User manual

RF Technology WinTekHelp User Manual Page 23
WinTekHelp User Manual 3.2.2.5 Tx Start Delay
By clicking at the top or the bottom of the “Spin button” to the right of this field, one can step up or down
to the next “standard” RS470 tone. The field will display the tone value selected (in Hertz) and its EIA
code.
As well as CTCSS tones, from Rev 4 hardware, DCS codes can also be sent. These can be entered in the
conventional way as 3 digit octal codes. To specify that a DCS code is to be transmitted on a particular
channel, the checkbox called “DCS Enable” should be clicked on, and the appropriate code entered into
the “CTCSS Tone or DCS Code” edit box.
DCS codes can be transmitted “as is”, or “inverted”. The latter is convenient when dealing with a 3
rd
party receiver that effectively inverts the signal upon reception, ie “1”s cause a negative shift in the
frequency of the last IF stage before the discriminator. To “invert” a code before transmission, click on
the checkbox marked “Invert”.
.3.2.2.5 Tx Start Delay
In some repeater applications, it is helpful if the Exciter can be held up from keying up for a short while,
to avoid some race conditions. The field is in units of milliseconds.
The user can enter the number of milliseconds that they wish to use, or they can click at the top or the
bottom of the “Spin button” to the right of this field, in order to increase or decrease the value.
.3.2.2.6 No Tone Period
Generally, at the end of transmission, an exciter will remove the tone from being generated before the
transmission is stopped. In this way, the receiver, if it has tone squelch, will kill its Squelch before the
RF ends, to stop the impulse caused by the step response of the audio circuit when there is a sudden
cessation of the Carrier. The length of this No Tone Period can be entered into this field.
The user can enter the number of milliseconds that they wish to use, or they can click at the top or the
bottom of the “Spin button” to the right of this field, in order to increase or decrease the value.
.3.2.2.7 Tx Tail
In some repeater applications, it is useful to have an exciter remain keyed up for a period after PTT or
Loop has been released. This period can be entered in this field. The field is in units of seconds, but
fractions of a second can be defined with a decimal point, eg “2.2 seconds”.
The user can enter the number of seconds that they wish to use, or they can click at the top or the bottom
of the “Spin button” to the right of this field, in order to increase or decrease the value in seconds.
.3.2.2.8 Maximum Deviation
Exciters are required to limit the peak frequency deviation of the Carrier to any applied audio signal. The
level of this deviation is a function of the channel spacing and the frequency band.
Each exciter is factory configured with maximum deviations that range from 1.5Khz to 5.0kHz in 500Hz
steps. One can select the maximum deviation to use, by clicking on the button with the upside down
triangle, which is to the right of this field. This opens a menu of available maximum deviations, from
which the user can select one.
.3.2.2.9 Tone Deviation
Different tone panels and systems prefer CTCSS tones and DCS codes to be generated with different
deviations.
One can select the tone deviation to use by clicking on the button, with the upside down triangle, which is
to the right of this field. This opens a menu of available tone deviations, from which the user can select
one.
The actual tone deviation is set up at calibration to be a percentage of maximum deviation. Nominal
values of 15%, 14%, etc down to 3% are programmed into the exciter. As a consequence, the numeric
values shown are dependent on the choice of maximum deviation. For example with a maximum
deviation of 5kHz, the tone deviations will range from 150Hz to 750Hz in steps of 50Hz, but with 2.5kHz
maximum deviation, they will vary from 75Hz to 375Hz in 25Hz steps.