Difference between revisions of "Portsdown 2018 Band Switching"
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| + | ===Introduction=== | ||
| + | |||
| + | The Portsdown band switching has been extended in the Portsdown 2018 software to allow 8 or 9 discrete bands. The bands are listed in this table. | ||
| + | |||
{| class="wikitable" | {| class="wikitable" | ||
|- | |- | ||
| Line 21: | Line 25: | ||
| Tvtr 4 || Any || 1 1 || 1 || Set by user | | Tvtr 4 || Any || 1 1 || 1 || Set by user | ||
|} | |} | ||
| + | |||
| + | ===Characteristics of each band=== | ||
| + | |||
| + | For each band, the following discrete parameters are stored: | ||
| + | * A label for the Band button, which can be edited using the touchscreen keyboard | ||
| + | * The attenuator level that should be applied for the band | ||
| + | * The DATV Express Transmit power level | ||
| + | * The DATV Express port settings for the band. This is a number between 0 and 16, corresponding to the binary configuration of the ports. | ||
| + | * The LO frequency that should be applied when calculating the final output frequency if a transverter is being used. Enter a negative number if it is a high-side LO. | ||
| + | * The contest numbers to be displayed in Contest mode | ||
| + | |||
| + | Note that, even for the bands not designated as a "transverter band" an LO frequency can be entered and it will be used in the calculations. The final output frequency should be entered on the keyboard (in an effort to save mental gymnastics). | ||
| + | |||
| + | ===LO Filter Switching=== | ||
| + | |||
| + | The transverter bands are identified by setting GPIO pin 7 high, and then using the binary code that would normally be sent to the LO filter. So, to enable the use of the transverter switching, some extra logic needs to be put between the GPIO outputs and the LO filter. This extra logic must also have knowledge of what IF frequency is to be used for each transverter. | ||
| + | |||
| + | It is hoped to provide a PIC-based replacement for the current 4-band output switch whioch iwill provide this logic together with 8 DIP switches allowing the correct IF frequency (and hence LO filter) to be programmed for each transverter band. | ||
Revision as of 17:02, 5 February 2018
Introduction
The Portsdown band switching has been extended in the Portsdown 2018 software to allow 8 or 9 discrete bands. The bands are listed in this table.
| Band | Freq Range | VCO Filter Drive MSB LSB |
Tvtr Line | VCO Filter Needs MSB LSB |
|---|---|---|---|---|
| 71 MHz | < 100 MHz | 0 0 | 0 | 0 0 |
| 146 Mhz | 100 - 250 MHz | 0 1 | 0 | 0 1 |
| 437 MHz | 250 - 950 MHz | 1 0 | 0 | 1 0 |
| 1255 MHz | 950 - 2000 MHz | 1 1 | 0 | 1 1 |
| 2400 MHz | > 2000 MHz | 1 1 | 0 | 1 1 |
| Tvtr 1 | Any | 0 0 | 1 | Set by user |
| Tvtr 2 | Any | 0 1 | 1 | Set by user |
| Tvtr 3 | Any | 1 0 | 1 | Set by user |
| Tvtr 4 | Any | 1 1 | 1 | Set by user |
Characteristics of each band
For each band, the following discrete parameters are stored:
- A label for the Band button, which can be edited using the touchscreen keyboard
- The attenuator level that should be applied for the band
- The DATV Express Transmit power level
- The DATV Express port settings for the band. This is a number between 0 and 16, corresponding to the binary configuration of the ports.
- The LO frequency that should be applied when calculating the final output frequency if a transverter is being used. Enter a negative number if it is a high-side LO.
- The contest numbers to be displayed in Contest mode
Note that, even for the bands not designated as a "transverter band" an LO frequency can be entered and it will be used in the calculations. The final output frequency should be entered on the keyboard (in an effort to save mental gymnastics).
LO Filter Switching
The transverter bands are identified by setting GPIO pin 7 high, and then using the binary code that would normally be sent to the LO filter. So, to enable the use of the transverter switching, some extra logic needs to be put between the GPIO outputs and the LO filter. This extra logic must also have knowledge of what IF frequency is to be used for each transverter.
It is hoped to provide a PIC-based replacement for the current 4-band output switch whioch iwill provide this logic together with 8 DIP switches allowing the correct IF frequency (and hence LO filter) to be programmed for each transverter band.