Z Technology 's RF Newsletter - DTV Edition

Broadcast News, Edition 1

May 1st is approaching

With the May 1st FCC DTVdeadline* fast approaching, many broadcasters have opted to initiate DTV service to their communities with low power transmitters and interim antenna systems. Whether this is right for your station depends on your circumstances, goals, and perhaps on your budget, but it does offer a flexibility to approach 8VSB transmission in a manner that could in the long run serve your technical needs and viewers better.

DTV is a complete change in your method of distributing your programs over the air to home antennas. It involves not only a new transmission format, but also a new channel frequency, a new transmitting antenna, probably a new antenna height, and maybe even a new antenna location. All things not to be taken lightly.

Here is the good part. DTV receivers are coming on the market and your affluent viewers (think advertisers) are starting to see what you are up to. Even a low power signal will be first directed at this "audience", and this is what will get DTV rolling.

What is good about low power?

This signal is also a "test transmitter" for your station. Using this signal, your station engineers can make real measurements in your community to determine what will be ultimately required to keep a viable signal to your audience when your 8VSB DTV signal is the only one under your complete control.

As development work moves beyond the laboratories and test sites into your real world, Z Technology products provide the real information as to how your signal is reaching your viewers. Using this measured coverage data, you can determine what has to be done to continue a viable on-air business. Real data will help determine your ultimate power level, and reveal changes to your design to reach the audience you want to reach.

New RF measurement products for DTV

Z Technology has introduced two new products to help station engineers and consultants design and implement the best system for your community. The first, a laboratory reference demodulator that will let you see your DTV signal free from receiver artifacts. This demodulator, the DM1010W, would be used in evaluation of your RF signal, or it can be married with an MPEG analyzer or transport stream decoder for subjective evaluation.

The DM1010W 8VSB demodulator features a laboratory quality RF front-end for television channels 2 through 69. Outputs include RF at the intermediate frequencies centered at 44 MHz and 4 MHz suitable to drive other instruments or test receivers, and a transport stream output suitable to drive MPEG decoders or transport stream analyzers. Controlled from a PC running Z Technology Windows XPô application software, the DM1010W provides a display of tap energy, signal to noise ratio, segment error rate and RF input level. It also provides an indication of sync lock and equalizer lock. Although the DM1010W is a true test instrument, it will find long term application in critical monitoring applications when coupled with an MPEG transport stream decoder.

The second new product is really an extension of our DriveTest measurement system used throughout the world for analog and digital coverage measurements. Our new DSS5800 DTV measurement system consists of a programmable field strength meter, GPS receiver, 8VSB decoder, and a laptop PC running Z Technology Windows XP(tm) application software, all in a compact airline-under-seat sized case. This measurement system both measures and documents DTV and analog signals while driving throughout the coverage area, and, when used with calibrated antennas, plots signal strength in dBuV/m on street maps. The system records extensive data on multiple signals during the drive test, which may be used for post analysis and retained for historic records. This data is invaluable when taken before changes are made to the RF system, and provides information to judge how the system coverage compares with new frequencies, powers, antennas, and signal formats.

Low Power may be the fastest way to full coverage

The move by many stations to low power DTV, then, may in fact both speed up the development of the viewer base, and in the long run give the engineer a "tool" to improve the quality of the final full power transmission of digital quality television. The key is to "measure" each step, technically, and act using real information.

Z Technology, Inc. is in the RF measurement business. We are a team of engineers, committed to the RF transmission industry. In partnership with you, we believe in the value of the transition to digital television transmission and understand the economic commitment you must make to reach your business goals.

Watch this space

Newsletters have a way of coming and going. It is our goal to update this newsletter with current information as it becomes of interest to the broadcast community. We want to offer information that will help you provide the best on-air DTV coverage to your audience, and of course we believe Z Technology RF measurement systems will help you do that.

We value your input. Please click here to tell us what you think, and what will help you best reach your viewers. newsletter@ztechnology.com

*FCC DTV information is located at: http://www.fcc.gov/dtv/2002ForumDTVTransition.ppt