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Configuring FT 991A and GPredict for ISS and Satellite Tracking

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Rodrigo Freire edited this page Jul 15, 2022 · 5 revisions

Configuring the FT-991A and GPredict for ISS and Satellite Tracking

When doing Satellite communications, especially when working with UHF band, the Doppler effect plays a big effect - to the extent to hinder your communication, depending of the shift.

GPredict uses satellite data and can interact with your 991A to keep your frequency at the center and sweet spot, improving your TX/RX capabilities.

To say that it is tricky is the understatement of the year, but I hope this step-by-step guide helps guide you in the journey.

Estimated completion time: ~ 30 minutes.

Initial Install

  1. First, ensure that you have your COM ports properly set. We will be using the Enhanced COM Port. Write down its number.

1-device-manager

  1. Download GPredict's latest version - the Windows content is the .ZIP file

2-gpredict

  1. Unzip the contents from the previous step in C:\HAM\

3-install

  1. Go to the C:\HAM\ folder and rename the GPredict folder to GPREDICT, only that.

4-rename

  1. Now, download Hamlib latest version. Choose the EXE file that matches your operating system (probably, the 64-bit).

5-down-hamlib

  1. Install Hamlib at c:\ham\gpredict\hamlib

6-install-hamlib

Configuring GPredict

  1. Go back to c:\ham\gpredict and run gpredict.exe
  2. First thing - Update the TLE file - this file contains updated satellite track positioning, otherwise your computer will predict the satellite position with stale data - and wrong positioning. Go to menu Edit - Update TLE Data from Network

8-gpredict-run

  1. Follow suit and update the Satellite Transponder data - Go to menu Edit - Update Transponder Data

9-update-transponder

  1. Go to the Edit menu and select Preferences
  2. In Number Formats tab, check the boxes Show local time instead of UTC and Use N/S/E/W for geographical coordinates. If you live in a country which uses imperial units, check Use Imperial units instead of Metric too.

11-settings-gpredict

  1. Move to the Ground Stations tab. Double-click at the sample entry
  2. Give it a name. Mine I labeled it Home, with description My Home. At Location, I have written Votorantim, Sao Paulo. Move to the Locator field, and type your grid locator - it should populate the latitude/longitude fields. Set your estimated altitude above sea level in Altitude, and if you happen to know the nearby weather station, put its ICAO identifier over there. Or select one from the list. Otherwise, it is not critical (Actually, I failed to perceive the use of that field so far).

13-set-home

  1. This is how it should look:

14-home-set

  1. Now move to the TLE Update tab. Check the box Perform automatic update in the background

15-tle-updates

  1. Move to the Modules category in the left bar. In the Layout tab, select the Map, table, polar and single sat (wide) setting.

16-modules-layout

  1. Go to the Polar View tab. Check the Show the sky tracks automatically tab.

17-modules-polar

  1. Move to the Interfaces category in the left bar. In the Radios tab, click in the Add New button.
  2. Give it a Name - Mine is labeled 991A. Host set localhost. Leave Port as is. Radio type use Duplex TRX. PTT status define as Read PTT. VFO Up/Down set as B⬆️/A⬇️. Leave the rest as is. Click OK.

19-module-config-radio

  1. Click OK to save all settings and go back to GPredict main screen
  2. At the top-right screen, above the 'target' Satellite screen, click on the small drop-down arrow and select Configure

21-select-sat

  1. In Ground Station, select Home that you have set in Step 13. If you want, clean-up your satellite list - I have removed everything else and just left ISS.

22-filter-sats

  1. Right-click your favourite satellite and check Ground Track

23-show-ground-tracks

  1. Exit GPredict

Configuring Rigctl/Hamlib

  1. Open the Notepad

25-notepad

  1. Paste the following content in the Notepad:
start C:\Ham\GPredict\gpredict.exe
start C:\Ham\GPredict\hamlib\bin\rigctld.exe -v -r \\.\com4 -m 1035 -s 38400 -t 4532 -C "serial_speed=38400,stop_bits=2,rts_state=ON,dtr_state=OFF,serial_handshake=None"
  1. Change the COM port (red arrow) to the COM port number that matches Step 1. Set the CAT Speed (Blue Arrows) to the number that matches your radio menu 031 - CAT RATE.

27-rigctl-cmd

  1. Save this notepad file as c:\ham\gpredict\gpredict.cmd

28-save-gpredict

Action Time

  1. Go to the c:\ham\gpredict\ folder and double-click the gpredict.cmd file

29-run-gpredict

  1. If it have started successfully, you should have GPredict running and a black screen app (rigctl) running like this:

30-rigctl-running

  1. Now it is the big time - at the top-right screen, above the 'target' Satellite screen, click on the small drop-down arrow and select Radio Control

31-enter-radio-control

  1. FIRST hit the Engage button - and then click the Track button - it's SHOWTIME!

32-start-tracking

  1. If everything worked fine, you will see your 991A enter the Split mode and the VFO A and VFO B frequencies changing

33-tracking

  1. Small hints - For SSTV use the Mode V Imaging. For the Voice Transponder/Repeater, use the Mode V/U FM - Voice Repeater. And finally, Mode V/V APRS for APRS.

34-iss-xpndr

Pro-Tip

If you want to configure the radio to properly encode the required tone for the V/U ISS Repeater, use this batchfile to start gpredict:

@echo off
REM ### CONFIGURE YOUR COM PORT HERE
set COMPORT=COM4

REM ### THE BELOW BAUD RATE MUST MATCH
REM ### YOUR TRANSCEIVER BAUD RATE!
mode %COMPORT% BAUD=38400 PARITY=n DATA=8 > NUL

REM Set Freq UP; FM; Tone ENC; Tone 67; A=B; Set Freq DN; FM; Tone OFF
set CAT=FA145990000;MD0B;CT02;CN00000;AB;FA437800000;MD0B;CT00;

echo| set /p="%CAT%"> %COMPORT%

start C:\Ham\GPredict\gpredict.exe
start C:\Ham\GPredict\hamlib\bin\rigctld.exe -v -r \\.\com4 -m 1035 -s 38400 -t 4532 -C "serial_speed=38400,stop_bits=2,rts_state=ON,dtr_state=OFF,serial_handshake=None"

Enjoy!

73 de PY2RAF.

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