DCS reverse burst:
Another feature of DCS is the 134.3 Hz reverse burst tone. When a receiver using a DCS code to control its squelch opening sees the 134.3 Hz reverse burst, it turns off the receive squelch while the reverse burst is still being sent. This eliminates the squelch tail noise burst when the received signal drops out. This DCS reverse burst is exactly the same for Motorola and other manufacturers radios (they all work together without problems). When CTCSS and DCS are both used on the same frequency, it is worth noting that 131.8 Hz and 136.5 Hz are both CTCSS tones. The DCS reverse burst can false some receivers using these CTCSS tones. It depends on the transmitter and receiver. The transmitter DCS reverse burst tone could be off frequency, the receiver CTCSS decoder may not be on frequency or the receiver CTCSS decoder may not be selective enough to reject the nearby DCS reverse burst tone. This potential problem is why some people do not like to use these two CTCSS tones on frequencies that also have DCS on them.