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⟦48cf1bc25⟧ Wang Wps File
Length: 11234 (0x2be2)
Types: Wang Wps File
Notes: Answers to questions
Names: »2682A «
Derivation
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WangText
aug 25, 1982 jpr/amn
to: rockwell-collins
att: mr. h. o. hall ms 401/130
copy: mr. r. alldredge ms 423/100
from: christian rovsing a/s
our ref: alfa/1591/tlx/0002
subject: answers to questions
-----------------------------
dear sirs,
Please find enclosed answers to the remaining questions
on project Alpha and clarifications to questions raised
in your telex of 24 august 1982.
QUESTION NO 8
-------------
The answer already provided needs to be amended as
follows: "Section 1.3.1.(i) will be amended with the
following addition : ..."
QUESTION NO 10
--------------
CR will rephrase the answer:
By comparing question 9 to question 10 and considering
the IFB reference the relevant proposal reference in
question 10 should possibly have been 4.2.1.1.1.b(6).
Assuming this to be the case the called for requirement
is fulfilled by the proposal reference 4.2.1.1.1.b.(2),
i.e. the general log facility referenced also in the
answer to question 9.
QUESTION NO 14
--------------
The following requirements of the IFB: Section 5.1.2.2.7.3.,
section 5.1.2.2.2.(e) and fig. 5.5 have lead to the
format proposed in section 4.2.2.1.1., table 4.2.2.1.1.-1
and fig 4.2.2.1.1., table 4.2.2.1.1.-1 and fig 4.22.1.1-1
of appendix I, Vol. IV.
Section 5.1.2.2.7.3. of the IFB requires the deletion
of format lines 1 to 4 in messages transmitted via
Broadcast. The requirement of section 5.1.2.2.2.(e)
and Fig. 5.5. is for addition of a pilot. The mandatory
ACP127 header lines that consists of the two first
lines in a Broadcast Message (General Call followed
by a line with Broadcast call sign, Channel Designator
and Serial No) has been interpreted to be the pilot
called for, and FL 1 to 4 of the original message have
been deleted. We are open for a discussion of other
interpretations with the purchaser.
QUESTION NO 21
Please amend the introduction of ANNEX F with the following
addition: "All the sections of the ICD will apply for
the Alpha project except for the following sections:
4.3.1, 4.3.2., 4.3.3., 4.3.8., 4.11.2.1.6.-8, 4.11.5-10,
4.12.1.1.9.,7. Message screening and vetting procedures
will be introduced in section 8 and 4.5."
QUESTION NO 26
--------------
The sections 4.2.4.9.b,c,e, have been amended (as a
result of Questions 27, 28 and 29) to clarify the system
monitoring. Section 4.2.4.9.a. will be amended to include
the monitoring facility: "The responsibilities of the
engineer are mainly to monitor and control from this
position the system components and handle error situations.
The monitor and control of the system queues, routing
tables, etc. are handled by the supervisor.
QUESTION NO 36
--------------
Section 4.2.9.3 will be amended by replacing the existing
text: "The checkpointing philosophy will determine
the extent to which information is recoverable. In
principle there will be two methods of transaction
checkpointing:
a) checkpointing of log records containing an extract
or key pointer to the information of a transaction.
In this case checkpointing is performed after 5
log entries or every 30 second, whichever comes
first.
b) direct checkpointing of the transaction is performed
in case of messages. The checkpointing mechanism
to message data of received and stored messages
(including partly received) will be lost, and no
data from a partly finished message preparation
session are lost.
QUESTION NO 39
--------------
Continuity of the reporting system is described in
section 4.2.9.8. Section 4.2.9.6. has been amended
according to the answer to question 38. Section 4.2.9.8.
will be amended by replacing the existing text as follows:
"The reporting system continuity is essential for the
maintenance after message accounting system in so far
that lack of reporting in case of a discontinuity in
the message sequence numbering might lead to loss of
a message in case retransmission (based an automatic
service message request or manually) is not initiated.
However, a sequence numbering and annotation of all
reports will support the detection of missing reports,
and a following log trace or retrieval action will
then reveal any discontinuities this may then result
in retransmission requests".
QUESTION NO 43
--------------
The MPF delivered by Christian Rovsing A/S has all
its external interfaces in the red area and is thus
not concerned with PTMF facilities. Please regard our
previous answer to question 43 as obsolete. Red/Black
patch panels are provided by Collins. Possibly the
appendix 1, technical proposal should be amended instead
at this point with a printer to the section of the
main body of the proposal where the red/black interface
is addressed.
QUESTION NO 56
--------------
The section 7.2.4 will be amended by replacing the
sentence "The test simulator will be used ..." with
the following text: "A test drive system will be set
up at the contractors premises utilizing the second
deliverable MPG system in a back to back configuration.
Internal channels will thus be simulated. The local
message preparation on the supervisor and message service
positions will be simulated by emulating the major
load contributing VDU transaction.
QUESTION NO 113
---------------
Answer to Collins
-----------------
We can not identify any such statement in our para.
4.4.2.
The statement might refer to the skew between the four
data stream. In this case, we can tolerate a relative
delay of up to 20 milliseconds.
QUESTION NO 114
---------------
a) The statistical properties should for this purpose
be divided into:
o channel characteristics which is used for the
design of the algorithm. This is e.g. the probability
of two or more bit errors in one character, nominal
bit error rate and the probability of a character
being in error, provided the previous was in
error.
These characteristics must be assessed although
they are likely to be difficult or impossible
to calculate or measure with any significant
accuracy.
o Data Statistics.
The polarity of the start and stop bits is known.
It is therefore possible to monitor the bit error
rate based upon this. The correlation between
the characters from the different channels is
another measureable quantity
b) The filter function will be defined during the
detailed design. The channel status (the confidence
level) is derived by applying the filter function
on the data statistics. The requirements to the
filter function are, in addition to the functional
requirements of proposal ref. 4.4.2.2., that the
requirements for channel exclusion are met, since
channels are included or excluded according to
the value of the channel status, compared with
a fixed threshold value.
The channel is included if the confidence level
equals or exceeds (the quality better than) that
corresponding to corruption of five start and/or
stop elements of the preceeding ten characters
of the channel.
If less than ten characters have been received,
corruption of the start or stop elements shall
not have occurred in more than half of the characters,
(fractions rounded upwards) for the channel confidence
level to exceed the threshold value and therefore
be indcluded in the evaluation of the characters.
See also answer to question No 118
QUESTION NO 115
---------------
Para 1:
------
USARTs can handle synchronous as well as asynchronous
serial transmision.
Para 2:
------
The phasing sequence etc. is handled in compliance
with Annex 5E page 1A. USARTs we use, is programmed
to the proper character format from the built-in microprocessor
according to the software performing the set-up. This
format will be changed during the synchronization on
the four inputs as well as on the composite output
such that transparency is achieved.
This approach assures the capability to detect idle
periods, start of eight bit and start of seven bit
formats.
Further details are available upon request, but can
not be disclosed here due to its classification.
Para 3:
------
An internal register in the USART holds a complete
character until the next has been received.…0f…
QUESTION NO 116
---------------
Establishment of the "channel confidence level": Please
refer to the answer to question No 114.
Use of "channel confidence level" is described in VOL
IV appendix I section 4.2.1.1.2. point d.
QUESTION NO 117
---------------
The detailed contents of the look-up table will be
defined during the detailed design.
The IFB requirement for channel exclusion is met as
described in the answer to question No 114.
QUESTION NO 118
---------------
The intention of this phrase is to inform the purchaser
that we are aware of functional properties which, although
not specifically mentioned in the IFB, are desirable
for a properly functioning system.
The channel exclusion requirement in the IFB requires
only a single bit (exclude or not-exclude decision).
The channel confidence level in our proposal has been
chosen to a three bit binary value (0 to 7).
The term "degree of freedom" in our proposal is meant
to illustrate that compared with the IFBs exclude/not-exclude
decision, we have an added freedom to design a filter
function that can use the exclusion threshold and the
confidence level as weight factors to obtain the best
character.
QUESTION 119
------------
The IFB requirements of part III appendix 5J section
3.3 means that the history of the channel shall be
continuously recorded and updated in order to:
o exclude garbled channels
o resolve ambiguity
We have envisaged an eight-value channel confidence
level (see answer to question No 118) giving a relative
measure of the probability that the current character
is free of errors, based upon the previous characters
of that channel.
Since we do have such a measure, we felt that we could
use it as part of the selection criteria in order to
select the character with highest probability of being
correct.
However, we can provide you with selection being based
only upon the quality of the characters on the different
channels after possible exclusion of a particular channel,
as requested in the IFB.
QUESTION No 120
---------------
An ambiguity indication is given if the selection procedure
leads to two equally likely but different character
values.
This information is further handled by the MPF as discribed
in Vol IV Appendix 1 Section 4.2.1.1.2. para d.
QUESTION NO 121
---------------
The term TBD is used for values to be defined by the
contractor during the detailed design.
The reason for sending a status message reflecting
the current channel confidence level and how it is
used: please see answer to question No 120.
The channel confidence level is set to "neutral" after
a period of no data reception.
QUESTION NO 122
----------------
To be answered by COLLINS
-------------------------
This adapter should be described by you. The function
is to:
o Convert v. 28 levels to the levels required for the
KW-7.
o Implement the functions required for the synchronization.
QUESTION NO 165
---------------
The IFB requirement is covered in Vol. IV, appendix
1, para 3.2.2.
best regards
christian rovsing a/s
Jens Peter Ringgaard
