[hpsdr] Automatic Notch Filter

[Peter Uhrich]

Hi All,

the other day when i run my hpsdr transceiver on 80 m I found that the ANF
functionality did not perform well with PSDR version W5SC 06/12/2010 (SVN
rev 1523).
K5TFDs PSDR (SVN rev 3407) has a much better ANF performance.

Both versions of PSDR are configured with the same ANF parameters (taps 65,
delay 50, gain 25, leak 15).
I am using a Mercury-EU programmed with firmware 2.9 and Ozy 1.7

Then I feed an unmodlulated carrier into the rx and varied its level until
the beat tone disappeared with ANF on. 

W5SC 06/12/2010 (SVN rev 1523):
RX 3,7 MHz, LSB, 2,7 kHz Filter, Preamp off, S-Meter -109 dBm
With a carrierlevel of -86 dBm after pushing ANF the beat tone disappears
slowly after approximately 50.

K5TFDs PSDR (SVN rev 3407):
RX 3,7 MHz, LSB, 2,7 kHz Filter, Preamp off, S-Meter -109 dBm
With a carrierlevel of -105 dBm after pushing ANF the beat tone disappears
immediately.

Where does this different behavior come from? Is it a hardware, a software
or a configuration issue?

Looking forward to reading your comments.

Regards
Peter (DK7SP)