Yaesu VX-120 Operating Manual

Also see for VX-120 Series: Brochure Specifications Technical supplement

VX-120 OPERATING MANUAL 63DCS CODE INVERSIONThe DCS system was first introduced in the commercial LMR (Land Mobile Radio) ser-vice, where it is now in widespread use. DCS is sometime referred to by its different pro-prietary names, such as DPL® (Digital Private Line®, a registered trademark of Motorola,Inc.).DCS uses a codeword consisting of a 23-bit frame, transmitted (subaudible) at a data rateof 134.4 bps (bit/sec). Occasionally, signal inversion can result in the complement of acode to be sent or received. This prevents the receiver’s squelch from opening with DCSenabled, as the decoded bit sequence would not match that selected for operation.Typical situations that might cause inversion to occur are: Connection of an external receiver preamplifier. Operating through a repeater. Connection of an external linear amplifier.Note that code inversion does not mean that any of the above listed equipment is defective!In certain amplifier configurations, the output signal (phase) is inverted from the input.Small signal or power amplifiers having an odd number (1, 3, 5, etc.) of amplificationstages may result in inversion of a transmitted or received DCS code.While under most circumstances this should not occur (amplifier designs and industrystandards take this into account), if you find that your receiver squelch does not open whenboth you and the other station are using a common DCS code, you or the other station (butnot both) can try the following:1. Press the [F] key, then press the [LOW(LOCK)SET] key to enter the Set mode.2. Rotate the DIAL knob to select Set Mode Item 14: DCS.N/R.3. Press the [F] key momentarily, then rotate the DIAL knob toselect one of the following modes:T/RX N: Encoder, Normal; Decoder, NormalRX R: Encoder, Normal; Decoder, Reverse (Inverted)TX R: Encoder, Reverse (Inverted); Decoder, NormalT/RX R: Encoder, Reverse (Inverted); Decoder, Reverse (In-verted)4. When you have made your selection, press the PTT switch to save the new setting andexit to normal operation.5. Remember to restore the default setting to “T/RX N” (Encoder; Normal, Decoder;Normal) when done.MISCELLANEOUS SETTINGS