The following documents the general scheme used for Newton MessagePad units built for the United States:
- Communication Scheme: Bi-directional half-duplex
- Modulation Type: Amplitude shift keying (ASK) carrier = space, no carrier = mark
- Carrier: Infrared (900-1050 nm), 1000nm peak sensitivity
- Transmission Rate: 38,400 bps(max), under SW control, fall back to19,200 bps when error rate becomes too high. (Sharp module specified to 19.2)
- Transmission Modulation Frequency: 500kHz & 38 kHz
- Receive Modulation Frequency: 500kHz only
- Communication Range: 8 cm - 1 meter @ 19.2 kbps
- Emission directional cone +/- 13 degrees
- Receive directional cone +/- 13 degrees