In a message dated 05/01/2008, ian@........... writes:

I'm  squirting the data across my own intranet to the graphing computer, so 
am  getting most of the available 100 Mb/s bandwidth with minimal  latency.
Hi Ian,
 
    Communication links usually have fixed baud rates.  What are you using?

For  those using the internet, there shouldn't be a problem provided the data 
are  timestamped at source.  It then doesn't matter how long the data takes 
to  arrive or whether the times between samples varies, the data can be 
properly  reassembled using the individual rimestamps.
    ? If you are sending asynchronous data, you send a  byte maybe ~11 cycles 
long overall, which has start and stop bits. You usually  send the signal, 
the receiver processes it and sends an ACK signal back. Then  you send the next 
byte. If you try simply sending at a fixed baud  rate, you inevitably get 
dropouts. You have to complete the process with  the time stamp data to be able to 
reassemble it. Your bus also has a fixed  interrupt repeat rate, when the CPU 
checks what tasks are currently  waiting. Only a few interrupts in a 
multitasking system redirect the CPU  instantly.
 
    Things though are more limited with 56K  modems.  I'd be interested to 
hear how there is a 12 Km "gap" in your  system. 
 
    Dead simple. This is the distance between my modem  and the digital 
receiver in the phone exchange.
 
    56 K modems rarely work at this rate. I limit  mine to 38 K, sometimes 
less. This avoids my computer having to request a lot of  data repeats, which 
can waste a lot of time.



I note that the ADC board uses the computer supply  lines. These can be quite 
noisy. What noise do you generally see with the input  line to earth?
 
    How many times has your system had to use a  restricted amplification 
range channel? These are only common if you get  local quakes. I have yet to 
receive an out of range quake signal with my 16 bit  +/-1/2 lsb system.
 
    Regards,
 
    Chris Chapman



   





In a message dated 05/01/2008, ian@........... writes:
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  style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size=
=3D2>I'm=20
  squirting the data across my own intranet to the graphing computer, so am=20
  getting most of the available 100 Mb/s bandwidth with minimal=20
latency.
Hi Ian,
 
    Communication links usually have fixed baud rat=
es.=20
What are you using?
<=
FONT=20
  style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size=
=3D2>For=20
  those using the internet, there shouldn't be a problem provided the data a=
re=20
  timestamped at source.  It then doesn't matter how long the data take=
s to=20
  arrive or whether the times between samples varies, the data can be proper=
ly=20
  reassembled using the individual rimestamps.
    ? If you are sending asynchronous data, you sen=
d a=20
byte maybe ~11 cycles long overall, which has start and stop bits. You usual=
ly=20
send the signal, the receiver processes it and sends an ACK signal back. The=
n=20
you send the next byte. If you try simply sending at a fixed baud=20
rate, you inevitably get dropouts. You have to complete the process wit=
h=20
the time stamp data to be able to reassemble it. Your bus also has a fixed=20
interrupt repeat rate, when the CPU checks what tasks are currently=20
waiting. Only a few interrupts in a multitasking system redirect the CP=
U=20
instantly.
 
    Things though are more limited with 56K=20
modems.  I'd be interested to hear how there is a 12 Km "gap" in your=20
system. 
 
    Dead simple. This is the distance between my mo=
dem=20
and the digital receiver in the phone exchange.
 
    56 K modems rarely work at this rate. I lim=
it=20
mine to 38 K, sometimes less. This avoids my computer having to request a lo=
t of=20
data repeats, which can waste a lot of time.


 
    I note that the ADC board uses the computer sup=
ply=20
lines. These can be quite noisy. What noise do you generally see with the in=
put=20
line to earth?
 
    How many times has your system had to use a=20
restricted amplification range channel? These are only common if you ge=
t=20
local quakes. I have yet to receive an out of range quake signal with my 16=20=
bit=20
+/-1/2 lsb system.
 
    Regards,
 
    Chris Chapman