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Noise Cancellation
Techniques
A presentation by
Kaihatsu Techno Centre Pvt. Ltd.
As a reference document for their customers
Version 1.0, 2002
http://www.ktcpl.com
This presentation is a property of Kaihatsu Techno Centre Pvt. Ltd. This is intended for the restricted use for the customers and prospective clients of Kaihatsu Techno Centre. This is a
reference document only. The information given in this presentation is correct up-to the knowledge of the company. However this information is only for reference and can not be used by
any one against Kaihatsu Techno Centre for any legal matters. The use of this document is only for general guidelines about selecting the best possible network link for his/her application.
This presentation can not be considered for any loss of data or any other loss. This presentation must be utilised in full with total 9 pages. This presentation or the writer or Kaihatsu
Techno Centre can be held responsible for any loss what so ever. The pricing given in this document may vary depending on the market situation. The pricing is given for comparison only
and it should not be treated as an offer from Kaihatsu Techno Centre Pvt. Ltd. This presentation has 9 pages including this one. The figures, symbols and names used in this presentation
is a trade mark property of respective individual or company.
Reference Document
1
Topics in this Presentation
• Following communication methods are
addressed in this presentation. Click on
the name to see the explanation of that
mode.
Analogue Voltage Channel
RS 232
RS 485
Power Line Carrier Communication
Radio Frequency
Telephone
Reference Document
End
2
Analogue Voltage Channel
• Use two pair shielded
wire. Shield should be
grounded at one point at
source. Second point for
shield should be left
open.
• Use resistor capacitor or
pi circuit to filter the
noise.
• It is also recommended to
use pull down resistor to
cancel the noise.
Reference Document
3
RS 232 C
• Use nine shield core wire.
• Wire should be as far from
power line as possible.
• Shield should be connected to
instrument side chassis earth.
Other side left open.
• If instrument and PC are
supporting use hardware flow
control & even parity.
• Reduce the baud rate.
• Instrument baud parameters
(baud rate, parity, flow control,
stop & start bit) must be the
same as that of PC software
and PC port setting in control
panel.
Reference Document
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RS 485
•
•
•
•
•
•
•
•
•
•
Use twisted pair shielded wire. Min 7 twists
in meter.
One end of the shield must be grounded to
instrument and other left open.
Keep the wire away from power line.
At least one instrument or the PC must have
termination resistor.
Use pull up and pull down resistor on both
wires at least at one place in entire network.
Although limit is 32, do not connect more
than 30 instruments on one line.
Note that baud rate is inversely proportional
to distance. For more than 1,000 meters use
very low baud rate like 300 bps.
Instrument baud parameters (baud rate,
parity, flow control, stop & start bit) must be
the same as that of PC software and PC
port setting in control panel.
Do not interchange A & B (+/-) of the wire.
All A’s (+) must be connected to A’s (+) only.
Check the instrument addresses. They
should not clash.
Reference Document
5
Power Line Carrier Communication
• Phase, Neutral and Earth should be
connected properly.
• Use Low baud rate 300 bps
• The other instruments used on the same
power line must have proper noise filter.
One can check this by switching them on
one after other and determining when the
PLCC communication fails.
Reference Document
6
Radio Frequency
• Use proper antenna, terminal wire and
terminal connector.
• The electrical line should be as fas as
possible.
• High voltage spike generating electrical
fields should not be in a vicinity.
• Use very good quality power supply.
Specially designated for RF use.
Reference Document
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Telephone
• Single strand twisted wire specially
marked for telephone connection.
• Do not use parallel connection.
• Tune modem to match the impedance of
the telephone exchange.
• Avoid wire routine with power line line
routes.
• Use telephone connection box.
Reference Document
8
Thank you.
Property of Kaihatsu Techno Centre Pvt. Ltd.
Quit Show
This presentation is a property of Kaihatsu Techno Centre Pvt. Ltd. This is intended for the restricted use for the customers and prospective clients of Kaihatsu Techno Centre. This is a
reference document only. The information given in this presentation is correct up-to the knowledge of the company. However this information is only for reference and can not be used by
any one against Kaihatsu Techno Centre for any legal matters. The use of this document is only for general guidelines about selecting the best possible network link for his/her application.
This presentation can not be considered for any loss of data or any other loss. This presentation must be utilised in full with total 9 pages. This presentation or the writer or Kaihatsu
Techno Centre can be held responsible for any loss what so ever. The pricing given in this document may vary depending on the market situation. The pricing is given for comparison only
and it should not be treated as an offer from Kaihatsu Techno Centre Pvt. Ltd. This presentation has 9 pages including this one. The figures, symbols and names used in this presentation
is a trade mark property of respective individual or company.
Reference Document
9