Subject: General comments

From: "Victor Papanaoum" <[email-masked]>
Date: Tue, 8 Dec 1998 17:37:09 +0800

Having studied the proposals from EACEM (proposal to ETSI) and 
WavePhore, please find my comments below.  These comments 
are only for the purposes of discussion.  Io Research is not 
attempting to submit another proposal.

EACEM vs Original Philips Proposal (since been withdrawn and 
I'm working from memory)

1.  The EACEM FEC appears to have the same error correcting 
performance as the original Philips proposal.

2.  EACEM proposes to use Data Channel 15.  It would make 
more sense to use Data Channels 8 to 11. My email to the 
IETF mailing group has already detailed this point.

3. The protocol overhead and transmission latency appears the 
same as the original Philips proposal.  

The transmission latency for single line VBI transmission (worst 
case) is 320ms.

WavePhore vs IETF draft

1. For random noise the WavePhore FEC has practically the same 
error correcting performance as the IETF draft.  

For burst noise and single line VBI transmission, the WavePhore FEC 
has slightly inferior performance than the IETF draft.  This is a 
result of the larger bundle size.

For burst noise and multiple line VBI transmission, the WavePhore 
FEC has better performance than the IETF draft.  This is a result of 
the interleaving scheme.

2. The protocol overhead is marginally lower than that of the 
IETF draft. 

3.  The transmission latency is fixed at 300ms, regardess of how 
many VBI lines are used.  Note, for the IETF draft the transmission 
latency for single line VBI transmission (worst case) is 270ms.

Comparison with Io Research technology (as a reference only)

1.  For random noise, Io's FEC performs better than the other FEC schemes 
as it can correct three randomly located bits per video line.  The 
other schemes can only effectively correct one bit per video line (unless all of 
the bit errors occur in the one byte, which is statistically improbable.)

For burst noise, Io's FEC performs better than the other FEC 
schemes for transmission of 1 to 4 lines per VBI.  For greater than 
4 lines per VBI, the WavePhore interleaving scheme is better at 
correcting burst errors that corrupt no more than 1 in 18 VBIs. If 
more than 1 in 18 VBIs are corrupted then Io's FEC will perform 
better.

2.  Protocol overhead is a few percent higher than the other proposals.  
This is due to the superior random noise FEC.

3.  Transmission latency is approximately twice that of the IETF 
draft and EACEM proposal.  This is due to the superior burst FEC.  

In our experience strong FEC is the deciding factor for the success 
or otherwise of a IP over VBI system.  The protocol overhead, 
transmission latencies or any other factors are effectively irrelevant. 
Other members of the group may argue this point for North 
American or European markets based on their own experience, but 
strong FEC is a pre-requisite for Asian markets.

Io Research has already developed a Java-based IP over VBI 
system using its own VBI technology.  It has been adopted as the 
delivery mechanism for a remote education platform for use in 
Australia and Asia.  As a matter of interest we have discovered that 
there are additional factors, above the layers defined by the IP over 
VBI protocol, which help to make IP over VBI reliable.  All of this, 
however, relies upon strong FEC at the VBI level.

Best Regards

Victor Papanaoum
General Manager
Io Research Pty Ltd 
ACN 057711305
Email:  [email-masked]
Fax:    +61 8 93226631
Phone:  +61 8 93226933