WI Rockets for Schools

Payload Telemetry Information

The audio portion of the TV signal from the super-loki payload contains telemetry information. The telemetry is derived from on-board sensors wired into a microcontroller (PIC 16C71). The microcontroller includes four analog to digital (A/D) circuits in one 18 pin integrated circuit. The microcontroller is programmed to send the telemetry using an audio tone. The telemetry is sent using morse code. Each frame of telemetry sent consists of the following:

Station Identification, frame number, battery voltage, internal payload temperature, external temperature, and altitude.

Aside from the station identification, all telemetry is sent as hexidecimal numbers. The frame number will have four (4) hexidecimal digits, the remainder have two (2) hexidecimal digits each.

Sample Frame:

WB8WKN 0007 DB 40 C1 00

Station identification: WB8WKN
Frame Number: 7
Battery voltage: DB = 219 (decimal) = 8.6 Volts
Internal Temperature: 40 = 64 (decimal) = 57 C
External Temperature: C1 = 193 (decimal) = -2 C
Altitude: 00 = 0 (decimal) = too high to get a good reading