ember 31, 2007 14:25 UTC
Subject: Re: [digitalradio] Re: [illinoisdigitalham] Re: Power Mask for
Bandwidth Rules - USA
At one time the ARRL published plans for class B modulators with no
filters. What they publish will stay with the times. There is no reason
higher order analog filter
- Original Message -
> From: W2XJ
> To: digitalradio@yahoogroups.com
> Sent: Sunday, December 30, 2007 23:16 UTC
> Subject: Re: [digitalradio] Re: [illinoisdigitalham] Re: Power Mask for
> Bandwidth Rules - USA
>
>
> Modern filters that have been used i
To: digitalradio@yahoogroups.com
Sent: Sunday, December 30, 2007 23:16 UTC
Subject: Re: [digitalradio] Re: [illinoisdigitalham] Re: Power Mask for
Bandwidth Rules - USA
Modern filters that have been used in real equipment since the 80s can
be -1 db at 3100 and down 25 db at 3.5 k
Modern filters that have been used in real equipment since the 80s can
be -1 db at 3100 and down 25 db at 3.5 k with negligible overshoot and
ripple in the 10ths of a DB. Chebyshev filters are not really the filter
of choice for this, elliptic tilers with some custom tweaks are a better
choice.
An emission mask must accomodate AM so I looked at the speech amplifier and
modulator chapter in the 1955 Radio Amateur's Handbook. It advocates up to 25
dB of clipping and no circuit has more than a 3-pole filter. The best that can
be done today is a Chebyshev filter with 1 dB ripple and a 2.5
