[linux-dvb] ves1820 FEC, have problems, further investigated, recommend piezo tweeters

thomas schorpp t.schorpp at gmx.de
Thu Jul 28 07:23:14 CEST 2005


thomas schorpp wrote:
> thomas schorpp wrote:
> 
>>Andrew de Quincey wrote:
>>
>>
>>>>claimed MTBF is surely 5-10 years for such chips.
>>>>more likely your card got overheated in summer in the pc case... ;)
>>>>this would cause chip damage, or electrostatics.
>>>
>>>
>>>The machines are well ventilated: they're in air conditioned comms. rooms at 
>>>multiple sites - I don't think they're overheating. It is a major pain 
>>>though :(
>>>
>>>
> 
> 
> UPDATE
> 
> mmmh... since today 4:00 UTC all is ok again, and even no more burst on
> kerrang! tv.
> 
> someone's done his homework at kablebw, many thx :)
> 
> y
> tom
> 
> 

no. not really... but...

yesterday kabelbw has turned off all bskyb tv channels on 690MHz in
karlsruhe region (? in mannheim it was running) hopefully to investigate
the burst problem, seems without much success, so ill look for a
software way to filter the bursts activating power amps' protection
circuits... (output relay designed are too slow to protect tweeters from
such signals, maybe latest switching power supply controlling or
dsp-based are fast enough but *expensive*, even the kenwood krf v5050d
series has relays yet on the output not protecting even ferrofluid
cooled tweeters and i see no way to do that passively in the speakers
without quality loss, i recommend exchanging coil to piezoelectric
tweeters like miranda pht-1000 or motorola for digital audio appliances
and have done so, they can take such distortion signals up to 20-30 volts.)

beloved JBL tweeter, R.I.P. :(

ive investigated my equipment too and changed connection cables with
*handmade* highest quality double-shielded cables from netherlands with
respective connectors and checked the home connector:

- the siemens dvb-c *is* fine as can be expected from "made in germany"
(take a good look at the pcb quality and that of other manufacturers,
and theres a good reason for this card being that large - best layout
quality, a pity, siemens management has chosen to mass-murder the jobs
of the people making such good quality here, as recently done for
mobiles manufacturing, just for the shareholders and neoliberalisms :[ )

- the ves1820 *is* fine and has *no* temperature or MTBF problems (my
chip is at least 3 years old), applying heatsink does not change.

the ber is somewhat lower now, but the breaks and burst on kerrang! tv
appear every few minutes... (this log is too short to show them):

cycle: 3370  d_time: 0.002 s  Sig: 65535  SNR: 60138  BER: 2020  UBLK: 0
 Stat: 0x1f [SIG CARR VIT SYNC LOCK ]
cycle: 3371  d_time: 0.002 s  Sig: 65535  SNR: 60652  BER: 2020  UBLK: 0
 Stat: 0x1f [SIG CARR VIT SYNC LOCK ]
cycle: 3372  d_time: 0.002 s  Sig: 65535  SNR: 60138  BER: 2020  UBLK: 0
 Stat: 0x1f [SIG CARR VIT SYNC LOCK ]
cycle: 3373  d_time: 0.002 s  Sig: 65535  SNR: 60138  BER: 2020  UBLK: 0
 Stat: 0x1f [SIG CARR VIT SYNC LOCK ]
cycle: 3374  d_time: 0.002 s  Sig: 65535  SNR: 60395  BER: 2020  UBLK: 0
 Stat: 0x1f [SIG CARR VIT SYNC LOCK ]
cycle: 3375  d_time: 0.002 s  Sig: 65535  SNR: 60395  BER: 2020  UBLK: 0
 Stat: 0x1f [SIG CARR VIT SYNC LOCK ]
cycle: 3376  d_time: 0.002 s  Sig: 65535  SNR: 59624  BER: 2020  UBLK: 0
 Stat: 0x1f [SIG CARR VIT SYNC LOCK ]

y
tom














More information about the linux-dvb mailing list