Skip makes a good point. Passband tuning and IF shift are effective in dealing with AGC capture. In some cases I have added attenuation in to the receiver as an additional measure to reduce front-end overload.
philw de ka1gmn On Tue, Jun 16, 2009 at 9:27 AM, kh6ty <kh...@comcast.net> wrote: > > > Frank, often the loss of a weak signal in the presence of a strong one > is due to AGC capture by the strong station, which reduces the gain you > need for the weak one. Try using passband tuning or IF shift to reduce > the presence of the strong station in the passband so the AGC will not > be affected by it so much. > > If you see the waterfall suddenly grow more dim when a strong station > comes one, then you can suspect that the strong station has caused the > AGC to reduce gain. > > On our PSK-20 QRP design (Smallwonderlabs.com), we do not use any AGC > but have a wide dynamic range detector and there is never any loss of a > weak signal when a strong one comes on, even right adjacent to the weak > signal. I wish the transceiver manufacturers would start designing > receivers that can dispense with AGC on digital modes without > overloading the IF chain. > > 73, Skip KH6TY > > > frankk2ncc wrote: > > > > > > More an issue for me is losing the other stations from the over-driven > > signal of a strong one. I have a noise canceling signal enhancer now, > > but it's proving to require more experience and a good sensing antenna. > > > > Using a Kenwood TS-450S and a Sound Blaster Live PCI card. SignaLink > > interface (no USB, thus no soundcard in it.) > > > > f > > > > > > > > >
