[TenTec] INRAD Filter Question

[Bill L. Fuqua]

         There is just too much emphasis on filter ripple, linear phase, and skirt slope of filters for audio especially voice and CW applications.  People talking of these concerns have read articles, papers or have been involved in the digital industry.  In high speed data communications there is a necessity of having filters with near perfect linear phase response and ripple. That is because these systems use a method of sending higher bit rated and bandwidth. For example a 56K modem transfers 56Kbits per second over a bandwidth of less than 4KHz. This is done by having several bits represented by a galaxy of vectors ( phase and amplitude modulation). 3 bits may be transmitted at the same time by changing the phase and amplitude of the transmitted signal to new value each time.  To transmit 3 bits at a time there are 8 such unique values. 
	In voice, CW (OOK) and simple modes of digital communications these concerns are not are  unnecessary. The important issues are that you hear the signals you want to hear and eliminate those you don’t. Also, the issue of ringing is related to the bandwidth of the filter. Narrower the filter the longer it will ring. This is due to the fact that a signal can only change just so fact when passed thru a bandwidth limiting filter.
	If you saw what microphones, propagation and speakers did to your voice and CW  signals you would entirely forget the concept of filter perfection except for the two issues of passing wanted signals and eliminating unwanted ones.    

73
Bill wa4lav done by having several bits represented by a galaxy of vectors ( phase and amplitude modulation). 3 bits may be transmitted at the same time by changing the phase and amplitude of the transmitted signal to new value each time.  To transmit 3 bits at a time there are 8 such unique values. 
	In voice, CW (OOK) and simple modes of digital communications these concerns are not are  unnecessary. The important issues are that you hear th