SBE CHAPTER 40 NEWSLETTER
Roy Trumbull - Editor firstname.lastname@example.org
Bill Dempster - Artist
Babes/SBE Luncheon on Wednesday April 28th.
This month we'll do our NAB wrap-up with contributions from all
those who visited the place where a double latte means double the
normal price of a single latte, Los Gouge-em, NV. The place were
almost all equipment question can be answered if you work for a
huge group and come to a vendor's booth 6 or 8 at a time.
will join us with his post NAB road show. Last year he was in 31
cities and looks to make it to over 50 this year. This show tends
to last a little long, but it is worth sticking around for.
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. To
make reservations call Paul Black at 925-827-9511 and leave a message
on his machine.
Tax-Exempt At Last
Prior to NAB, Dane was in touch with various State offices that had
questions regarding our Articles of Incorporation and our application
for tax-exempt status. To make an all too long story a bit shorter,
it looks like we may finally get tax-exempt status. We are a
non-profit corporation but that doesn't exempt us from a minimum
levy of $800/year. Tax-exempt takes care of that.
Paul Black's Wheels
Last month Paul came to the meeting in a wheelchair. He had a
stepladder to garage floor re-entry and took a real beating. He
expects to be in the chair for some months. So give him a call and
some good cheer. It's the sort of thing that eventually happens to
At NAB, a friend told me of running some radials using Longley Rice
and finding that the predicted field went up when the transmitting
center of radiation was lowered. There were also some counterintuitive
results when the receive antenna height was lowered.
I once thought that the height of optimism was predicting contours
using the Part 73 method. Then I tried Longley-Rice and found just
how conservative Part 73 actually was.
All programs of this sort have certain limits and the results are
often impacted by user specified parameters. Beware Garbage In to
The current chapter 48 newsletter from Denver describes an effect
produced by too many Mpeg encode and decode cycles of the same radio
program. The clue is that the local break sounds just fine. Check
it out at
And The Bandwidth Played On
I was reminded of an experience I had with a T1 line by a friend
who ran into the same thing with much more bandwidth. The terminal
gear that lies between point A and point B is generally out of your
control and there is no reason to believe that it has been optimized
for your application.
A T1 can be used for 24 telephone voice channels and, as such, the
distribution of usage channel to channel is fairly soft. If you
send MPEG video and audio using the entire bandwidth, the stress
is considerably higher than it is for voice. The result might be
that a very high error rate develops because one piece of gear in
the chain can't handle the stress. The test for this is to seed a
random number in one channel and cycle the number. Then do it to
another channel and continue adding channels with this kind of
activity until the error rate goes bad. None of the classic telco
data circuit tests work as well. In fact the bad circuit will likely
pass them all but this test it will flunk big time. Now let's try
this with a much larger bandwidth circuit and stack a bunch of 4.4
MHz Mpeg signals into it and see what happens. If it's a dedicated
circuit and there is access to the equipment in each leg, we can
make it work. But if it goes onto the Internet, we may find that
it works part of the time and fails most of the time.
Bob & Don
Here is another story from my collection of the adventures of Don
Lincoln and Bob Morrison
Don liked to "do lunch" with a short list of longtime friends and
one time they were in Berkeley. Don had read an article to the
effect that the Coop stores in Berkeley were selling ladybugs to
control garden pests. Don and friends went to a Coop store. A young
man from Berkeley central casting waited upon them. That is to say
he was thin, wore sandals and wire rims, and had his hair in a
ponytail. Don asked about the ladybugs and the young man told him
they didn't have them at that store but they could be found at the
one on University. He then launched into an organic gardening lecture
to the effect that more than ladybugs were needed to restore balance
and harmony and environmental soundness to a garden. He went on for
a good ten minutes and other shoppers gathered around to hear these
words of wisdom. When he was done, Don's next interlocution was,
"You say the store on University has them?"
KBLX/KVTO/KVVN is looking for a
maintenance engineer. Please contact Paul Marks at 415-284-1029
for further information.
High School Low Power Looking For Equipment
KSRH (San Rafael High School LPFM) is a LPFM High School radio
station located at San Rafael High School in San Rafael in the North
SF Bay. They are in dire need of a replacement console in their
main broadcast studio. A production size board (12-14 channels)
would be ideal. KSRH is still using carts for the present, and if
any ITC stereo units are gathering dust they would be put to good
use at the station. Also, if a spare EAS unit needs to find a good
home, they would appreciate. If you can help, please call Bill
Smith at 415-456-4481 or Marianne Melnick at the station 415-457-5314.
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