[DSP-10] Power Levels

[Bob Larkin]

Hi Courtney,

I'm sure the settings of 52 would be OK. Below some point, the transmitted 
signal-to-noise ratio gets pretty poor, since the radio just keeps turning 
down the signal at the DAC, but the gain after that is still high.  The 
calculation of the power multiplier and its use in the DSP should support 
very low power settings. Yes, a multiplier is supplied to the DSP and it 
just multiplies each signal by that multiplier.  The arithmetic is all 16 bit.

At  a setting of 22, you are roughly using sign bit and 2 value bits for 
the signal generation. I think this i OK, but I have never studied that!

If you have a 20 dB pad, you might put that in the antenna line and try a 
setting of 42 and see if it is like 22, but with less noise..

Lokks like great fun!

73,
Bob  W7PUA

At 09:58 PM 8/31/2005, you wrote:
>I have a question for Bob or anyone who knows:
>
>I've just made power measurements on my brickette and interpolated / 
>extrapolated output levels for the DSP-10 itself.  Charts are at the bottom of
>
>http://home.earthlink.net/%7Ejccool3/dsp10.html
>
>A drive setting of 82, for example, produces about a watt from the 
>Brickette and about a milliwatt from the DSP-10.  These results seem about 
>right.
>
>Does this mean that if I set the drive to around 52 I get a microwatt and 
>if I set it to 22 I get around a nanowatt?
>
>Chip Angle who probably lives around 20 miles from here might well get 
>thrilled at the idea of twenty billion milles per watt QSO with me at 
>setting 22, but I would have trouble believing that this was what we had 
>actually accomplished without some independent measurement
>
>Is this setting just a digital multiplication in software?  Do settings 
>below 50 mean anything?  Would digitization distortion start to be 
>noticable at these levels?  Has anyone been able to make QRPppp 
>measurements or QSOs on a DSP-10?
>
>Sorry if you've answered this before somewhere and I just missed it.
>
>Courtney, n5bf/6
>_______________________________________________
>DSP-10 mailing list
>DSP-10 at mailman.qth.net
>http://mailman.qth.net/mailman/listinfo/dsp-10
>