User's Manual

6.5.1 FREQUENCY SELECTION
The Frequency page has fields for the transmit and receive frequencies for each channel. Channel
information can be entered by clicking on the appropriate box and entering the desired frequency. The
frequency chosen must be within the operating range of the radio and on a frequency for which the
synthesizer is capable of channeling i.e. for VHF, divisible by 2.5 kHz and for UHF, divisible by 5 or 6.25
kHz. When the RNET compatibility mode is chosen via the settings menu, only channel one and two are
available for programming.
6.5.2 SETTINGS
The Settings page allows for programming various parameters of the radio. These are detailed below:
Audio Input-Allows a choice between the two audio inputs for transmit, the Aux In input and the
Microphone input. As a rule, the microphone input has higher gain, but conversely, cannot accept as high
an input level. If the Microphone input is selected, the Microphone Gain box to its right will allow a choice
of two gain settings; there is no microphone gain setting available on the alignment page. Note that even if
signals are applied to both inputs, only the one selected will be transmitted. Factory default is AUX IN.
TX Pre-emphasis-Allows for the signal path from AUX IN and the MIC IN input to be either pre-
emphasized or flat. Most applications where the AUX IN input is used work best with a flat response.
Factory default is flat response.
RX De-emphasis-Allows for the signal path from the discriminator to the AUX OUT and Audio Out to be
either de-emphasized or flat. Most applications where the AUX OUT output is used work best with a flat
response. Factory default is for flat response.
Busy Channel Lockout-Prevents the transmitter from activating when the carrier detect output is true. Used
to prevent interference on a channel where activity already exists. Not normally enabled in half duplex
operation since the transmit and receive channels are not on the same frequency. Factory default is for this
function to be off.
Squelch Enable-Allows the receive audio paths to be muted when the carrier detect output is false. Used to
prevent the output of noise from the audio outputs when no signal is present. Due to the finite squelch
attack time, some high-speed modems work best with unsquelched audio. The factory default is for this
function to be set for never mute.
DCD Output Logic Level-Allows the setting of the polarity of the DCD (Data Carrier Detect) output.
Active high means that the true state is a logic high while active low means that the true state is logic low.
Normal setting is active high. The factory default is active high.
Microphone Gain-Available when the Audio Input selection is set to Microphone. This box allows the gain
of the signal at the Microphone input to be set either low or high. Factory default is for the Microphone
input gain to be set to low. Note that if the Audio Input is set to AUX IN above, no signal from the
Microphone input will be passed to the transmitter.
Audio PA-Turns the AUDIO OUT output on or off. Turning the AUDIO OUT output off when not needed
saves current drain in receive.
RX Discriminator Coupling-Selects whether the coupling from the discriminator output on the RF board is
AC or DC coupled to the control/loader board. Since the audio outputs of the control/loader board are AC
coupled, this function is normally set for AC as well. Setting this function to DC will extend the low
frequency receiver response somewhat, but makes the audio output subject to clipping due to DC offsets on
the discriminator output. For true response to DC, a hardware jumper options can be made for DC coupling
at the AUX OUT. (See the Hardware Options section under Maintenance for details on this option.) If this
is done, this function should be set for DC. For direct-modulated type of data streams such as true FSK,