The SDR Link top HAT transceiver uses an AT86RF215 which contains two independent transceivers in the 900 or 2400 MHz bands. Both are low power at -14dBm, but using an external power amplifier the 900 MHz radio can output up to 20 watts, and, with an external 12dB gain Yagi antenna, can provide a link that can span over 60 Km with line of sight.
The transceiver has several built-in data modes conforming to the 802.15.4g standard, and, depending on the bandwidth used, can provide different link speeds and performance characteristics using either multi-rate FSK or OFDM, or offset QPSK.
In the multi-rate FSK mode, the transceiver implements symbol rates from 50 to 400 KHz, with either one or two bits per symbol.
In the multi-rate OFDM mode, it can occupy bandwidth from 156 to 1094 KHz, on which it can deliver from 50 to 2400 bits/sec, depending on the carrier modulation method, which can be either BPSK, QPSK, or 16-QAM. The higher the order of modulation, the higher the receive signal to noise ratio must be in order to maintain a good quality link, which in turn limits the maximum distance.
In the offset QPSK mode, it can operate at chip rates from 100 to 2000 Kchips/sec, and deliver from 6.25 to 1000 Kb/sec data rates.
A 3D rendering of the board is shown below. It also implements the three sense inputs, and has fully decoded outputs for transmit and receive controls, buffered by FET transistors.
