[amsat-bb] Re: SATPC32 and IC-910H

Stephen E. Belter seb at wintek.com
Tue Apr 23 14:40:38 PDT 2013


Here is the procedure I've used with SatPC32 and my Icom IC-821 for
Doppler correction when operating SSB.  It should work with any rig that
is CAT controlled.  (This is a corrected version of something I wrote a
couple of years ago in response to a similar question.)

Your success operating SO-50 is a good proving ground.

Here is the approach I took:

(1)  Install SatPC32, enter your station's latitude and longitude, update
the Keplarian elements, and synchronize the PC clock to a national
standard like WWV/NIST.

(2)  Get your radio and SatPC32 communicating, and verify the operation
(including Doppler correction) using an FM satellite (for example, SO-50).

(3)  Wait for a good pass of VO-52, for example 60+ degrees maximum
elevation.  I suggest VO-52 because it is the newest (compared to AO-7 and
FO-29), it was more tolerant of using too much transmit power, and it had
the smallest transponder correction.  Note:  This was true in 2011 with
the Indian transponder.  Since then the Indian transponder has failed and
VO-52 is using the Dutch transponder which is not as tolerant of high
power and isn't as frequency stable.

(4)  Open the "CAT" window.  You can move the Window so that it doesn't
block access to the main SatPC32 window.  Tune the radio above the center
of the satellite passband to reduce the QRM to other users.   Make sure
you are in SSB mode on the radio ("CW-" on SatPC32).

(5)  Using your call and "Test 1-2-3", listen for yourself while you are
transmitting.   You probably won't hear yourself at all, at least I
didn't.  Using the +100 and -100 buttons in the Transmit Correction part
of the CAT window, try to find yourself.  For VO-52, you should hear
yourself within +/- 1500 hertz.  (I think I was about +800, but that is
from memory on the Indian transponder.)

(6)  Once you hear yourself using the +/-100 buttons, fine tune using the
+/-10 buttons.

(7)  You can improve the tuning of your uplink/downlink using CW mode
("CW+" on SatPC32).  Zero-beat the Icom's CW sidetone with your received

(8)  *Save* the result by using the "Save" button in the CAT window.  When
given the choice, save the transmitter correction.

(9)  Verify that things are working by working a few VO-52 QSOs.

(10)  Repeat using FO-29 and AO-7, in that order.  You may need to search
over a wider frequency range (+/-3000 hertz).

(11)  One other important change when moving from FM to SSB.  Your power
output is important!  Learn how to reduce your power and use the minimum
power needed to hear yourself on the satellite.  If you use too much
power, you'll trash other conversations on the satellite and your
transmissions will be badly distorted!  This is especially true of AO-7
mode B; you'll be able to hear the entire satellite passband modulated by
a single CW operator running too much power.

Good luck!

73, Steve N9IP

Steve Belter, seb at wintek.com

On 4/23/13 3:40 PM, "Les Rayburn" <les at highnoonfilm.com> wrote:

>I'm very new to satellite operation but have been having a blast for the
>past couple of weeks. Using an IC-910H with attic antennas that include
>a 7 element 432 Arrow
>antenna with an SSB Electronics pre-amp mounted at the antenna. 1/2"
>hardline makes the 70' run from the attic to the shack in the garage. 2
>Meters shows a 6 element K1FO Yagi with an SSB Electronics pre-amp and
>1/2" hardline.
>Rig is controlled by SATPC32 via the CI-V interface at 9600 baud.
>On SO-50, I have no problems with doppler correction as you would
>suspect. With the other birds, doppler is sometimes an issue. Sometimes
>I hear stations strongly but when I call them, I don't hear my own
>uplink and the other station obviously doesn't hear me either.
>On other passes, the difference is not so great, and I'll hear my own
>uplink, though usually slightly off frequency.
>I know its possible to adjust the uplink frequency in the software, and
>I've tried it during passes without much success. The translated help
>file from German isn't much
>assistance to me so far.
>Can someone on the list point me towards a better explanation on the
>web, or offer suggestions on how to correct the situation? Any help is
>Les Rayburn, N1LF
>121 Mayfair Park
>Maylene, AL 35114
>6M VUCC #1712
>AMSAT #38965
>Grid Bandits #222
>Southeastern VHF Society
>Central States VHF Society Life Member
>Six Club #2484
>Active on 6 Meters thru 1296, 10GHz & Light
>Sent via AMSAT-BB at amsat.org. Opinions expressed are those of the author.
>Not an AMSAT-NA member? Join now to support the amateur satellite program!
>Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb

More information about the AMSAT-BB mailing list