HAM Radio 3/hamradioversion3.0examsandprograms1992.iso/news/inham89/1013.

Text File | 1979-12-31 | 15KB | 336 lines

INFO-HAMS Digest            Wed, 13 Dec 89       Volume 89 : Issue 1013

Today's Topics:
                         1200 baud PSK modem
                  ARRL Propagation Forecast Bn Nr 49
                 Automatic satellite antenna tracking
                              Mac vs IBM
                            Meteor Showers
                             rec.scanners
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Date: 13 Dec 89 17:44:59 GMT
From: idacrd![e-mail]  (Robert McGwier)
Subject: 1200 baud PSK modem
Message-ID: <[e-mail]>

>From article <[e-mail]>, by [e-mail]:
>
> My understanding of the situation is this:
>     400 baud G3RUH PSK for telemetry
>     1200 baud G3RUH PSK for PACSAT or AO-13 voice transponder
>     9600 baud G3RUH FSK for UOSAT-D
>
> Am I close?
>


Close but NOT complete.  What is AO-13 voice?  In the U.S. there is available
a 1200 BPS modem from TAPR, Inc. Tuscon, Az.  It is decidely superior to
the G3RUH PSK modem BUT (1) it costs more, (2) it is harder to build though
not ridiculously so, (3) the gain in BER over the G3RUH modem will not
be needed if you are already using directional antennas.  If you wish
to be able to copy Microsats with an omni antenna with an acceptable bit
error rate (BER) then the G3RUH is not the way to go.  James is a good
friend of mine, he has done an outstanding job in bringing a low cost
modem to market for the masses but he took shortcuts that make its
performance about 10 dB worse than the TAPR/W3IWI version.  They are
(1) He used a squaring loop (more on that in a moment before you jump
on me) (2) HE HARD LIMITED THE SIGNAL AS IT `COMES IN THE DOOR'.  This
latter lost him several dB but it made analog conditioning of the signal
a breeze, there is NONE ;-).  It is a bit harder to implement a good
squaring loop than it is a Costas loop even though they are THEORETICALLY
equivalent and the Costas takes more parts (and thus costs more).  The
bottom line is he was there first with a commercially available modem,
it was and is cheap but it has a 10 dB implementation loss over the
TAPR version for much less than a 10 dB increase in cost.

The hands down winner for copying and talking to UOSAT D is the G3RUH
modem.  He has done an outstanding job on that modem.  No short cuts their
and it is a winner.  He has hundreds of those operating in the field and
they are copying 9600 bps FSK now which is what UOSAT D uses as you
mention.

There are new alternatives to the 400 bps, 1200 bps stuff coming
out from Paccomm (also the source for the 9600 G3RUH in the states).
It was announced in the AMSAT Journal.  It does both in the same box.
Call them for details.

The Microsat will operate 4800 bps PSK.  There is but ONE modem that
does this at present.  That is the soon to be released DSP-232.  A
DSP based modem that will be coming soon to a dealer near you from
AEA.  It does all the modems you have mentioned above and more.
I hope this doesn't sound to self serving since I designed it, just
trying to keep you informed and you did ask ;-).

Bob

--
____________________________________________________________________________
    My opinions are my own no matter    |    Robert W. McGwier, N4HY
    who I work for! ;-)            |    CCR, AMSAT, etc.
----------------------------------------------------------------------------

------------------------------

Date: 13 Dec 89 19:46:21 GMT
From: victim.dec.com![e-mail]  (Jim -- LTN1-2/H03 -- DTN 226-6905)
Subject: ARRL Propagation Forecast Bn Nr 49
Message-ID: <[e-mail]>

In article <[e-mail]>, [e-mail] (Scott Ellington) writes...

>Does anyone out there understand the wierd propagation we've had on 20
>Meters at night for the last week or so?  The polar path is open, even
>though there's no sunlight there, but the Pacific path is dead.  At the
>same time, the dark path to ZS6 is wide open.

What (zulu) time are you referring to? I worked the pacific (3D2XR on
Rotuma) easily last night at 0450Z.  I wish the polar path were better on
15, have heard XW8CW several times but he's too weak to work.

We have been having some solar disturbances lately, that might have
something to do with it.

jim, AD1C

=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=

"The opinions expressed here in no way represent the views of Digital
 Equipment Corporation."

James J. Reisert                Internet: [e-mail]
Digital Equipment Corp.         UUCP:     ...decwrl!tallis.enet!reisert
295 Foster Street
P.O. Box 1123
Littleton, MA  01460

------------------------------

Date: 13 Dec 89 17:53:29 GMT
From: idacrd![e-mail]  (Robert McGwier)
Subject: Automatic satellite antenna tracking
Message-ID: <[e-mail]>

>From article <[e-mail]>, by [e-mail]:
> Just wondering what the current "state of the art" is in automatic
> satellite antenna rotor controllers.  I've heard about something
> called "The Kansas City Tracker" and seen ads for some stand-alone
> box of which the name escapes me.  What I'm looking for is a controller
> than works with Quiktrak or the new Instant-Track... and preferablly
> runs by itself without using the host CPU.  Any one have any
> comments on this?


Yes I have comments on that as well.  You are asking great questions
especially from my point of view ;-).  I wrote Quiktrak.  Brooks and
I designed the software interface for the Kansas City tracker and
it is a plug in card for the PC BUT from the `between the lines'
of your question, I don't think you understand how it works.  Forgive
me if I am wrong and ignore what follows.  It does use the CPU but
IT DOES NOT PREVENT YOU FROM USING THE CPU TO DO OTHER JOBS WHILE IT
ROTATES THE ANTENNAS!  That was the purpose of the entire design,
hardware and software.  It is fired up on the timer interrupt in your
PC, the interface is a TSR (termintate and stay resident driver).
Quiktrak loads a table and lets you quit quiktrak and go edit, run
your terminal program, etc. while IN THE BACKGROUND in updates the
antennas.  He has a small accessory that adds onto the board which
will also tune your radios from the input from Quiktrak.  Instanttrack,
the now and latest WOW available from the AMSAT software exchange has
supplanted my Quiktrak as the `latest and greatest' piece of tracking
software.  Their approach is slightly different.  They do not load
the table BUT they have their own TSR which fires up on the timer
interrupt and computes an AZ/EL point and then shoots it off to
the Kansas city tracker interface.  They cannot at this time support
the automatic tuning of the radios but I understand and hope that
they will in the near future.  If you object to leaving your computer
on in any way or if you don't own a PC compatible, then forgive my
comments.  I thought there might be others who were interested in
the details.

Bob

--
____________________________________________________________________________
    My opinions are my own no matter    |    Robert W. McGwier, N4HY
    who I work for! ;-)            |    CCR, AMSAT, etc.
----------------------------------------------------------------------------

------------------------------

Date: 13 Dec 89 18:33:26 GMT
From: tellab5![e-mail]  (Peter Chrzanowski)
Subject: Mac vs IBM
Message-ID: <[e-mail]>

In article <[e-mail]>, [e-mail] (Mike Chepponis) writes:
> Actually, you can have the best of both worlds by getting a Mac and running
> a program called SoftPC on it.  SoftPC completely emulates an XT machine
> (in software!), down to the comm ports, v20 processor compatibility, etc.
> Currently, SoftPC v1.3 has a Norton SI rating of 5.5 on my IIci, which is
> quite respectable.

Note: the Norton SI rating is notoriously poor as an indicator of a PC's
speed (but unfortunately there IS no widely accepted, GOOD benchmark).

>
> SoftPC only runs on Mac II, IIx, IIcx and IIci at this time, however, Insignia
> Solutions (the maker of SoftPC) promises support for the SE and Portable in
> a couple of months.
>


The SoftPC costs $595. and requires 2MB of RAM and a hardisk
with at least 3MB of available free space.  On a Mac II it runs
at PC/XT speeds;  an SE would probably require an accelerator
card to run even that fast.

COMMENTS: For $595. you could BUY the actual PC hardware rather than
    simulate it on a MAC.  Furthermore, SoftPC requires some
    rather expensive MAC hardware!

    Modems, ports cards, IEEE-488 interface, A/D and D/A data
    acquisition and control, printers, plotters: these are all
    now available for MACs, but at MUCH higher prices than for
    PCs (try pricing a MAC parallel port card sometime!).  PC
    accelerator cards are also relatively cheap, should you
    want performance significantly better than XT level.

    Of course, if you're primarily MAC oriented, already own
    most or all of the required hardware, don't want to add
    any PC hardware, find XT performance adequate, and don't
    want another computer cluttering your workspace then
    SoftPC might be a good solution.  In any case it does
    represent a 'tour de force' of the MAC's capabilities.

  IMHO there are more fanatics in the MAC camp than in the
  PC camp, for some reason (NO, I am NOT accusing or suggesting
  that Mike Chepponis is a fanatic: his posting provided useful
  info).  MACs are very nice for some uses and some users
  (although there are a few things PCs are better for, such
  as low level hardware hacking).

  For me, the bottom line counts: PCs are cheaper and, for most tasks,
  the PC is adequate (a lot of application software runs about the same
  on either machine).  That is, some of us would just as soon use a Chevy
  (Hyundai?) a as Porsche: the Porsche is more fun to drive but either
  vehicle will get you to work, and who wants to pay $40K+ for a car?

------------------------------

Date: Wed, 13 Dec 89 15:44:15 EDT
From: Mike Owen W9IP <[e-mail]>
Subject: Meteor Showers

Regarding meteor showers...

There are several sources of information about VHF
meteor scatter (or, if you prefer, meteor burst).
If you are interested in how/when/why - type
information, you might check out QST, June, 1986.
If all you want to do is work 2m DX, try the ARRL
Operating Manual.

BTW, the Quadrantids is NOT the biggest of them all,
and in fact it's very easy to miss because its peak is so
narrow.  The Geminids (just past) are reasonably abundant but
they are slow and consequently not too hot for DX.
The Eta Aquarids, Perseids, and Orionids are by far the better
showers for 2m & up VHF DX.

QRZed meteors ...

------------------------------

Date: 13 Dec 89 19:01:37 GMT
From: [e-mail]  (Mark Robert Smith)
Subject: rec.scanners
Message-ID: <[e-mail]>

NOTE:  to rec.radio.shortwave readers:  I have cross-posted this
because it concerns rec.radio.shortwave users more than rec.ham-radio.
I have also redirected followups to rec.radio.shortwave.

In article <[e-mail]> [e-mail] (Robert J. Drabek) writes:

> In article <[e-mail]>, [e-mail] (Chuq Von Rospach) writes:
> > [e-mail] (Mike Owen W9IP) writes:

> > >This is rec.Ham radio, after all.  Scanner fans have every right to
> > >air their views, [but] discuss [it elsewhere]

> > If the ham radio folks don't want you scanner folks, then come on over to
> > rec.radio.shortwave. You're welcome to join us until you decide you want
> > your own group. (This is, in fact, one reason why rec.radio.shortwave
> > was created was to get away from just this attitude.
> > Chuq Von Rospach   <+>   [e-mail]   <+>   [This is myself speaking]

>                       NO!  NO!  NO!
> Rec.radio.shortwave was created to keep the noise level down or at least
> within a specific spectrum.  Create a rec.radio.scanner if you want, I'd
> certainly vote a resounding yes, but we do not want our (shortwave)
> bandwidth chocked full scanner stuff, please.  Most of us don't have the
> time to hit the ignore-article key too many times per day, and keeping
> things segregated helps a lot.

> If you want to continue reading the things in the ham group, that's
> why it's here.

> Robert J. Drabek                            [e-mail]

Below follows the call for votes for rec.radio.shortwave, which as you
will see specifically includes scanners, and any other radio receiving
and monitoring, possibly including even TV!

In article <[e-mail]> [e-mail] (Charles J. Guest) writes:
>(Does anyone out there have a copy of the orig. charter they can send
>me?).

Here's the first part of the "call for votes":



This is a formal call for votes for the proposed group
REC.RADIO.SHORTWAVE (originally rec.swl).

Purpose: to discuss all issues of interest to short wave listeners,
i.e.  those who are interested in listening to programs on the
shortwave broadcast bands. Topics will include, but not be limited to,
program schedules, program recommendations, receiver reviews, dx news,
the politics of international broadcasting, information about
periodicals of interest, tips for improved reception, pirate and
clandestine station information, etc.

This group will also welcome articles on dx'ing other broadcast bands
(lw, mw, vhf-fm & tv), and on shortwave listening of non-broadcast
stations.

It is expected that this newsgroup will be gateway'd to the swl-l
mailing list (though a few details remain to be worked out).
[yeah, well, it's halfway working...]

Voting procedure:
[etc]
 ----------------

If you feel that rec.radio.shortwave should prohibit scanner
information, then either hold a vote in rec.radio.shortwave to see how
the majority feels, or hold a vote to create rec.radio.scanners so
that such traffic can move out of rec.radio.shortwave.  I have no
objection to moving that traffic out of rec.radio.shortwave;  I only
object to scanner enthusiasts being left without ANY newsgroup.

Mark
--
Mark Smith, KNJ2LH                All Rights Reserved
RPO 1604               You may redistribute this article only if those who
P.O. Box 5063                 receive it may do so freely.
New Brunswick, NJ 08903-5063              [e-mail]

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End of INFO-HAMS Digest V89 Issue #1013
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