Pre 0.4 version are under the CW folder. It was called CW receiver though there was nothing CW specific about it. It was actually a DSB receiver.

Version 0.4a
This was the first true SSB receiver employing a passband filter with complex taps. This version suffered from LSB and USB being the opposite as expected, i.e. positivie filter settings received the lower side band while negative filter settings received the upper side band.

Version 0.4b
This was an experiment where the bandpass filtering has been moved to after the xlating filter and the xlating filter was equipped with a lowpass filter instead. This was used to confirm that it was indeed the xlating filter that changed the sign of the bandpass filter parameters

Version 0.4c
This was where the sign of the bandpass filter coefficients were negated to compensate for the xlating filter weirdness. This version suffered from working at too high rate (256k in, 64k out) which caused the filter to "explode" at narrow bandwidth and high sharpness.

Version 0.4d
Decided to go with the "double filter" architecture tested in 0.4b and reworked the decimation values:
- USRP decim: 256 -> 250k
- xlate decim: 5  -> 50k
- Rat. resampler  -> 44.1k
Moved AGC in front of the resampler so that it runs at 50k
The low pass filter is fixed at 25kHz
Slightly improved AGC attack rate.
Changed audio sink to stereo.
Second FFT sink right after the frequency xlating filter showing the 50kHz IF spectrum.

Version 0.4d_LF - Same as 0.4d but USRP source set up for LFRX.

Version 0.5 and 0.5_LF
Improved AGC values.
Interactive AGC selection seems not to work in GRC generated code.
Good values: 100m attack rate, 10-100u decay rate.

Version 0.5_LF_multi_agc
Special receiver that allows recording several AGC settings at the same time.

Version 0.5_LF_bin
A simple experiment to implement binaural CW reception using low pass and high pass filters on the L-R channel.
Also tried the IQ method but that only works in double side band mode, so I think this method is better.

Version 0.6 and 0.6_LF
Added frequency entry field to allow changing of USRP frequency (about time).
Created AM and FM receivers.


Future versions:

- Improved AGC (flatness)
- Notch filter
- NR filter