12 December 2003
MEMORANDUM
From: MIDN 1/c C S Thompson, USN
To: LtCol B R Smith, USAF (ret)
Via: MidSTAR Team
Subj: IC Sat End-of-Semester Status Report And Turnover Guide
Encl: (1) Mission Requirements Memorandum
(2) Transmit Block Diagrams
(3) Receive Block Diagrams
(4) Layout 1
(5) Layout 2
(6) Component Inventory
(7) Mass Properties and Calculations
(8) ComBlock Register Values
1.0 System Requirements
The Requirements document to which all designs must adhere was approved on 09 April 2003 by LtCol Smith. This document specifically dictates all capabilities and constraints of the ICSat experiment. Before making and potentially drastic changes to the design of the ICSat experiment (component replacements, etc) it is imperative that the requirements document be reviewed to ensure that any changes will not negatively affect the mission requirements.
A shorter, more condensed memorandum was drafted at the beginning of the semester for focus on the more immediate design concerns and for easy reference.
The full requirements document is posted on the website Archives. The memorandum is not posted, but can be located on the Cronus Drive at N: \ MidSTAR \ web-docs \ ICSat. A printed copy of the memorandum can be found in Enclosure 1.
2.0 Current Design Decisions
2.1 Block Diagrams
Two types of block diagrams exist, one for transmission components and one for receiver components. There are three variations of each side (TX and RX) which show the evolution in design. These increasingly complex diagrams show different components and their relative location within the system.
The first block diagram is the most basic, showing just blocks as placeholders for components. The second contains the ComBlock boards, and the third contains the ComBlock boards, amplifiers, and splitters/combiners.
The block diagrams for both sides were drawn in AutoCAD and exported as bitmaps for the website Archives. The files can be located on the Cronus Drive at N: \ MidSTAR \ web-docs \ ICSat \ Diagrams and Schematics.
Printed versions of the block diagrams for both the TX and RX sides can be found in Enclosures 2 and 3.
2.2 Wiring Diagrams / Mechanical Layouts
Two different mechanical layouts have been drawn. Layout 2 was the first design drawn, but Layout 1 is currently the favored design. These layouts also serve as basic wiring diagrams, although L1 is not completed at present.
The major difference between the two layouts is that L2 stacks the Modulator above the D/A Converter. This was done so that all components in both the TX and RX strings would connect to each other without employing any cables.
L1 features larger boundaries (the exterior dimensions of the box were increased to 10 x 11”). This allows the three RX ComBlock boards to connect in plane without stacking. However, the amplifiers and combiners will have to be positioned in the center of the box most likely above the +5Volt and Ground Buses. The large vacant area on the TX side of the box is currently reserved for a controlling circuit board. This board will most likely be custom-made and assembled by the MidSTAR team.
Both Layouts were drawn in AutoCAD and exported as bitmaps for the website Archives. The files can be located on the Cronus Drive at N: \ MidSTAR \ web-docs \ ICSat \ Diagrams and Schematics.
Printed versions of both layouts can be found in Enclosures 4 and 5.
2.3 Component Inventory and procurement status
The only components required for assembly which are not currently in stock are the Miteq amplifiers. These have not been purchased because of their relatively high cost and the uncertainty of choice in that specific model and manufacturer. Further discussion with Dr. Parise needs to occur before placing the order for these components.
The desire to purchase redundant components has been discussed and approved by LtCol Smith but at present the orders have not been placed. Given the current pace of progress the need for these redundant parts is not immediate, although they should be purchased early in the spring semester.
Dr. Parise has suggested that gold headers be mounted all circuit boards on the satellite. No research has been done to find vendors or prices for the headers required for ICSat, which would include 40-pin and 12-pin headers.
The inventory is a Microsoft Excel spreadsheet that can be located on the Cronus Dive at N: \ MidSTAR \ web-docs \ ICSat.
A current inventory is posted on the website Archives and is attached in Enclosure 6.
2.4 Mass Properties
The mass properties of the entire ICSat experiment have been tabulated and updated as components arrived. The current mass is estimated at 1.329 kg, but none of the calculations or estimates includes the mass of wires, cables, voltage buses, or extra connectors. As such, the actual mass will be closer to the 2.0-2.5kg range.
A certain amount of flexibility exists in the final mass of the experiment because the bulkheads of MidSTAR are currently being used to ballast the mass of the entire spacecraft. This flexibility should not be abused, but it does exist to a moderate degree.
The Mass Properties were tabulated in a Microsoft Excel spreadsheet that can be located on the Cronus Dive at N: \ MidSTAR \ web-docs \ ICSat.
A current inventory is posted on the website Archives and is attached in Enclosure 7.
2.5 Power Requirements
No power requirements documents have been created or reviewed this semester. However, the Electrical Power System (EPS) team knows all of the DC voltage requirements.
Three different voltages will be required for ICSat to operate according to the current design. +5V DC is required for all ComBlock components. The Mini-circuits power amplifier requires +12V DC, and the Miteq amplifiers require +15V DC. Given cable losses it will be necessary for the EPS to provide higher voltages at the batteries so that these voltages are still available in the wires at the connections to the proper components.
The current design features a +5V DC and Ground bus to be mounted inside the box to serve as a central voltage source for all five ComBlock boards. A specific design for the buses has not been made; currently in the shop the voltage and ground bus is a 1-pair 10-gauge wire.
2.6 Interface Issues
As the secondary communications system for MidSTAR, ICSat will require very reliable connections with the rest of the satellite. These connections are simplified by running most of the data through the main computer system and then to ICSat.
The connections that will be required are as follows:
3 Voltage connections (mentioned above): +5V DC, +12V DC, +15V DC.
1 Ground bus connection
2 SMA connections leading to the two receiving antennas
2 SMA connections leading to the two transmitting antennas
1 connector to the PC-104
3.0 Schedule
The following is a list of milestones and the anticipated order of completion. This list is instead of choosing tentative completion dates for work which will undoubtedly change many times.
1. Add additional board stands to aluminum mounting plate.
2. Cut wires to be attached to the ComBlock card test points. These should be long enough so that the oscilloscope probe will not be attached to the wires over the ComBlock card.
3. Complete calibration of ComBlock boards.
4. Communication from TX to RX across SMA connection.
5. Communication from TX to RX across room over wireless.
6. Construct aluminum mounting plate for ICSat.
7. Construct +5V DC and GND buses.
8. Design and build controlling custom control circuit board.
Certain tasks must be accomplished prior to the execution of the above steps. For example, prior to wireless transmission across the room, TX and RX antennas must be made and mounted to the respective ComBlock cards.
4.0 Performance
4.1 Hardware
All unsealed ComBlock components in stock are fully functional and have been tested to ensure successful power-up. A spreadsheet has been created to easily explain the register inputs. The spreadsheet exists for most components (COM-1001, 1002, 3001-A, 4001-A, 4004) and translates individual bit values into hexadecimal register entries (see Enclosure 8). The hardcopy in the workshop has further notes and is commonly used for daily adjustments.
The Bit Register spreadsheet is posted on the website archives and can be located on the Cronus Dive at N:/MidSTAR/web-docs/ICSat/ComBlock Registers.
As of late there ahs been some concern over the quality of the COM-4001 Modulator and COM-3001-B Receiver. Attempts to calibrate and test these two components have been difficult. According to the manufacturer, the 4001 card typically varies off its assigned frequency between 0 and 100 kHz high. At present it appears that the specific card in use varies on the order of 34 MHz. No success has been made in getting the 3001-B card to recognize an incoming signal (transmitted across an SMA connection from a signal generator).
Significant progress was made on the last day of class. Using a different receiver card we were able to locate the incoming signal by plugging into the card’s test points with oscilloscope probes. An offset of 43 kHz high was observed.
4.2 Workshop Hardware
4.2.1 Work Area (including ESD prevention materials)
Currently ICSat real estate is the back right corner of the workshop as you walk through the door. That is likely to change as the workshop benches, tables, and the new clean room are being moved around. All ICSat hardware is located in the top shelf of the black filing cabinet labeled (incorrectly) “MidSTAR.” Nothing of importance is stored in the second shelf labeled “ICSat.”
All work on the ComBlock cards and related hardware should be done on the ESD mat. Any personnel with hands-on the hardware should be wearing both a blue smock and a blue wristband.
4.2.2 Signal Generators
At least one of the signal generators (the one mounted in the wooden roller cabinet under the receiver) is not calibrated and/or is unreliable. A second signal generator is being used. Its reliability is not certain, but it appears to be in fine condition.
4.2.3 Spectrum Analyzers
The HP analyzer currently in use appears to be working fine. There was some earlier concern that it was also faulty, but the results obtained on the last day of class indicate that it works fine.
4.2.4 Oscilloscopes
ICSat is using one oscilloscope right now. The scope and both 10x probes appear to be working fine.
Respectfully Submitted,
Casey S Thompson
MIDN USN
MidSTAR ICSat