Welcome to the FlexRadio Community! Please review the new Community Rules and other important new Community information on the Message Board.
The latest SmartSDR Software:
SmartSDR v4.1.5 | SmartSDR v4.1.5 Release Notes
SmartSDR v3.10.15 | SmartSDR v3.10.15 Release Notes

The latest 4O3A Genius Product Software:
The latest 4O3A Genius Product Software and Firmware
How to Receive Technical Support::
If you are needing assistance with FlexRadio products, please refer to the product documentation or check the Help Center for known solutions. Need technical support from FlexRadio? It's as simple as creating a HelpDesk ticket.

Setting Output Power

Jerry Gardner
Jerry Gardner Member ✭✭
edited November 2017 in SmartSDR for Windows
What is the best way to set output power for digital modes on a Flex-6000? I have used the following two methods, but an not sure which is preferred for efficiency, etc. I like to run 25 watts output on these modes, so the examples below are based on this power output level.

1. Set the RF Power slider to 25 and adjust the DAX TX Gain slider until the "peak" bar in the Level bar graph is just below 0 dB.

2. Set the RF Power slider to 100 and adjust the DAX TX Gain slider until the indicated output power is 25 watts

Answers

  • Al K0VM
    Al K0VM Member ✭✭✭
    edited November 2017
    I personally prefer to set the RF output to MAX and use the DAX  control and/or the modem program ( wsjt, etc.) to set the actual output power.  Reason: SSDR audio clipping occurs if the Level indicator exceeds 0db.

    AL, K0VM
  • Tim - W4TME
    Tim - W4TME Administrator, FlexRadio Employee admin
    edited March 2017
    Either way is just fine.  I use the same method that Al uses; I set my power to 100W and turn down the DAX audio input gain to achieve the output wattage for the mode I am operating.
  • Steve-N5AC
    Steve-N5AC Community Manager admin
    edited February 2017
    If you didn't know anything about the system you were using, the general recommendation would be to keep the gain slider high and set the power low so that your signal into the radio has a high SNR.  In the case of DAX, however, everything is floating point rather than fixed point.  This is kind of an esoteric detail, but in a floating point system data retains its SNR independent of scaling.  So this is like saying that 0.444 * 0.25 * 10 == 0.444 * 10 * 0.25.  In a fixed point DSP system, you would likely lose SNR if you divide and pass the bits around first -- you would be lopping off bits and losing dynamic range.

    TL;DR - Tim is correct, it doesn't matter.
  • Michael - N5TGL
    Michael - N5TGL Member ✭✭
    edited December 2016
    For ease of adjustment, I set the levels in the DAX panel once and forget it.  I then use the power slider to (shockingly!) adjust the power level.  For me, this is easiest as I don't have to open other panels, and the adjustment is always right at hand.  The only time I may open DAX is if I am trying to work at QRPp levels (less than 1 watt) and the power slider doesn't let me turn the wick down enough.

Leave a Comment

Rich Text Editor. To edit a paragraph's style, hit tab to get to the paragraph menu. From there you will be able to pick one style. Nothing defaults to paragraph. An inline formatting menu will show up when you select text. Hit tab to get into that menu. Some elements, such as rich link embeds, images, loading indicators, and error messages may get inserted into the editor. You may navigate to these using the arrow keys inside of the editor and delete them with the delete or backspace key.

Comment As ...

Categories