TO: CAPS Team FROM: Dave Young REF: New CAPS telemetry rates; CAPS Team meeting at CRPE on April 10-11
Attached to this message you will find a table giving the new CAPS data modes for rates of 1000, 500, and 250 bits/s. There are two flavors of
the 500 bits/s mode: one for direct observations of the solar wind, and one for periods when the spacecraft is aimed so that IBS cannot view the
solar wind. Although I donít like the idea of using rates as low as 250 bits/s there will be times during the cruise periods starting in May when that
will be the only rate available to CAPS (other MAPS instruments are similarly afflicted).
These low rate modes are based on discussions that the CAPS team had starting in 1994. We are asking that you look at the tables and give us your
comments. The new modes are now being coded at SwRI and GSFC but tweaks to their design are still possible. I request that the Co-I teams
especially should look at the tables and comment on the sensor for which you are responsible. Your comments should be sent to Judy Furman
(firstname.lastname@example.org) no later than February 21.
IMS: The 1000, 500, and 250 bps modes contain IMS data collapsed to 32E x 4EL x 1AZ x 2 IONs (H+ ST and He2+ ST). The 1000 and 500 bps
modes also have TOF spectra with each A-cycle product containing 1E x 256 TOF for both LEF and ST. With the 250 bps mode this drops to
64 TOF per A-cycle. The low rate modes are designed to look at the high energy component of the solar wind and for pickup ions. None of the low
rate modes have IMS singles data included. The low modes will alternate every ~10 hours with higher rate modes in which singles are included.
IBS: The 1000 bps mode has all 3 IBS fans included. Do we want to modify the current 2000 bps mode to keep all 3 IBS fans but average them over
an A-cycle or would we rather attempt to take both snapshot and collapsed data with only 2 fans (as we currently do)? The 500bps SW mode will
collapse energy to 128 steps and will use only the central fan (averaging over the 3 fans is also possible). In the 250 bps mode IBS will not be able to
view the solar wind and will not take data.
ELS: The ELS products at 1000 bps are the same as for the current 2000bps SW mode. In the 500 bps SW mode the collapse goes to
32E x 8EL x 1 AZ in order to give more rate to IBS. The 250 bps mode is the same. The 500bps MAG mode increases the ELS rate to include
63E x 8EL x 1AZ.
A reminderóthe CAPS team meeting is still scheduled for April 10 and 11 in or near Paris. Jean-Jacques will select the site. I will have a preliminary
agenda out in 2 weeks. Let me know if there are any topics you wish to raise at the meeting.