AGH B.Piwakowski Analog
Electronics Chapter V Data
trasmission principles
1
Cable properties
Transmission of analogue signal
Analog digital conversion
Characteristics of digital data flow
Signal transmission of digital data
Rozdzial V Podstawy transmisji danych analogowych i cyfrowych
Chapter V Analog and digital data transmission principles
Receiver
ITEEM IE3 B.Piwakowski : Télécommunications, Chapitre 3 Transmission dans la bande de base
Wlasnosci kabli transmisyjnych Cable proprieties
- Twisted pair
- Coaxial cable
2
]
/
1
[
/
1
km
L
e
r
ou
e
P
P
km
(dB/km) coefficient
(absorption) of cable or ,
….
cable
L
Input power
P
e
R
c
R
c
v
s
R
g
U
e
R
g
output source resistivity
source
R
e
Emitter
Received power
P
R
U
e
R
c
= characteristic resistivity
attenuation
L Lenght
Bandwidth B
cable
Parameters of cable
R
e
input receiver resistivity
Power balance
c
g
e
c
g
e
R
R
R
R
r
,
,
Reflection coefficient at
the and of cable
Matching condition!
c
g
c
e
R
R
R
R
Receiver
ITEEM IE3 B.Piwakowski : Télécommunications, Chapitre 3 Transmission dans la bande de base
If cable is not matched
3
câble
L
Input power
P
e
R
c
R
c
R
g
U
e
R
g
output source resistance
R
e
Emitter
Received power
P
R
U
R
R
e
input receiver resistivity
c
g
e
c
g
e
R
R
R
R
r
,
,
output
at
matched
r
R
R
input
at
matched
r
R
R
if
c
e
c
g
0
0
sortie
la
à
adaptation
d
pas
r
R
R
entrée
l
à
adaptation
d
pas
r
R
R
Si
s
c
e
e
c
g
'
0
'
'
0
U
e
U
R
If Re>0 , Rs>0
ITEEM IE3 B.Piwakowski :
Télécommunications, Chapitre 3
Transmission dans la bande de base
4
bandwidth B
cable
, Cable!: properties
(dB/km) attenuation coefficient
, L B
cable
,
L
f
f
c=
B
canal
L
f
B
f
c
canal
c
1
Cable bandwidth decrease with:
•
Attenuation (quality of cable)
•
Length L of cable
ITEEM IE3 B.Piwakowski :
Télécommunications, Chap.I,
Introduction et rappels
5
SNR
eff
eff
dB
dB
eff
eff
n
U
Log
N
S
Log
SNR
N
S
Log
SNR
R
n
R
U
N
S
SNR
10
10
10
2
2
20
20
10
/
/
Quality os transmission system is expressed by signal to noise ratio
N
S
P
P
SNR
bruit
signal
SNR : Signal to Noise Ratio
Example : Noisy Sinusoïdal signal.
- 2 0
- 1 5
- 1 0
- 5
0
5
1 0
1 5
2 0
s
i g n a l o r i g i n a l
s
i g n a l f i l t r é
SNR=2
SNR=0.25
SNR=20
SNR=
R
s(t)=U(t)
Received
: Even in noise is present the receiver is able to resolve the emitted signal Quality of transmission
is measured by error probability P
err
which is a function os SNR .
Signal Analogue/ Digital signal transmission
Analog
: Because of noise the receiver can not resolve the emitted signal . Quality of transmission is measured
by signal to noise ratio SNR.
Emitted signal
Signal received
+
n(t)
s(t)
r(t)
1
0
receiver
a
2
a
1
seuil
decision
Compaparato
r
threshold
0
1
EC-Pekin B.Piwakowski : Chap 11 , Numérisation et codage des signaux
6
Analog signal
source
Cable
Transmission by cable of analog signal
Récepteur
Emitterr
Signal
received
Signal emis s
B
signal
N
, L
B
cable
,
P
e
P
r
SNR
L
min
SNR
SNR
B
B
B
B
signal
recepteurl
signal
canal
Conditions of correct operation
B
recepteur
Signal emis
7
ITEEM IE3 B.Piwakowski :
Télécommunications, Chapitre 3
Transmission dans la bande de base
AGH B.Piwakowski Analog
Electronics Chapter V Data
trasmission principles
8
Digital signal transmission
AGH B.Piwakowski Analog
Electronics Chapter V Data
trasmission principles
9
Analog-Digital Conversion (ADC) Sampling
T
e
t
s
e
(t)
s(t)
t
s(t)
t
s
e
(t)
t=0 => perfect samplig
T
s
=sampling period
f
s
=sampling frequency
F
s
=1/T
s
AGH B.Piwakowski Analog
Electronics Chapter V Data
trasmission principles
10
s
e
(t)=p(t).s(t)
S
e
(f)
f
F
s
F
s2
-F
s/2
Frequency domain
Time domain
S(f)
f
F
max
- F
max
s(t)
t
t
s
e
(t)
ADC Sampling
B
g
alia
not
if
F
F
s
sin
2
max
Shannon principle
AGH B.Piwakowski Analog
Electronics Chapter V Data
trasmission principles
11
ADC
Quanatification et binary conversion
bits
in
resolution
conversion
bits
of
number
k
n
b
b
b
b
S
value
k
k
i
1
2
2
2
2
)
(
2
2
1
1
0
0
Exemple
n=8, m= 256, D=48 dB,
If Value (S
i
)=5
Binary word:
S
i
<=> 1+4 =>1, 0, 1, 0, 0, 0, 0, 0
Binary signal
)
(
6
2
log
20
log
20
2
dB
n
n
m
D
CAD
of
Dynamics
m
dB
n
tension
t
s
s
1
s
2
s
3
s
n
q
V
q
V
V
m
pp
min
max
q quantification step
V
max
V
min
m =number of voltage intervals
Binary coding
full scale voltage range
AGH B.Piwakowski Analog
Electronics Chapter V Data
trasmission principles
12
Quantification noise
• quantification noise :
12
2
2
q
)
(
)
(
)
(
t
x
t
x
t
q
x(t)
x
q
(t)
t
t
Quantification noise power:
Quantification step n
pp
eff
dB
q
V
s
n
SNR
log
20
8
.
10
6
AGH B.Piwakowski Analog
Electronics Chapter V Data
trasmission principles
13
For n et V
pp
given :
s
1eff
> s
2eff
.
SNR
1
> SNR
2
.
t
V
max
V
min
SNR
1
t
SNR
2
pp
eff
dB
q
V
s
n
SNR
log
20
8
.
10
6
V
pp
Quantization noise
AGH B.Piwakowski Analog
Electronics Chapter V Data
trasmission principles
14
- Le Débit Binaire D :
s
bits
bitrate
rate
bit
nF
T
n
T
D
n
T
T
bit
one
for
required
time
T
s
s
b
b
b
/
)
(
1
/
10 00
11
00 00
01
T
b
1 s
Samples m=4 :
Bauds
T
R
s
1
Number of
samples/second.
Ts = sampling period
Ex: Ts=0.25s, R = 4 (Bauds)
Ts
10 00 11
00 00 10
1 s
m=2
n
=> n=log
2
m
n = bit number
(here n=2)
m = (ici m=4). Number of quantifocatio levels
3
2
1
0
Ex: n=2 ; m=4; T=0.25s; T
b
=0.125 s;
fs=4Hz D = 8 bit/s
Characteristics of digital data flow
AGH B.Piwakowski Analog
Electronics Chapter V Data
trasmission principles
15
Coding
1 0 0 0 0 0 0 1 0 1 0 0 0 0 1
Densité spectrale de puissance
0
1/T
b
2/T
b
3/T
b
f
D
D
2
D
3
4/T
b
D
4
B
signal
Clock
T
h=
T
b
=> f
h
= D
NRZ code :
0 => 0
1 => 1
AGH B.Piwakowski Analog
Electronics Chapter V Data
trasmission principles
16
1
Manchester ( Biphase) code :
0 => 01
1 => 10
1 0 0 0 0 0 0 1 0 1 0 0 0 0 1
Power spectrum
0
1/T
b
2/T
b
f
D
D
2
3/T
b
D
3
4/T
b
D
4
-:
- B=2D = .
B
signal
Coding
AGH B.Piwakowski Analog Electronics Chapter V Data trasmission
principles
17
Attenuation,: signal level drop :
• Low pass filterin,, fc increases with a length
Low pass
filtering
Band=B
canal
Distortion of numeric data :
•Multiple refections; no match effect:
• Noise:
17
Received signal s(t)
• All factors together
AGH B.Piwakowski Analog Electronics Chapter V Data trasmission
principles
18
:
Source
format code NRZ
D
B
signal
= D
•
Bandwidth of câble
signal
canal
B
B
Adapted Receiver
Recived power Pr
Conditions of
succesful transmission:
Adapted Amplifier
Output resistivity Rs=Rc
Outpu power Pe
Cable
Rc =caracteristic resisitivity
atténuation
bandwidth
B
canal
]
/
1
[
]
/
[
]
/
1
[
3
.
4
/
1
km
km
dB
km
L
r
e
r
ou
e
P
P
km
L km
Exepmle : Direct asynchrone transmission of digital data :
L
B
L
f
f
B
canal
c
c
canal
1
1
For given D, L is limited
•
Amplitude condition
min
R
R
P
P
1
0
1
0
ITEEM IE3 B.Piwakowski :
Télécommunications, Chapitre 3
Transmission dans la bande de base
Cable transmission :
Source
Power amplifier
s
E
(t)
s
R
(t)
N
, L,
P
e
P
r
SNR
]
/
1
[
/
1
km
L
r
e
r
ou
e
P
P
km
Receiver
19
R
P
A
P
P
R
P
P
A
A
P
P
km
dB
dBm
E
dBm
E
dBm
R
km
dB
dBm
R
dBm
E
dBm
E
dBm
R
/
)
(
)
(
)
(
/
)
(
)
(
)
(
)
(
dBm
dBm
r
r
r
dB
dBm
N
P
mW
N
mW
P
N
P
SNR
mW
N
N
W
bruit
du
puissance
N
)
1
/
1
/
log(
10
)
log(
10
)
1
/
log(
10
)
(
dB
dBm
dBm
R
R
R
SNR
N
P
SNR
N
P
N
P
SNR
SNR
SNR
min_
)
(
)
min(
_
min
min
_
min
_
min
min
)
(
N
P
R
SNR
min
R(km)
maximal communication ragne
A
ITEEM IE3 B.Piwakowski : Télécommunications, Chapitre 3 Transmission dans la bande
de base
20
Asynchrony transmission :without clock signal
Exemple: Transmission aRS 232
D<115000 bit/s
R≈D/11 bauds
Synchronization is performed for
each symbol
8 bits
Stop/start
Stop/start
"0" level => +3V à +12V => min 3V
« 1 » level => -3V à -12V => max =-3V
0
Version with parity bit
D
B
signal
ITEEM IE3 B.Piwakowski : Télécommunications, Chapitre 3 Transmission dans la bande
de base
21
Coding ASCII
table ascii ( 0 - 127 )
Décimal Octal Hex Binaire Caractère
------- ----- --- --------
------
000 000 00 00000000 NUL (Null char.)
001 001 01 00000001 SOH (Start of Header)
002 002 02 00000010 STX (Start of Text)
003 003 03 00000011 ETX (End of Text)
004 004 04 00000100 EOT (End of Transmission)
005 005 05 00000101 ENQ (Enquiry)
006 006 06 00000110 ACK (Acknowledgment)
007 007 07 00000111 BEL (Bell)
008 010 08 00001000 BS (Backspace)
009 011 09 00001001 HT (Horizontal Tab)
010 012 0A 00001010 LF (Line Feed)
011 013 0B 00001011 VT (Vertical Tab)
012 014 0C 00001100 FF (Form Feed)
013 015 0D 00001101 CR (Carriage Return)
014 016 0E 00001110 SO (Shift Out)
015 017 0F 00001111 SI (Shift In)
016 020 10 00010000 DLE (Data Link Escape)
017 021 11 00010001 DC1 (XON)(Device Control 1)
018 022 12 00010010 DC2 (Device Control 2)
019 023 13 00010011 DC3 (XOFF)(Device Control 3)
020 024 14 00010100 DC4 (Device Control 4)
021 025 15 00010101 NAK (Negative Acknowledgement)
022 026 16 00010110 SYN (Synchronous Idle)
023 027 17 00010111 ETB (End of Trans. Block)
024 030 18 00011000 CAN (Cancel)
025 031 19 00011001 EM (End of Medium)
026 032 1A 00011010 SUB (Substitute)
027 033 1B 00011011 ESC (Escape)
028 034 1C 00011100 FS (File Separator)
029 035 1D 00011101 GS (Group Separator)
030 036 1E 00011110 RS (Request to Send)(Record Separator)
031 037 1F 00011111 US (Unit Separator)
032 040 20 00100000 SP (Space)
033 041 21 00100001 ! (exclamation mark)
034 042 22 00100010 " (double quote)
035 043 23 00100011 # (number sign)
036 044 24 00100100 $ (dollar sign)
037 045 25 00100101 % (percent)
038 046 26 00100110 & (ampersand)
039 047 27 00100111 ' (single quote)
040 050 28 00101000 ( (left opening parenthesis)
041 051 29 00101001 ) (right closing parenthesis)
042 052 2A 00101010 * (asterisk)
043 053 2B 00101011 + (plus)
044 054 2C 00101100 , (comma)
045 055 2D 00101101 -
(minus or dash)
046 056 2E 00101110 . (dot)
047 057 2F 00101111 / (forward slash)
048 060 30 00110000 0
049 061 31 00110001 1
050 062 32 00110010 2
051 063 33 00110011 3
052 064 34 00110100 4
053 065 35 00110101 5
054 066 36 00110110 6
055 067 37 00110111 7
056 070 38 00111000 8
057 071 39 00111001 9
058 072 3A 00111010 : (colon)
059 073 3B 00111011 ; (semi-colon)
060 074 3C 00111100 < (less than sign)
061 075 3D 00111101 = (equal sign)
062 076 3E 00111110 > (greater than sign)
063 077 3F 00111111 ? (question mark)
064 100 40 01000000 @ (AT symbol)
065 101 41 01000001 A
066 102 42 01000010 B
067 103 43 01000011 C
068 104 44 01000100 D
069 105 45 01000101 E
070 106 46 01000110 F
071 107 47 01000111 G
072 110 48 01001000 H
073 111 49 01001001 I
074 112 4A 01001010 J
075 113 4B 01001011 K
076 114 4C 01001100 L
077 115 4D 01001101 M
078 116 4E 01001110 N
079 117 4F 01001111 O
080 120 50 01010000 P
081 121 51 01010001 Q
082 122 52 01010010 R
083 123 53 01010011 S
084 124 54 01010100 T
085 125 55 01010101 U
086 126 56 01010110 V
087 127 57 01010111 W
088 130 58 01011000 X
089 131 59 01011001 Y
090 132 5A 01011010 Z
091 133 5B 01011011 [ (left opening bracket)
092 134 5C 01011100 \
(back slash)
093 135 5D 01011101 ] (right closing bracket)
094 136 5E 01011110 ^ (caret cirumflex)
095 137 5F 01011111 _ (underscore)
096 140 60 01100000 `
097 141 61 01100001 a
098 142 62 01100010 b
099 143 63 01100011 c
100 144 64 01100100 d
n=8 bit
m=2
8
=256 symbols
ITEEM IE3 B.Piwakowski : Télécommunications, Chapitre 3 Transmission dans la bande
de base
22
Asynchronytransmission RS232
Exemple: Transmission asynchrone RS 232
• RS 232 series connection , since 1981 ,
• Called « series port ».
• At Windows, RS-232 are designed as COM1,
COM2, etc.
• « ports COM », are used presently but replaced by
ports USB
• RS 232 is commonly used to connect different devices
to PC (GPS, modems, sensors, etc.)
• Few PCs are equipped with this port
• If RS 232 is absent , it can be substituted by an
adapter USB/port serie..
maximum length de câble RS2323
Bit rate (bit/s) ) D
Length (m) L
2 400
60
4 800
30
9 600
15
19 200
7,6
38 400
3,7
57 000
2,6
simplex / duplex
D
B
B
signal
canal
L
B
canal
1
Uwaga: Kazdy kabel jest antena
Each cabled acts like antena
AGH B.Piwakowski Analog
Electronics Chapter V Data
trasmission principles
23
Para skrecona Twisted pair
Kabel nieekranowany Non shielded cable
Tani, low cost
Ale But:
Silnie promieniuje ≈ L/l ,
wrazliwy na odbior pola elektomagnetycznego ≈ L/l Sensitive to receive electrompagnetic field ≈ L/l
Rozwiazanie dla polaczen polacznie symetryczne Solution for connections: Symmetric connection
1
1
2
1
2
1
2
s
R
R
2
)
v
v
R
R
v
v
v
s
v
2
+
-
-V
cc
V
cc
R
1
R
2
v
1
R
3
R
4
V1+N
-V1+N
+
-
Uwaga: Kazdy kabel jest antena
Each cabled acts like an antenna
AGH B.Piwakowski Analog
Electronics Chapter V Data
trasmission principles
24
Para skrecona Twisted pair
Kabel concentryczny Coaxial cable
Kabel ekranowany Shielded cable
Drozszy, higher price
Uzywany w polaczeniach asymetrycznych (sygnal + masa
Used in assymetric connections (signal + ground)
1
1
2
s
2
R
R
v
0
v
v
v
s
v
2
+
-
-V
cc
V
cc
R
1
R
2
v
1
R
3
R
4
V1
+
-
Synchrone transmission of digital data: clock signal recovery and use
Source
Signal numérique
câble
Récepteur
Emetteur
Codeur
decodeur
Received signal
SNR
, L B
cable
,
L
0
1
25
Source
Code, format
Débit : D,R
B
signal
=D ou 2D
Receiver
B
recepteur=
B
canal
SNR
•Théorème de Nyquist :
1. Canal Bandwidth
canal synchrone avec récepteur optimal
:
2
/
signal
canal
B
B
If code NRZ , n=1, m=2 => SNR
min
=4.7 dB
N
S
m
1
Two conditions for correct operation :
2. Sur le rapport S/N
cable
receiver
B
B
ITEEM IE3 B.Piwakowski :
Télécommunications, Chapitre 3
Transmission dans la bande de base
clock
Cable quality
Power Balance
AGH B.Piwakowski Analog Electronics Chapter V Data trasmission principles
26
Synchrone reception
Receiver :
Gain
Filtering
Matched filter
Decodeur
format
Signal
received
Data
Clock
Recovery
Seuils
Clock
1 0
1
1 1
1 1 1
0
0 0
Clock
Threshold
P
e
=f(S/N
)
•Probability of error P
e
Detected signal
ITEEM IE3 B.Piwakowski :
Télécommunications, Chapitre 3
Transmission dans la bande de base
27
Synchronic reception
Clock Signal Recovery
Transmission synchronic
(two signals are required)
ITEEM IE3 B.Piwakowski : Télécommunications,
Chapitre 3 Transmission dans la bande de base
28
Synchronic transmission: error probability Perr
N
S
z
z
Q
Perr
2
)
(
)
2
/
(
5
.
0
)
(
z
erfc
z
Q
1
2
3
4
5
6
10
-7
10
-6
10
-5
10
-4
10
-3
10
-2
10
-1
Pe=Q(z)
z
N
S
z
2
Goal:
To move the signal bandwidth b
towards
another bandwidth B assigned by carrier
frequency f
c
Transmission with modulation
f
Signal BF
MHz
GHz
kHz
Signal HF
Badwidth
e
B
B/f
c
<<1
Original bandwidth
b
f
Exemple: organisation TV programs in cable
BF
MHz
GHz
f
c1
f
c2
f
c3
ITEEM IE3 B.Piwakowski :
Télécommunications Chap 5,
modulations linéaires
29
ITEEM IE3 B.Piwakowski : Télécommunications Chap 5, modulations linéaires
30
modulations pourquoi ?:
Goal 2 : Enable radio transmission: :
Increase signal frequency
=> Dicrease the signal
wavelength => enable
antennes use .
Example : signal audio f
m
10 kHz.
f
c
l
Antenna shouild have a length ≈ l/4 ! But !
km
m
Hz
s
m
5
.
7
7500
10
.
10
/
10
.
3
4
1
4
3
8
l
7500
m
If wavelength decreases the size
of antenna decreases
7500
m
ITEEM IE3 B.Piwakowski : Télécommunications Chap 5, modulations linéaires
31
Source
Modulation
Récepteur
receiver
Signaux numériques
signaux analogiques
Emitter
Démodulation
Transmission using modulation modulation
s
E
(t)
s
R
(t)
atmosphère, eau
Câbles
fibre optique)
Milieu de Propagation
= canal de transmission
SNR
AGH B.Piwakowski Analog
Electronics Chapter V Data
trasmission principles
32
Antennas examples
2
,
,
4
;
2
l
l
a
r
e
r
e
S
D
L
D
R
c
AGH B.Piwakowski Analog
Electronics Chapter V Data
trasmission principles
33
Cables
Câbles :
Twisted pair
Coaxial
Fiber Optics :
Twisted wire coaxial cable
Fiber optics
Frequency
AGH B.Piwakowski Analog
Electronics Chapter V Data
trasmission principles
34
Fiber optics connecting
ITEEM IE3 B.Piwakowski : Télécommunications Chap 5, modulations linéaires
35
Modulation :
)
(t
s
m
)
(t
s
)
(t
s
c
Signal modulating
Information to transmit
Signal (carrier)
Modulated Signal
)
cos(
)
(
c
c
c
c
t
A
t
s
Modulation
= perturbation bt
MODULATEUR
)
(t
s
m
c
A
c
c
AM ASK
FM, FSK
PM, PSK
Amplitude Ac dépends on sm
Fréquence of carrier signal dépends on sm
1
1
1
0
0
t
t
Phase of carrizer signal dépends on sm
ITEEM IE3 B.Piwakowski : Télécommunications Chap 5, modulations linéaires
36
Illustratrion of three familles of modulation
AM
FM
PM
Analog Signal
Digital Signal
Tb
t
a
0
1
1
1
0
0
t
Tb
t
a
0
Tb
t
a
0
ASK, OOK
FSK
PSK
Source Canal and Receiver , case with carrier frequency:
Source
format code
D
B
signal
=
D or 2D
Adapted Receiver
Recived power
Adapted Amplifier
Output resistivity Rs=Rc ant
Outpu power Pe
Distance
L km
modulator
fc
carrier frequency
Modulation type: PSK,FSK QAM
Emitting Antenna
Wi FI
Other radio connections
Receiving
Antenna
Pr
N
SNR=10log(Pr/N)
Pe
Pr
dBm
dBm
R
km
km
dB
km
dB
dBm
E
dBm
R
km
L
f
r
e
r
N
P
SNR
f
f
L
P
P
ou
e
P
P
)
(
]
/
1
[
]
/
[
/
)
(
)
(
]
/
1
[
)
(
)
(
3
.
4
)
(
2
2
)
4
(
L
D
D
P
P
r
r
e
e
e
r
l
2
,
,
4
;
2
l
l
a
r
e
r
e
S
D
L
D
B
sigmod
=2R
AGH B.Piwakowski Analog Electronics Chapter V Data trasmission
principles
37
SNR>SNR
min
fc
carrier frequency
demodulator
Using antenna
Using cable