Satellite operation is difficult to control. Anyone who wants to fully utilize the potential of a satellite transponder and have an excellent signal on both the uplink and the downlink needs to pursue:
- rotate antennas in azimuth
- rotate antennas in elevation
- debug RX (TX) on downlink
- debug TX (RX) on the uplink
- make a connection
- write down the connection
Doppler effect
Pri LEO FM satellites such as SO-50 and AO-51 have an uplink in the 2m band and the Doppler effect is smaller than on 70cm, so it is usually enough to set the transmitter to the uplink frequency. However, the Doppler on the downlink in the 70cm band is three times as large as in the 2m band, and even if the FM modulation is understandable even with a minor detuning, tuning to 70cm cannot be avoided. However, if we do not have the device connected to the computer with the HamRadio Deluxe program.
Calculating the Doppler effect in HamRadio Deluxe
The Doppler effect is calculable, which HamRadio Deluxe uses in the Satellite Tracking function. So how to use this feature?
- We will insert the current Keplerian data into the "amateur.txt" file in the Satellites subdirectory
- We will connect the device to the computer with a CAT cable
- After starting HamRadio Deluxe, we select the manufacturer, radio, COM port and transmission speed. If we have CAT powered from the COM port, we also select the output from which the supply voltage is taken (DTR or RTS). Of course, the device must be switched on and CAT configured
- The correct connection is indicated by loading the control screen, where the frequency is lit. If it didn't work, check the settings or the CAT cable
- Now tap on the Satellites icon in the top menu, which will open a window
- We select the ones we are interested in from the list of satellites
- Tap on the Observer folder and enter your position, confirm Add
- We tap on the Ground Control folder. We select satellite and mode. VFO check RX and write the downlink frequency in the Satellite field. To the right, under the name of the device, we see the frequency recalculated by the Doppler frequency shift. Of course, it changes with the movement of the satellite
This is how the abbreviated tuning plan looks like during the AO-51 flyby:
| Satellite | Date / Time | Azim | Elev | Receive | Transmit |
|---|---|---|---|---|---|
| AO-51 | 02-Dec-2006 16:56:00 | 76.6 | -1.1 | 435.305.386 | 0 |
| AO-51 | 02-Dec-2006 16:56:30 | 73.1 | -0.2 | 435.304.883 | 0 |
| AO-51 | 02-Dec-2006 16:57:00 | 69.3 | 0.7 | 435.304.323 | 0 |
| AO-51 | 02-Dec-2006 16:57:30 | 65.2 | 1.5 | 435.303.704 | 0 |
| AO-51 | 02-Dec-2006 16:58:00 | 61.0 | 2.1 | 435.303.031 | 0 |
| AO-51 | 02-Dec-2006 16:58:30 | 56.5 | 2.7 | 435.302.308 | 0 |
| AO-51 | 02-Dec-2006 16:59:00 | 51.9 | 3.1 | 435.301.545 | 0 |
| AO-51 | 02-Dec-2006 16:59:30 | 47.1 | 3.3 | 435.300.752 | 0 |
| AO-51 | 02-Dec-2006 17:00:00 | 42.3 | 3.4 | 435.299.945 | 0 |
| AO-51 | 02-Dec-2006 17:00:30 | 37.5 | 3.3 | 435.299.138 | 0 |
| AO-51 | 02-Dec-2006 17:01:00 | 32.8 | 3.1 | 435.298.348 | 0 |
| AO-51 | 02-Dec-2006 17:01:30 | 28.2 | 2.7 | 435.297.587 | 0 |
| AO-51 | 02-Dec-2006 17:02:00 | 23.7 | 2.1 | 435.296.868 | 0 |
| AO-51 | 02-Dec-2006 17:02:30 | 19.5 | 1.5 | 435.296.199 | 0 |
| AO-51 | 02-Dec-2006 17:03:00 | 15.5 | 0.7 | 435.295.585 | 0 |
| AO-51 | 02-Dec-2006 17:03:30 | 11.7 | -0.2 | 435.295.028 | 0 |
| AO-51 | 02-Dec-2006 17:04:00 | 8.2 | -1.1 | 435.294.529 | 0 |
In the described way, the number of "necessary hands" is again reduced a bit - satellite operators know what it's about, HI. The description of what Ham Radio Deluxe offers alone would be enough for several articles. But try what I'm going to write for yourself. You can find the HamRadio Deluxe program on the site .: HERE .: