I CANNOT FIND KLCS, WHERE DID YOU GO?
Engineering has answered about 25 e-mails and 10 phone calls in past weeks with respect to inability to receive KLCS beginning on Sunday 9-29. The transmitter itself has been working properly, but we were transmitting bad (station ID) data for part of the weekend. The failure in the Program Information System Protocol (PSIP) data was traced to computer that generates the information. We have a backup computer and switched to it as soon as we confirmed the failure.
WE IDENTIFY KLCS AS CHANNEL 58, BUT TRANSMIT ON 41:
KLCS is channel 58 only because we transmit the data (as the FCC requires) that identifies the station as 58-1, 58-2, 58-3, and 58-4. Channel
58 was our analog channel and no longer exists. The programs identified
as 58-1 (etc.) are actually transmitted on channel 41. When the FCC
mandated that all stations transition from analog to digital, it became
necessary for each station to transmit information embedded in its data
stream identifying all the station program subchannels. Especially when a
single transmitter broadcasts multiple channels, as does KLCS, how do you
define the individual channels? So PSIP (Program System Information
Protocol) was created to tell the receiver how to locate and decode the
multiple channels being sent out. It also provided a way to associate the
actual channel (41) with the virtual channel (58). There is no channel 58
anymore; that spectrum was reclaimed and auctioned to 4-G and wireless
services. PSIP contains many data tables that identify the Virtual Channel
Table (VCT), Ratings Table (RRT), Event Information Table (EIT),
Extended Text Table (ETT), system time tables (SST), and Program
Specific Information (PSI). There are more, but your receiver will make use
of this information to display the sub-channel (station) you select. The
generator device we use to create these information tables comes from a
computer running “GuideBuilder,” a special program devoted to that
purpose. If this information is incorrect or missing, the receivers will not
function properly, and may display “No Signal.” This is not the same as
being off-the-air; it simply means that your receiver could not find us.
WHY DON’T YOU IDENTIFY KLCS AS CHANNEL 41?
If you recall, when the transition from analog to digital went forward, each
station was assigned a (temporary) second channel and broadcast in both
modes for almost 5 years. On June 12, 2009 analog telecasting ceased.
Some stations did revert to their analog channels and continued there in
digital such as 7, 9, 11, 13, 28. Some remained on their transition channels
such as KLCS-41and KDOC-32. The low VHF channels 2 through 6 were
found to be too prone to electrical impulse noise interference to be usable
for ATSC television, and were abandoned. This is why KCBS-2 uses
channel 43, KNBC-4 uses 36, and KTLA-5 uses 31. At the same time all
the channels above channel 51 were harvested by the FCC and sent to
auction for cellular and 4-G type services. (A second round of
“compaction” is under way that will further reduce the bandwidth available
for terrestrial television broadcasting, which may reduce the upper limit to
channel 36 or lower.)
The FCC in its “wisdom,” pressured by the major network affiliates seeking
to retain their prestige channel numbers, required all stations to use their
original analog channel numbers in identifying their stations regardless of
where they actually transmitted. This was to avoid confusion, which is
ultimately more confusing, especially with time.
IF THE DATA IS RESTORED, WHY WILL MY RECEIVER STILL NOT
WORK?
All DTV stations must transmit their virtual channel ID in order for the
receivers to tune in the station. Once the data is restored (and presuming
that no “channel scan” was performed during the failure) the receiver
should resume normal operation. This is not what we found in all cases.
The channel table in some receivers was corrupted by the bad data when
attempting to tune in the station only one time.
In talking with viewers last week we found that some receivers switched to
our actual channel (ch. 41) and that any reference to the virtual channel
(ch. 58) was ignored. I ran a quick experiment with a viewer on the phone
and switched to our backup PSIP (program identifier) generator. He
reported that the program stream returned, that the identifier was correct,
and that program descriptions returned. We remained on the backup PSIP
until the problem with the main generator was resolved. KLCS uses a onemegawatt
transmitter at Mt. Wilson (donated to us in 2009 by WVEC in
Norfolk, Virginia). We actually run 30% more power than KNBC, so signal
strength is seldom a problem.
HOW DO I REMEDY THIS CONDITION?
Many receivers (but not all) allow the viewer to tune directly to the actual
channel. You might try this first. Enter 41-1 on your remote control. If it
displays what it finds there, it will show 58-1 on the screen. Advance
(channel up) to the other three channels we are transmitting, then tune
away to channel 28-1 or channel 7. Now enter 58-1 and see if it tunes
now. If it does, your receiver data has been restored. If it does not work,
you will have to do a fresh channel scan or setup from the menu. All
receivers are different, so look up the procedure in the owner’s manual. It
is termed “channel scan” or “channel config,” or something like that. It is
usually found in the MENU on the TV remote. Once the process is
completed, you may manually go through the “edit” electronic table
(another menu function) and delete any foreign language or undesired
channel from the table. You should see 41 and 58 together in the table. In
the scanning process, the receivers sample each actual channel and
record in the tuner memory (Electronic Channel Table – ECT or Virtual
Channel Table – VCT) the identification codes (from PSIP) that it finds.
Then when you ask for 58-1 which does not exist in fact, it will look through
its electronic channel table (ECT) for 58, and associate that with where it
was actually foundI. Channel 41. All this happens in the background, and
unless the ECT becomes corrupted for some reason or the current PSIP
data fails, everything is wonderful. It is a little embarrassing to be solidly
on-the-air but not discoverable because of a data anomaly. Some tuners
(and converters) allow direct selection of channel 41, and it will then display
whatever station it finds there, while other tuners require a complete ECT
channel table or nothing will happen. Go figure.
If a viewer performed a channel scan while the PSIP was incorrect or
incomplete, they may have to do another scan now in order to reprogram
the channel table in memory. If they did not do a scan, the current data
should be correct. Try the 41-1 backdoor trick. If problems persist do a full
channel scan or feel free to contact engineering directly.
Thank you for taking the time to inform us of the problem. We apologize for
the inconvenience.
