 Complete the following phrase:  By 1990, most Army units had replaced their older VRC-12 series FM radios for the new SINCGARS SINgle-Channel Ground-Air Radio Systems family of equipment. Rather than sending a signal along one signal frequency, the SINCGARS radios sent its signals across many frequencies, hopping from one frequency to another at high speed. This allowed many nets to share an already-crowded frequency spectrum. Later generations of these radios combined the communications security COMSEC encryption devices with the receivertransmitter, making a single easier-to-program unit. Most significant, the SINCGARS radios could send and receive digital traffic with great fidelity. By the advent of 