开云体育

I'm not a crystal filter guru.? ?Building a 25kHz wide filter with minimum crystals sorted from a pile of them is quite an achievement, so I'm not throwing stones, just seeing ways we can use computing power to improve hardware performance, the same way the varying power levels with frequency can also be addressed in frequency.

Here is a screen shot of background noise on the 10 meter band when it is getting no "real" signals:? ?You can see the ripples in the 25kHz-wide,? 40MHz filter by the alternating lighter and darker bands in the waterfall:



This may be different on every radio, and it is possible that mine is a little better or a little worse than the population average.? ?No way for me to tell.? You can even see that the upper side of suppressed carrier frequency is a little lower level than the lower side -- this may correlate with the difficulty I had getting USB power to match LSB power.? ?But by measuring this response and applying matched coefficients to the FFT, a filter can be constructed that makes the output "perfect."? ? All I did, was work on the 6kHz right around the center, to get the transmitter response "flatter".? ?The same effort should easily fix the receiver response (which was less important to me, but for INTELLIGIBILITY of upper side band signals, is probably worth working on also!)

AUTOMATED CORRECTIONS
EVENTUALLY, some really bright person will write some software that automatically observes this ripple in the filter response and automatically computes the corrections and stores them so the radio uses them to have a more perfect filter.??

This sort of adjustment is what we did to create our study of mitigation of high frequency hearing loss.? ?

It could easily also allow "equalization" or emphasis of transmitted audio on the radio, or emphases on the receiver response to help hams with hearing difficulties!? ?It is only a matter of time until these things are built, and the sBitx is the perfect radio for this!? ?It could be set up as an external program to set the coefficients, which would then be used from then on, and would replace $$$$ external equalization systems.

73
Gordon KX4Z