[Asterisk-Users] Static (Distortion?) and noise on FXO (TDM04b)

[Pete Doyle]

Hi All,
I'm trying to get my TDM04B (TDM400P w/ 4FXO) to work well at a new
office we have, but am getting a lot of static and a faint high-pitched
whine in the background on all calls to/from the PSTN.  I was able to
get it working well at our main office, but once I moved it to the new
office (which is actually an older building), the problems popped up.

I have tried to remove all non-essential things so I can test, and ended
up with the server connected to the power and one phone line only.  No
switches/hubs, phones, etc.  The problem is still there when I call in
from an external line.  We've also tried turning off all electronic gear
near the server in case there was interference.  The problem is there on
FXO ports 1 and 2--have not tried yet on 3 and 4.

I would guess its either 1) the computer / digium card combo (i.e. IRQ
problems), 2) the power could be dirty, or 3) the phone line itself has
problems.

I think I have the interrupts set up correctly (see cat /proc/interrupts
and lspci -v below), and when I use the server from our main office
sound quality is good.

I haven't been able to rule out power.  The entire building is either
ungrounded or has grounding faults as indicated by a standard outlet
tester.  I was able to put in a new outlet directly to the power box,
properly grounded, etc, and still have the same problem.

As for the line, it seems to work really well with a regular analog
phone but not with the Digium FXO.  The FXO is plugged in directly to
the test port at the demarc to bypass any possible wiring issues.  Even
tried it with a custom phone cable made with cat5 (twisted pair).  Are
there some simple tests I can do to test the line itself?

I'm kinda at whits end trying to figure it out, and figured someone out
there has been through this problem before :)  Any ideas?

This is on asterisk 1.2.0 on Centos 4.2, 2.6 kernel (AsteriskAtHome
2.1).
Thanks,
Pete


# cat /proc/interrupts
           CPU0
  0:  732297480          XT-PIC  timer
  2:          0          XT-PIC  cascade
  8:          1          XT-PIC  rtc
 10:  732115071          XT-PIC  wctdm
 12:     731674          XT-PIC  eth0
 14:     603283          XT-PIC  ide0
 15:    6953596          XT-PIC  ide1
NMI:          0
ERR:          0



# lspci -v
00:00.0 Host bridge: VIA Technologies, Inc. VT82C693A/694x [Apollo
PRO133x] (rev c2)
        Flags: bus master, medium devsel, latency 0
        Memory at e8000000 (32-bit, prefetchable) [size=64M]
        Capabilities: [a0] AGP version 2.0
        Capabilities: [c0] Power Management version 2

00:01.0 PCI bridge: VIA Technologies, Inc. VT82C598/694x [Apollo
MVP3/Pro133x AGP] (prog-if 00 [Normal decode])
        Flags: bus master, 66Mhz, medium devsel, latency 0
        Bus: primary=00, secondary=01, subordinate=01, sec-latency=0
        I/O behind bridge: 0000a000-0000afff
        Memory behind bridge: dfe00000-dfefffff
        Prefetchable memory behind bridge: dec00000-decfffff
        Capabilities: [80] Power Management version 2

00:07.0 ISA bridge: VIA Technologies, Inc. VT82C686 [Apollo Super South]
(rev 1b)
        Subsystem: VIA Technologies, Inc. VT82C686/A PCI to ISA Bridge
        Flags: bus master, stepping, medium devsel, latency 0

00:07.1 IDE interface: VIA Technologies, Inc.
VT82C586A/B/VT82C686/A/B/VT823x/A/C PIPC Bus Master IDE (rev 06)
(prog-if 8a [Master SecP PriP])
        Flags: bus master, medium devsel, latency 64
        I/O ports at ffa0 [size=16]
        Capabilities: [c0] Power Management version 2

00:07.4 SMBus: VIA Technologies, Inc. VT82C686 [Apollo Super ACPI] (rev
20)
        Flags: medium devsel

00:0f.0 Communication controller: Tiger Jet Network Inc. Tiger3XX
Modem/ISDN interface
        Subsystem: Unknown device b119:0003
        Flags: bus master, medium devsel, latency 64, IRQ 10
        I/O ports at dc00 [size=256]
        Memory at dfffb000 (32-bit, non-prefetchable) [size=4K]
        Capabilities: [40] Power Management version 2

00:10.0 VGA compatible controller: Matrox Graphics, Inc. MGA 2064W
[Millennium] (rev 01) (prog-if 00 [VGA])
        Flags: stepping, medium devsel, IRQ 11
        Memory at dfffc000 (32-bit, non-prefetchable) [size=16K]
        Memory at df000000 (32-bit, prefetchable) [size=8M]
        Expansion ROM at dffe0000 [disabled] [size=64K]

00:11.0 Ethernet controller: 3Com Corporation 3c905 100BaseTX
[Boomerang]
        Flags: bus master, medium devsel, latency 64, IRQ 12
        I/O ports at d800 [size=64]
        Expansion ROM at dffd0000 [disabled] [size=64K]


# ./zttest
Opened pseudo zap interface, measuring accuracy...
99.987793% 99.987793% 100.000000% 99.987793% 99.987793% 100.000000%
99.987793%
100.000000% 99.987793% 99.987793% 100.000000% 99.987793% 99.987793%
100.000000% 99.987793%
100.000000% 99.987793% 99.987793% 99.987793% 100.000000% 99.987793%
99.987793% 99.987793%
99.987793% 99.987793% 100.000000% 99.987793% 99.987793% 99.987793%
99.987793% 100.000000%
99.987793% 99.987793% 99.987793% 99.987793% 100.000000% 99.987793%
99.987793% 99.987793%
99.987793% 100.000000% 99.987793% 99.987793% 99.987793% 99.987793%
99.987793% 99.987793%
99.987793% 99.987793% 99.987793% 100.000000% 99.987793% 99.987793%
99.987793% 99.987793%
100.000000% 100.000000% 99.987793% 99.987793%
--- Results after 59 passes ---
Best: 100.000000 -- Worst: 99.987793 -- Average: 99.990690