Electronics
Group
SUBJECT: CFHT Electronic Systems
TITLE: Status Report
DATE:
AUTHOR: W. Cruise REVISION: 0.6
OBJECTIVE
This report presents the status of each of the observatory and headquarters
systems which the Electronics Group is expected to maintain. Some of these
systems are the responsibility of the egroup, while most belong to other
groups. In all cases, when they break, the egroup will be called, and must
(should?) Be prepared to act. The report is intended to give, in a very honest
fashion, the egroup’s feelings on whether it can reasonably maintain each
system so that it can perform its part in accomplishing the mission of the
observatory.
The report is divided by systems, which are listed alphabetically. For each
system the report addresses the same areas. These sub-sections and their
purposes are:
Description This is a brief description of the system, from the perspective of
the egroup. Often this perspective has a role in how the egroup approaches the
maintenance of the system.
Importance This explains how essential the particular system is to the good
running of the observatory, again from the egroup point of view (which
hopefully coincides with the overall corporate view). One may also infer that
this has a strong bearing on where the system appears on the egroup priority
lists.
Backup This section discusses how the particular system is backed up. There
are several possible categories of backup, but not all are appropriate to all
systems. The highest level of backup is a fully redundant, on-line system,
which automatically switches itself in to take the place of a failed system.
Downhill from this are on-line systems requiring operator intervention,
off-line systems with longer startup times, spares which must be brought in and
connected, and further down are solutions which might take a very long time to
implement. All have their place, but which is right for a particular system
may be a real judgement call. This report simply discusses how the egroup
looks at the system when it thinks about the catastrophe scenarios, and how it
plans to react. In many cases there are no backups, and the only reaction is
to try to fix it, or to order a new one.
Condition This section gives the egroup’s view of how the system is
working, and sometimes some thoughts on its survivability.
Documentation This item is often the key to maintaining the systems in their
present state, or to improving them. Unfortunately, most of the systems are
very poorly documented. In addition, most of then were designed, constructed,
and installed before any of the present egroup members joined the group. Much
knowledge has gone away with the originators. The workload has prevented the
egroup from embarking on the ambitious documentation projects which would be
necessary to improve this situation. For each system, this report states what
is known about the system documentation. In some cases, it is guesses, as
nothing has been found.
Training Training covers how much expertise the egroup has on a particular
item. The report lists who in the group is knowledgeable and has experience
with the system. It also discusses whether we have held group training
sessions on a system.
Spares This part details the known spares situation for a system.
Recommendation This section presents the recommendations of the egroup about
the system. Not everything presented is possible, but it is listed anyway.
Where possible in the overall priority and overwork scheduling, this list of
recommendations will be worked on.
TABLE OF CONTENTS
1. AOB — Adaptive Optics Bonnette 1
2. Autoguider 2
3. CAMAC 5
4. Cassegrain Bonnette 7
5. Cassegrain Environment Rotation 8
6. CCD Detector Systems 9
7. Coudé f/4 Spectrograph — GECKO 9
8. Coudé f/8 Spectrograph 10
9. Dome rotation control 10
10. F/8 Upper End 12
11. F/35 Upper End 14
12. FOCAM — Faint Object Camera 14
13. FTS — Fourier Transform Spectrograph 14
14. Herzberg Spectrograph 14
15. HRCam — High Resolution Camera 14
16. Intercom and audio system 14
17. LAMA 17
18. Meteorological Monitoring System 17
19. MOCAM — Mosaic CCD Camera 18
20. MOS/SIS — Multi-Object Spectrograph/Stabilized Imaging Spectrograph
18
21. Network Systems 19
22. OASIS — ?? 19
23. Personal Computers 20
24. Prime Focus Bonnette 20
25. Power Systems 21
26. Primary Mirror Tip/Tilt System 26
27. RedEye — Infrared Camera 27
28. Telescope Control System 28
29. Television Systems 28
30. Template 30
updated 1994
The Adaptive Optics Bonnette is a project intended to provide state of the art
imaging improvements to the CFH telescope. AOB will work only with basic
imaging systems, such as FOCAM, and with specifically designed new instruments,
such as OASIS. The system is an extremely complex combination of optics,
detectors, electronics, and software. It will probably be the most complicated
system at CFHT.
It operates by splitting off a portion of the telescope light, sending it to a
wavefront detector where the curvature of the incoming light's wavefront is
detected, then processing this information in a very fast real-time computer so
that it can be used to correct the wavefront in real-time. A real explanation
of the system would require as much space as this entire document.
The parts of the system which directly affect the Electronics Group are the
Optical Table Control System (OTCS), the wavefront sensor, the tip-tilt mirror
control, and the deformable mirror control. These parts are all being built
under separate contracts. The OTCS and wavefront sensor are being supplied by
DAO, the tip-tilt mirror by OPM, and the deformable mirror and adaptive optics
computer and software by LaserDot. In addition, user interface software will
mainly be supplied by CFHT.
The AOB will probably become a very important part of the telescope. Certainly
expectations will be high for this adapter. Consequently, it may require a lot
of Electronics Group work to get it to operate at its best, and to make it
operate reliably. While it is almost a piece of pure research, this may not be
the way it is perceived by the astronomical community. It is believed that the
expectations may drive the way this system is handled at CFHT after delivery
more than the actual capabilities and realities of the instrument. This may
cause significant problems for CFHT staff in the first year or two after
delivery of the system.
The system will have no on-line redundancy. It will have a backup mode whereby
it can be completely bypassed, in place, to allow the mounted instrument to
function in its normal fashion if the AOB has a failure. Whether an instrument
can function this way will depend on the instrument, as the bypass will result
in the instrument input beam changing from f/20 to f/8.
At present the system is under development.
The system will come with documentation which is relatively good by CFHT
instrumentation standards. Each of the supplying institutions is documenting
their part. Overall documentation, as an instrument, may not be as good.
The Electronics Group has been represented on the project by R. McGonegal, and
W. Cruise. G. Matsushige has been assigned to the project, has been studying
the system, and will participate in the tests on the OTCS and wavefront sensor.
In addition, the OTCS builds on some of the control technology used by DAO in
the MOS/SIS and GECKO spectrograph projects.
The system should be delivered with a reasonable spares complement. This will
include a complete replacement computer for the OTCS, and some spares for other
parts. The real-time adaptive optics computer will have no spares, but the
parts are currently commercially available.
The Electronics Group should attempt to be well prepared for the delivery of
this equipment. It may result in a large expenditure of time to get the system
into condition to be used. It may also be a large maintenance burden to the
group. At this time it is too early to assign others to the project, as it
will be 8 months to one year between the initial tests and final delivery.
Updated 4 January 1995
The autoguider system comprises several different means of autoguiding,
depending on the method used to detect an object. All of the systems
eventually end up at the TCS III computer. In all cases computer uses
decentering error information to modify the tracking rate of the telescope. It
also performs rotation of the incoming signal based on the angle of the
instrument rotator -- either cass environment or the prime focus instrument
rotator. The basic algorithm applied to the errors is simple. Half of the
error is corrected by applying a rate which should remove the error in one
second. When the guider next runs -- about 0.3 seconds for the TV version --
it again computes the correction. This results in an asymptotic approach to
the correct position, if the image does not move. The guider has no
integration, so there can be some residual uncorrected error, which is
proportional to the inherent tracking rate error in the telescope.
The guider software is empirically configured to match each guider
configuration. The configuration parameters are stored in config files, and
are loaded into the guider program prior to starting guiding. The parameters
can be changed on the fly for the TV guider and the HRCam guider. The changed
parameters can then be saved in the same, or another, config file. The MOS/SIS
version of the guider uses a separate program which has separate guide
parameters, and is not affected by the parameter adjustment commands. There
is, however, a separate MOS test guider program which used the basic parameter
set, and can therefore be adjusted in real time, and can have the parameters
saved. One can also edit the guider config files with the normal system
editor.
Normally the guider operates in a mode where the center of the TV box is
considered to be the zero error point. The guider works to bring the image to
this position. This usually results in a slight displacement when the guider
is initiated. It is possible to change the configuration to have the guider
adopt the initial point where the centroid is located as the zero point. This
causes the guider to attempt to keep the image where it was at the start of
guiding. It is possible to move the guide box while guiding, thus moving the
telescope and image. Unfortunately, this must be done in pixel increments, and
this is too coarse for many purposes. A better method would be to have dynamic
adjustments in the software.
The guiders which supply XY error signals have an implicit zero guiding point,
and the system always strives to center the signal on the 0,0 of the error
signals.
The original guider used the target acquisition TV cameras as the guide signal
sensor. The signals are digitized in a leaky memory, or video integrator. The
leaky memory was initially purchased only to integrate on the signal for a
signal to noise ratio improvement. It was later modified to provide computer
readout for guiding. A 16x16 pixel area around the guide box is read by the
TCS III computer using a parallel I/O module in the system CAMAC crate. The
signal processing algorithm uses the average of the outer border pixels as a
background signal, which is subtracted from the whole image. A center of mass
algorithm is used to obtain a sub-pixel centroid of the image. This is
expressed in XY errors in pixels.
The guider software first scales this XY signal so that it represents
arcseconds on the sky. This is necessary as the TV cameras have a non-unity
aspect ratio, which also varies from camera to camera. The correction of this
aspect ratio was one of the main achievements which has resulted in the rather
good guide performance obtained today. The error signal is then rotated, as
explained above, and applied to correct the telescope tracking.
The HRCam guider was the first configuration to use externally supplied error
signals. The HRCam fast tip-tilt system has added software to supply the TCS
with average errors of the guiding mirror. These are supplied over a standard
RS-232 line (HP 1000 multiplexer), in XY pairs, at a one second rate. The TCS
software for the HRCam guider is a modification of the original program, with
all the leaky code removed, and the errors injected into the guider by reading
a serial multiplexer port. The guider does a standard FORTRAN read, suspending
on the serial port until a signal arrives. It then runs the XY error pair
through a scale factor adjustment, rotates it onto the sky, and applies it as
rate corrections. The guider is very successful in keeping the HRCam mirror
centered in its active movement range.
This guider is basically the HRCam guider slightly modified. As with HRCam,
the SIS uses a fast tip-tilt mirror, and sends integrated errors to the TCS for
correction to keep the mirror in its active range. MOS has two guide sensors
near the image plane to permit guiding without the possibility of differential
flexures between the bonnette TV camera and image plane. After initial
problems using a HP 1000 multiplexer port, the guider was modified to use a
BIRA RS-232 CAMAC module to read the serial line from the MOS control computer.
At the request of the astronomer in charge and the Software Group, the program
was modified to be entirely separate from the TV guider, so the two can be
quickly exchanged.
The coudé guider uses a second TV camera permanently pointed at a
beamsplitter mounted just in front of the slit or image slicer. Because of
image rotation in the coudé field, it is necessary to guide on the
science object. The TV camera is connected to the normal leaky memory, and
from there it follows the path of the bonnette guiders. To route the TV error
signals to the correct telescope axis, it is necessary to perform a signal
rotation based on the telescope position. This correction varies depending on
which coudé spectrograph is being used, and necessitates having separate
configuration files for each guider.
The autoguider is crucial to efficient observing. The telescope tracks
abominably, due to the fact it still goes "open loop" after acquiring a target.
Without autoguiding the observer is forced to constantly correct by handset.
This typically results in larger images, unhappy observers, and complaints.
With the active tip-tilt systems, and their small range of active corrections,
error correction is a necessity.
There is no ready backup for the present TV based guider system.
The leaky memory is a custom unit, made by a small outfit in Tucson, Arizona.
We only have one leaky which is currently capable of being used as guider. The
second leaky is much different from the original. It would be possible to have
it available as a spare if cabling is constructed, and software is written to
integrate it into the TCS. This would also require some means of switching
between the two sets of guiding software. At the moment, however, there is no
backup for the leaky.
The CAMAC module used for the guider is a standard module with sufficient
backup. The MOS guider's RS-232 module is the same as the ones used for TCS
links to data acquisition and visitor computers. There should be a spare, but
it has recently been placed on the suspect list. These were commercial
modules, and may still be available.
The guiding system is in good operating condition at this time. However, the
leaky memory is a weak link, and a single point of failure for TV guiding. It
would be quite difficult to repair in house if it has a significant failure.
The manufacturer, who seems a bit "crazy", may not be able to fix it. If he
can, it would cost an inordinate amount, and might take a long time. In case
of a complete failure of the original leaky, it might be better to launch a
crash effort and implement the second unit.
The CAMAC modules present no particular problem, but the spare RS-232 module
should be repaired, and/or another spare obtained.
There is no single, overall document for the guiding system.
The AG II guider software is covered by a draft manual which is several years
out of date, and does not consider the RS-232 input guiders. It does, however,
give a good overview of the guider, and explains in detail how to configure the
guider for new configurations. The guider code is a thoroughly mixed up
amalgam of code from two authors, spanning several distinct systems, and
covering several years. In addition, there is a bunch of original code,
written for test purposes, which is no longer used, but is still mixed in with
the working code. Nonetheless, it is all there, and somewhat readable.
The Leaky memory is covered in a manual from the manufacturer. It has
schematics, theory of operation, and operating instructions. While not a great
manual, it is fairly complete. The one critical item it does not have is
anything on the many Programmable Array Logic devices in the instrument. The
manual is just about sufficient to repair the unit, but it is one giant step
from the short theory section to being able to jump into the schematics and
hardware and diagnose anything but the most simple problems.
Most of the remaining expertise for the guider -- both hardware and software --
rests with W. Cruise. The leaky memories have never really been delved into at
CFHT. Either they have just worked, or the repairs have been exceedingly
simple. The autoguider is high on the list of important systems for
cross-training.
As stated above, there is no spare leaky memory. Because of the specialized,
high speed nature of the leaky, we do not even have all the integrated circuits
used in the system. CAMAC modules do have spares, but the situation on the
RS-232 modules could be improved.
The guider situation should be improved as expediently as possible (but no
faster). A failure of the TV guider system would be a blow to normal
operations. A replacement for the leaky memory system is part of the TCS IV
design. It is only at the conceptual level at this time, but a set of hardware
modules have been purchased for evaluation. The system will use commercial VME
modules residing in the TCS IV VME crate. It will be controlled by a vxWorks
CPU. Unfortunately, none of this has never happened!
It should be possible to construct this guider system, using the hardware
already purchased, and operate it standalone with the TCS III computer. This
guider would take the TV signal, process it, and produce XY error signals on an
RS-232 line. The TCS III guider would then accept this as it does the present
HRCam and MOS/SIS guiders. A plan will be advanced to have an initial attempt
on this conceptual using a University of Victoria co-op student.
The other main recommendation is to speedily complete TCS IV. The guider
should be a high priority in that system, perhaps moving ahead of some of the
other system features.
Updated 1994
The CFHT CAMAC system was initially intended to be the only interface medium
for all instrumentation at the observatory. Initially, it was not involved in
the Telescope Control System. The system, while based on the IEEE and
worldwide CAMAC standard, has a custom designed interface to the HP 1000
computers. This interface was designed at GEC Elliot (later Fisher Automation)
in England.
The system, at its height, consisted of two complete systems connected to the
DAIC and PICA HP 1000 computers. Each system could be patched into branches
running to the main observing stations throughout the observatory. A
development system was installed in the Waimea offices. During this period the
main problems with the system were due to the frequent changes in
configuration, and to "fake" Hughes connectors on the British modules. This
also lead to a bad reputation for the CAMAC. With the advent of HP 9000
computers, the use of the CAMAC system for data acquisition purposes decreased
greatly. With fewer system reconfigurations, the reliability has improved.
In its present configuration, the CAMAC system has experienced a dramatic
decline from its previous use. It is now used with the TCS to interface the
real-time TV display, dome control, autoguider, remote links, MOS guider, WWVB
clock, cass bonnette and prime focus bonnette. It is connected in a
configuration where the two TCS computers can share the entire system
transparently. In addition to the TCS access, the branch crates also have
access by the data acquisition system. This access is accomplished by use of
auxiliary crate controllers, using RS-232 and IEEE-488 interfaces. It speaks
well of the original CAMAC standard that the system is inherently capable of
this expansion. The data acquisition system uses the CAMAC for control of the
FTS, Reticon, FOCAM, and MOS calibration lamp system. It has recently been
adapted for remote assisted dewar filling.
The CAMAC system represents a single point failure for most of the systems
mentioned above. Many of these, such as dome control, autoguiding, and
bonnettes could seriously impact operations. Other failures might affect only
portions, and might be more tolerable.
There is no on-line backup for the CAMAC system. In the case of the TCS, where
both computers are interfaced to the same system crate, there is the small
possibility that an interface problem might affect only one computer. At this
time, there are no viable alternatives to most of the CAMAC interfaced
systems.
The system is currently in good working condition. The system components are
mostly over ten years old, and some are over fifteen. Some of the pieces are
certainly out of production at this time, but much generic CAMAC equipment,
such as crates, modules, and interfaces is still readily available. With some
luck, it should be possible to keep the system going for another ten years, at
least. That should allow sufficient time to get TCS IV on line to replace most
of the critical CAMAC uses.
Since the routine reconfiguration of the system has stopped, the failure rate
has dropped significantly. Currently the major failure mode is the crate power
supplies. These are typically easy to repair or replace. The system crate
modules which interface to the HP 1000 computers are a point of concern, since
they are of custom design. In addition, their intimate connection to the HP
1000 I/O buss makes them extremely difficult to repair. There are no useful
diagnostic methods for this. A failure of these modules would be a major
problem. However, given the desire borne of an emergency, it would be possible
to develop software to permit use of newer, standard, RS-232 interfaces, and
recover use of the system. There are already a few failed system modules.
This was not a concern when TCS IV was going to be completed by this time, but
given the current situation, a re-evaluation of this position is in order.
At one point, when data acquisition was still done on HP 1000 computers, the
Software Group purchased some new interface modules. Some of these modules
were never placed into operation due to incompatibilities. Some were also
altered, and may still be non-operational.
The interface board into the HP 1000 computer, while made by HP, is now a true
orphan. One of these boards has failed, and has not been repaired. As
mentioned in the above paragraph, this is probably a good time to thing about
getting this done.
The documentation of this system, as a system, is probably non-existent. There
are some manuals, put together in 1979, that document the system of that date.
Nothing as ambitious has been done since. However, there are manufacturer's
manuals for all the commercial modules acquired since the original system was
put into service.
The CAMAC driver in the TCS is an ancient, well proven piece of software. It
was written by B. Grundseth in 1979, and has not seen too much modification
since. It should not pose any problems.
Almost all of the current Electronic Group CAMAC expertise rests with W.
Cruise. He has worked with all parts of the system over the last 15 years.
However, much of this work is far back in the past. D. Josephson has worked
some with parts of the system, but not all with the custom, system crate
modules. B. Grundseth has a lot of hands-on experience in days gone by, and
could lend a hand if needed.
There are lots of spare modules and crates. The only area of concern is the
custom interface modules and the HP 1000 interface cards. With an original
complement of four installed systems, and their spares, there are enough
modules to more than cover the present TCS use. However, an accurate inventory
of the system modules, and their condition, is probably called for.
The main recommendation here is to get on with TCS IV, and replace the TCS
connections through CAMAC with newer systems. Failing that, the system should
be able to hold on for many more years. Getting a better handle on the system
crate modules should be a priority. It should be adequate to have three
operating sets of modules. Heavy training on these systems is probably not
cost effective.
If the powers deem the priorities to warrant it, it would be useful to develop
an RS-232 interfaced CAMAC system for the present TCS III. This could provide
an additional level of backup in the event of a real disaster.
Updated ??
Updated 4 January 1995
This system rotates the cassegrain instrument environment, including the cass
bonnette. The system was designed and implemented by the Electronics Group
during the period of P. Waddell. It utilizes the original motors designed into
the telescope. These motors are hidden inside the central core of the mirror
cell, and are only accessible when the cass bonnette is removed. The control
system is designed around an industrial type variable frequency controller. It
is mounted in an electrical box on the north side of the mirror cell. User
control is done through standard telescope handsets, which can be connected at
the cass environment, or in the control room.
A computer control interface for the rotation was designed and installed by P.
Waddell. It was intended to go through the cass CAMAC system. However, due to
reasons not understood, it was never implemented in software.
The rotational position of the cass environment is measured by an encoder
independent of the rotation control. The encoder is a small 13-bit Itek
useries unit, with an electronics box mounted on the north side of the mirror
cell. The encoder is interfaced through a TCS Remote Interface Unit encoder
interface board located in Control Station 6. This interface is part of the
original TCS design. The encoder is displayed on the channel 13 display, and
is passed to the data acquisition system for use in annotating recorded data.
In the TCS it is used to perform error signal rotation for autoguiding.
Rotation of the cassegrain environment, and the instruments it carries, is
essential, or at least very useful, to many of the cassegrain observing
programs. Without the control system it is not possible to rotate the cass
environment. Most observing would probably continue after a failure, as would
the complaints.
The rotation encoder is essential for autoguiding. Without it, the error
signals would not be fed to the correct axis.
There is no on-line backup for the rotation system. There is also no ready
method of jury-rigging the rotation motors.
There is also no on-line backup for the encoding system. However, it would be
possible to autoguide in several ways if the encoder completely failed. If the
environment were rotated to approximately 0 degrees, the guider would probably
guide unassisted (assuming the TCS is getting a reading of zero). It might
also be possible to guess rotation angles, and enter them in the autoguider
configuration. If these don't work, it would be possible to tweak the
autoguider software to adapt. Finally, it would be possible, with a bit of
crash software work, to complete the idea of a guider auto-calibration system
which could automatically determine the rotation angle. This was attempted on
AG I, but was a dismal failure due to improper procedures.
The system appears to be in good condition, and is used routinely. However, it
is probably approaching ten years old, and has not had any maintenance. On 2
January 1995 it was discovered that the system will no longer work in manual
mode. This mode, which is normally never used, uses the pushbuttons on the
front of the AB motor controller.
At least two manuals are available in the documentation room in Waimea. They
were used for the construction of the system, and do not provide a good
overview or theory description of the system. Their completeness and
suitability for learning and maintaining the system are unknown, but seem
unsatisfactory after a cursory look.
There really isn't any knowledge of this system in the current Electronics
Group.
Unknown. The controller is a complete unknown. There is a probability of
having spares for the encoder, as it is similar to one used in the prime focus
rotator. There are sufficient spares for the RIU interface board used in the
TCS.
When time is available the system should be investigated, and some expertise
gained. The spares situation should be studied, and necessary spares obtained
for the control unit and encoder system. As a long term goal, the system
should be made computer controllable. This could either be used with the
present control system in an on/off mode, or by using a servo controller.
The encoder does not have sufficient resolution (and probably not accuracy
either) for some of the guiding tasks already being done. While no replacement
has been planned, this should be considered for TCS IV.
Updated 4 January 1995
The computer control of dome rotation is performed by a custom electronic
system, in conjunction with the TCS III computer and CAMAC system. It uses a
parallel I/O register to read the dome encoder, and to control the dome control
electronics. It uses a digital to analog converter to control the rotation
speed of the dome via a servo amplifier and speed valves on the dome hydraulic
motors. The system was designed and constructed in approximately 1984. It is
connected into the remote interface connections on the original hydraulic dome
rotation system. The system also uses the dome rotation position encoder,
which predates the system.
The TCS III computer has a separate dome control task. It was written by John
Kerr, and has only been slightly modified from the original system. The
computer software continuously monitors the telescope position, and computes
where the dome should be to permit unobstructed observations. When it is
necessary to move the dome, it decides whether to utilize the single hydraulic
pump which is kept on at all times, or to start the second pump. It them
applies an analog voltage, as a step function, to the control system. The
control has a rather sophisticated hardware ramp which forces gradual control
on both the servo amplifier and manual users. In spite of the hardware
capability, the control software only has three steps of control speed. It is
not a true servo, but a state type system which relies heavily on predictive
behavior of the dome. As the dome rotation parameters have changed over the
years, the control software has exhibited poorer performance.
The computer dome control is used nightly for observations. It use greatly
improves the accuracy of dome positioning for observations. A failure of the
system would require the T.O. to use a backup means of dome positioning. It
would not shut down observing.
The dome encoder is absolutely critical to telescope operation. Without it the
dome cannot be positioned accurately enough for most observations. It is a key
part of backup strategies.
There is no direct computer controlled backup for this system. The first
backup plan is to use the console mounted manual controls. There are two
computerized dome misalignment indicators to permit accurate, manual control.
However, the manual control also goes through much of the same electronics and
servo amplifier as the computer control, and would be knocked out by many of
the same malfunctions that would take out computer control.
The second level of backup is supposed to be a handset which connects into the
control box on the wall behind the T.O. console. When last tried about three
years ago, it did not work. The third level of backup is to have someone
control the dome from the control panel on the fifth floor by the freight
elevator. This would have to be done in conjunction with communications with
someone at the control desk monitoring the misalignment indicators.
The system is presently in fairly good operational condition. The control
panel at the T.O.'s console has some non-operational status indicators. In
addition, that panel has some digital readouts which have never been
implemented, mainly due to the Software Group's inability to upgrade the
software of the "System D" computer. The equipment is all original, except for
one power supply which was replaced.
While the system operates well, the TCS III control software could use
upgrading. There are some serious deficiencies in the software. It samples
the encoders too often, with the result that the average bit rate per cycle is
less than one. While there are other problems, this is the biggest.
The system suffered serious damage in the great computer room electrical short
in about 1988. Everything was repaired except for some of the console
indications of status of the hydraulics.
The backup manual control unit is presently non-operational. The problem has
not been investigated.
The system has a manual which was prepared during the original construction,
and has not been revised since. The manual gives a fair coverage of the
control electronics and console control panel. It does not even attempt to
give system wide documentation, interconnections, or theory information.
The dome encoder is documented separately from the control system. Or perhaps
it would be more fair to say that it is undocumented separately. The only
known documentation is some rough schematic sketches in the W. Cruise files.
They were made during emergency repairs at the time of the great electrical
short. They were useful in restoring the system at that time, but are of
limited usefulness for long term maintenance.
The system predates all of the present electronics group members. There is no
one who is an expert on the system. The only persons who have studied the
documentation are W. Cruise and S. McArthur. There is no one who has really
worked on the system.
As far as is known, there are no spares for any of the custom electronic parts
of the system. The servo amplifier has two channels, of which only one is
used. Having an old spare which is always on is probably not a good guarantee
of having an operational spare. It is not known whether there is a spare of
the CAMAC AtoD module. There are spares for the parallel register.
The dome encoder is the same 13-bit Sequential encoder used for the prime focus
focus encoder. There is one spare unit. There are no spares for the encoder
electronics.
This system has been on the electronics group "to-do" list since R. McGonegal
took over the group. Time and priorities have combined to thwart this plan.
It is highly recommended that the group gain familiarity with the system. This
should include updating the documentation so that it shows all the connections
of the system to the rest of the equipment. Following this, the group should
investigate whether the system should be improved and better spared, or whether
it should be replaced. It is highly recommended that it be replaced as a
follow on to TCS IV. TCS IV is already planned to replace the control
algorithms with a standard PID type servo control algorithm.
Updated 1994
The f/8 upper end has several electronic and electro-mechanical systems which
fall into the area of responsibility of the Electronics Group. These are the
f/8 secondary control for vacuum and pressure, the f/8 focus control, and the
f/8 fine focus encoder.
This system was built at CFHT to control the vacuum and pressure pumps which in
turn control the positioning of the f/8 secondary mirror. The actual pumps,
valves, and plumbing on the secondary cell are the responsibility of the Optics
Group. The electronics system consists of a rack mounting chassis in the
control room, and various electronic parts on the cell, along with the
necessary cabling. The system is fairly simple, consisting mostly of switches,
power supplies, and an analog meter.
This system is used to control the position of the secondary mirror for
focussing the telescope. The basic control system is a copy of the f/35
control, and was mostly built by ASA of Canada, but installed by CFHT. It is
based on a Galil servo control system, and used a PC type computer for
elementary control. The system has a separate precision potentiometer for
focus position readout, in addition to the digital encoders on the Galil
motors.
The control for this system should eventually be integrated into the TCS IV VME
crate, so that focussing can be performed through the TCS. At present control
is accomplished through a button box which is wired to the ASA control
system.
This system has been used to provide an independent f/8 focus position. It
uses a Sony Magnascale encoder which is read through a custom interface on the
TCS R-buss.
The secondary vacuum/pressure control and the focus control are essential to
all observations at f/8. The f/8 focus is used for well over half of all
observing. The fine focus control is useful in some situations, but is not
essential.
There may be a backup system for the secondary control, which would completely
bypass the control room unit. This would be accomplished by making local
connections at the cell. This must be confirmed with the Optics Group. There
are also two sets of pumps for the system.
The focus control can be backed up in a kludgy fashion by connecting a power
supply to the motor connections. This has been tested in the past, and remains
as a possibility. However, it is not an easy switch over, requiring skilled
personnel, and is not well documented.
The focus encoder is backed up by both the regular f/8 focus encoder, and by
the encoders on the Galil. The regular encoder has lower resolution, and has
calibration changes, as it is an analog unit. The Galil encoders currently
cannot be easily read except through the PC in the computer room.
The f/8 focus control system is in good condition. There have been significant
problems with the ASA control systems, but currently they seem to be operating
very well.
The f/8 fine focus encoder system is currently not operational.
The f/8 secondary control system has several sets of CFHT prepared
documentation. As with many of the older systems, the documentation is fairly
thorough, but it is intended for construction, rather than for the end user and
maintainer.
The f/8 focus control system has the documentation supplied by ASA. This gives
their idea of the system, and perhaps misses a bit on describing the system as
it currently exists. In addition there are various CFHT notes. This should be
sufficient for all maintenance required on the system. However, a thorough
update would help things for the long term.
The f/8 fine focus encoder is covered by some original construction
documentation in W. Cruise’s file cabinet. This should be sufficient for
maintaining the unit.
Presently no Electronics Group members have any familiarity with the f/8
secondary control.
The f/8 focus control is well understood, in both theoretical and practical
aspects, by G. Matsushige. He performed much of the installation of the
system, and has worked extensively with ASA to finally commission the system.
Additionally, W. Cruise, S. McArthur, and D. Wilcox have varying levels of
knowledge of the system, or of similar systems.
There is little expertise on the fine encoder system.
The spares situation for the secondary control is not known.
The f/8 focus system is well spared. There are spares of all major components,
and additionally there is a complete spare servo control chassis. The control
computer can easily be replaced by almost any personal computer.
There is a spare, operating Sony encoder system. The R-buss card is a unique
item, but being Wire-Wrapped and fully socketed should be easily repairable.
Improve training on the f/8 secondary controller. Perform an inspection of the
system, and make an inventory of spares. Improve the documentation with theory
of operation and operation procedures sections.
The f/8 focus system is in reasonably good shape. The main suggestion is to
get on with converting the system to a VME based control computer. Another
item would be to bring the documentation up to date, and convert it so that it
can be maintained at CFHT.
The fine focus encoder should either be repaired, or it should be
decommissioned. This will require a survey to determine whether better focus
encoding is needed for scientific purposes.
Decommissioned
Visitor instrument -- decommissioned
Updated 4 January 1995
This overall system consists of the Phillips intercom, which also has a paging
system, the Clear Com intercom, and the music system.
The observatory was apparently originally equipped with the Phillips system.
The wiring for this system even extends throughout the telescope structure. It
is a commercial office type intercom from the late 1970's, and is no longer
available. The Phillips system has seldom been used in its intended role of
station to station conversations. Instead, it is hooked up to access the
paging system, and everyone just uses the page feature.
Paging is accomplished by calling station number 14 on the Phillips intercom.
There is an actual station 14, which is hidden somewhere in the back of the
T.O. console. Station 14 unit has been modified, and its output is hooked to
the paging system. Paging is handled by a commercial Public Address amplifier,
also located behind the T.O. console. This amplifier, and the companion music
amplifier, have both been replaced at least once. The paging system has a
graphic equalizer in the circuit, and it is adjusted to (or at least attempt
to) minimize feedback.
The building music system has its own PA amplifier, of a similar type to the PA
amplifier. The PA speakers throughout the building are of a two voice coil
design. This permits independent control of the music volume at each speaker,
and a fixed paging level. As in standard PA systems, the audio distribution
is done with a common 70.7 volt buss. Each speaker has a 70.7 volt to voice
coil transformer. These transformers have multiple taps, and the intent is to
change taps to adjust the speaker volume. The overall system volume is
adjusted at the PA amplifier. When paging it is necessary to mute the music
system. There is some sort of home brewed interface behind the T.O. console
which accomplishes this.
When observations first started it was quickly discovered that a different type
of intercom system was needed. This turned into the Clear Com system we have
today. Clear Com is a large commercial maker of communications systems for a
wide variety of services, including a lot of systems used in theaters. The
system allows a variety of stations, and handles full duplex communications
fairly well without excessive feedback. The system has designed in canceling
for feedback. It is quite possible that this present system could be better
tuned up for our application.
The Clear Com system also has a telephone connection which allows callers on a
certain line to be patched into the intercom circuit, and talk with all who are
on the intercom. The Clear Com system has headphones which can be plugged in
at any intercom station, as an alternative to the normal speaker and
microphone. It also has a cordless headset, which communicates with the main
system by VHF radio. This headset normally resides behind the T.O. console, on
a wall bracket. It is rather large, but is more rugged than many smaller units
which did not last long in our summit environment. The radio base station,
located to the right of the stairs to the dome mezzanine, is normally turned
off, as it has been shown to cause interference on CCD's.
The actual music system is comprised of a collection of normal stereo
components. These have been replaced several times over the life of the
observatory. There is nothing special about this part of the system. The
system supplies low level audio to the music PA amplifier for distribution
throughout the building. It also drives the Bose speakers in the control room
and the third floor coudé observing room. Some time back, the system
also fed the Clear Com system, which as an auxiliary input with level control
for this type of use. Over the years the setup of the system has changed, and
mostly deteriorated in functionality.
All of the intercom equipment is (or is supposed to be) powered through the
small UPS (the one used for the timing portions of the TCS), so it has a rather
long operating time in case of power failure. This has the dual advantage of
providing emergency communications throughout the building, and also of keeping
the music on to hold down anxiety in the darker parts of the building.
Good communications is essential in those situations which use remote observing
locations. This makes the Clear Com virtually a necessity for some of our
observing setups.
The building paging system is used continually for many purposes. When it has
been out of commission, everything slows down at the observatory.
The music system is helpful, but not essential to anything but good spirits.
There is no on-line backup for the Clear Com or music systems. However, the
new telephone system provides a reasonable substitute for the paging system.
Two-way radios can also serve as emergency backups for a Clear Com failure.
The system is in a mostly operational condition, but is on a downhill curve.
It was fairly well taken care of by P. Papasian, but with his departure it has
not found another person who really understands it, and cares to work on it.
The deterioration extends to excessive feedback, broken microphones and
headsets, and speakers where the volume is not well adjusted or where the
volume controls the paging volume instead of the music.
Presently the telephone interface is disconnected. This happened with the
installation of the new telephone system. The telephone interface could be
connected to one of the modem phone lines in the computer room, or to the
computer room emergency monitor line.
The only person who works with the intercom system is R. Song. His
understanding of the system is not too deep.
The present spare situation is not completely identified. In the past spares
have been bought for the Clear Com and the PA amplifiers. Their present
condition and location are not known. There do not seem to be any spares for
the microphones or headphones. Spares have been purchased several times for
the Phillips system, but it is not known whether any are left.
System training, including getting at least one more egroup member up on the
system is essential. The Clear Com system should be thoroughly gone over, and
adjusted and repaired where necessary. We must also collect and inventory and
the system components and spares, and ensure we have enough components on hand
to provide a satisfactory level of service.
The obsolescence of the Phillips system means that it will someday quit
working, and we will not be able to revive it. The egroup decision, at this
time, is to not replace this intercom system. It has never been used as an
intercom, and there is no need for such a complicated system. The new
telephone system provides a very good capability for use as an intercom, if
this function is desired. Additionally, the new phones have the capability of
being tied into a paging amplifier. Upon failure of the Phillips, we should
remove it and hook up the phone system to the building paging.
Updated 4 January 1995
This item describes any systems which are used to supply power, AC, DC, or 50
Hz, to other systems on the telescope. In its original design, the telescope
was intended to have power sources so that individual equipment and instruments
would not each have to supply their own power. Over the years the
implementation of this ideal has varied.
Many of the telescope power systems clearly do not fall into the responsibility
of the egroup, but are more suited to the skills of an electrician. However,
as they often have direct bearing on the performance of electronic systems
which are the responsibility of the egroup, they are included here. Also, some
of systems are gray areas, and a lot of the systems have been worked on by
egroup members over the years. When it comes to the bottom line of making the
telescope work, the egroup may have to assist, or even attempt repairs alone.
We need to be aware and ready to work in this area.
The power systems can be divided into several sub-systems:
All of the power going to the telescope, and to most of the other electronic
systems connected with the telescope, is conditioned by the MG set. It is
located in the basement area. Three phase power from the utility is used to
turn a motor which has a generator and a flywheel on its shaft. The generator
is completely isolated electrically from the motor. The flywheel provides some
“ride-through” capability for handling short input power glitches.
The system is rated at 50 KVA, but is currently used at less than 20% of this
capacity. The MG set has been very reliable, and has proved quite valuable in
isolating sensitive equipment from the power line. Originally all of the
computers were powered off the MG set. However, the sgroup bought a UPS which
is somewhat incompatible with the MG set, and the computer load has been
removed. Also, when the MG set was first installed our power came from local
generators, and was much less stable than HELCO power. We lost several pieces
of electronic and electro-mechanical equipment to power problems.
This power control panel, located in the main control room, was a modification
made in about 1984. Prior to its installation, all AC power to the telescope
went directly through breakers to the telescope wiring. Panel F incorporates
relays into these circuits so that switching can be done with pushbuttons,
rather than switching the breakers directly.
Physically the pushbutton panel of Panel F is built over the breaker panel,
which is still functional. The relay bank is remotely located inside the
fourth floor crawl space.
All power going to the telescope, except for the 50 Hz AC power, goes through
Panel F. All of this power also comes from the MG set. Panel F is divided
into single phase and three phase control circuits. Several spare circuits are
still available.
This power system supplies 48 volt DC power, with high amperage capability,
from a large Hewlett Packard power supply located in the fourth floor crawl
space, near the south pier of the telescope. This 48V power supplies all of
the DC motor needs in the telescope auxiliary systems. This includes focus
motors and pneumatic solenoids. It also powers the telescope security system.
This system was part of the original telescope design. The power supply is
powered by three phase AC, and is controlled by a pushbutton on Panel F.
This system also dates from the original telescope design. It is controlled by
several pushbutton circuits on Panel F. Its use is to power the DC supplies in
the telescope control stations, and to power DC supplies for the telescope
position encoders, the balance weight encoders, the cass bonnette rotation
encoder, and for the horizon limit switches.
This original system provides three phase 120/208 volt power to the telescope
control stations for operating three phase motors. There are three control
circuits on Panel F which control these circuits.
This system is also part of the original design. It provides three phase power
to outlets and light fixtures throughout the telescope structure and its bases.
It is controlled by the pushbutton on Panel F marked “Telescope
Lights”.
This system provides AC power to the cassegrain and prime focus areas. It was
added when the instrumentation cabling system was installed. It receives three
phase power from Panel F, routes it through a circuit breaker panel located in
the fourth floor crawl space, and then to the two foci. At prime focus the
power is provided to instruments through permanently installed power outlets in
the cage. As cass, distribution is mostly through power strips.
This system provides DC power to the cassegrain and prime focus areas. It was
also added when the instrumentation cabling system was installed. The DC
voltages provided at each focus are +/-48, +/-24, +/-15, +/-12, and 5 volts.
The 48 volt supplies are common to cass and prime focus, and are located in the
fourth floor crawl space. For cass all the other supplies are located in the
crate CPP1A. For prime focus, the 24 volt supplies are located in CS5, while
all the others are under the floor of the cage.
All of the supplies receive their AC power from Panel F and the instrumentation
power circuit breaker panel. There are switches on the distribution panels to
control the power to the user connectors. In the case of local power supplies,
the switches control the AC input. For the remotely located supplies, the
switches are in series with the power line.
50 Hz AC power at 240 volts is provided at the cass and PF foci for European
instruments. This facility was added when the instrumentation cabling system
was installed. Initially the 50 Hz power was generated by an electronic
frequency converter installed in the fourth floor crawl space. However, these
units became hard to find, and had proven unreliable. A UPS with selectable
output was bought to perform the task. It is installed in the basement, near
the MG set and the computer UPS. It receives its input power from somewhere in
the basement, and is thus the one part of the telescope power that does not
come through the MG set. The power output is routed up to the fourth floor
crawl space, where it is tied into the circuit breaker panel and cables, and
then to the telescope foci.
The power systems vary in importance depending on the usage and the present
configuration of the telescope. Needless to say, if the correct power for the
present instrument is not available, observing cannot be performed. It is
possible, but has not happened, for power problems to shut down the telescope.
Some of the power systems provide power to basic telescope systems, and would
affect the telescope, but not the instrument. This is equally catastrophic.
The MG set can easily be bypassed by built-in switches. The backup mode would
be to run unconditioned power to the telescope. If the MG set is damaged to
the point where we must disconnect it, an electrician could simply connect the
present MG input to its output.
There is no ready backup for this built-in system. In a super emergency power
could be jumpered around parts of the system. Also, there are some spare
circuits already in place which might be used to feed power to a needed
circuit.
There is no on-line backup for this power supply. However, it should be
possible to jury rig another power supply in less than thirty minutes. There
are no spare cables on the telescope.
Several of the circuits are supposed to have in-place spares. These have
probably changed over the years, and are most likely not live. However, there
should still be in-place spare cables and junction box connections to all of
the control stations.
There are no backups for this system, and there are no spare cables on the
telescope.
This system has in-place spare cables and junction boxes for the cables on the
telescope.
The situation of this system is unknown, but assumed to have no provision for
spare cables or circuits.
There is no backup for this system. There would be no easy way to provide DC
power to an instrument if the system fails. Some instruments which use the
instrumentation power have their own power supply units, intended for use off
the telescope. These can be used for their specific instruments, but do not
provide a general solution.
There is no backup for this system. There is no way we would be able to
provide 50 Hz power if the UPS fails. All of the old inverters have failed.
Except for burned out light bulbs and missing trim rings, this system is in
good condition.
The 48 volt power supply is probably nearing its twentieth anniversary.
However, it still seems to be working well.
All of these systems consist of wiring, relays, circuit breakers, and other
heavy electrical items. They are all in good condition.
These systems are presently all in good condition. However, the power supplies
are mostly ten years old, and older. Increased failures should be expected.
The system design and installation make repairs very difficult, at both cass
and PF.
The UPS is about four years old, and is in very good condition. It is left on
all the time, but almost never has a load. It is unsure whether turning it off
between uses would improve its life, or hurt it.
As with most of the telescope original electronic systems, there were lots of
drawings of power systems, but very little, if any, written documentation. In
addition, the Book of Cables has data on most of the original cables.
There is very little usable documentation. Panel F, as an addition, is not in
the original documentation. To make things worse, its incorporation makes much
of the original telescope power documentation inaccurate.
The best current documentation exists in a Power Doc binder in W. Cruise’s
office. This starts with original Terry Nevin notes, to which W. Cruise has
added more notes and a lot of unfinished documentation drawings.
This system was fairly well documented in the original telescope drawings.
Except for the AC power input to the 48 volt supply, very little has changed.
In addition, W. Cruise’s Power Doc binder has system drawings of both the
original and as-built (unfinished) versions of this system.
These systems, being later additions to the telescope, are not included in the
original drawings. However, the Book of Cables has been updated to include the
instrumentation cabling in a separate section. Most of the documentation for
these systems is to be found in the manuals for the cassegrain and prime foci.
There is also some stuff in the observers and users manuals. However, most of
this is construction level documentation, and very little addresses it as a
system.
There should be a manual on the UPS, hopefully near the unit. The wiring
documentation should be in the same places as for the Instrumentation AC &
DC power. There is probably nothing on the power input connections.
The Operations Group no longer has anyone with real experience on the systems.
W. Cruise and R. Song have worked with different parts in the long ago past,
and both worked on the abortive documentation effort.
There are few specific spares for these systems. Much of the wiring and
connectors is generic equipment, or could quickly be replaced with generic
items.
There is a spare for the Telescope 48 volt DC power supply, but it is probably
as old as the working unit. Odds for its long term survivability are not good.
The other DC supplies have no direct marked replacements. Instead, the egroup
power supply strategy (if any) is to have sufficient generic supplies on hand
to replace almost any failing supply with something roughly equivalent. In
addition, a jury rig can almost always be made while a better physical or
electrical replacement supply is ordered.
The first thing to do on this system is to resurrect the documentation project
started by W. Cruise and bring it to a conclusion. This would also force
training on the persons working on the project.
In conjunction with the documentation, the system should be given a
comprehensive inspection. This would include first finding all the parts which
are shown on the drawings. Each connector should be inspected, and each
terminal connection tightened. Failing parts should be replaced. The
inspectors would also be expected to make general recommendations about the
future of the system.
The project should also ensure that we are sufficiently well supplied to
maintain the system over the long haul.
Updated 4 January 1995
The primary mirror tip/tilt system is part of an overall system designed to
improve the telescope image quality by providing the capability to collimate
the primary mirror so that it is parallel to the optical axis. The final
system will involve some form of computing the proper mirror position for any
telescope position. This will either be done with look up tables or a
polynomial on the Telescope Control System. The primary mirror will be moved
each time the telescope is slewed to a new position, or upon command by the
telescope operator or the observer.
The electronics part of the system consists of three Galil servo control axes
driving positioners under the primary mirror. They connect to junction boxes
on the outside of the mirror cell, and then to a control chassis, supplied by
ASA of Canada, is in the computer room. The control chassis connects to the
ASA supplied PC, which runs simple software to perform basic mirror
positioning. This computer is to be replaced by a VME based computer
(eventually to become TCS IV) which will provide the necessary connectivity for
remote control.
The system has a number of protective features. There are standard soft and
hard limits at each actuator. The primary mirror support air pressure is
sensed, and the control system is designed to retract the actuators upon
support air failure.
The system has precision potentiometers at each actuator. These are read
through the ASA computer. A separate encoding system is provided by a Sony
digital indicator at each actuator. They go to a Sony readout at the south
side of the cell. This is currently not used, but can be read by a computer.
Presently the system is not fully implemented. Additional data needs to be
taken, and full analysis performed to model the telescope’s coma. There
is not yet any software for performing the automatic positioning of the primary
mirror. All engineering has been performed by using the ASA control system to
manually enter mirror positions.
At present the system is performing the essential function of putting the
primary mirror into a default position. This is crucial to all observing.
When the full system becomes operational, it will provide significant image
improvements, but failure to automatically adjust position will not be a
shutdown type failure.
There is no ready backup for this system. In case of catastrophic failure of
some part of the control system, power supplies could be used to operate the
motors and get them to a rough position. The mirror could be left this way
during repairs. A complete failure of this system should not stop
observations, if the motors can be operated to perform a one-time positioning
of the primary mirror.
When the system is used for image improvement, a system failure would remove
access to this feature. There are no plans for a backup facility.
The system seems well documented, both by ASA, and by CFHT updates to the ASA
supplied documentation. However, much of the original documentation has not
been updated to reflect the reality of the installation. Additionally, there
is some know incorrect information in the documentation.
The level of knowledge and experience is very good. The local experts and
skilled helpers are, in order of expertise, G. Matsushige, W. Cruise, S.
McArthur, and D. Wilcox.
The system is well spared. There are spares for motors, switches, the servo
control card, servo amplifiers, and all small electronic components. There are
no chassis level spares.
The system should be converted to a VME based computer. A one-year follow up
should be made to ascertain the present condition of the system.