Satellite Tracking

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Satellite Tracking

Introduction

If you are new to satellite tracking visit http://www.amsat.org/ maintained by The Radio Amateur Satellite Corporation (AMSAT) for excellent articles written for new satellite users.

Ham Radio Deluxe‟s Satellite Tracking support would not be possible without the help of David Taylor and his open source satellite-tracking library. After using David‟s code to get started I wrote my own library, shipped as a DLL with Ham Radio Deluxe and based on NORAD SGP4/SDP4 Implementations by Michael F. Henry.

Note: The most important rule: it's the frequency on the satellite that is important, not the frequency on your radio. This is the most common mistake made when using a satellite.

If you are using two radios for satellite tracking – one for transmit, the other for receive – read this section first, then refer to Synchronizer on page 92. Dual radio support is arguably the most flexible way to work with satellites.

Satellites

The software requires information about the satellites you will be tracking, this information is known as Keplerian elements. Johannes Kepler (1571 – 1630) discovered the three laws of planetary motion in 1609 and 1619 – a remarkable feat!

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The satellites window lists the files containing the Keplerian elements used to plot the position of satellites and compute the correct frequencies for the uplink and downlink.
The default folder is Satellites located below the folder where you have installed Ham Radio Deluxe - for example:
C:\Program Files\Amateur Radio\Ham Radio Deluxe\Satellites
To change the folder just press Select.
It is recommended that you update the data files in the Satellites folder when you start using Ham Radio Deluxe as the files shipped in the kits will be out of date by the time you start to use them. These files should ideally be refreshed every few days.
If you check the ‘Download when Satellite Tracking starts’ option then the files are downloaded every time you start satellite tracking.
To download the latest Kepler data files press Download. The files are downloaded to the folder containing your satellite data.
To edit the list of files press Edit List. The file is Ham Radio Deluxe Satellite List.txt in the folder Satellites folder.
Example:

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New satellite data files can be downloaded from the Internet, for example from http://www.amsat.org/ or from http://www.celestrak.com/ maintained by T.S. Kelso.
The only supported file format is two-line element sets, for example:

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The verbose format is not supported.
The bare NASA format elements from http://www.amsat.org/ contain all satellites of interest to radio amateurs.
Alternatively if you look at http://www.celestrak.com/NORAD/elements/ you will see many files that can be downloaded. Just download these files and save them in the Satellites folder selected previously. For more information about the contents of these files browse http://www.celestrak.com
All text files in the Data Folder are loaded into Ham Radio Deluxe, so you should delete old files if you no longer need them.
Select up to 100 entries from the Available list by either double-clicking on individual entries or by highlighting one or more entries and pressing >. By pressing >> all entries (up to a maximum of 100) are moved to the Selected list.

Observer

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In the Observer window you enter your location and height above sea level in meters or feet (for users more familiar with imperial measurements: 1 metre is 3.3 feet). You also enter an optional list of stations that are plotted on the world maps. Only the checked [X] entries are plotted.
Enter your location either:
  • By entering your Maidenhead Locator in the Locator field and the pressing Convert >> or
  • By entering the Latitude and Longitude directly.
You also select the preferred time format; either Local (default) or UTC. Distance is displayed in either kilometers or miles.
You must press Apply to update the satellite settings.

Ground Control

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  • This window is used to adjust your radio's TX (uplink) and RX (downlink) frequency to compensate for the Doppler effect (the apparent shift in frequency of a wave due to the relative motion of source and observer). Doppler shift is calculated in accordance with Kepler's laws.
  • Enter the satellite uplink (your TX) frequency in the Satellite TX field.
  • Enter the satellite downlink (your RX) frequency in the Satellite RX field.
  • Select the VFO you will use for TX and RX (see rest of this section).
  • If you are using a transverter select the Options tab and enter the transverter offsets.
When you are tuning remember that the important frequency is the satellite frequency, not the frequency on your radio. The frequency on your radio is the satellite frequency corrected for Doppler shift.

Tabs

A plot of the selected satellite‟s position and footprint. Use the plot offset buttons to offset the plot time.

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Options

Infrequently used options are located here to avoid cluttering up the display.

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Swaps TX and RX frequencies.
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Copies TX frequency to the RX.
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Copies RX frequency to the TX.
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Displays pass details using the default text editor, useful for programming memories in a handheld UHF/VHF transceiver.
For example:

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Reloads the latest Kepler data – see Satellites on page 129.
Doppler – the current frequency correction.
Transverter – if you are using a transverter enter the correct offsets here and check TX and RX as appropriate.

AMSAT.org

The satellite‟s page in AMSAT.org (if available). Note: not all satellites are supported yet.
This is a useful way of getting information about satellites modes and frequencies.

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Kenwood TS-2000

The computer can only update both main and sub frequencies either:

  • In receive mode, or
  • In transmit mode with SAT selected.
A special solution is required when the uplink (TX) and downlink (RX) frequencies are in the same band. When you start the TS-2000 you have an extra TX VFO option Sub+XIT which is only used for same band split operation (see below). When selected the Sub VFO is used for transmitting, Doppler correction is applied by adjusting the XIT value.

Cross Band

In normal cross-band satellite mode (for example transmit on 70cms and receive on 2m) select:

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The TS-2000 must be in satellite mode so that the computer can update the TX frequency.
Be careful with the TS-2000's TF SET button, each time you press TF-SET the uplink (TX) frequency and the downlink (RX) frequency are swapped. So if the frequencies in Ham Radio Deluxe are the opposite of those shown on the radio just press TF SET once.

Same Band (Split)

An example is talking to the astronauts on the ISS where the TX frequency is 145.200.000 MHz and the RX frequency is 145.800.00 MHz. You cannot use SAT mode as this is only used for cross-band operation, so you use Split mode.

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XIT will be switched on as soon as you check TX [X] updates. If you switch it off then Ham Radio Deluxe will switch it on again.
The RX (main) frequency on the TS-2000 is set to the correct RX frequency (satellite + Doppler correction).
The TX (sub) frequency on the TS-2000 is set to the TX satellite frequency; the Doppler correction is applied by adjusting the XIT value. When you transmit the TS-2000 displays the TX (sub) frequency +/- XIT so the frequency displayed on the TS-2000 is the correct frequency (satellite + Doppler correction).
When you start transmitting you may hear beeps from the radio - it takes Ham Radio Deluxe a few seconds before it detects that you are transmitting. When Ham Radio Deluxe detects transmit mode it stops updating the RX (main) frequency until you return to receive as the frequency cannot be updated by the computer while transmitting with SAT off.

Yaesu

FT-847

You must select SAT mode on the FT-847 so that Ham Radio Deluxe can read and set both the TX and RX frequencies. It is not possible to determine the state of the FT-847's SAT button so you must press the SAT button in Ham Radio Deluxe so that it shows SAT as being enabled.
In normal cross-band satellite mode (for example transmit on 70cms and receive on 2m) select:

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The FT-847 must be in satellite mode so that the computer can update the TX frequency.
When in SAT mode the FT-847 takes a long time to respond to 'Read Frequency' requests - especially if tracking is on, as a result when you tune the FT-847 with the radio's tuning dial the displayed frequency will not update very quickly.

Other

The transmit frequency of some Yaesu radios such as the FT-817 and FT-857 cannot be changed while in transmit mode, so it is not possible to apply Doppler correction while transmitting. If you think your Yaesu radio can be updated while transmitting please contact the author.

ICOM

IC-910H

In normal cross-band satellite mode (for example transmit on 70cms and receive on 2m) select:

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The IC-910H must be in satellite mode so that the TX uses the Sub frequency. If the bands on the radio are the same as Ham Radio Deluxe but reversed press M / S to switch the Main and Sub frequencies.
Because the IC-910H cannot display the same band on both Main and Sub Ham Radio Deluxe cannot update the frequencies unless the correct bands are select using the radio controls.
In same-band mode:

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A few notes:
  • The TX mode is not updated from the radio.
  • The software has to switch between Main and Sub so that the Sub VFO is updated, it is not possible to detect the radio's current Main / Sub selection so the radio operates in main mode all the time. If you press Sub on the radio you will see that radio switch back to Main as soon as the Sub frequency is updated.

Single VFO Radios

If you are using a single VFO radio such as the FT-817 then you use the same VFO for TX and RX. Use the TX (F1) button to switch between TX and RX. When you switch to TX the transmit frequency is loaded into the radio before it switches to transmit, when you return to receive the receive frequency is loaded into the radio after it switches to receive.

So the rule is: always use the TX (F1) button to switch between transmit and receive.

Linear Transponders

Check [X] the Linear Transponder Tracking option if you are using a linear transponder such as HAMSAT / VUSAT / VO-52. These satellites receive a specific range of frequencies (typically 40 - 100 kHz) in one band, convert them to another band and amplify the converted signal for transmission back to your planet. The converted signal is inverted - LSB becomes USB etc. - this is known as an inverting transponder.

Do not use the satellite tracking built into your radio - let Ham Radio Deluxe do the work for you (for example on the FT-847 this is the Tracking option). To set up the linear transponder frequencies:

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As you tune your RX frequency the TX frequency will be correctly adjusted by applying [1] offsets from the center frequencies and then [2] Doppler correction. To adjust your transmit signal so that it matches the receive frequency use the spin button to the right of the TX center field. It will be necessary to adjust the transmit signal as your radio(s) may not be correctly aligned, also the linear transponder in the satellite may also not be correctly aligned.

The tracking option in a radio cannot correctly compensate for Doppler, this is one reason why many QSO's drift gently across the linear transponder's available bandwidth. Only correct computer control will ensure that two or more stations stay on the same frequency while the satellite passes overhead. When using the linear transponder option Ham Radio Deluxe will correctly control your radio's frequencies so that are they are both compensated for Doppler shift.

Frequency Resolution

The frequency resolution is set the 1 Hz for:

  • All ICOM,
  • All Elecraft,
  • All FlexRadio,
  • All Kenwood.

All other radios are set to 10 Hz. If you have a radio that supports 1 Hz resolution and is not in the above list please contact the author.

Options

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Schedule

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This window shows the pass schedule for the satellites selected in the Satellites window.

Current Data

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This window shows all computed information for a selected satellite. This window provides the data for the Ground Control and DDE windows.
Press Viewer to display the data with the default text file viewer, usually Notepad.

Mutual Visibility

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The mutual visibility window answers the question 'when is a satellite simultaneously visible from two or more locations'.
The information is determined up to 99 days in the future for any stations from the list defined in the Observer page.
The satellite is considered to be visible if the elevation is the same as or greater than the selected value.
Use the Viewer option to display the data in Notepad, for example:

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Visibility

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The visibility window gives you an overview of the satellites you have selected in the Satellites window.
Select the satellites that are displayed:
  • All - displays all satellites,
  • Visible now - displays only the satellites which are currently visible,
  • Visible in next… - displays the satellites visible at any time in the time period you select, for example the next 60 minutes.
For each entry in this display the columns are:

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Next Passes

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This window shows up to 1,000 passes for a selected satellite. Note: do not select more than 100 passes unless you have a very powerful computer, minimum CPU frequency of 2 GHz is recommended.
Press Alarm to add an audio alarm when a satellite is about to pass overhead. Press Plot to plot a selected pass in the Single Pass window.
Press Viewer to display the data with the default text file viewer, usually Notepad.

Single Pass

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This window plots a single pass for the satellite selected in the Next Passes window. The elevation is plotted on the left y-axis; time is on the x-axis. Select Azimuth, Altitude or Range to be plotted on the right y-axis.
If Popup info is checked a vertical dashed marker line is displayed which either tracks the current time or is positioned by clicking on the chart with the left mouse button.
As the marker position changes, the azimuth, elevation, altitude and range are displayed in the marker fields.

Plot

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This window shows the position of one to four satellites above the surface of the planet.

DDE

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This window controls the DDE server. If you want to use Ham Radio Deluxe's data with another program you must start Ham Radio Deluxe's DDE Server. Select the DDE format: currently only Nova is supported. Press Start to start the DDE server.

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