HamShield is a FM voice and data transceiver Arduino shield for three amateur radio bands (144MHz, 220MHz, and 440MHz) with wideband transcieving capability across 136-170MHz, 200-260MHz, 400-520MHz. It connects the FM transceiver to the ADC and PWM lines (filtered) and also features a TRRS jack for use with a smartphone headset.
The HamShield is based on a new variation of the RDA 1846, the Auctus A1846S and features a power amplifier to offer 250mW of filtered FCC/CE compliant RF output. This is a trade off between cost, heat, and adequate power output for use with an antenna or input to a larger power amplifier.
The HamShield also can operate at low power. We have used a 2.5 watt solar panel (4.5" x 7") to power the HamShield while transmitting a test morse code signal. You could easily build a solar powered packet radio station with a similar setup. Adding a battery charging circuit would help power the HamShield during less optimal sun exposure or overnight.
We have a powerful library that lets you write radio sketches fast! It supports control of every aspect of the radio, from power output level, transmit and receiving control, sub audio tones (CTCSS/CDCSS), RSSI detection and tone generator and detector circuits. In addition to voice, we have packet radio data capability using 1200 baud AFSK. Our library supports AX.25 frames as well as the popular APRS mode. There is work being done to bring 9600 FSK to the library, as the hardware is capable of higher bitrates.
We have also have a sketch that turns the Hamshield + Arduino into a serial controlled radio. This means you can connect it to a computer. We have written some Chrome browser applications that use the serial port to offer functionality such as packet radio in a web browser (APRS Text Messenger!) and another Chrome app that lets you operate the radio and talk to repeaters.