If, after running the hdcal schedule, there are null parameters in the output of the hdcalc
command (other than the ones that are correctly null if you have a VLBA recorder), then the
calibration procedure has failed at some point. For the VLBA drive the read head parameters
should be null. This section explains how to identify what went wrong and complete the
calibration. If you have any values missing, please save the log and contact Goddard. We will
want to understand the problem so that a better procedure can be developed.
The response of the hdcalc command is derived from values stored by the savev command. If
there are missing parameters in the hdcalc response, then there must also be missing
parameters in savev response. Issue a savev command and inspect the response to determine
which parameters are missing. The values are printed in the order:
savev/vrevw,v15rev,v15for,v15scale,v13,v15flip,vw0,vw8
The sub-sections below describe what to do if any of these values are missing. At this point, it is
not necessary to understand what these parameters represent. They are described in detail in the
section titled What the Calibration Schedule Does.
The last two parameters in the savev response are write head positions. If one of them is
missing and you are using a Mark III drive, then something truly disastrous has happened. These
parameters are not used for the VLBA drive. Either the schedule has screwed-up or the write
head positioning failed to converge. In either case, you should determine what went wrong before
continuing. You can look at the log for error messages or start the calibration procedure over
again and watch it to see what goes wrong. Of course, if the problem is intermittent, it may not
re-appear. After fixing the problem, if it re-occurs, you should re-run the calibration schedule
with a fresh tape.
The first six parameters in the savev response are read head positions measured after peaking
the reproduce signal. If one of these parameters is missing, the corresponding peaking operation
failed to find a good peak. It is possible to recover in one of three ways: (1) look at the log
produced by the schedule to see if there are usable position measurements that were not saved,
(2) reposition the tape and attempt to re-measure the missing positions, (3) re-run the schedule
and watch it to see which measurements are failing. The steps to take for each of these options
are discussed below. After the three options are discussed, how to complete the calculation is
described.
5.2.1 Recovering Positions From the Log
Examining the log is the quickest method of recovering, if it works. The explanation of what to
do is a bit long-winded though. For a voltage mnemonic x that was not successfully saved, there
is some point in the schedule where a savev=x command was issued. Closely preceding the
savev=x should be the results of three separate peak commands. The third peak response
must have an f for the next to last parameter. This parameter is f (for false) to indicate that
peak thinks the position did not correspond to a true peak, it would be t if it thought is was a
real peak. savev will not save the position if peak indicated a false peak. (This is just about the
only error detection in the whole calibration process.)
There are two reasons that peak might think that the peak was false: either the interpolated peak
measurement was not well centered among the last three positions sampled, or the signal level
was below that required to be considered a good peak. The minimum signal level is 0.2 volts by
default, but it is a settable parameter of the peak command. You can determine if the signal
level was the problem by comparing the measured peak voltage and the acceptable minimum that
was used, both are displayed in peak command response. If the f parameter was given because
the signal level was too low, there is probably no hope of recovering using this method. The
peak command probably never even found the track. You should just go to the method of
re-measuring the positions discussed below.
If the signal level is high enough and the second peak command indicated a true peak, then the
third peak may have failed because a tracking glitch moved the interpolated peak too far away. In
this case you may be able to recover. Compare the peak positions for the responses from the first
and second peak commands. If they agree within about 0.03 volts, the value reported by the
second peak command should be usable. It can be input manually, by issuing a savev=x,volts
where volts is the measured voltage position from the second peak command.
5.2.2 Re-measuring Positions
If acceptable values are not found from the log, it will be necessary to position the tape to the
correct area and attempt to re-measure the values. Table 7.1 contains a list of the footage counter
ranges, nominal read head positions, tape motion direction, read track, and tape orientation used
for measuring the read head position for the different voltage parameters. You can reposition the
tape to the appropriate footage, reset the appropriate command parameters, and attempt to
measure the track location. For example to re-measure v15flip, the set-up commands would be:
for Mark III: for VLBA:
tapepos=1000 rec=1000
(wait for tape to complete positioning)
stack=,-350,,f stack=-350,,f
(always use the forward calibration)
repro=raw,15,15 repro=read,18,18
st=for,135,off st=for,135,off
(wait for the tape to spin-up to speed)
(peak the reproduce signal)
For Mark III/VLBA: use the above VLBA commands.
To peak the reproduce signal you can use some combination of the read head inchworm
push-buttons, the locate and peak commands, and the oscilloscope. If you finally find the
peak with the peak command and peak indicates a true peak, you can save the voltage by
issuing a savev=x command where x is the mnemonic for the voltage being saved. If you end
up finding the peak by using the inchworm push-buttons and watching the eye pattern on the
oscilloscope, you can measure the final position voltage with the lvdt command. The result can
be saved by issuing a savev=x,volts command, where volts is the position of the read head
(write head for VLBA drive) returned by the lvdt command.
If v15flip is one of the missing values, it should be re-measured first, since the tape is already
mounted in the flipped orientation at the end of the schedule. To re-measure other values, the
tape will have to be returned to its normal orientation and the footage counter reset to make the
footage values in Table 7.1 correct. To get the footage counter reset correctly, flip the tape back
to its normal orientation. Then with all the tape on the take-up reel run the drive in reverse with
the srw command for 2m32s, if your "super-fast" speed is 330 ips. This will place the tape at
about 4200 feet from the far end. If your speed is lower than this you will have to wait longer to
get the tape to the same spot. When the tape drive stops, reset the footage counter with the
command: tape=low,reset (Mark III drive) or rec=zero (VLBA drive).
5.2.3 Starting Over
The third approach for recovering is to start over with a fresh tape and monitor the schedule as
it's running. When the savev command(s) fail, stop the schedule with the halt command,
reposition the tape and try to re-measure the track manually using the methods described for the
preceding approach. Once the peak is located, save the value with a savev command. Restart
the schedule after issuing a list command to see what is coming next. Some tape and/or
schedule positioning maybe necessary to get things back on track.
5.2.4 Finishing Up
If you used one of the first two recovery approaches and have stored all the voltages, you will
need to re-calculate the calibration parameters and inchworm speeds (the third approach does this
automatically since it uses the schedule). To finish the calculations, issue these commands:
for Mark III: for VLBA: for VLBA2:
hdcalc hdcalc hdcalc
lvdt=0,0 lvdt=0
worm=write,new worm=write,new
worm worm
worm=read,new
worm
If hdcalc now produces a complete set of commands you can proceed with saving the
calibration parameters as outlined in step (9) of the Calibrating the Heads section above.
6.0 Evaluating Results of Head Calibration
Once a full set of calibration parameters have been determined, they can in principle be used
right away. However, they should be checked at least a little. Three checks are described in this
section: (1) checking parity error rates, (2) checking forward-reverse guard bands, and (3)
repeating the calibration.
6.1 Parity Check for Head Calibration
The most important check that should be made is to record some tracks and make sure they can
be played back. For this check, take the following steps:
(1) Install the new calibration constants in head.ctl and restart the Field System.
(2) Mount a fresh tape, pre-pass it, and then position it to 1000 feet.
(3) Record mode C pass 1 from 1000-2000 feet at 135 ips.
(4) Check the parity errors with check2c1.
(5) Record mode C pass 2 from 2000-1000 feet at 135 ips.
(6) Check the parity error with check2c2.
(7) Record mode C pass 23 from 1000-2000 feet at 135 ips.
(8) Check the parity errors with check2c1.
(9) Record mode C pass 24 from 2000-1000 feet at 135 ips.
(10) Check the parity errors with check2c2.
(11) Re-check the parity errors for mode C pass 2 with check2c2, after re-setting up with
sx2c2=2.
(12) Position the tape to 2000 feet.
(13) Re-check the parity errors for mode C pass 1 with check2c1, after re-setting up
sx2c1=1.
(14) Re-check the parity errors for mode C pass 23 with check2c1, after re-setting up with
sx2c1=23.
The results of all the parity checks should show acceptable rates. What is acceptable depends
somewhat on the recorder and the heads, but parity error rates of less than 600 are typical. If the
read head position is off a little bit, the error rates will be larger than they should be. You might
try using the peak command to see if you can find a better peak response and then try the parity
check again. If the level of errors in the re-check of passes 1, 2, or 23 are significantly higher than
in the original checks, there may be some overwriting of adjacent forward-reverse tracks. If this
is so, the forward-reverse guard band test, discussed next, is strongly recommended.
6.2 Forward-Reverse Guard Band Check
The forward-reverse guard band test is one of the most complete checks of the head calibration.
The layout of passes for mode C is shown in a figure in the System Setup manual. Starting with
the tape recorded in the parity check test discussed above, follow these steps:
(1) Position the tape to 2000 feet.
(2) Set-up the read head to reproduce mode C pass 2 and set-up the peak command:
for Mark III: for VLBA:
sx2c2=2 sx2c2=2
enable= enable=
repro=raw,16,16 repro=raw,19,19
peak=3,1 peak=3,1
(3) Start the tape moving in reverse:
st=rev,135,off
If during the course of completing steps (4) through (8) below, the tape footage goes below 1000
feet, stop the tape, reposition to 2000 feet and continue where you left off.
(4) When the tape comes up to speed, issue the peak command to find the peak response.
(5) When peak completes, issue a pass command to measure the current head positions. The
last parameter, read head delta position, indicates how far the peak is from the nominal location,
typically a few microns.
(6) While the tape is moving, use the push-buttons on the head controller to move the read head
away from the plate. Select: Inchworm Two, Out ("Forward" on Burleigh controllers), and Slow.
(7) With your finger over the "stop" button on the inchworm controller, watch the eye-pattern on
the oscilloscope. This reproduce signal should fade away to no signal and then a new reproduce
signal should start to increase. When a signal starts to appear, usually within about 5 seconds,
press the "stop" button.
NOTE: You can also do steps (6) and (7) using the stack command to move the head. Check
the head position, then move the head in increments of about 30 until you find the track. Be
sure to specify the correct calibration type, f or r, when you move the head.
(8) Issue another peak command to find the peak of this track. The eye pattern will not be clear,
because you are running in reverse over pass 23, which was recorded in forward.
(9) Issue another pass command to determine the delta for the peak of this track. The delta
should be close (20 m) to 93.5 m.
(10) The difference of delta parameters from steps (5) and (9) gives the peak-to-peak distance
between passes 2 and 23.
(11) Stop the tape, and reposition it to 2000 feet.
(12) Set-up the read head to reproduce mode C pass 24:
for Mark III: for VLBA:
sx2c2=24 sx2c2=24
enable= enable=
repro=raw,16,16 repro=raw,19,19
peak=3,1 peak=3,1
(13) Start the tape running in reverse:
st=rev,135,off
(14) Repeat steps (4)-(10). This time in step (6) move the read head toward the deck plate using
the "in" button (reverse on Burleigh controllers). The result calculated in step (10) is the
peak-to-peak distance between passes 1-24.
Both peak-to-peak distances should be about 93.5 20 m. If this test fails or the results are
marginal (the values differ by more than about 40 m), it is recommended that the calibration be
tried again to see if it is repeatable. Evaluating repeated calibrations is discussed next.
6.3 Repeated Calibrations
It is useful to repeat the calibration procedure two or three times to see how much variation
occurs in the calibration parameters. Having several samples also helps to determine if a
particular calibration run is an outlier compared to the rest. Don't average different
measurements to get a final value, simply choose one that is close to the mean. This reduces the
chances of a data handling error.
If the hdcal schedule ran without any problems and the hdcalc command produced all the
calibration constants without additional work, then it likely that the calibration procedure will
work reliably for your tape drive. It should be easy to re-run the schedule. Be sure to use a freshly
degaussed tape for each run. Repeated measurements should have less than 5 m variation in the
offset constants (the first four hdcalc output parameters). The scale factors (the last two
hdcalc output parameters) should vary by no more than about 1%. The calibration constants
may vary systematically between different tapes.
7.0 What the Head Calibration Schedule Does
The procedure used to calibrate the heads was originally developed at Haystack by Dan Smythe
and Alan Whitney. A copy of their memo describing the procedure is included at the end of this
document. This section describes the assumptions made by the schedule, the sequence of
operations performed, and design considerations for the schedule.
7.1 Assumptions
The schedule file hdcal.snp should be able to calibrate any "normal" tape drive. A normal
tape drive meets the following assumptions:
(1) Mark III write head tracks 15 or 16 work.
(2) Mark III read head track pairs 13 and 15 or 14 and 16 work.
(3) Both inchworms can move over their full range of motion, 10 volts.
(4) The calibrated head offsets all have an absolute value of less than about 100 m.
(5) The voltage scales are within about 15% of the nominal 150 m per volt.
(6) The fast inchworm speed is no less than 100 m/s.
(7) The tape drive acceleration meets the specification of going from 270 ips to stopped in 45 5
feet.
(8) The footage counter is reliable.
(9) The peak reproduce power level when reproducing a track at 135 ips produces a signal level
measured at the A/D of 0.5-2.0 volts.
(10) The noise level when reproducing on a blank tape at 135 ips produces a signal level
measured by the A/D of less than half the value of the peak reproduce level.
(11) The voltage offset in the LVDT read-out has an absolute value of less than about 0.6 volts.
Tapes drives that do not meet these assumptions of "normality" can probably still be calibrated,
however the hdcal.snp schedule will probably have to be modified or the calibration done
manually.
7.2 Sequence of Operations
The sequence of operations that are used in the schedule are described here. Table 7.1 at the end
of this section summarizes the tape footage range, read track, nominal read head position, tape
motion direction, and tape orientation associated with each head position voltage that is saved.
The operations performed by the schedule are (described with parallel numbering to Dan and
Alan's memo).
(0) Set-up the Field System parameters and (except for VLBA2) make an initial refinement of the
inchworm speeds.
(1) Rewind the tape 3200 feet. For VLBA or VLBA2 rewind 2200 feet.
(2) Set the write head to a "forward calibrated" position of -350 m. Save the write head voltage
position as vw0.
For VLBA or VLBA2, skip to step (5).
(3) Record track 15 for 1000 feet in the reverse direction. Reset the footage counter. The range of
footage for the recorded track is 0-1000 feet after the footage counter has been reset.
(4) Playback the track recorded in step (3) in the forward direction peaking the reproduce power
with read track 15. Save the read head position voltage as vrevw. Footage range is 0-1000 feet.
Nominal read head position -350 m.
(5) Position the tape to 2000 feet. For VLBA set the footage to 2000 feet. For VLBA2, continue
to the next step.
(6) Record track 15 in the forward direction to the end of the tape. Footage range 2000-3800 feet.
(7) Playback the track recorded in step (6) in reverse direction, peaking the reproduce power with
read track 15. Save the read head position voltage as v15rev. Footage range 3000-2000 feet.
Nominal read head position -350 m.
(8) Playback the track recorded in step (6) in the forward direction, peaking the reproduce power
with read track 15. Save the read head position voltage as v15for. Footage range 2000-3000 feet.
Nominal read head position -350 m.
For a VLBA or VLBA2 drive, skip to step (13).
(9) Position the tape to 1000 feet.
(10) Set the write head stack to a "forward calibrated" micron position of 850 m. Save the write
head voltage position as vw8.
(11) Record track 15 in the forward direction for 1000 feet. Footage range 1000-2000 feet.
(12) Playback the track recorded in step (11) in the forward direction, peaking the reproduce
power with read track 15. Save the read head position voltage as v15scale. Footage range 1000-2000
feet. Nominal read head position 850 m.
(13) Position the tape to 2200 feet.
(14) Playback the track recorded in step (6) in the forward direction, peaking the reproduce
power with read track 13. Save the read head position voltage as v13. Footage range 2200-3200.
Nominal read head position 1047 m.
(15) Run the tape off the end of the reel. Reload it in the flipped orientation.
(16) Playback the track recorded in step (6) in the forward direction, peaking the reproduce
power with read track 15. Save the read head position voltage as v15flip. Footage range 1000-2000.
Nominal read head position -350 m.
(17) Calculate the calibration parameters:
For VLBA drives only the "read" head parameters are calculated. However these are actually the
correct values for the "write" head. There is only one head on a VLBA drive.
Read head voltage scale:
Write head voltage scale, generalized to include the actual voltage at which
the tracks were written:
Read head reverse
relative offset:
Write head reverse relative offset:
Write head forward absolute offset:
Read head forward absolute offset:
(18) Remeasure the inchworm speeds with the new voltage scale.
Table 7.1. Footage ranges, nominal read head positions, tape direction, read tracks, and tape
orientation to use to find specific voltages on the calibration tape.
| Voltage Mnemonic | Footage Range | Read Head Position (m) | Tape Motion Direction | MkIII
Read Track |
Tape Orientation |
| vrevw | 0000-1000 | -350 | forward | 15 | normal |
| v15rev | 3000-2000 | -350 | reverse | 15 | normal |
| v15for | 2000-3000 | -350 | forward | 15 | normal |
| v15scale | 1000-2000 | 850 | forward | 15 | normal |
| v13 | 2200-3200 | 1047 | forward | 13 | normal |
| v15flip | 1000-2000 | -350 | forward | 15 | flipped |
7.3 Design Considerations
This section describes some of the considerations that went into the design of the hdcal.snp
schedule. This section will probably only be useful to people who wish to understand why the
schedule does the things it does. The differences between Dan Smythe and Alan Whitney's
original procedure are described. Features of the Field System implementation of the procedure
are discussed as well.
7.3.1 Differences From the Original Procedure
A few features were changed from Dan and Alan's memo:
(1) The calibration tracks are written -350 m (out) from the positions used in the memo. This
gives a more symmetric use of the position voltage range.
(2) The positions are commanded by micron using the "forward" calibration. This automatically
positions the heads with a -698.5 m offset if the heads are defined as even in the head.ctl
control file.
(3) For systems with even write heads, track 16 is used for writing.
(4) The positions that the calibration tracks are written at are measured rather than assumed. This
makes the calibration more robust in the presence of positioning errors and allows the location of
written tracks to be moved.
(5) The footage at which the tracks are written and reproduced were adjusted so that a full 1000
feet of recorded tape would be available for each track peaking operation without getting within
1000 feet of the tape ends. This reduces the chances that tracking problems near the ends will
affect the results.
(6) For VLBA drives only one track needs to be written and it used to determine all the
parameters for the one head. The actual location where the track is written is never used.
Features (1)-(4), along with some generalization of the enable and repro Field System
commands, allow the same SNAP schedule to used for any combination, all, odd, or even, of
read and write heads.
7.3.2 Features of the Field System Implementation
This sections discusses features of the Field System implementation of the calibration procedure
beyond those discussed in the previous section.
In order to automate the original procedure for field use, new Field System commands, locate
and peak, were written to support peaking up on a recorded track.
Because of variations in tape drives, inchworm speeds, head offsets, and tracking, it was
necessary to make the schedule as insensitive to such variations as possible. Toward this end, the
following features are incorporated in the schedule:
(1) When attempting to peak-up the reproduce power, a coarse grid search is done with the
locate command to find the track first. This helps find the track even in the presence of large
head offsets.
(2) The fine peaking performed by the peak command is done three times for each track
peaked-up on. Two measurements of the peak location are needed at minimum, since the track
may not be well centered during the first measurement. The third measurement can be compared
to the second to evaluate how stable the measured peak position is.
(3) After a peaking operation is complete, the tape is positioned with the tapepos command
(Mark III) or rec command (VLBA) before the next operation, since the actual footage at which
at which the peaking will complete is unpredictable. The schedule must wait for the worst case
tapepos or rec to complete before continuing.
(4) The locate command for peaking on the flipped tape is done in a separate pass to allow a
wider range of positions to be searched. Flipping the tape magnifies the effect of a write head
misalignment by a factor of two. peak is used on the second pass.
(5) At the start of the schedule, a first cut is made at the inchworm speeds to make sure they
aren't completely unreasonable.
(6) The tape command is issued before and after writing and reproducing tracks. This is
intended to provide information to assist in interpreting the log for debugging purposes.
(7) The hdcalc command takes the head configuration in head.ctl into account when
calculating the calibration parameters.
Like the original procedure, the Field System implementation includes these features:
(1) The peaking operations, using the locate and peak commands are done on a minimum of
1000 feet of a recorded track. This allows for some variation in inchworm speeds, tape
positioning, and difficulty locating the track.
(2) Only one track is written in any footage range on the tape. This helps prevent confusion over
which track is being reproduced.
8.0 headp
headp is a utility used in conjunction with the narrow track calibration software. After
calibration parameters have been determined, headp can be used to save the results in a file.
The results are saved by default in output file /usr2/control/head.new. Alternatively, the
user can specify the output file name when the program is invoked by typing:
headp output
where output is the pathname for the output file. If the output file already exists, headp will
stop without modifying the file.
The output file for headp is in the same format as the head.ctl file described in the Control
Files manual. Data from the first two records are the same as those in the most recently used
head.ctl file. The remaining information comes from the most recent calibration results.
In order to help prevent partial or incorrect results from being written to disk, headp will not
save the results if any of the calibration parameters have not been calculated or either inchworm
has not had its speed calculated. In order to save partial results it is necessary to hand enter them
into the file.
9.0 Special Head Cal Cable for Mark III/VLBA
In order to calibrate a VLBA recorder connected to a Mark III rack a special cable or connector is
required. The connector or cable should be used to connect the J11 connector on the back of the
Mark III formatter to the J2 connector on the VLBA recorder I/O panel. This will allow only
Mark III track 15 to be written. To write only Mark III track 16, connect J12 to J1.
9.1 Cable
One end of the cable is terminated with a 50-pin connector that will fit the J11 or J12 connectors
on the back of the Mark III formatter. The other end is terminated with a 40-pin connector that
will fit the J2 or J1 connectors on the VLBA recorder I/O panel. Six conductor twist-flat is
recommended for the cable. The required connections are:
Mark III Formatter VLBA Recorder
Back Panel I/O Panel
J11, J12 J2, J1
50-pin 40-pin
Function Pin Pin
GND 1 37
GND 2 38
+Clock 17 39
-Clock 18 40
+HD 15(V18), 16(V19) 19 19
9.2 Connector
This approach uses a single 3M Intra-connector with some pins snipped off. This is a 'T'
connector with two sets of male pins connected to a female socket. Only one of the sets of male
pins needs to be modified. The female socket can be attached directly to the connector on the
formatter or the tape drive. The normal formatter to recorder cable can connected to the modifed
pin set. The unmodified male pins can be used to connect the system for normal recording.
The connector can be placed on either the VLBA recorder I/O panel or the Mark III Formatter.
For the VLBA recorder, use 3M part No. 922576-40-I and snip off pins 5-18 and 21-32. For
Mark III formatter, use 3M part No. 922576-50-I and snip pins 3-16 and 21-32.
[As an aside: The connector for the Mark III formatter would also work for a Mark III formatter
connected to a Mark IV recorder. Alternatively, on the Mark IV recorder side, use the 40 pin
connector and snip pins 7-20 and 23-24.]
10.0 Listing of hdcal.snp Schedule (Mark III)
The section lists the schedule for calibrating a Mark III drive. The schedule is distributed with the
Field System in /usr2/fs/st.default/sched/hdcal.snp. The local working copy
which is kept in /usr2/sched/hdcal.snp may have been customized.
TAPE
"HDCAL.SNP -- HEAD CALIBRATION SCHEDULE 96 JAN 03
"
"ASSUMES TAPE IS POSITIONED AT END
"
"SETUP
SAVEV=CLEAR
HDCALC=CLEAR
STACK=0,0,u,u
WORM=WRITE,UPDATE
WORM
WORM=READ,UPDATE
WORM
FORM=C,4
STACK=-350,-350,F,F
TAPE=OFF
LOCATE=201,1,40,R
PEAK=3,1,R
REPRO=BYP,0,0
CHECK=
" REWIND TAPE 3200 FEET
SRW
!+1M57S
ET
!+7S
TAPE=LOW
"RECORD FOR 1000 FEET IN REVERSE AT VOLTAGE 0
STACK=-350,,F,
SAVEV=VW0
ENABLE=15
REPRO=BYP,0,0
TAPE
ST=REV,135,ON
!+1M28.89S
ET
!+3S
"RESET FOOTAGE COUNTER AFTER 4200 FEET IN REVERSE
TAPE=LOW,RESET
TAPE
ENABLE=
REPRO=BYP,0,0
"READ BACK FROM 000 TO 1000 FEET
STACK=,-350,,F
REPRO=RAW,15,15
TAPE
ST=FOR,135,OFF
!+4S
LOCATE
PEAK
PEAK
PEAK
ET
!+3S
TAPE
REPRO=BYP,0,0
SAVEV=VREVW
"POSITION FROM 1000 -> 2000
TAPEPOS=2000
!+1M30S
"RECORD FROM 2000 -> 3800
ENABLE=15
REPRO=BYP,0,0
TAPE
ST=FOR,135,ON
!+2M41S
ET
!+3S
TAPE
ENABLE=
REPRO=BYP,0,0
"POSITION FROM 3800 -> 3000
TAPEPOS=3000
!+1M15S
"READ FROM 3000 -> 2000
STACK=,-350,,F
REPRO=RAW,15,15
TAPE
ST=REV,135,OFF
!+4S
LOCATE
PEAK
PEAK
PEAK
ET
!+3S
TAPE
REPRO=BYP,0,0
SAVEV=V15REV
"POSITON FROM 3000 -> 2000
TAPEPOS=2000
!+45S
"READ FROM 2000 -> 3000
STACK=,-350,,F
REPRO=RAW,15,15
TAPE
ST=FOR,135,OFF
!+4S
LOCATE
PEAK
PEAK
PEAK
ET
!+3S
TAPE
REPRO=BYP,0,0
SAVEV=V15FOR
"POSITON 3000 -> 1000
TAPEPOS=1000
!+2M
"RECORD 1000 -> 2000 AT VOLTAGE 8
STACK=850,,F
SAVEV=VW8
ENABLE=15
REPRO=BYP,0,0
TAPE
ST=FOR,135,ON
!+1M28.89S
ET
!+3S
TAPE
ENABLE=
REPRO=BYP,0,0
"POSITION 2000 -> 1000
TAPEPOS=1000
!+1M10S
"READ 1000 -> 2000
REPRO=RAW,15,15
STACK=,850,,F
TAPE
ST=FOR,135,OFF
!+4S
LOCATE
PEAK
PEAK
PEAK
ET
!+3S
TAPE
REPRO=BYP,0,0
SAVEV=V15SCALE
"POSITON 1000 -> 2200
TAPEPOS=2200
!+1M15S
"READ 2200 -> END WITH TRACK 13
STACK=,1047,,F
REPRO=RAW,13,13
ST=FOR,135,OFF
!+4S
LOCATE
PEAK
PEAK
PEAK
ET
!+3S
TAPE
REPRO=BYP,0,0
SAVEV=V13
"RUN TAPE OFF END OF REEL
TAPEPOS=4200
!+2M
TAPE=OFF
ST=FOR,135,OFF
" FLIP AND RE-THREAD TAPE, TYPE CONT WHEN READY
HALT
TAPE=OFF
ST=FOR,135,OFF
!+10S
ET
!+3S
TAPE=LOW
TAPEPOS=1000
!+1M
"READ FROM 1000 -> 2000
STACK=,-350,,F
REPRO=RAW,15,15
LOCATE=481,1,40,R
TAPE
ST=FOR,135,OFF
!+4S
LOCATE
ET
!+3S
TAPE
TAPEPOS=1000
!+1M
TAPE
ST=FOR,135,OFF
!+4S
PEAK
PEAK
PEAK
ET
!+3S
TAPE
REPRO=BYP,0,0
SAVEV=V15FLIP
"FINAL VALUES
SAVEV
HDCALC
STACK=0,0,F,F
WORM=WRITE,NEW
WORM
WORM=READ,NEW
11.0 Listing of vhdcal.snp Schedule (VLBA)
The section lists the schedule for calibrating a VLBA drive which has a VLBA DAR. The
schedule is distributed with the Field System in
/usr2/fs/st.default/sched/vhdcal.snp. The local working copy which is kept in
/usr2/sched/vhdcal.snp may have been customized.
TAPE
"VHDCAL.SNP -- VLBA HEAD CALIBRATION SCHEDULE 95 DEC 22
"
"ASSUMES TAPE IS POSITIONED AT END
"
"SETUP
SAVEV=CLEAR
HDCALC=CLEAR
STACK=0,,u,
WORM=WRITE,UPDATE
WORM
FORM=D15,4
ENABLE=
STACK=-350,,F,
TAPE=OFF
LOCATE=201,1,40,W
PEAK=3,1,W
REPRO=BYP,18,18,byp,alt1,alt1
CHECK=
" REWIND TAPE 2200 FEET
SRW
!+1M20S
ET
!+7S
"RESET FOOTAGE so that zero point is 4200 feet from end
TAPE=LOW,2000
"RECORD FROM 2000 -> 3800
STACK=-350,,F,
ENABLE=d15
TAPE
ST=FOR,135,ON
!+2M41S
ET
!+3S
TAPE
ENABLE=
REPRO=BYP,18,18,byp,alt1,alt1
"POSITION FROM 3800 -> 3000
REC=3000
!+50S
"READ FROM 3000 -> 2000
STACK=-350,,F
REPRO=READ,18,18,READ,alt1,alt1
TAPE
ST=REV,135,OFF
!+4S
LOCATE
PEAK
PEAK
PEAK
ET
!+3S
TAPE
REPRO=BYP,18,18,byp,alt1,alt1
SAVEV=V15REV
"POSITON FROM 3000 -> 2000
REC=2000
!+36S
"READ FROM 2000 -> 3000
STACK=-350,,F
REPRO=READ,18,18,READ,alt1,alt1
TAPE
ST=FOR,135,OFF
!+4S
LOCATE
PEAK
PEAK
PEAK
ET
!+3S
TAPE
REPRO=BYP,18,18,byp,alt1,alt1
SAVEV=V15FOR
"POSITON 3000 -> 2200
REC=2200
!+30S
"READ 2200 -> END WITH TRACK 13
STACK=1047,,F
REPRO=READ,16,16,READ,alt1,alt1
ST=FOR,135,OFF
!+4S
LOCATE
PEAK
PEAK
PEAK
ET
!+3S
TAPE
REPRO=BYP,18,18,byp,alt1,alt1
SAVEV=V13
"RUN TAPE OFF END OF REEL
REC=4200
!+1M12S
TAPE=OFF
ST=FOR,135,OFF
" FLIP AND RE-THREAD TAPE, TYPE CONT WHEN READY
" USE REC=RELEASE TO RELEASE BRAKES WHEN TAPE RUNS OFF
HALT
REC=LOAD
!+10s
TAPE=OFF,RESET
ST=FOR,135,OFF
!+10S
ET
!+3S
TAPE=LOW
REC=1000
!+36S
"READ FROM 1000 -> 2000
STACK=-350,,F
REPRO=READ,18,18,READ,alt1,alt1
LOCATE=481,1,40,W
TAPE
ST=FOR,135,OFF
!+4S
LOCATE
ET
!+3S
TAPE
REC=1000
!+36S
TAPE
ST=FOR,135,OFF
!+4S
PEAK
PEAK
PEAK
ET
!+3S
TAPE
REPRO=BYP,18,18,byp,alt1,alt1
SAVEV=V15FLIP
"FINAL VALUES
SAVEV
HDCALC
STACK=0,,F,
WORM=WRITE,NEW
12.0 Listing of 3vhdcal.snp Schedule (Mark III/VLBA)
This section lists the schedule for calibrating a VLBA drive which has a Mark III rack. The
schedule is distributed with the Field System in
/usr2/fs/st.default/sched/3vhdcal.snp. The local working copy which is kept in
/usr2/sched/3vhdcal.snp may have been customized.
TAPE
"3VHDCAL.SNP -- VLBA HEAD CALIBRATION SCHEDULE 95 DEC 22
"
"ASSUMES TAPE IS POSITIONED AT END
"
"SETUP
SAVEV=CLEAR
HDCALC=CLEAR
STACK=0,,u,
WORM=WRITE,UPDATE
WORM
FORM=C,4
ENABLE=
STACK=-350,,F,
TAPE=OFF
LOCATE=201,1,40,W
PEAK=3,1,W
REPRO=BYP,18,18,byp,alt1,alt1
CHECK=
" REWIND TAPE 2200 FEET
SRW
!+1M20S
ET
!+7S
"RESET FOOTAGE so that zero point is 4200 feet from end
TAPE=LOW,2000
"RECORD FROM 2000 -> 3800
STACK=-350,,F,
ENABLE=d15
TAPE
ST=FOR,135,ON
!+2M41S
ET
!+3S
TAPE
ENABLE=
REPRO=BYP,18,18,byp,alt1,alt1
"POSITION FROM 3800 -> 3000
REC=3000
!+50S
"READ FROM 3000 -> 2000
STACK=-350,,F
REPRO=READ,18,18,READ,alt1,alt1
TAPE
ST=REV,135,OFF
!+4S
LOCATE
PEAK
PEAK
PEAK
ET
!+3S
TAPE
REPRO=BYP,18,18,byp,alt1,alt1
SAVEV=V15REV
"POSITON FROM 3000 -> 2000
REC=2000
!+36S
"READ FROM 2000 -> 3000
STACK=-350,,F
REPRO=READ,18,18,READ,alt1,alt1
TAPE
ST=FOR,135,OFF
!+4S
LOCATE
PEAK
PEAK
PEAK
ET
!+3S
TAPE
REPRO=BYP,18,18,byp,alt1,alt1
SAVEV=V15FOR
"POSITON 3000 -> 2200
REC=2200
!+30S
"READ 2200 -> END WITH TRACK 13
STACK=1047,,F
REPRO=READ,16,16,READ,alt1,alt1
ST=FOR,135,OFF
!+4S
LOCATE
PEAK
PEAK
PEAK
ET
!+3S
TAPE
REPRO=BYP,18,18,byp,alt1,alt1
SAVEV=V13
"RUN TAPE OFF END OF REEL
REC=4200
!+1M12S
TAPE=OFF
ST=FOR,135,OFF
" FLIP AND RE-THREAD TAPE, TYPE CONT WHEN READY
" USE REC=RELEASE TO RELEASE BRAKES WHEN TAPE RUNS OFF
HALT
REC=LOAD
!+10s
TAPE=OFF,RESET
ST=FOR,135,OFF
!+10S
ET
!+3S
TAPE=LOW
REC=1000
!+36S
"READ FROM 1000 -> 2000
STACK=-350,,F
REPRO=READ,18,18,READ,alt1,alt1
LOCATE=481,1,40,W
TAPE
ST=FOR,135,OFF
!+4S
LOCATE
ET
!+3S
TAPE
REC=1000
!+36S
TAPE
ST=FOR,135,OFF
!+4S
PEAK
PEAK
PEAK
ET
!+3S
TAPE
REPRO=BYP,18,18,byp,alt1,alt1
SAVEV=V15FLIP
"FINAL VALUES
SAVEV
HDCALC
STACK=0,,F,
WORM=WRITE,NEW
13.0 Listing of v2hdcal.snp Schedule (VLBA2)
The section lists the schedule for calibrating a VLBA2 drive which has a VLBA DAR. The
schedule is distributed with the Field System in
/usr2/fs/st.default/sched/v2hdcal.snp. The local working copy which is kept in
/usr2/sched/v2hdcal.snp may have been customized.
TAPE
"V2HDCAL.SNP -- VLBA2 HEAD CALIBRATION SCHEDULE 95 DEC 22
"
"ASSUMES TAPE IS POSITIONED AT END and Footage counter reads zero
"
"SETUP
REC=LOAD
!+10S
SAVEV=CLEAR
HDCALC=CLEAR
STACK=0,,u,
FORM=D15,4
ENABLE=
STACK=-350,,F,
TAPE=OFF
LOCATE=201,1,40,W
PEAK=3,1,W,.25
REPRO=BYP,18,18,byp,alt1,alt1
CHECK=
" REWIND TAPE 2536 FEET
SRW
!+1M32.22s
ET
!+7S
"Footage counts down from 65535=-1 feet
"RECORD FROM 63000 -> 64800
STACK=-350,,F,
ENABLE=d15
TAPE
ST=FOR,135,ON
!+2M41S
ET
!+3S
TAPE
ENABLE=
REPRO=BYP,18,18,byp,alt1,alt1
"POSITION FROM 64800 -> 64000
REC=64000
!+1M
"READ FROM 64000 -> 63000
STACK=-350,,F
REPRO=READ,18,18,READ,alt1,alt1
TAPE
ST=REV,135,OFF
!+4S
LOCATE
PEAK
PEAK
PEAK
ET
!+3S
TAPE
REPRO=BYP,18,18,byp,alt1,alt1
SAVEV=V15REV
"POSITON FROM 64000 -> 63000
REC=63000
!+46S
"READ FROM 63000 -> 64000
STACK=-350,,F
REPRO=READ,18,18,READ,alt1,alt1
TAPE
ST=FOR,135,OFF
!+4S
LOCATE
PEAK
PEAK
PEAK
ET
!+3S
TAPE
REPRO=BYP,18,18,byp,alt1,alt1
SAVEV=V15FOR
"POSITON 64000 -> 63200
REC=63200
!+40S
"READ 63200 -> END WITH TRACK 13
STACK=1047,,F
REPRO=READ,16,16,READ,alt1,alt1
ST=FOR,135,OFF
!+4S
LOCATE
PEAK
PEAK
PEAK
ET
!+3S
TAPE
REPRO=BYP,18,18,byp,alt1,alt1
SAVEV=V13
"RUN TAPE OFF END OF REEL
REC=65535
!+1M35S
TAPE=OFF
ST=FOR,135,OFF
" FLIP AND RE-THREAD TAPE,
" RESET THE FOOTAGE COUNTER
" LOAD THE TAPE
" TYPE CONT WHEN FINISHED,
"
" USE REC=RELEASE TO RELEASE BRAKES WHEN TAPE RUNS OFF
HALT
REC=LOAD
!+10s
ST=FOR,135,OFF
!+10S
ET
!+3S
TAPE=LOW
REC=1000
!+46S
"READ FROM 1000 -> 2000
STACK=-350,,F
REPRO=READ,18,18,READ,alt1,alt1
LOCATE=481,1,40,W
TAPE
ST=FOR,135,OFF
!+4S
LOCATE
ET
!+3S
TAPE
REC=1000
!+46S
TAPE
ST=FOR,135,OFF
!+4S
PEAK
PEAK
PEAK
ET
!+3S
TAPE
REPRO=BYP,18,18,byp,alt1,alt1
SAVEV=V15FLIP
"FINAL VALUES
SAVEV
HDCALC
STACK=0,,F,