or less and/or a color bar graph indication at the low end of the yellow scale and/or in the red portion of the graph. Low signal strength can be caused by one or more of the following; a) poor line-of-sight between the receive antenna (you) and the transmit antenna (KPIX/KBCW), b) improperly aimed receive antenna, c) poor physical connection between the receive antenna and your receiver(s), d) lack of a good quality RF pre-amp installed in-line between your antenna and the receiver, e) improperly installed RF splitter(s), f) antenna with insufficient gain. If you notice the color or numeric values change; either gradually or erratically, it suggests that you are experiencing multipath; see section 5, below.

a) Poor line-of-sight – See section 2, above.

b) Improperly aimed receive antenna – Outdoor antennas need to be properly aimed towards the desired transmit antenna. Your reception of stations transmitting on UHF channels will benefit most from precise aiming, particularly at receive locations further from the transmitter, as compared to stations transmitting VHF signals. To receive KPIX/KBCW, your antenna must be pointed towards Sutro Tower. If you are unsure of the exact direction to aim your antenna or need help selecting an antenna you can consult www based resources such as; tvfool.com or antennaweb.org.

c) You should verify that the physical connection between your antenna and antenna coax and receiver is good - Some antennas are wired to the inside of the house with round cable, typically referred to as coax, while others may use a flat cable typically referred to as twin-lead. While either cable type will work, coax is the preferred cable. The connections should be tight at all junctions and the cable should be free of any cuts, kinks or deformities. When in doubt, consult a professional antenna contractor.

d) Lack of a good quality RF pre-amp installed in-line between your antenna and your receiver - Low signal strength indicated on your receiver can be improved with the installation of a good quality RF pre-amp. Frequently, viewers living at a distance from Sutro Tower will already have a pre-amp installed. This is particularly true for viewers in Northern Marin, Sonoma and Napa counties as well as Southern Santa Clara county. If you live 20 or more miles from Sutro Tower, you should consider installing a good quality RF pre-amp with at least 15 dB of gain/amplification in-line between your antenna and your receiver.

e) Improperly installed RF splitter(s) – If you have more than one television or converter box being fed by your antenna, you will also have at least one RF splitter installed somewhere between the antenna and the TVs and/or converter boxes. Improper installation can cause reception problems. The splitter will have one connector labeled as; 'input' or 'antenna'. You should connect the output of your antenna into this connector. The remaining connectors should be labeled as; 'output' or 'TV'. You should connect your TV or converter box to these connectors.

Pre-amp – How do I know if I need one?
See section 3 (d), above.

Multipath – How do I know it's affecting my reception and how do I fix it?
Multipath is caused by the transmitted signal reflecting off of two or more points, resulting in the two signals arriving at the receive antenna slightly out of sync with each other. In practice, there are hundreds, if not thousands of reflections of the transmitted signal all being picked up by the receive antenna. With now obsolete analog signals, multipath would cause 'ghosting' in the picture. Many viewers who used set-top antennas, or 'rabbit-ears', had long ago learned that the 'ears' needed to be frequently moved to reduce the ghosting effect.

Most recent model digital TVs and converter boxes have circuitry that filters out the reflections and allows for the tuning and display of a reliable, stable picture. If the amount of multipath is too great, the receiver may not be able to decode the signal at all resulting in no picture, or it may only provide a picture intermittently with resulting picture freeze, audio dropouts, etc. While multipath cannot be eliminated, it can be reduced. The easiest solution is to reorient the receive antenna. For viewers with indoor antennas, some experimentation is needed. As the antenna is moved, you will need to view all of the stations you wish to watch to insure that solving the problem for one station has not created a problem for others. For viewers with outdoor antennas, reorientation may not be quite so easy without an antenna rotor. Nevertheless, the effect of multipath will not be reduced without moving the antenna. One more note; multipath is random and unpredictable. You can experience a stable picture for a sustained period of time and then without reason, the picture will deteriorate or disappear.

Rescanning for channels – Why is it needed and when should I do it?
When installing a new TV or converter box you need to make sure the device can 'see' all of the available channels. Some devices will automatically scan for channels, while others will need the process initiated manually via a menu selection. If you have installed a new antenna, relocated an existing antenna, installed any new antenna cables, splitters, pre-amps, etc. you should rescan for channels as you may find that the above mentioned changes allow your TV to receive more channels. Rescanning is also suggested if you are reorienting your antenna in an effort to reduce multipath.

What is the difference between your virtual channel and your actual broadcast channel?
Each digital TV station is assigned a broadcast channel to transmit their signals on. In most cases, this channel is different from what is displayed on your TV which is a virtual channel. Example; KPIX-TV uses the brand 'CBS-5' in all advertising, promotions and on-air mentions. KPIX opted to use 5.1 as its virtual channel, while its broadcast channel is UHF channel 29. You can tune KPIX via your remote control by entering 5.1 or 29. Either one will tune in KPIX though the TV will display '5.1' as the channel.


FCC Info On DTV Education - KPIX

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