NCAR AVAPS Interface Control Document

1.1 This document describes the AVAPS interface to the aircraft’s subsystems.  The following requirements define the aircraft electrical interface with AVAPS.

2.1. Vendor:  Sensor Systems, P/N S65-1217

2.1.1. NSN 5985-00-034-2320

2.2. Electrical Characteristics:

2.2.1. Conforms to AT-896/A specs

2.2.2. Military Specs: MIL-E-5400, MIL-E-5272, MIL-A-27164

2.2.3. Frequency Range: 390-450 MHz

2.2.4. Polarization: Vertical

2.2.5. Coax Connector type:  N

2.2.6. Impedance: 50 ohms

3.1. Vendor:  Sensor Systems, P/N S67-1575-82

3.2. Electrical Characteristics:

3.2.1. Coax connector type:  TNC

3.2.2. Federal & Mil Specs: FAA TSO C115a, ARINC 741, DO-160, FED-STD-595, MIL-C-5541, MIL-E-5400, MIL-E-5272

3.2.3. Frequency: 1575.42 MHz

3.2.4. Polarization: RHCP

3.2.5. Coax Connector type:  TNC

3.2.6. Impedance: 50 ohms

3.2.7. Antenna Preamp: Active 35 dB Gain, +5 Vdc required on center conductor of coax

4.1. The system requires 115 VAC, 50/60Hz, power not to exceed 500 watts.

4.1.1. Computer typical current consumption:

4.1.1.1. 3U  Computer      1.0  @ 115 VAC

4.1.1.2. 6U Computer    1.3 Amps  @ 115 VAC

4.1.2. CRT monitor typical current consumption:  0.35Amps @ 115 VAC

4.1.3. Telemetry Chassis typical current consumption:  0.3 Amps @ 115 VAC

4.1.4. Telemetry Chassis Cooling Fans typical current consumption:  0.6 Amps @ 115 VAC

4.1.5. Launch Tube Power 28VDC 2.0 A typical 6A peak

4.2. Connector type: TBD

5.1. 3U Computer weight:  36 lbs, size:  19”W x 3.5”H x 24”D, allow additional 4” depth for cabling.

5.2. 6U Computer weight:  41 lbs, size:  19”W x 7”H x 18”D, allow additional 4” depth for cabling.

5.3. Monitor weight:  20 lbs, size:  19(W) x 13.97(H) x 3.1(D)

5.4. Telemetry Chassis: 18 lbs, size:  19”W x 5.25”H x 13.5”D

5.5. Telemetry Chassis Cooling Fans:  7 lbs

5.6. Miscellaneous interconnect cables:  3 lb

6.1. 400 MHz antenna input coax connector type: N

6.2. GPS antenna input coax connector type: TNC

7.1. An open collector circuit applies ground potential to the dropsonde launch system to activate the motor.  The maximum current allowed through this line is 500 mA.

7.2. There are two input lines which can monitor a DC voltage in the range + 5Vdc to +28 Vdc and ground (1 bit A/D). Typical use would be for Arm Detect, and Valve Open.

7.3. The connector type is a 9-pin D-shell female connector.

7.4. DB-9 pin connections:

7.4.1. Pin 1 - Ground

7.4.2. Pin 4 - Output, Bipolar transistor open collector

7.4.3. Pin 5 - Ground

7.4.4. Pin 6 - Input, Voltage Input (Arm Detect)

7.4.5. Pin 7 - Ground

7.4.6. Pin 8 - Input, Voltage Input (Valve open)

8.1. Electrical characteristics for both serial ports:

8.1.1. EIA-232 8.2. Connector type is 9-pin D-shell female receptacle.

8.2.1. No hardware or software handshake is implemented. The serial communication is a EIA-232 three wire connection.
8.2.2. EIA-232 pin connection (25-pin)

8.2.2.1.1.   Pin 1 - Ground  Chassis Ground

8.2.2.1.2.   Pin 2 - TxD Transmitted Data (Output)

8.2.2.1.3.   Pin 3 - RxD Received Data  (Input)

8.2.2.1.4.   Pin 7 - Signal Ground

8.3. Flight Level Data input data format to the AVAPS Computer from the Aircraft Data System computer.

8.3.1. The message is transmitted in ASCII

8.3.2. Data fields are space delimited.

8.3.3. A carriage return (cr) and linefeed (lf) are the end of line delimiters.

8.3.4. Standard serial protocol is 9600 baud, 8 data bits, no parity bit, one stop bit.

8.3.4.1. The baud rate is software selectable from 9600 baud to 38.4k baud.

8.3.5. Each message is asynchronously broadcast once per second (typical).

8.3.6. The data format is described in the following table:

8.3.7. Additional data format information.

8.3.7.1. Sample Message: (note: _ denotes a space delimiter in the following example)

8.3.7.2. hhmmss_mmmm.m_sdd.d_sddd.d_ddd.d_mmm.m_ddd.d_mmm.m_

8.3.7.3. ddd.d_mmm.m_smm.m_sddd.dddd_sdd.dddd_mmmmm.m_mmmmm

8.3.7.4. .m_dd

8.3.7.5. 89 data chars + 15 field delimiters + 2 end of line delimiters = 107 characters.

8.3.7.6. The above table describes the preferred format for the pre-launch data used to initialize the AVAPS system for a sounding.  Each of the parameters above are assembled into an ASCII message, then broadcast once per second to AVAPS via RS-232.

8.3.7.7. Except for the ‘GMT Measurement Time’ parameter, strict adherence to the character format given in the ‘Format’ column is not required.  AVAPS parsing software can easily handle parameter values to any level of precision but the precision should not be less than that given in the table.  Standard floating point format (example: 1.23E+4) can also be accommodated without modification.

8.3.7.8. The GMT Measurement Time applies to all parameters.

8.3.7.9. The sign of the Aircraft Vertical Velocity value indicates as follows:

8.3.7.10. + (plus) or none = aircraft ascending,  - (minus) = aircraft descending.

8.3.7.11. The sign of the Aircraft Longitude value indicates as follows

8.3.7.12. + (plus) or none = East,  - (minus) =  West.

8.3.7.13. The sign of the Aircraft Latitude value indicates as follows:

8.3.7.14. + (plus) or none = North,  - (minus) = South.