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  Video
generators have come a long way from the good old days of NTSC products. The new
breed of high-definition displays requires significantly higher scan rates and
tri-level syncs. The need for high-definition capable video generators has also
increased as more consumers hire ISF (Imaging
Science Foundation) certified technicians to calibrate their displays and
has become an important part of today's serious home theater enthusiast. Accurate
color tracking and properly adjusted black and white levels produce the best picture
possible. Video calibration requires a video generator capable of multiple scan
rates and a variety of different reference patterns. B&K Precision has introduced
the new affordable Model 1253 Multi-standard Video Pattern Generator to service
this market. The Model 1253 is capable of generating 720p and 1080i high-definition
timing as well as standard definition 480i and 480p video. Fourteen video patterns
and twelve of the most popular video scan rates are preprogrammed into this video
generator. Commonly used video patterns include SMPTE color bars, PLUGE, needle-pulse,
staircase, multi-burst, cross hatch, focus and multi-level IRE windows. An overscan
bounce test is also built into the 1253 for checking the high voltage stability
of CRT-based displays. The unit is light and fairly small, measuring only 5.6"
x 3.1 x 1.1" and operates from a standard 9 volt battery. The unit is even
smart enough to warn the user when the battery level has dropped too low.
 Three
BNC connectors for component video (YPrPb) and the standard mini-DIN connector
for the S-video connection are provided. The catch is the S-video signal really
only contains the Y portion of the Y/C signals needed for true color reproduction.
Therefore, the S-video output on the 1253 is monochrome. The Y output of the component
signals can also be used to drive the composite input of the display under test
when selecting NTSC, PAL or SECAM formats. However, this signal also lacks any
color carrier information, so the image will always be black and white. The unit
comes with a BNC to RCA adapter cable to accommodate the RCA jacks found on most
consumer displays. In addition, a zippered case is provided to protect the video
generator. Operation
The 1253 is a very simple unit to operate. The unit defaults to 1080i during power-up.
To change the video format, the user must press the VIDEO FORMAT button and then
press the desired format button. This method allows the buttons on the panel to
be used for two functions. Once the format is selected, the user simply selects
the pattern depending on the type of calibration needed. The Window pattern
used when setting the color temperature across various IRE levels start at zero
and works its way up to 100 IRE units in increments of 2.5 IRE units. In other
words, forty button pushes are required to reach the full 100 IRE level from zero.
Once the peak level (100 IRE) is obtained, the level ramps back down in 2.5 IRE
unit steps. This can cause some confusion if the user loses track of the current
IRE level during the calibration. The PLUGE (Picture Line-Up Generation Equipement)
pattern worked well for setting the black level with the flashing inner rectangle
and provided a good way to check DC restoration on the display. SMPTE color bars
looked good and allowed us to set the proper color saturation and tint adjustments.
The Needle Pulse pattern was used to set the best possible white level
without causing distortion on our display. The Staircase pattern allowed
us to double check our levels and was particularly useful with digital displays
such as plasmas and DLP projectors. How
it works
The 1253 only supports component (YPrPb) outputs and a luminance
only S-video connection. The reason for this is that the video signals are not
generated by a video encoder chip, but instead are derived from a Ubicom™
RISC-based embedded processor. The downside is there is no way to generate the
chroma signal needed for the S-video or composite video. Therefore, both these
outputs are black and white only. The processor uses a 27MHz crystal which means
the highest resolution you'll see on the screen is 13.5MHz which is used on the
multi-burst pattern for HDTV formats. The maximum burst frequency displayed for
SDTV formats is 6.75MHz or half of the 13.5MHz. Conclusion
Even with some of the limitations of the Model 1253, the unit offers consumers
and professional calibrators a means to properly adjust a display without breaking
the bank on an expensive high-definition video generator. The cleverly designed
B&K Model 1253 is certainly affordable for calibrators and even most home
theater enthusiast and allows them to properly adjust their display in both 720p
and 1080i high definition modes. Since few tools are available to consumers for
adjusting HDTV modes, the Model 1253 just may be the answer.
-
Kevin Nakano | 
