MDSR uses Notched noise to test transmitter performance

Hi Everybody;

MDSR is the software that let you get SDR performance out of your analog RIG. To see how go to our website - see below.

Adam Farson uses a -90dB notch to test the performance of receivers in a test called NPR (noise power ratio). I personally believe it is the best way to test a receiver regardless if it is an SDR or a conventional receiver. Unfortunately a -90dB noise notch with 3kHz bandwidth is very difficult to reproduce. Up to date there is no digital test unit that can do it and we have to use old satellite test equipment with fixed frequencies.
But notched noise has also very interesting test applications for testing the performance of transmitters. The MDSR team has introduced notch filters into the new version of their software (V2.9 Beta). This worked so well that we also decided to use notch filters with white noise on the TX side and see what performance one can get with a 24Bit sound card and the BiLIF up-converter. Although the performance did not come close to the NPR test notch of -90dB the team managed to get a -65dB notch at the output of the BiLiF IF port. The measurement below shows the notch output at 14.100MHz for the FT-950 transceiver driven by the BiLiF for 5W and 50W (60W is the max capability for the test set used; HP-8921A). What is noticeable about the measurements is the degradation of the notch depth with higher output power. A higher output produces more IMD (intermod) and fills up the notch with noise. This is a very useful test if you are interested in finding the IMD issues in your transceiver.

For more information please join the MDSR Group;
https://groups.yahoo.com/neo/groups/mdsradio/info

..or check out our website at:
http://users.skynet.be/myspace/mdsr

All the best and please download the V2.9 Beta. It is free for amateur radio use. Available from the group only.

The MDSR Team

 

I'm enjoying my FT950 and 857D much more now. Thank you!

 

You are welcome...thanks for the compliment;

Alex
VE7DXW