PSAS Naming Conventions
(There are ANSI standards, Y1.1-1972, Y10.5-1968, Y10.19-1969, can't find them)
The purpose of this page is to document a framework for consistent usage within the project. The goal is to make the project easier. There are no enforcement mechanisms beyond infrequent whining.
Airframes
We have built a series of airframes of increasing size. The first was "LV0" for Launch Vehicle 0. The second "LV1", then "LV2". On occasion there have been multiple designs in the same size class, likewise there have occasionally been multiple copies of a single airframe design.
We encode this information as:
<nop>VVNrC
Where VV is the vehicle identifier, "LV" or Launch Vehicle, in the case of the airframe, N is a single decimal digit identifying the design sequence. A single lowercase letter r identifies the design revision, and C is a digit identifying the particular copy of a design.
For example, after crunching an LV2a airframe in Aug. 2005 (LV2b was destroyed in an earlier flight), the next airframe design was designated LV2c, meaning the 3rd design revision of the LV2 airframe. The 1st incarnation of this design would be called LV2c1
Historical Note: We previously used a different naming system for the launch vehicle. LV2a was called LV2.1 and LV2b was called LV2.2.
Avionics Packages
The avionics package is named in analogy to the airframe scheme.
<nop>PPNrC
Here PP is the component group designator, "AV" for avionics. The NrC is just as explained in the Airframe section.
For example the avionics package designation in 2006 was AV2b. The "2" refers to the major design revision. In this case targeting the LV2 size airframe. We intend to keep the N-major revision of the avionics in sync with the N-major revision of the airframe. The "b" refers to the 2nd generational revision of the LV2-targeted avionics.
As a final example the 2nd copy to the "b" avionics targeting the LV2 airframe, and installed into the LV2c1 airframe would be LV2c1-AV2b2. Dropping the "AV2" is allowable LV2c1-b2.
Components
A very good feature to have is a unique designation for each part. Here is the basic form of a part number:
TTTTNNNNFF
Where TTTT represents an alphanumeric type-code, and NNNN is a numeric part number. The FF field is the "extra" part number provided for special cases, normally this field is not used.
Sometimes a more elaborate scheme might be called for. Something like this:
PPPPLL:BBBBB-VVVSS:TTTTNNNNFF.AA
This decodes as follows
| Field | Type | Length | Meaning | Notes |
|---|---|---|---|---|
| PPPP | alphanum | 1 - 4 | Project Code | omit unless ambiguous |
| LL | alpha | 0 - 2 | Launch Series | use only if PPPP present |
| BBBBB | alphanum | 1 - 5 | Board or Assembly Code | omit unless ambiguous |
| VVV | numeric | 0 - 3 | Integer Version Number | omit unless ambiguous |
| SS | alpha | 0 - 2 | Unit Build Sequence | omit unless ambiguous |
| TTTT | alpha | 1 - 4 | Part Type Code | see table |
| NNNN | numeric | 1 - 4 | Numeric Part Number | |
| FF | alpha | 0 - 2 | Extra Part Number | special circumstances only |
| AA | numeric | 0 - 2 | Actual Device Code | special circumstances only |
Examples:
- LV2:GPS1:D204.2
- Diode number 204 on GPS board revision #1 of Launch Vehicle #2. The suffix `.2' refers to the 2nd part installed in this position. Normally a part is installed only once and no suffix is used.
- D204b
- Usually, the second component of a multi-part component called D204. Sometimes, undesirably, letter suffixes may be used to add distinct parts without re-numbering.
- LV2a:GPS03:VR204a.1
- Maximum--style part code. Launch Vehicle #2, flight `a' (first flight), GPS board revision 3 (the `03' is the same as 3). Variable resistor number 204a (Could be entirely unrelated to VR204!). The `.1' refers to the 1st part installed on the board. Normally a part is only installed once, therefore most parts are implicitly designated `.1', the actual `.1' is almost always omitted. Presumably a part labeled `.1' has had a replacement contemplated at some point.
- Q101
- If there is no ambiguity, the simple form of the part number is used. In this case transistor number 101.
Details:
The major field separator is the `:' (colon), always used between major fields, such as between board designator and part designator. The `.' (dot) is an optional subfield separator to disambiguate difficult cases, e.g. 802.1:R1100
- Project Code
- PPPP
For our purposes this will be of the form LV1, LV2, LV3, etc. This could be extended with a prefix like "PSAS:". Ground support equipment might use another designator such as "LTC" for Launch Tower Computer.
- Launch Series
- LL
Flight sequence number. Follows the alphabetic sequence a, b, c,... z, aa, ab,... Note that this is a time sequence code as opposed to a serial number. Perhaps a date code could also be used here.
- Board or Assembly Code
- BBBBB
Board designation, alphanumeric, usually upper case.
- Integer Version Number
- VVV
Board-level version number. Numeric starting from `1'. Leading zeros are not significant.
- Unit Build Sequence
- SS
Alphanumeric, lower case. a,... ab, ... Designates separate builds of the assembly. This is the serial "number" of the board.
- Part Type Code
- TTTT
Designates what kind of part this is. For example `C' is for a capacitor, `R' for a resistor. The recommended codes are tabled below.
| Component Type | Designation | Motivation |
|---|---|---|
| Power Diode | CR | Current Rectifier |
| Signal Diode | D | |
| Photo Diode, solar cell | PD | PhotoDiode |
| Photo Diode, solar cell | DL | Diode `Lite' |
| PIN Diode | PIN | |
| Zener Diode | Z | |
| Transistor | Q | No idea |
| Transistor Array | QA | |
| Photo Transistor | QL | |
| Resistor | R | |
| Variable Resistor | VR | |
| Resistor Array | RA | |
| Thermistor | RT | |
| PhotoResistor | RL | |
| Capacitor | C | |
| Variable Capacitor | VC | |
| Variable Capacitor Diode | VCD | |
| Capacitor Array | CA | |
| Crystal / Resonator | X | |
| Inductor | L | No idea |
| Variable Inductor | LV | VL sucks |
| Inductor Array | LA | |
| Strain Gage | SG | less generic |
| Switch | SW | |
| Integrated Circuit | U | Convention? |
| Light Emitting Diode | LED | |
| Transformer | T | |
| Test Point | TP | |
| Removable Jumper | J | |
| Male Connector | CM | |
| Female Connector | CF | |
| Generic Connector | CN | |
| Fuse | F | |
| Ferrite Bead | E | Convention? |
| Wire (also fixed jumper) | W | |
| Wire Bundle | WB | |
| Transient Voltage Suppressor | TVS | |
| EM Shield | EMS | |
| SCR | K | ??? |
| other Thyristor | Y | ??? |
| Motor, actuator | M | |
| Piezo element | PZ | |
| Battery | B |
Part Number NNNN
Never zero. Leading zeros are not significant. Part numbers need only be unique within a given board and revision, however, it is desirable that part numbers convey as much information as possible. We therefore try to keep them unique across a project, and to keep part numbers grouped by functional section.
Major subsystems have a common 4th digit, as in the case of the flight computer using 1xxx numbers, the GPS using 5xxx, etc. Current Nxxx subsystems are:
Function TLA numbers Flight Computer FC 1xxx Generic Node GFE 2xxx Avionics Power System APS 3xxx Inertial measurment IMU 4xxx GPS GPS 5xxx Telemetry (ATV, WiFI) TLM 6xxx Pyro/Recovery PYR 7xxx Fin Control FIN 8xxx
Future Nxxx series systems are proposed to be:
Function TLA numbers Magnetometer MAG 9xxx Pressure PRS 10xxx Propulsion control PRP 11xxx Backup uplink radio UPL 12xxx
Each major subsystem (Nxxxx) have application sections which have a common 3rd digit (xNxx). These are defined per major subsystem, but since some of the boards have commone components, some of the number range is reserved:
Function TLA numbers Switching Power Supply SPS 000 - 099 High Availability Power Supply HAP 100 - 199 Microprocessor & Misc. UC 200 - 299 Application specific sections ??? 300 - 999
... which leaves 7 possible application section left per major subsystem.
- Extra Part Number
- FF
This field is legitimately used when a single logical part has multiple physical components. For example when two resistors are placed in series to increase power handling capability or precision, each resistor might be designated R101a, R101b, etc. A less legitimate use for this field is as a quick and dirty way to wedge part numbers into a previous scheme without having to re-number everything.
- Actual Device Code
- AA
This field distinguishes between parts installed on the same board in the same place at different times. The field should always be separated from the part number by a `.' dot. When a board is first assembled the parts are implicitly `.1' coded. If a part fails or is otherwise replaced, the replacement becomes a `.2' part. If the original part is reinstalled, it would again be the `.1' part.
Suggested schematic layer usage
This is mostly for xfigs, but may apply more broadly.
| Components | 100 |
| Component Marks | 90 |
| Interface + Power | 80 |
| Labels | 60 |
| Values | 40 |
| Signals | 0 |