modelPartialRadioModem

Information

Base class of the transparent radio modems. It cannot be instantiated directly: see Peripherals.Radio.RadioModem.

The modem is connected electrically to two GPx pins of an MCU (machine.UART), and to the other module(s) by one antenna wire. What it receives on its UART leaves on air, and what it hears on air comes out on its UART:

• a byte received from the microcontroller waits in the transmit buffer (txBufferSize bytes) at least txDelay, then leaves in a radio frame of 8N1 type at airBaudrate, possibly different from the serial speed;
• a radio frame heard intact waits in the receive buffer (rxBufferSize) at least rxDelay, then leaves on the UART;
• a byte that finds its buffer full is lost; a corrupted radio frame (different air data rates, for example) is dropped, as by a real module that checks its packets; in half duplex, a frame arriving while the module transmits is lost.

Masked synchronisation. The receiver does not demodulate sTx: the antenna wire also carries the bit being transmitted, which the receiver decodes as a real serial receiver would, at its own air data rate. The modulated signal is drawn for teaching purposes, with a scaled carrier (fDisplay) since a real carrier cannot be drawn; to see it, reduce the output interval of the simulation well below 1/fDisplay. A receiver only hears a transmitter on its channel (fCarrier within half a channelWidth) and with its modulation.

The icon shows the radio frames being transmitted (amber dot) and received (cyan dot) and the filling of the two buffers, while replaying a result with animation in OMEdit. At the end of the simulation, each module writes a summary line in the log: bytes passed, bytes lost and why.

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Components