> What do each of these do and what are the optimum settings?
> Tx BPF check box [default = Selected?]
Enables a bandpass filter in the AFSK output. The bandpass filter
removes distortion products and harmonics.
> Tx LPF check box [default = not Selected]
Enables a lowpass filter in the AFSK output. The lowpass filter
removes harmonics, it does not impact distortion or switching
transients.
Note: these filters only act on the audio generated by the sound
card. They do not remove distortion/harmonics generated by
running the sound card at maximum output level (clipping in the
analog output) or over driving the input of the transceiver. Nor
do they remove hum caused by improper grounding/bonding of the
computer soundcard, interface, and transceiver.
> Tap (range 24-512) [default = 48]
Controls the steepness of the filter skirts. Full details is an
in depth topic on the mathematics of digital signal processing.
> Freq in hz (range 40-600) [default = 100]
Controls the width of the bandpass filter. Note: with high tap
numbers (steep sided filters) the bandwidth should be *greater than*
400Hz to prevent loss of "sharpness" in the mark/space transitions.
73,
... Joe, W4TV
On 4/26/2017 9:00 AM, Kermit (aka Ken) via RTTY wrote:
I'd like some info on setting parameters in the TxBPF/TxLPF box in the
MMTTY TX Tab section .
I can't find good documentation in the MMTTY help file. There has been
some discussion here recently.
The parameters and their apparent default settings (from most Profiles)
are:
Tx BPF check box [default = Selected?]
Tap (range 24-512) [default = 48]
Tx LPF check box [default = not Selected]
Freq in hz (range 40-600) [default = 100]
What do each of these do and what are the optimum settings?
Thanks & 73,
Ken, AB1J
In a message dated 2017-04-25 2:18:13 P.M. Coordinated Universal Tim,
lists@subich.com writes:
On 4/25/2017 10:04 AM, Ed Muns wrote:
Set MMTTY taps to 512 too.
AND *check* TxBPF (TX tab) it is not checked by default.
TxBPF is not needed for FSK and increases the processor
load (for marginal systems) on AFSK.
You will also want to set Freq (bandwidth) to 600 Hz (or
enter 400 Hz manually). 300 Hz is too narrow with 512
taps.
73,
... Joe, W4TV
On 4/25/2017 10:04 AM, Ed Muns wrote:
AFSK on the K3/K3S is fine with low tones if the radio AFSK TX filter
is enabled. Set MMTTY taps to 512 too. Make sure to set the same
audio tone pair in both the radio and MMTTY.
73,
Ed W0YK
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