Langstone Update 16/10/20
Posted: Fri Oct 16, 2020 9:56 pm
I have just released another update which adds an Rx gain control setting for each band.
The new setting is accessible through the settings menu and is titled 'Rx Gain'
The default setting is 'Auto', in this mode the Pluto automatically adjusts its RF gain so that all signals within its receiver bandwidth are below the maximum allowable level. The RF bandwidth of the Pluto is quite large so even signals that are not showing on the display can cause the gain to vary. The automatic gain control starts to reduce the gain on signals exceeding about S9 +15dB on the S meter.
Selecting away from 'Auto' will switch to manual gain control and will display the Rx gain value in dB.
Selecting one click above the maximum gain value will revert to 'Auto'
The allowable range of settings depends on the frequency being received.
70-1300 MHz -1dB to 73dB
1300-4000 MHz -3dB to 71dB
4000-6000 MHz -10dB to 62dB
These values and the automatic gain behaviour are those defined by Analogue Devices as the optimised settings for the Pluto.
The 'Auto' mode is the same as has been used in previous versions and works very well. In most cases it will not be necessary to change this.
If however if you have a very strong adjacent frequency signal that keys on and off (Local packet node or repeater) you may see the receiver gain adjusting to compensate. This can cause the wanted signal to vary in level.
In that case it might be better to adjust the gain manually to a level that allows reception of the wanted signal without being affected by the stronger one.
Note however that when set manually there is no protection from overloading the A to D converter, this won't do any harm but will probably produce unexpected results.
I did consider making the RX Gain setting available directly from a button on the screen but in practice I don't think that it will be needed very often so it is probably better left in the settings menu.
Colin G4EML
The new setting is accessible through the settings menu and is titled 'Rx Gain'
The default setting is 'Auto', in this mode the Pluto automatically adjusts its RF gain so that all signals within its receiver bandwidth are below the maximum allowable level. The RF bandwidth of the Pluto is quite large so even signals that are not showing on the display can cause the gain to vary. The automatic gain control starts to reduce the gain on signals exceeding about S9 +15dB on the S meter.
Selecting away from 'Auto' will switch to manual gain control and will display the Rx gain value in dB.
Selecting one click above the maximum gain value will revert to 'Auto'
The allowable range of settings depends on the frequency being received.
70-1300 MHz -1dB to 73dB
1300-4000 MHz -3dB to 71dB
4000-6000 MHz -10dB to 62dB
These values and the automatic gain behaviour are those defined by Analogue Devices as the optimised settings for the Pluto.
The 'Auto' mode is the same as has been used in previous versions and works very well. In most cases it will not be necessary to change this.
If however if you have a very strong adjacent frequency signal that keys on and off (Local packet node or repeater) you may see the receiver gain adjusting to compensate. This can cause the wanted signal to vary in level.
In that case it might be better to adjust the gain manually to a level that allows reception of the wanted signal without being affected by the stronger one.
Note however that when set manually there is no protection from overloading the A to D converter, this won't do any harm but will probably produce unexpected results.
I did consider making the RX Gain setting available directly from a button on the screen but in practice I don't think that it will be needed very often so it is probably better left in the settings menu.
Colin G4EML