FCC ID: K6620285X20
IC ID: 511B-20285X20
VX-3R Operating Manual
3. Rotate the DIAL knob until “DCS” appears on the display; this activates the DCS Encoder/Decoder.
Note: Do not forget to pull the DIAL knob to rotate the DIAL knob.
4. Press the PTT switch to save the new setting.
5. Press and hold in the [TXPO] key for one second to enter the Set mode.
6. Rotate the DIAL knob to select Set Mode Item 24: DCS CD.
7. Press the [TXPO] key momentarily to enable the adjustment of the DCS code.
8. Rotate the DIAL knob to select the desired DCS Code (a three-digit number). Ask the repeater
owner/operator if you don’t know DCS Code; if you are working simplex, just set up the DCS Code to
be the same as that used by your friend(s).
9. When you have made your selection, press the [TXPO] key momentarily, then press the PTT switch to
save the new settings and exit to normal operation.
R.F. Says: 1) Remember that the DCS is an Encode/Decode system, so your receiver will remain muted
until a matching DCS code is received on an incoming transmission. Switch the DCS off when you’re just
tuning around the band!
2) During DCS operation, you may set up the VX-3R such that a ringing “bell” sound alerts you to the fact
that a call is coming in. See page ?? for details.
DCS Code Inversion
The DCS system was first introduced in the commercial LMR (Land Mobile Radio) service, where it is now
in widespread use. DCS is sometime referred to by its different proprietary 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 rate of 134.4 bps
(bit/sec). Occasionally, signal inversion can result in the complement of a code being sent or received. This
prevents the receiver’s squelch from opening with DCS enabled, 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 amplification stages may result in inversion of a
transmitted or received DCS code. While under most circumstances this should not occur (amplifier
designs and industry standards take this into account), if you find that your receiver squelch does not open
when both you and the other station are using a common DCS code, you or the other station (but not both)
can try the following:
Vertex Standard Co., Ltd.
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