ROMEO2

The basic functionality of the ROMEO2 receiver may be seen by reference to the accompanying block diagram (see figure 1). It is fully compatible with the TANGO3 transmitter.

The RF section comprises a mixer with image cancelling, followed by an IF band-pass filter at 660kHz, an AGC controlled gain stage and OOK and FSK demodulators, the desired modulation type being selectable by the SPI interface. The data output from the circuit may either be the data comparator output, or, if Data Manager is enabled, the SPI port.

The local oscillator is controlled with a PLL referenced to the crystal oscillator. The received channel is defined by the choice of the crystal frequency.

An SPI bus permits programming the modulation type, data rate, UHF frequency, ID word etc., though to accomodate applications where no bus interface is available the circuit defaults at power-on to a standard operating mode.

Depending upon the configuration, the circuit can be either externally strobed by the STROBE input or internally wait-and-sleep cycled to reduce the power consumption. At any time, a high level on STROBE overrides the internal timer output and wakes up ROMEO2. When the circuit is switched into sleep mode its current consumption is approximately 100A. The circuit configuration which has previously been programmed is retained.