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FDM-S2 S-Meter measurements #fdm-s2


Jeff Patterson
 

I am happy to report the S2 is within .5 dB of the Collins Standard across the entire range S0 to S9+60, measured against my Wandel & Goltermann SPM-19 selective level meter and unlike an analog receiver, the S-meter reading is independent of the AGC setting. Well done Elad!

Given its superb accuracy, its too bad there is not a software option to pop-up a beter meter with finer gradations and the ability to read in dBuv.
73
Jeff NG6X


Neil Smith G4DBN
 

Simple enough to write a bit of code to pull the levels into an S meter application over the TCP interface in SW2.  If I send a sequence of "RX00;" commands to the enabled port 1893 TCP server in SW2, I get back this:

RX00-088.841180;
RX00-091.352560;
RX00-091.580530;
RX00-087.392460;
RX00-089.737100;
RX00-090.094110;
RX00-091.092120;
RX00-086.744520;
RX00-090.968040;
RX00-090.595830;

I can then run some smoothing algorithms on it and feed that to whatever sort of graphical display I prefer.  You can use it on all eight VRX slices independently.  Documentation is at http://sdr.eladit.com/FDM-sw2%20Software/Doc/SW2_TCP_IP_Protocol/FDMSW2_TCP_PROTOCOL_v0_11.pdf

You can also pull the bin values for the entire spectrum as 1024 point values, look at the GS02; command.

If you want to get really fancy, you could easily map actual output to actual input with a calibration lookup table or polynomial curve-fit with some simple coding. Endless fun with ELAD!

Neil G4DBN


On 26/12/2019 16:04, Jeff Patterson via Groups.Io wrote:
I am happy to report the S2 is within .5 dB of the Collins Standard across the entire range S0 to S9+60, measured against my Wandel & Goltermann SPM-19 selective level meter and unlike an analog receiver, the S-meter reading is independent of the AGC setting. Well done Elad!

Given its superb accuracy, its too bad there is not a software option to pop-up a beter meter with finer gradations and the ability to read in dBuv.
73
Jeff NG6X
-- 
Neil
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