Privateline.com: Daily Notes Archive

Privateline.com: Daily Notes Archive

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November 1, 2003

Saturday. Spent the day exploring the south side of Black Diamond Mines Regional Park in Contra Costa County, California. Here's a URL for it: http://www.ebparks.org/parks/black.htm. (external link) A nice day. Shorts and shirtsleeve weather. Spectacular scenery. Not much wildlife but two good looking tarantulas, one about three or four inches long. Rose colored with much hair. Can't find a good photograph to show you. Had a dog try to bite me. Odd experience. Must have spooked him. The clothing on my pant leg kept the dog from drawing blood but I do have a scrape.

You might wonder why I include in full the URLs like the one above. They're ugly to present this way so why do I do it? It's done so you'll have the link if you print the page. If all you have are links like the ones below, internal links within my site, ones I don't bother showing the address for, you'll not have a specific location to go to when you print this page unless the URL is included in full. I think this is a good practice and I wish more sites did it.

October 31, 2003

Happy Halloween! Little site work today. I'm off to the ranch that I do work for once or twice a week, and then to Rio Vista, to pick up medicine for my treasured cat. He's just been diagnosed with hyperthyroidism, a common disease of mid-age to older cats. The outlook for recovery is good, but he will need surgery or radiation treatment. I wish this problem would just go away, I'd rather not think about it, but I must handle it.

October 30, 2003

Geoff Fors checks in again with more recollections of the communal telephone service he described in his China article:

Hi Tom: I thought I would pass on further details about the Chinese telephone system as it was in the 1970's, at least in Shanghai. You recall the round brick hut near where I lived, which I mentioned earlier. I asked my friends who lived through that era exactly how the system worked. It seems the huts were strategically located and contained a PA system with loudspeakers on the roof. When a call came in, the attendant would get on the PA mike and broadcast for a three block radius: "so-and-so of building # 433, apartment 201, you have a phone call !" Then so-and-so would come running and get his message, and presumably return the call, whereupon the attendant at a distant hut at the other end would then duplicate the process, until someone broke the loop by actually being present when the call came in. One thing that occurred to me was what happened after dark, that is, how could you sleep with that speaker blasting announcements all night ? It was then explained that the hut closed after a certain hour, maybe at dinnertime, and in general, so few people got calls that it wasn't that much a source of noise-pollution even with one phone hut per 5000 homes. For gossips, it must have been a dream come true. Get a call, and everyone in the entire neighborhood knows it. Geoff

October 29, 2003

Marconi's 1901 trans-Atlantic radio transmission questioned

It's accepted that in 1901 Marconi received the first trans-Atlantic radio signal, the letter "S", three clicks, tapped out in Morse code. Don Kimberlin now questions that accomplishment in a well written and researched article, "Investigating Radio's Roots: What Did Marconi Hear? The World's Most Heralded Radio Failure." The article is in .pdf form:
http://www.oldradio.com/archives/jurassic/marconi2.pdf (external link)

There's do doubt Marconi's team transmitted a single "S" from Poldhu in Cornwall, near Land's End. But did Marconi actually receive it? Or did he and the sole witness to the event hear something else? Something they mistook for the signal? I've written many times how difficult it is to determine radio firsts; Marconi's claim now proves equally hard to establish. Time to rewrite the history books. Again.

Update. In response to my question to Don, How could an experienced operator like Marconi confuse telegraph dashes for lightning produced static?, Kimberlin responds:

Tom:

How did Marconi might mistake lightning for his desired signals? The key lies in the sound he wanted to hear.

Perhaps I didn't speak enough to the point of the way they had tuned the Poldhu spark transmiter. At the time, their financial strain was such that in order to minimize stress on the Poldhu transmitter, they had reduced the duty cycle of the spark to such a short period that each "key down" on the transmitter produced only a very short "click" of transmission, not the "buzz" we are accustomed to expect from a Type B emission. That way, heating and possible damange while producing maximum power at Poldhu was reduced.

Certainly, Marconi had heard lighting before, but here he was expecting merely a train of 3 clicks in an earphone. They could as easily have come from a natural source as from his transmitter.

I think what is key here is to have some understanding of just how much more favorable a south-north equatorial transmission path is than an east-west one. I may be more sensitive that difference than most people who are not HF propagation specialists, merely because I worked in AT&T's HF radio plant at Fort Lauderdale, FL -- a place that ran largely north-south paths in the equatorial region. It meant we could run commerciallly suitable links most any day of most any part of the solar cycle - high or low - while the AT&T plants at New York and San Francisco often had days of downtime, particularly in lows of the solar cycle.

And, December 12, 1901 was the lowest of low -a day of absolutely zero sunspots.

Since writing the article, it has crossed my mind there could have been a minor geomagnetic storm, which would be highly unlikely, and I can't rule out one of the annual meteor showers, and I intend to correspond with an expert or two on those. I rather expect their opinion will be neither of those as a cause on 12/12/1901.

Don Kimberlin

October 28, 2003

Tech time! Always more on modulation . . .

A privateline.com/TelecomWriting.com reader asks:

I'm confused. How in GSM can we fit a gross bit rate of 270 Kbps in the 200 KHz channel on the air interface? GSM uses Gaussian-filtered Minimum Shift Keying or GMSK. That technology has a spectral efficiency of 1 bit/symbol/Hz. Does that mean we use1 bit per symbol and not more?

Professor R.C. Levine responds:

I am writing this quickly and may not remember all the numbers exactly, so if you find other numbers in other source documents, I may have the numbers wrong.

GMSK modulation has a "spectral efficiency" of APPROXIMATELY 1 bit per symbol or 1 bit per hertz of bandwidth. The word "approximately" is used because there are several different ways to measure the bandwidth of a signal.

The method used for GMSK signals in GSM is to find the bandwidth that contains about 99% of the radio signal power. GMSK was developed specifically for GSM by the COST (Council on Science and Technology, a scientific advisory group funded by CCITT and later ETSI). GMSK is a type of minimum frequency shift (MFS) modulation that achieves an approximately optimum compromise . . . .---> (continues here within the GSM article)

October 27, 2003

On September 17, 2003, California Highway Patrol Officer Mike Terry was badly wounded in a motor vehicle accident while on the job. His recovery will be long and expensive. If you can send him a greeting, make a donation, or attend a November fund raiser in the Sacramento, California area, I'm sure his family would appreciate it. To sign his guest book or to get further information, please visit his website: http://officerterry.com/ (external link)

My links to Brigade Quartermasters don't seem to be working. They were just a few days ago, so try later. They're a really fun store, with an unusual mix of products. Sort of like a dressed up Army/Navy surplus store except they really don't sell surplus. Nearly all new equipment and clothes, no funky, moldy smelling cammo. I have an e-mail into them, asking what's going on. Apologies for the inconvience.

Speaking of ads, I'm bothered with how ad placements look at this site. One is supposed to put ads at the top of every page because that's what people see first. But that makes for one ugly looking page. I am now removing these ads because the money made from them does not justify their appearance. From now on all ads will be on left side of pages and at the bottom.

Oh, and WISPCON starts today in Dallas. Think about attending if you're near. WISPCON stands for Wireless Internet Service Providers Conference. Of course. Here's a link to them. (external link)

http://www.wispcon.info/US/WISPCON-IV/WISPCON-IV.htm

October 24, 2003

Web site work continues. Snore!

October 23, 2003

Beirut: twenty years on

Twenty years ago today 241 servicemen were killed in a Marine Corps barracks in Beirut, Lebanon. A truck bomber blew them apart. As with Iraq today, these soldiers came to guard the peace, to put stability into an area that had little. The United States did not come to occupy but to help. And they were killed for that. Today, Beirut is blossoming once again, it's a vibrant, busy city. The United States helped make that happen. No group took responsibility for the bombing, but the characters who planned it are, I assume, well known, and with God's assistance, dead or are being hunted. May they burn in hell.

The first duty is to remember: http://www.beirutveterans.com/ (external link)

Number Portability

Number portability means keeping your old telephone number when you pick a new telephone company. That hasn't been possible with mobile phones before but it will soon become law in the United States. Starting on November 24, 2003, wireless companies in the 100 top American markets must maintain your present number, even if you switch carriers. It's also required that you can get your home telephone number transferred to your wireless. Background information is here:

http://wireless.fcc.gov/wlnp/ (external link)

Wireless carriers will delay implementing it but eventually portability will become standard practice. It's estimated that up to 40% of wireless users may switch carriers in portability's first year. Will portability improve cost, service, and coverage? Perhaps. If customers can change providers as easily as their long distance company, wireless companies might try harder to keep people happy. This is an optimistic view.

Besides some effort to improve, wireless companies will focus on writing long term contracts, with two years becoming the norm. And they'll keep making wireless plans so confusing that you won't be able to easily compare different carriers. Don't sign a contract until after the 24th. Cellular radio is wonderful technology but the way it is sold and marketed is miserable. A shame.

Consumers' Union has excellent information on this subject, including ways to protest delaying tactics to Congress:

http://www.consumersunion.org/

campaigns/escapecellhell/ (external link)