Re: Baycom USCC noise

From: pa3gcu (ukg@toya.net.pl)
Date: Wed Oct 29 2003 - 18:56:30 EET

  • Next message: Curt Mills, WE7U: "Re: [HELP] Sound card as TNC, Kernel 2.4.22, Intel board"

    On Wednesday 29 October 2003 11:50, Øyvind Hanssen wrote:
    > We are using a Baycom USCC card with DF9IC modem with
    > a T7F radio. It works ok, but since the radio is not squelched
    > there is a high number of rx interrupts and error rx packets.
    >
    > Also, some bad packets seems to slip through. Much garbage is
    > seen in the mheard list.
    >
    > Is this normal? Is there a way to workaround this?
    >
    > 73 de LA7ECA
    >
    > The sccstat returns (for instance):
    > speed : 9600 baud
    > txdelay : 5

    txd of 5 is rather on the short side, you could well do better with it set to
    8 which should suit fine.

    > persist : 64
    > slottime : 8
    > txtail : 8
    > fulldup : 0
    > waittime : 2
    > mintime : 3 sec
    > maxkeyup : 7 sec
    > idletime : 3 sec
    > maxdefer : 120 sec
    > group : 0x00
    > txoff : off
    > softdcd : off
    If you dont have a squelched radio why do you have softdcd off.?
    Should it not be on otherwise the card will always be in a busy state as per
    below, IF i remember correctly that is.

    > Status:
    >
    > HDLC Z8530 Interrupts Buffers
    > -----------------------------------------------------------------------
    > Sent : 147746 RxOver : 0 RxInts : 30689899 Size : 384
                                                                                                       ^^^^^^^^^^^^
    I played with buffersize a lot when i used a scc card (PA0HZP) i found that
    defining the following was best. ( i am presuming one still needs to define
    buffers in /etc/z8530drv.conf .
    If it is not a option in that file then recompile scc.c with more buffers
    defined.
    /usr/src/linux/drivers/net/hamradio/scc.c
    #define SCC_BUFSIZE 1024

    > Received : 212184 TxUnder: 0 TxInts : 4982360 NoSpace : 0
    > RxErrors : 1804229 ExInts : 7823901
    > TxErrors : 0 SpInts : 1006105
    > Tx State : busy

    You will always get a lot of ints without a hardware squelch, every spec of
    noise is an interrupt.
    I had much the same problem with decoding at 4800 baud and a software dcd, too
    many interrupts make bad performance.
    However having said that i have not followed or used my scc card for a few
    years now things may well have changed.

    >
    > -
    > To unsubscribe from this list: send the line "unsubscribe linux-hams" in
    > the body of a message to terhi.victor@logonet.com
    > More majordomo info at http://vger.kernel.org/majordomo-info.html

    -- 
    If the Linux community is a bunch of theives because they
    try to imitate windows programs, then the Windows community
    is built on organized crime.
    

    Regards Richard terhi.victor@logonet.com http://people.zeelandnet.nl/pa3gcu/

    - To unsubscribe from this list: send the line "unsubscribe linux-hams" in the body of a message to terhi.victor@logonet.com More majordomo info at http://vger.kernel.org/majordomo-info.html



    This archive was generated by hypermail 2b30 : Wed Oct 29 2003 - 18:56:16 EET