[TenTec] Questions about NR i.e. Orion

[Lin Davis]

Bill, W4ZV

> ***NR will not do anything that adjusting DSP
> BW and Gain controls will not do faster and
> more directly.***


There is an important difference between the NR filter (Adaptive Predictor with 
Leaky LMS) and just narrowing the passband with the BW control; the NR will 
quickly increase attenuation during the period between CW elements and during 
pauses/low level points in speech, which helps readability beyond what the 
narrow filter can do. Saying it another way, a narrow band filter doesn't change 
the attenuation in the passband, it is static, whereas the NR dynamically 
changes the passband attenuation in direct proportion with the strength of a 
coherent signal within the passband. As used here, I mean the passband set by 
the DSP BW function. And by coherent, I mean periodic in time. The simplest 
example is a sine wave (CW or carrier).

To get the most out of the NR, the RF gain (usually) needs to be reduced until 
the noise starts to be attenuated more than the desired signal.

Unfortunately, I believe the whole section on NR in the manual is no longer 
applicable and needs to be updated. The NR implementation has changed from Doug 
Smith's (WF6DX) original design, on which the write-up was based.

Just my 2 cents,
73,
Lin
WB1AIW