long distance serial communication

Status
Not open for further replies.
P

pallu87

New Member
hii...
i am working on a project where i need to transmit serial data over a long distance approx 2 miles...on twisted copper lines(2 wires)
can you offer suggestions on how it is possible...
i googled it and found out that there are many drivers and modems for this but with insanely high prices like a 1000$

please help me out i am really stuck against a wall here....

Its a Data acquisition system
i am using avr to measure temp humidity and power and tx it via uart to a PC
there will be many avrs joining 2 the pc... i am using only 2 wires tx and gnd
no feedback needed, the problem is...
the distance between avr and pc is approx 2 km
 
Sory, i thought you might mean that the two places where on the same site. I run fiber cables for lengths of just 120 meters at times.
 
Have a look at this: https://www.commfront.com/RS232-RS485-RS422-Serial-Converters/Serial-Repeaters.htm

And only $104 each
 
I would also go repeater.
But it's important to ensure there are nothing to add noise in the form of EMF to your signal cable, with the repeaters that can be problematic.
 
I would try RS 232 or RS485 direct with no repeater. If you keep the baud rate down to 1200 baud or so the capacitance and delays should not affect you.

I have used 3 V CMOS levels over 100 m at 4800 baud with no problems.
 
Hi Bill.

Tell us more. I know that pallu specifically stated 2 copper wires.
But I'm always interested in RF, what sort of frequency are you taking about, what final stage power output, etc. for licensing purposes. Will it not be overkill?

wifi has become cheap, then there is the new(old) wireless usb standard. If he has DLOS he can also build a neat optic wireless solution. Love those.
 

At 30'/Ω, a 4 mile loop resistance comes out to ~700 Ω, so using a 50 v P-P 300 ohm source impedance transmitter into the sending end of 300 ohm twin lead gives ~40 mA P-P into a 300 ohm load.
What minimum bandwidth do you need? With the setup above you might get 16 kHz.
 
Last edited:
Status
Not open for further replies.

Similar threads

Z
Need some help for a FM LIFI communication
Replies
1
Views
2K
rjenkinsgb
J
  • Solved
Help with RX UART Serial Data Conflicting With TX on an ESP32
Replies
11
Views
3K
danadak
C
  • Question
Output Issue with LMX2594 Serial Data
Replies
5
Views
2K
cooperhow
C
I
  • Question
Project feasibility - Police Speed Gun
Replies
9
Views
2K
rjenkinsgb
Voltmeter 20' Long Wire Length
Replies
5
Views
2K
picbits
P
Menu
Log in
Register
Cookies are required to use this site. You must accept them to continue using the site. Learn more…