User manual

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can be emitted by pressing the corresponding keys. They can also be entered during reception
and emitted when the next transmission begins.
Compander (compressor/expander)(settings menu: S03 EXP, S04 COM).
Compander is an invented word consisting of com(pressor) and (ex)pander.
With each radio communication, undesired background noise is transmitted along with the voice.
For reducing this noise to a minimum, a compander system is used: The voice signal is compressed
in the transmitter, i.e. quiet voice is intensified, loud voice is attenuated. In this way, the original
dynamic range, i.e. the difference between loud and quiet passages of the voice transmission,
is reduced. For the xm 4006e, the compressor functions with a fixed compression ratio of 2:1.
The compressed signal can be transmitted a bit louder without being distorted. Thus, the so called
signal-to-noise ratio is increased. In the receiver, the voice signal is again expanded with a ratio
of 1:2 to its original dynamic range. Although the voice signal has again the original dynamic
range during reception, the signal-to-noise ratio has been increased.
Generally, the compander system should only be used, if all radio sets in a speech circuit are
equipped with this function. Sometimes its expedient to use the compressor only, e.g. in case
of very weak radio contacts in AM, when the voice signal can hardly be understood. For this
reason, the compressor and expander can be switched separately in the xm 4006e radio set.
Note: If you wish to transmit data with this device (e.g. packet radio), the compander system must
be switched off!
Roger beep (settings menu: S09 RB)
Tone signal at the end of a transmission: Signals to your radio partner that the message is finished
and the channel is free to transmit an answer.
Transmit time limit (memory menu: M01 TOT)
On one hand, a permanent transmission on one channel can lead to damages on the radio set.
On the other hand, messages shall be as short as possible to give other radio partners the
opportunity to participate in the discussion. The time-out timer prevents the permanent transmission:
If the duration of a transmission exceeds a specified time, it is automatically interrupted.
Tone squelch methods CTCSS and DCS (settings menu: S01 RXC, S02 TXC)
The xm 4006e features three tone squelch methods. The most well-known method is CTCSS
(Continuous Tone Coded Squelch System), the two other ones are DCS methods (Digital Coded
Squelch): DCSN (n for normal) and DCSI (i for inverse). All three methods have one thing in
common: They replace the manual squelch and simultaneously function similar to a selective call
system. Squelch function often depend on the field strength or are controlled via the signal-to-
noise ratio. This means that they always depend on the varying conditions or reception: Each
transmission on the selected channel and each interference carrier as well will open the squelch.
This is particularly disturbing if the radio set is used in an Internet gateway: Each interference/over-
shoot opens the squelch and the interference is transmitted to all other gateways in the network.
Nothing but permanent monitoring through the SysOp (system operator) and switching off the
concerned gateway can resolve this problem.
As long as the reach is not exceeded, the CTCSS and DCS functions are much more reliable
and comfortable: All radio sets belonging to a certain speech circuit have to be operated using
the same CTCSS frequency or the same DCS code. The squelch of the receiving radio set only
opens when a signal featuring the corresponding CTCSS frequency/the corresponding DCS code
is received. The manual squelch and ASC are switched off. CTCSS and DCS still function when
the signal is already very weak and has a considerable background noise. The xm 4006e provides
you with 50 different CTCSS tones. For DCSN, 107 codes are available, for DCSI another 107
codes. In the settings menu, the method (CTCSS, DCSN, DCSI) and the frequency or the code
for reception are entered under S01 RXC and the same is entered for transmission under S02
TXC. Using the TSQ key on the radio set, the selected method is switched on or off. A different
method and a different frequency or code can be stored for each channel.