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PA2AGA > HDDIG 08.07.00 22:04l 190 Lines 6885 Bytes #-9405 (0) @ EU
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Subj: HamDigitalDigest 2000/183C
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To : HDDIG@EU
Date: Sat, 08 Jul 00 14:15:30 MET
Message-Id: <hd_2000_183C>
From: pa2aga@pe1mvx.ampr.org
To: hd_broadcast@pa2aga.ampr.org
X-BBS-Msg-Type: B
"Flashing this 12.7 mile optical path confirmed that there were no trees,
bushes or buildings in the way--constant problems in optical work," Gonsett
said. Hams have conducted laser communication over paths of 100 miles or so,
he noted, so the distance was not record-breaking. The PARC experiment
showed that laser communication can be accomplished with simple, inexpensive
gear.
Equipment involved two full-duplex voice-modulated laser units constructed
by Kerry Banke, N6IZW, and Chuck Houghton, WB6IGP, using PVC pipe housings.
Each uses an ordinary 0.5 mW red "pointer" laser costing less than $3 apiece
as a transmitter. The lasers were mounted outside the PVC tubes. "Because a
laser beam is very narrow, the apparatus is aimed with the aid of a rifle
telescope," Gonsett explained. Precise positioning was accomplished using
two micrometers salvaged from microwave tubes.
At the transmitting end, a "stock" pointer laser is powered by a 35-kHz
oscillator. A microphone frequency modulates the 35-kHz oscillator at 5 kHz
deviation. At the receiving end, the incoming red laser light hits a plastic
Fresnel lens that focuses the light onto a photo detector. Out of the photo
detector comes the 35-kHz FM signal. That signal is mixed with a 145.000 MHz
local oscillator, producing a signal on 145.035 MHz. That signal is run
through coax to a ham radio H-T tuned to 145.035 MHz--the H-T serving as the
FM demodulator/receiver. The system is full-duplex.
Gonsett said observers at the PARC Field Day site were "blown away" by the
brilliance of the one-half milliwatt red laser beam coming from the distant
mountain. "While the beam shimmered with atmospheric turbulence, voice
communications were clear and steady with only a hint of rumble, thanks to
the use of FM," he reports.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
73
Ian, G3NRW
------------------------------
Date: Fri, 07 Jul 2000 13:07:40 GMT
From: "Arto Peltomaki" <artsi@estla.pp.fi>
Subject: Simultaneous multimode RX
I would like to know, what possibilities there is to receive many (different
mode)
transmission at the same time in 5kHz (or wider) band?
Now I use skysweeper (www.skysweep.com) for that purpose, but the bandwidth
is limited
in it to 5.5 kHz.
-Artsi
------------------------------
Date: Fri, 7 Jul 2000 16:44:34 -0500
From: "Steve Sampson" <ssampson@usa-site.net>
Subject: Simultaneous multimode RX
Slim to None.
"Arto Peltomaki" wrote
> I would like to know, what possibilities there is to receive many (different
> mode)
> transmission at the same time in 5kHz (or wider) band?
------------------------------
Date: Sat, 08 Jul 2000 01:27:26 GMT
From: "George , W5YR" <w5yr@att.net>
Subject: Simultaneous multimode RX
Depends upon how many receivers/demodulators you choose to operate, all
tuned to the same passband, etc.
I commonly operate PSK31 with a 3.5 KHz passband displayed on my computer
screen in a waterfall display. With my Kachina transceiver, I can display
and copy CW, PSK31, Pactor, etc all simultaneously. Makes quite a unique
set of sounds at times!
72/73, George
Fairview, TX 30 mi NE Dallas in Collin county
Amateur Radio W5YR, in the 54th year and it just keeps getting better!
R/C since 1964 - AMA 98452 RVing since 1972 Kachina #91900556
Steve Sampson wrote:
>
> Slim to None.
>
> "Arto Peltomaki" wrote
> > I would like to know, what possibilities there is to receive many
(different
> > mode)
> > transmission at the same time in 5kHz (or wider) band?
--
72/73, George
Fairview, TX 30 mi NE Dallas in Collin county
Amateur Radio W5YR, in the 54th year and it just keeps getting better!
R/C since 1964 - AMA 98452 RVing since 1972 Kachina #91900556
------------------------------
Date: Fri, 07 Jul 2000 20:58:18 +0200
From: Helmut Wabnig <hwabnig@aon.at>
Subject: Tech question - AM/FM digital radio
On Thu, 06 Jul 2000 20:45:34 -0700, mjs
<relaxndeletethis@frontiernet.net> wrote:
>Actually Glen, you described what I thought was the problem after the
>first Sony radio started to "die". I was at work listening to some
>music as usual (volume up too loud for my age), and as I noticed the
>left side getting weak I really thought that I had either blown out my
>eardrum or had a large accumulation of ear jam. Went to KMart after
>work and bought a nifty ear wash kit thingy. After thoroughly
>douching my ear I tried my headphones with my home stereo and was
>releived to discover that I was not in fact going deaf as I probably
>should be from listening to loud headphone music!
>
>Martin.
>
>
>On Thu, 06 Jul 2000 16:44:16 -0400, Glen Menendez <menendez@eznet.net>
>wrote:
>
>>Put a Q-tip in your left ear then twirl it around a bit. If you see some
>>yellow stuff - that could be the problem.
I would be suspicious and get my wishbone.
Check the place, where the radios used to fail.
w
>>
>>mjs wrote:
>>
>>> I'm looking for an answer to a problem that I have had with my last
>>> five digital AM/FM stereo pocket radios. All five of them have died
>>> the exact same death. Two of them were Radio Shack Optimus radios and
>>> three of them were Sony SRF-M32 Walkmans. They all ran on two AAA
>>> batteries. The Optimus has a small external speaker (which I never
>>> used), and the Sony radio does not. These radios were priced in the
>>> $30 to $40 dollar range and performed exceptionally well at first. I
>>> used each of these radios for about 3 to 5 hours every day with a
>>> variety of quality headphones or earbuds. 95 percent of the time I
>>> listened to FM music stations, a lot of the time I had the volume up
>>> fairly loud. Battery usage was excellent on all of the radios (using
>>> Duracell Ultra's). Now my problem: after about 3 or 4 months each of
>>> these radios lost output on the left "speaker". The loss was gradual,
>>> but quick, and after a short time the left channel just quit. So of
>>> course I am puzzled by this pattern of malfunction. I really need a
>>> radio like this for my job, but I don't want to waste any more money.
>>> So, first of all, why are my radios konking out like this? And is
>>> there a quality pocket digital AM/FM stereo on the market that I can
>>> depend on? Thanks in advance for any help.
>>>
>>> Martin S. in Arizona.
>>>
>>> Reply to: relaxn at frontiernet dot net, remove "deletethis".
>
>
>
>Reply to: relaxn at frontiernet dot net, remove "deletethis".
------------------------------
End of Ham-Digital Digest V2000 #183
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