QRZ! Ham Radio 4/QRZ Ham Radio Callsign Database - Volume 4.iso/digests/space/940157.txt

Internet Message Format | 1994-11-13 | 12KB

Date: Wed, 15 Jun 94 04:30:29 PDT
From: Ham-Space Mailing List and Newsgroup <[e-mail]>
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Subject: Ham-Space Digest V94 #157
To: Ham-Space


Ham-Space Digest            Wed, 15 Jun 94       Volume 94 : Issue  157

Today's Topics:
                    PRO-2006 as satellite receiver
                 Satellite Tracking Hardware (2 msgs)
                            space shuttle

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herein consists of personal comments and does not represent the official
policies or positions of any party.  Your mileage may vary.  So there.
----------------------------------------------------------------------

Date: 14 Jun 1994 11:11:57 -0400
From: ihnp4.ucsd.edu!usc!howland.reston.ans.net!spool.mu.edu!torn!nott!cunews!freenet.carleton.ca!freenet3.scri.fsu.edu!freenet3.scri.fsu.edu![e-mail]
Subject: PRO-2006 as satellite receiver
To: [e-mail]

A  few  years ago I bought a PRO-2006 scanner with the hopes
that  I could use it to receive the OSCAR satellites. As  it
turns out this versatile programmable scanner can be used in
the  down link for all the digital satellites to date.  Here
are  the modifications and operating procedures that I  have
used  with  the  PRO-2006 scanner for use as the  down  link
receiver for the digital OSCAR satellites.

First of all, in response to several questions, the PRO-2006
will receive 1200 baud AFSK (typical terrestrial packet  and
DOVE  DO-17  (145.825MHz) telemetry)  without  modification.
Simply  connect the external speaker jack to a TNC. Any  TNC
that  will work with terrestrial packet BBSs will demodulate
DO-17 telemetry. A 2 Meter antenna typical of that used  for
FM  voice  or  packet will suffice. (DO-17 also  transmitted
synthesized  voice  shortly  after  launch  in  1990  and  I
understand  will  be  doing  so again  soon,  after  a  long
silence).  I use a couple of adapters that came  from  Radio
Shack  to adapt my type N and PL259  coax connectors to  the
PRO-2006's  BNC antenna jack. I don't think that the  little
telescoping  antenna  will pick  up  DO-17  well  enough  to
demodulate much telemetry.

My  next  attempt at satellite reception was PACKSAT  AO-16.
This  satellite  transmits  1200  baud  PSK  modulation.  In
addition to the PRO-2006 I use my HF rig, a Kenwood TS-430S,
and  an  L.L.GRACE   DSP-12 TNC. Since the PRO-2006  doesn't
demodulate single sideband I use it as a very wide band down
converter  feeding  signals to my HF rig.  This  is  a  very
simple modification. I tapped off the cathode of D33 with  a
10pf  capacitor  and  a few inches of   RG  174  coax  to  a
phono/video  type connector that I added to the back  panel.
D33  is  inside the top cover about 3 inches back  from  the
front  panel  and 2 inches over from the left  side  of  the
linear  PC  board. The glass cased diode is end mounted  and
the cathode is the end pointing up.

This  gives  you access to the 455KHz final IF  signal  just
prior  to  the PRO-2006's demodulator circuitry. The  signal
has  a  bandwidth  of about 8 to 10 KHz. My  HF  rig  has  a
transverter input on the back that I connect this signal to.
You  could also connect it directly to the HF rig's  antenna
jack  but if you were to accidentally key the HF transmitter
the PRO-2006 would be toast! Next tune your HF rig to 455KHz
upper  sideband and, using AO-16 as an example, the PRO-2006
to  437.050 MHz. Because the signal bandwidth is at least  8
KHz  wide  you  can tune your HF rig to cover  much  of  the
Doppler  shift during a pass. When your HF rig's dial  reads
451  KHz you will be receiving 437.046 MHz. The DSP-12  (and
other  PSK  TNCs) uses a phase locked loop to track  Doppler
shift by generating "mike click" signals. These you send  to
your HF rig. This setup will work with  AO-16, WO-18, LO-19,
FO-20 and IO-26 (although I haven't tried IO-26).

440  MHz signals are subject to much more attenuation in the
coax than 144 MHz signals.  I needed 50 feet of coax to  get
above the trees and even with very high quality coax (4XL) I
needed  a  mast  mounted  preamp. The  preamp  made  a  huge
difference.

The above modification also lets you use your HF rigs entire
front  end,  including  the signal strength  meter,  at  any
frequency  that the PRO-2006 will receive. Try listening  to
some of the odd signals across the bands in SSB or with your
HF rigs FM section. Very interesting.

Next  I  was  ready to tackle the 9600 baud FSK  satellites.
This requires an additional modification, as simple as,  and
much  like  the  one  described above. 9600  baud  FSK  data
contains wave form components that are too high in frequency
to  make it through the audio amplifier section of most,  if
not  all,  radio receivers. This, by the way, leads  to  the
rather confusing fact that if you tune in to a 9600 baud FSK
signal you will not hear anything that sounds like 1200 baud
AFSK  or  PSK.  What  will happen is that  the  signal  will
solidly  break the squelch but it will sound very much  like
background noise. "T" the output from this modification  out
to  an  oscilloscope  however and you can  readily  see  the
difference.  With experience you can hear the difference  as
well.

Make  this modification exactly like the last one but  leave
out  the capacitor.  Solder the center conductor of the coax
to  TP2. That's it. TP2 is located about one quarter  of  an
inch toward the left front corner of the PC board from diode
D33 where the previous coax was terminated. It looks like an
end  mounted resistor with no bands on it and the  top  lead
cut  off short.  Run this signal to the 9600 baud FSK  input
of your TNC, tune to a 9600 baud satellite and if everything
worked at 1200 baud you should have no problem at 9600.

There  is  a  serendipitous feature  of  the  PRO-2006  that
provides automatic Doppler compensation with 9600 baud  FSK.
I  will  use  UO-22  which transmits on 435.120  MHz  as  an
example.   The  PRO-2006 has 10 programmable "limit  search"
memories  (enough  for 10 satellites).   Program  the  upper
limit  of  search to 435.130 MHz and lower limit to  435.110
MHz. Then press the down arrow so that the search progresses
from  higher to lower frequencies, the direction of  Doppler
shift. Set the squelch at about one and a half and the radio
will  lock  onto  the signal when the satellite  comes  into
range,  then follow the Doppler shift until it goes  out  of
range. When the signal fades deep enough to return to search
mode  the  search  wraps around and locks  on  again  within
fractions  of  a  second after the signal returns.  Use  the
delay  option  to minimize return to search mode.  With  the
frequencies  for each satellite programmed into a  different
limit search memory you can change satellites with the press
of a single button.

Considering  the price of radio equipment I think  the  PRO-
2006 with these modifications gives you very good "bang  for
the  buck". Many people already own an HF rig and a 2  meter
rig  by the time they decide to get into the satellites. All
mode 440 MHz rigs are quite pricy and AO-21 is the only  low
earth orbit satellite with a 440 MHz uplink.

Anyway I hope this helps. Good luck.

Bruce  N4USH

--
Bruce M. Marshall  [e-mail]  voice 615 481 0990  fax [phone]

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

Date: Tue, 14 Jun 1994 10:51:00 GMT
From: ihnp4.ucsd.edu!swrinde!cs.utexas.edu!utnut!torn!news.unb.ca!upei.ca!UPEI.CA![e-mail]
Subject: Satellite Tracking Hardware
To: [e-mail]

In article <[e-mail]> [e-mail]  (Ken Durham) writes:
>From: [e-mail]  (Ken Durham)
>Subject: Satellite Tracking Hardware
>Keywords: satellite
>Date: Mon, 13 Jun 1994 15:17:08 GMT
>Dialing WWV to calibrate the PC system clock has shown that the error is too
>large to be able to track the low earth orbiting satellites without calibrating
>several times a week. This could get expensive since the call is long distance.
>
>Does anyone know of a plug-in board intended to take over the clock's time
>function with greater accuracy?
>
>The computer clock problem seems to be a common one (from comments heard on
>AO-13.) Any info on the subject would help.
>
>Ken Durham  K5MBV
>

Sorry to post here but mail to your address bounced.

Try a shareware package - Rightime and Settime.  This package does two
things very well in my initial try-out:

1. Settime:  sets computer clock automatically via connection to US
         Naval Observatory.

2. Rightime: Keeps computer clock (DOS AND CMOS ) to within 0.1 seconds
         over time after system is set ( takes 3 - 6 time sets or
         calls - I used WWV  twice over 24 hours and then Settime
         twice. Over 2 weeks the program did an excellant job.

One caveat - rightime uses the serial interrupts  in doing its job so get
the most recent version as there are switches in the program to sense when
serial ports are used and it stops using the interrupts. Over the time I
tried it - the program worked very well and I have had only a few  overruns
in DOS  at 19.200 operating KO-23 or KO-25. Will try WISP later and
I suspect the buffers and 16550s will eliminate overruns.

THe two programs are avilable at Air Systems Technologies BBS:

[phone]

they are listed as:

Tset....  .zip
ritm....  .zip

....  : equate to the version number

73 for now - DAve Seeler, VY2DCS
Internet: [e-mail]

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

Date: Tue, 14 Jun 1994 18:13:27 GMT
From: ihnp4.ucsd.edu!usc!howland.reston.ans.net!sol.ctr.columbia.edu!news.ess.harris.com![e-mail]
Subject: Satellite Tracking Hardware
To: [e-mail]

In Article <[e-mail]> "[e-mail]  (Ken Durham)" says:
> Dialing WWV to calibrate the PC system clock has shown that the error is too
> large to be able to track the low earth orbiting satellites without calibrating
> several times a week. This could get expensive since the call is long distance.
>
> Does anyone know of a plug-in board intended to take over the clock's time
> function with greater accuracy?
>
> The computer clock problem seems to be a common one (from comments heard on
> AO-13.) Any info on the subject would help.
>
> Ken Durham  K5MBV
>
>
Judging from the K5MBV, I would think the obvious solution would be to use
WWV HF service on 2.5, 5.0, 10.0 or 15.0 MHZ would be an easy solution to
the cost problem.

Your manual setting of the clock ought to be within a second or so, which
seems close enough unless you have a _real_ narrow beam.

Another choice would be to use this problem as an excuse to buy yourself
a hand-help marine GPS receiver for about $500.00, about the cost of a
specialized pc-card.  I think some of them will display the time that they
use for their position calculation.



  R.C. LOKERSON (BOB)      MAIL ADDRESS:      VOICE : 407.729.2257
  HARRIS MDSO/MIS/DCC/ATG     HARRIS E.S.S.   SMTP  : [e-mail]
  BLDG 15/RM 838              P.O. BOX 37     CCMAIL: RLOKER01
  PALM BAY, FLORIDA           MELBOURNE FL    FCC   : WA3PKX
                              32902           HOME  : 407.725.8024

  (I WROTE IT, NOT MR. HARRIS)

  "ANYONE WHO WEARS A TIE TO SHOW HOW SMART HE IS CANNOT BE VERY SMART"

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

Date: Tue, 14 Jun 94 00:02:00 +0000
From: ihnp4.ucsd.edu!swrinde!cs.utexas.edu!utnut!torn!uunet.ca!uunet.ca!softbbs![e-mail]
Subject: space shuttle
To: [e-mail]

I ask this question with maturity....Is there a E-mail address on the
space shuttle?

 * 1st 1.11 * Romulan warbird decloaking sir... ..[.... NO CARRIER

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End of Ham-Space Digest V94 #157
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