There may be multiple other ways to do this, not sure, but one effective way is to tune the SDR to a frequency that is some offset from the desired target frequency. Then a software LO is used if and as needed to retune the signal, cancelling the offset. The spike is still there, so the offset must be large enough to place the spike outside the passband of the target signal.
This is something that must be supported in the SDR software of course. Not sure if and/or how to do so in sdr# .
Another approach (untested) might be to take an FFT and drop the 0 (DC) bin...
Max
