Hi,
Gerd wrote:
> > > But setting an option for either serial or parallel or MIDI connected PTT
> > > circuit failed. It seems that sethdlc is broken, too.
> >
> > I suspect that you still had the parport and serial device drivers
> > loaded
> > or some hardware problem. If not please investigate and send patches.
>
> Hmm. Since I used a serial mouse at that machine I was not able to unload the
> serial driver as a whole. If my memory serves me right it was possible at
> least under 2.0.35 or later to simply disable the serial driver for a certain
> port using a command like
>
> setserial /dev/ttySx uart none
>
> Doesn't that work any more?
That should still work (again).
> > > sethdlc -i -d bcsf0
> > >
> > > failed on both computers.
> > > I am not sure if this is a fault of sethdlc or the driver.
> can be used for testing if the driver is able to work with the hardware.
> Especially the numbers shown for "demodcyc" (soundmodem) or "dbg2" (baycom)
> are interesting. They should constantly be changing. If they do not or simply
> remain zero, the driver will be unable to detect incoming packets.
That�s true. Please check also if the interrupt counter (/proc/interrupt)
increases
for the device in question. I suspect you have an interrupt problem here.
I re-checked at least the soundmodem driver in the distributed version, and
that
works, except for a problem in the GETMODELIST ioctl() which causes an oops
after
which the driver is unuseable. This will be corrected soon.
Make sure you specify a valid mode, e.g:
sethdlc -i sm0 -p mode wss:fsk9600_5:fsk9600_5_30 io 0x530 irq 7
dma 0 dma2 1 pario 0x378
do not forget to up the interface:
ifconfig sm0 hw ax25 dg1kjd-8 up
> Unfortunately, the smdiag utility does not work any more so I have no idea
> how to detect if there is a signal available at the soundcard's inputs at all.
I did not notice. I will bring it back in with the next tools release.
> In another message, Thomas Pinz <[EMAIL PROTECTED]> stated that one has to set up
> filters for RX and TX when using soundmodem. I have to ask here what exactly
> does that mean. Are there filters needed in form of external hardware or is
> it a certain software that I have to set up additionally?
A direct FM modulation with a rectangular pulse would result in a very broad
spectrum and cause problems in the neighbour channels. Thus you have to
low-pass
filter the transmit signal. You can set the filter coefficient data using the
smfilter
utility. If you do not, standart DF9IC-modem TX filter coefficients (loopback)
are used.
If your radio has a reasonable frequency response that should be sufficient.
In addition to that, the receiver has an input filter. Again, a default filter
is
loaded. This filter is neccessary for two reasons:
- Interpolating the signal from 4->32 times oversampling ratio (or 5->30
respectively).
This is neccessary to ensure a proper clock recovery.
- Limiting the noise spectrum. This directly increases the Eb/N0 directly.
For more information take a look at my paper which was presented on last year�s
convention.
-- Jens
