Like most things, there is a middle path on this. Most of the time I can operate digital modes with a wide setting on my passband. The maximum on my ICOM 756 Pro 2 is 3.6 kHz. If I do get some very strong signals, they can and will desense the rig and the waterfall display will weaken, sometimes unacceptably.
Then I either use my passband tuning controls to tighten up the filtering and block out the interfering signal. This PBT is not as good as using the selectable filters. The rig has three selections that you can use as defaults but you can also change any one of them with a few keypresses. I often set up my digital modes for 2.3, 1.0 and 0.5 kHz. I can go down to 50 Hz which is very impressive DSP filtering for CW and even PSK31. But you don't have much leeway in tuning. So most of the time (90%+) I use a wider setting and only tighten it up if I have a problem decoding the station I am working. If I have the station centered on 1500 Hz, I can change the filters or the PBT and know that it is the best fit for the passband. My QTH is very rural and far from any local QRO operators. My main QRM is from my own 6 joule energizers (electric fencers) of which I have two to cover different sides of the farm. Thankfully, my rig's noise blanker is very effective against that kind of noise. I have never been very impressed with DSP noise reduction, although it may help a little bit. 73, Rick, KV9U Roger J. Buffington wrote: > A strong adjacent PSK31 > signal inside the passband will desensitize any rig's receiver by > activating the AGC such that if you try to receive a weaker adjacent > signal, you will be unsuccessful. If you disable the AGC often the > stronger signal will simply overload the receiver. IF filtering is > essential for preventing this, and countless times filtering has made > the difference between good copy and no copy. DSP filters are only > helpful if they are in the IF, preventing AGC action by signals outside > the passband. Software solutions, such as those in MixW or PSK Deluxe, > cannot affect the rig's AGC action and are no substitute for good IF > filtering. > > >
