MAY 2001
San Francisco
Roy Trumbull - Editor
Bill Dempster - Artist
Advertisers for this month's newsletter are:

Zack Electronics - Judi Lomas - (888) 329-0225
Advanced Marketing - Frank A. Santucci - (650) 365-3944
Belden - Steve Lampen - (415) 440-8393
Orban - (360) 715-1913
MARCOM - Martin Jackson - (408) 768-8668
William F. Ruck, Jr. Broadcast Engineer - (415) 564-1450
Audio Accessories - Rosie Alexander - (510) 787-3335
Hammett & Edison, Inc. - Dane E. Ericksen, P.E. - (707) 996-5200
LeBLANC - David A. Hill - (650) 574-4600
Gentner Communications - Kelly Hanning - (800) 879-9317
Improbable Missions Fource - Mike Schweizer - (888) 4-ISDN4U
Econco - George Badger - 650-327-7599
RF Specialties of California - Bill Newbrough - (888) 737-7321
Kathrein (Scala Division) - Michael Wm. Bach - (541) 779-6500
Harris - John Briskie - (650) 593-1837
ADC - Russ Erickson - (877) 440-7877
Enco Systems - Steve Rooney - 800-ENCO-SYS

Babes/SBE Luncheon on Wednesday May 30, 2001

This month our speaker will be from Z Technology of Beaverton, OR. They make a line of instruments that permit automating the process of field measurements of RF signals by using GPS to track the measurement locations.

As usual, our luncheon will be at Sinbad's just south of the Ferry Building on the Embarcadero near the foot of Mission St. We meet at 11:30 and are seated at 12:30.

8VSB Seminar in LA in June

SBE and Zenith are sponsoring a one day seminar on 8VSB. It will be June 18th from 8:30 am to 5:30 pm at the Los Angeles Airport Marriott. The enrollment fee is $65 and space is limited. Contact Mike Gianneschi at 847-941-8043. ( A light lunch will be provided. This is a very good program. Several of us attended one held in San Jose. This one has even more cases of equipment for show and tell.

If you make an early flight you won't even have to pay for a hotel room. Shame your boss into sending you.

Orban Job

If you look good wearing a star set and can handle calls from "Speed Bump, NV", Orban has a job for you! Their coveted customer service position is open. Ability to WOW (walk on water) and LTB (leap tall buildings) may come in handy.


COFDM - 8VSB and Lo-Band

Dennis Wallace, Mr. Measurements, gave a talk on the results of comparative studies done in the Baltimore/Washington area and in Cleveland, OH. In excess of 5000 measurements were taken. The stations involved in the first test were WUSA ch 9, WETA 26, WRC, & WBAL. The Cleveland test used WKYC.

The 4 dB difference in threshold between the two systems showed up fairly consistently giving 8VSB an advantage at the mid to distant locations. The advantage of COFDM showed up in the strong signal areas subject to high reflections.

Sinclair protested that the COFDM receiver didn't use a pre-selector and that caused a disadvantage. That's probably true, but whether it would have had an impact in the weaker signal areas is uncertain. It's pretty hard to find a COFDM receiver designed for a 6 mHz channel; let alone, one with a preselector.

The eyebrow raiser was the test in Cleveland involving a Ch2 - Ch3 combination. In that test, 8VSB beat COFDM 2:1. The bad news was that only about 26% of the sites worked. The culprit was impulse noise. Impulse noise is bad in lo-band VHF and is particularly deadly to COFDM.

Two questions came up as a result of this test. One is whether lo-band VHF can be used for DTV? The other is whether the planning factors used to set power need to be revised? It may be that lo-band will require much higher power levels than are presently permitted.

Oded BenDov of Dielectric published a paper a few years ago to the effect that the planning factors used for DTV ignore a number of well known factors and are downright absurd with regard to receiver noise and line matching. Oded is on my short list of people I consider to be experts.

In Band Digital FM

This was a paper I didn't get to hear. But I did chat with an engineer responsible for a group of 80 FM stations. His read was that too many factors had to be maintained for it to work. Particularly at issue was the need to keep a number of potentially interfering carriers at precise relationships.

Since the FCC lawyers don't drive monitoring trucks, and the enforcement staff is at an all time low, it's a little scary.

Advanced Marketing Moves to Mi Wuk Village

I got a note to the effect that Frank Santucci, long time SBE supporter, has pulled up stakes and gone to Mi Wuk Village. I was speculating that if he had sold any serious real estate on the peninsula, he might just as easily have bought a coastal village on the Mediterranean.

Gin Pole Standard

Early in 2002 there will be a TIA/EIA standard on gin poles that will pretty well tie down all of the particulars of a permitted pick. Everything will be spelled out. The impact on you will be that you'll want to reference that spec. in any contract you sign for tower work. Picks not permitted by the spec. will require an on-site professional engineer to supervise the work. You need to be familiar with this to avoid potential liability. The proposed spec. is TIA/EIA-PN-4860-Gin Poles. After you read it, you'll be able to tell a "rooster head", "bridle", and "basket" from one another.

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