Z Technology 's RF Newsletter - DTV Edition

Broadcast News, Edition 3

This is the third issue of Z Technology, Inc.'s DTV Newsletter. Fifty-four television engineering managers asked to be added to our email list this past month, and about a half-dozen folks sent their no-thank-yous, so it seems worth the effort. Thanks. As always, your suggestions are welcome.

U.S. DTV Scorecard

As of July 17th, 2002, the FCC (http://www.fcc.gov/mb/video/files/dtvsum.doc) reported 1535 stations, 91%, had been granted a DTV licence or construction permit. 262 Television stations are now on the air with licensed DTV facilities, plus another 233 stations are operating under special or temporary authority, for a total of 495 on-air. http://www.fcc.gov/mb/video/files/dtvonairsum.html

Z Technology, Inc. co-sponsors DTV Seminars in Phoenix and Atlanta, SMPTE meeting in Portland, SBE meeting coming up in Sacramento.

We were pleased to meet with many of you as we co-sponsored Zenith/ATSC Digital VSB Transmission Seminar's in Albuquerque, NM May 23rd and Atlanta June 6th. These are very educationsl seminars and we look forward to participating again.

Z Technology, Inc. hosted the Pacific/Northwest SMPTE chapter at our plant in Beaverton, Oregon, Thursday, July 25th, 2002. The subject was DriveTest Coverage Testing of 8VSB and NTSC signals. We have been invited to present to the Sacramento SBE on August 27th. See you there!

New Broadcast Sales Representatives

Z Technology, Inc. has appointed two new U.S. sales representatives to serve customers locally. We are proud to be associated with Dan Rau, and his firm, Radio Applications Unlimited, to better serve Broadcasters in the Northeastern states of Connecticut, Maine, Maryland, Massachusetts, New Hampshire, New Jersey, New York, Pennsylvania, Rhode Island, Vermont, Virginia, West Virginia, and the District of Columbia. Dan can be reached by telephone at 978 425 2470, or by EMAIL at danrau@compuserve.com.

Our second new appointment is Mel Engel, who will cover Broadcast customers and Broadcast Equipment Manufacturers in Arizona, New Mexico, and the metro areas of Las Vegas, and El Paso. Mel's telephone number is 480 948 0223, and his EMAIL address is mely@azboss.net.

We welcome these professionals aboard and look forward to their helping us serve our Broadcast customers.

Monitoring your DTV signal

(Warning: the following is a little bit commercial, but has been abrieviated in respect of your time. Please visit the Z Technology website, Monitoring_DTV_signal.html for the full story including pictures.)

An initial reaction is to consider an off-air DTV receiver, with video output to a picture monitor and audio to a set of speakers.... but that just describes the digital television set soon available in local furniture stores! First, we need robust reception of the digital signal; distribution of that signal to the house monitoring system; and a means to accurately determine that a good signal is also available to viewers. A studio DTV receiver needs to receive the signal on the broadcast channel, and deliver a clean replication of that signal on a vhf channel for easy distribution within the plant. The receiver should also provide tools to adjust the antenna, check the signal for validity, analyze and record the digital data parameters, and provide RF and MPEG transport stream feeds to the station's RFA300A RF analyzer and MPEG transport stream analyzer.

A professional 8VSB DTV demodulator will have better RF front-end performance than consumer receivers designed around consumer tuners. It will provide a high quality signal on VHF for house monitoring; PC analysis and data logging for the engineer and a feed at the studio for the station's RFA300A high-level 8VSB test system; and it will have a transport stream output so the master control operator can check Program Identification and ancillary data values with an MPEG analyzer.

RF signal quality monitoring

Professional 8VSB demodulators feature a laboratory quality RF front-end for television channels 2 through 69. The 8VSB signal is received from an antenna at an input level of from -80 dBm to -10 dBm.

System bandwidth will be flat, +/- 1 dB and Group Delay <10 nS over the 6 MHz channel. Noise figure will be <7 dB, with a RF System Phase Noise of -90 dBc/Hz @ 20 kHz offset. A third order intercept of +20 dBm will provide excellent immunity to interference from undesired signals.

To aid in antenna positioning, the demodulator should provide a graphic TAP value display on an attached PC. This feature will assist in adjusting the receiving antenna for minimum multipath, assuring the best signal to all receivers on the distribution system.

RF Signal Measurement

An included PC application can facilitate setup of the demodulator (Channel Frequency, Manual Gain, AGC on/off, IF/RF input selection, Alarm setting and on/off), display the RF signal input power in dBm (with a settable alarm) and log data. A screen capture makes operation and record keeping easier.

Data Signal Measurement

The PC application will capture and display digital Signal-to-Noise Ratio, Segment Error Rate, Sync Lock, Equalizer Lock, Average TAP energy, and graphs Dynamic TAP energy (-2.3 to +10, 22, 46, or 80 uS).

Alarms should include RF Input Power, Sync Lock, Equalizer Lock, Tap Energy, Digital SNR, and SER.

8VSB RF Signal Analysis

The demodulator should accept an antenna-level signal and provide a faithful image of that signal at a high level on a selectable VHF TV channel (7 or 8 prefered). This signal will enable high level 8VSB analyzers such as the Tektronix RFA300A to be used with channel 2 through 69 signals at a location away from the transmitter. The demodulator must provide preselection, preamplification, and frequency translation, and allow flexible use of high level 8VSB analyzers.

House distribution system monitoring

In many plants, the house distribution system is High VHF to minimize RF losses while providing reasonable immunity to electrical noise. The demodulator should provide a faithful, uninterrupted high-level channel 7 or 8 image of the channel 2 through 69 antenna-input signal. This highband VHF signal output (about 0 dBm) can be padded to directly feed the house distribution system for reception by ATSC set-top boxes or receivers at each viewing location.

MPEG data analysis

The demodulator should incorporate an MPEG decoder to provide information on digital Signal-to-Noise Ratio, Sync Lock, Equalizer Lock, and provide Tap Value data as a graphic display. When these analysis displays are not needed, the MPEG decoder is available to provide a parallel LVDS transport stream for identification and analysis using an external MPEG data analyzer.

Full utilization

These features of Z Technology's DM1010 8VSB demodulator (you suspected we made a product like this, didn't you?) make it a best buy for television stations. The wide dynamic range, low noise figure RF front-end means quality signal reception in the presence of strong nearby signals. Display of RF and data parameters assist in antenna placement, orientation and adjustment for the best possible signal, and these signals may be recorded as an indicator of long term performance. The stability of the DM1010 minimizes test equipment variabilities so you know what you are really receiving. The high level VHF RF output means more efficient utilization of your existing 8VSB test equipment, and the transport stream output, used by the application for data reporting and antenna adjustment, is available for PID confirmation and MPEG data analysis.

 

This extra versatility means a professional demodulator will be in use full time, providing an 8VSB reference standard no longer available to the NTSC world.

Guy Lewis - your contact for comments or to be added/removed from the newsletter distribution.
Director, Sales and Marketing
Z Technology, Inc.
Phone: 503-614-9800, FAX: 503-614-9898
1815 NW 169th Place, Suite 3070
Beaverton, OR 97006  USA