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- Subject: INFO-HAMS Digest V89 #909
- To: INFO-HAMS@WSMR-SIMTEL20.ARMY.MIL
-
- INFO-HAMS Digest Mon, 20 Nov 89 Volume 89 : Issue 909
-
- Today's Topics:
- Costas Loop in Digital Form
- FT980 INFO
- H&W traffic during disasters
- Never heard of "BEGOHMS" before...
- Scanner with spectrum analyzer
- The End of Amateur Radio {Part 1/3}
- ----------------------------------------------------------------------
-
- Date: 20 Nov 89 22:20:21 GMT
- From: kchen@apple.com (Kok Chen)
- Subject: Costas Loop in Digital Form
-
- mac@idacrd.UUCP (Robert McGwier) writes:
-
- >From article <4858@abaa.UUCP>, by esker@abaa.uucp (Lawrence Esker):
-
- >BECAUSE the things you mentioned counters, multipliers, filters, etc.
- >WHICH ARE NEVER perfect in analog hardware, ARE nearly perfect in digital form.
- >I apologize for the tone but your statements are just plain completely
- >false. The transition followers, and other forms of hard limiting you
- >mentioned, are decidedly INFERIOR. This is called Van Vleck's law about
- >the approximately 2 dB (in a perfect implementation) loss in output SNR
- >caused by the limiting process (which is an information theoretic result
- >which follows intuitively since you are throwing away all the information
- >except when zero crossings occur).
-
- Van Vleck's (also known as the Arcsine law [e.g., in Papoulis' Probability
- theory book]) sqrt(2.pi) result is in fact only good for small signals in
- Gaussian noise - AND you have to adjust the spectrum by the arcsine law to
- boot. In practice, I expect Mr. Esker's system to underperform Mr. McGwier's
- system by MORE than 1.96 db.
-
- For those unfamiliar with Van Vleck, it is described in the series of MIT
- Rad. Lab. books on radar that were unclassified after the war. One of the
- amazing result of applying it was when Sandy Weinreb (then at MIT, now at
- NRAO) used it to build instrumentation in the mid-60's that finally detected
- the OH radical in galatic space. I had hoped to catch a glimpse of Van
- Vleck in the recent PBS documentary on Radar during WWII, but he was not
- interviewed. Perhaps some Harvardite can tell us if Van Vleck is still
- among us (or, did we lose another Nobel laurate to old age?).
-
- If you REALLY have small-signal-in-Gaussian-noise case (like you guys
- working satellites), then an extension to Van Vleck shows that a 16-level
- (4-bit) quantizer only sustains a loss of 0.05 db if the levels can be AGC'ed
- appropriately to the RMS noise level.
-
- --
- ----
- Kok Chen kchen@apple.COM
- Apple Computer, Inc.
-
- ------------------------------
-
- Date: Mon, 20 Nov 89 16:21:17 EST
- From: Clark Fishman (FSF) <cfishman@PICA.ARMY.MIL>
- Subject: FT980 INFO
-
- WANTED-- schmatic diagram and pc-board layout for the
- RF power amplifier section of the Yaesu FT- 980 HF tranceiver.
-
- I will be most happy to pay copying and postage. Tnx,
- Clark Fishman WA2UNN
- ` 9 Sunset drive Andover, NJ 08821
-
-
- ------------------------------
-
- Date: 20 Nov 89 22:02:11 GMT
- From: coherent!athertn!steveh@apple.com (Steve Harding)
- Subject: H&W traffic during disasters
-
- I pass along an editorial I wrote for the NTS Northern California Net
- newsletter, The RELAY.
-
- Lessons to be Learned From the Quake of '89
-
- Good job. Those of you involved with disaster communications deserve a pat on
- the back. ARES and RACES volunteers were active within minutes after the
- earthquake. Other hams did what they could to help in shelter communicatons,
- various nets, and as relief for other volunteers.
-
- Those of you involved with Health and Welfare traffic deserve kudoes, as well.
- Much of it got delivered. Some of it did not. It was not for the lack of
- trying, however. We were flat out overloaded.
-
- What have we learned from this experience? First of all, under the present
- setup, do not expect Health and Welfare traffic to be delivered during the
- first 48 hours. Hams trained in disaster communications are busy doing their
- thing. The rest of us are taking stock of our own situation. Some stations
- may be off the air because of power disruption. Others may have had equipment
- failure for a number or reasons.
-
- Secondly, the first reaction of most people is to help those who need help.
- Once their own situation was well in hand, hams rushed to help out wherever
- they could -- as relief operators in shelters, net control operators for the
- various disaster communication nets, shadows for disaster officials, and other
- such. Health and Welfare traffic was the least of their concern.
-
- So...for the first 24 to 48 hours we have Health and Welfare pouring into the
- area and few people handling it. On packet, the traffic was stacking up on the
- various NTS BBSs at an alarming rate. The CW nets were overloaded as well.
- With the suspension of NCN-VHF, NTS lost another outlet. Incoming health and
- welfare traffic sat and grew whiskers.
-
- The lesson here is, during the early stages of a disaster, people on the
- outside are worried about their friends and loved ones. People on the inside
- are concerned about putting things back into some semblance of order.
-
- Your editor suggests the following:
-
- For the first 48 hours, no one should try to pass Health and Welfare traffic
- into a disaster area. Let the folks get their feet on the ground, assess their
- damage, and find workaround solutions for their own internal communications
- problems. Only outbound Health and Welfare traffic should be taken.
-
- During the 48-hour "moratorium", those people minimally affected by the
- disaster will have had the opportunity to make contact with the outside. This
- will mean that fewer messages will be sent.
-
- ARES and RACES volunteers should be alert to the needs of the outside world as
- to the fate of their loved ones. When a shelter is set up, someone should be
- there checking with each refugee as to whether there is someone outside to whom
- they would like to send a message. This person can be a member of ARES or
- RACES, or a volunteer. This will also cut down on the number of messages being
- sent into the area.
-
- Frequencies should be made available and manned by persons skilled in NTS
- traffic to place these outbound messages into the system as soon as possible.
-
- Following the 48-hour period, messages into the affected areas should follow
- NTS procedures. This makes it easier for the delivering station to service
- back what action has been taken. It also gives the delivering station the
- information necessary to deliver the message. There were many instances of
- messages like: To "415/555-2345 Call back 619/555-5432". What happens if
- 555-2345 is an incorrect number?
-
- Keep the incoming messages short. Dan (WF6O), SCN Packet Manager, reports that
- he serviced back a message that was over 200 words. Remember that delivering
- hams may have dozens of messages to handle.
-
- Packet operators especially, do not book Health and Welfare traffic. The books
- have to be broken down somewhere along the line, and valuable time is lost.
-
- agree, or if you have other suggestions, The RELAY would like to hear from you.
-
- 73...Steve (KA6ETB)
-
- Steve -- KA6ETB @ N6LDL -- NTS NCN packet manager -- steveh @ atherton.com
-
- ------------------------------
-
- Date: Mon, 20 Nov 89 17:25:58 CST
- From: rlwest@flopn2.csc.ti.com (Bob West - WA8YCD - DSEG/HRD Computer Systems Training - MSG HRD1 - 995-1908)
- Subject: Never heard of "BEGOHMS" before...
-
-
- Reference recent postings discussing UNITS
-
-
- I have a rather yellowed and crumbling "Webster's New Collegiate Dictionary"
- Copyright (c) 1956 by G. & C. Merriam Co., which has on page 78, right-hand
- column, about 8th entry from the bottom,
-
- beg'ohm (...), n. Elec. A unit of resistance equal to one billion ohms, or
- one thousand megohms.
-
- that's one I never heard about in school... interesting.
-
-
- ------------------------------
-
- Date: 20 Nov 89 21:20:01 GMT
- From: helios.ee.lbl.gov!pasteur!east.Berkeley.EDU!phil@ucsd.edu (Phil Lapsley)
- Subject: Scanner with spectrum analyzer
-
- Paul Bame asked about a scanner with a LCD spectrum analyzer he saw in
- an EEB catalog. I saw a full page ad for what I suspect is the same
- scanner in Electronics and Wireless World.
-
- The model is the the Standard AX700E Scanning Receiver. It's hard to
- tell from the photo, but I'd guess it's about the same size as a FRG
- 9600, maybe a bit smaller, with about a 3"x4" LCD display that shows
- the frequency and the spectrum. It covers 50 to 905 MHz, receives AM,
- WBFM, and NBFM, and can scan in 5, 10, 12.5, 20, and 25 kHz
- increments. There is also a 1 or 5 kHz up/down button. It runs on 12 V
- and has 100 memories. The pan display can be set for 100 kHz, 250
- kHz, or 1 MHz wide.
-
- The company selling it is Lee Electronics, 400 Edgeware Rd, London W2,
- England. I'd be very interested in comments from people who've actually
- used one.
-
- Phil Lapsley, N6TCT phil@ucbarpa.Berkeley.EDU ...!ucbvax!phiL
-
- ------------------------------
-
- Date: 20 Nov 89 21:41:18 GMT
- From: ux1.cso.uiuc.edu!tank!eecae!cps3xx!usenet@iuvax.cs.indiana.edu (Usenet file owner)
- Subject: The End of Amateur Radio {Part 1/3}
-
- In <6847@portia.Stanford.EDU> paulf@jessica.Stanford.EDU writes:
- >From "A History of the 20th Century" by Peter B. Long (c) 2031:
- >Chapter 23: The Hobbyist Mentality: AMATEUR RADIO
- >[stuff deleted]
- >became a subsidy of the UN. The ability to make a free phone call anywhere
- >in the world had a dramatic political impact (see Ch. 2), but it sounded the
-
- I think this is highly unlikely! Free phone calls? Anywhere in the
- world? Not while there is a buck to be made by somebody. Besides, it
- costs money to maintain the telephone network. Somebody has to pay (and
- somebody will be making a profit!).
-
- Some of the ideas you portray, however, are truthful. They should be
- sersiously considered by the bureaucrats at the ARRL.
-
- Fat chance of this happening, though: when members write in with their
- concerns, they get sent a form letter which does not address their
- concerns or the issues they raised. Then said members resign from the
- league, having made the decision that the situation is hopeless.
-
- In the rare case that original ideas Kenneth J. Hendrickson N8DGN
- are found here, I am responsible. Owen W328, E. Lansing, MI 48825
- Internet: hendrick@frith.egr.msu.edu UUCP: ...!uunet!frith!hendrick
-
- ------------------------------
-
- End of INFO-HAMS Digest V89 Issue #909
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