Sydney DTTB Field Trial

1
DTTB SystemMultipath Character

• Drawing on both the Field Trial data and the
  Laboratory test data this presentation seeks to
  explain some DTTB questions, particularly in the
  areas of static and dynamic multipath character.

These questions are
(1) What is the minimum C/N required at various
levels of echoes ? (2) What effect does Rx NF
have on the C/N requirement ? (3) How does
Flutter modify the C/N requirements ? (4) How
does Impulse noise modify the requirements ?
2
DTTB System Static Multipath Character
(Conditions Static multipath, Equal Rx NF, No
Co-channel or impulse interference)
Indoor Antenna
Outdoor Antenna
35
8VSB
COFDM
C/N Threshold (dB)
(64QAM,2/3,1/8)
Picture
(above curve)
19
15
No Picture
15
0
3
30
(Below curve)

Multipath Level ( - dB)
W.T.Dickson 29 March 98
3
Field Trial Multipath Character
(Conditions Static multipath, Equal Rx NF, No
Co-channel or impulse interference)
Indoor Antenna
Outdoor Antenna
35
8VSB
COFDM
C/N Threshold (dB)
(64QAM,2/3,1/8)
Picture
(above curve)
19
15
SYDNEY FIELD TRIAL TESTS
No Picture
15
0
3
30
(Below curve)

Multipath Level ( - dB)
W.T.Dickson 29 March 98
4
DTTB System Multipath Character - Unequal NF
(Conditions Static multipath,Unequal Rx NF, No
Co-channel or impulse interference)
Indoor Antenna
Outdoor Antenna
(31)
35
8VSB
With NF(X4)dB
COFDM
With NFXdB
(64QAM,2/3,1/8)
Picture
C/N Threshold (dB)
(above curve)
(15)
19
No Picture
(Below curve)
15
0
3
30

Multipath Level ( - dB)
W.T.Dickson 29 March 98
5
DTTB System Dynamic Multipath Character
(Conditions Dynamic multipath (flutter), Equal
Rx NF, No Co-channel or impulse interference)
Indoor Antenna
Outdoor Antenna
35
8VSB
w/o flutter
8VSB
with flutter
Dependent upon flutter level (amplitude and
doppler shift)
COFDM
C/N Threshold (dB)
(64QAM,2/3,1/8)
Picture
With or without flutter
(above curve)
19
15
No Picture
15
0
3
30
(Below curve)

Multipath Level ( - dB)
W.T.Dickson 29 March 98
6
DTTB System Impulse Noise Character
(Conditions Static multipath, Equal Rx NF, No
Co-channel, but with impulse interference)
Indoor Antenna
Outdoor Antenna
35
Dependent upon level and character of impulse
noise (up to 10 dB higher than 8VSB)
8VSB
COFDM
With impulse noise
Picture
C/N Threshold (dB)
COFDM
(above curve)
(64QAM,2/3,1/8)
19
15
No Picture
(Below curve)
15
0
3
30

Multipath Level ( - dB)
W.T.Dickson 29 March 98
7
DTTB System Multipath Performance Improvement
(Conditions Static multipath, Equal Rx NF, No
Co-channel or impulse interference)
Indoor Antennas
Outdoor Antennas
35
8VSB
COFDM
(64QAM,2/3,1/8)
COFDM
(Nov. 1997)
Picture
C/N Threshold (dB)
(above curve)
Current implementations
(April 1998)
19
15
No Picture
(Below curve)
15
0
3
30

Multipath Level ( - dB)
W.T.Dickson 16 April 98