RELM Communications Inc SRU50ABC ユーザーズマニュアル
S Series Repeater USER MANUAL
©RELM Communications Inc. Revision 1.0
20
Note: The modulation flatness will rise around 2KHz if the SR35/50 is fitted with Butterworth or Chebychev type
filters for the main limiter post LPF as used in the EIA-603 Build. It is due to the filters group delay distortion. For
a flatter response ensure the standard Bessel filter is fitted.
filters for the main limiter post LPF as used in the EIA-603 Build. It is due to the filters group delay distortion. For
a flatter response ensure the standard Bessel filter is fitted.
7. Set the transmitter carrier center frequency by adjusting the "Ref Bias" Level if necessary. Check again step 6 as
there is some interaction from the reference oscillator due to non-linearity. Repeat as necessary.
there is some interaction from the reference oscillator due to non-linearity. Repeat as necessary.
8. Save as defaults.
9. Return the jumpers as previous in step 2. Adjust the Tx Compress Level RV2 for the standard system deviation
level. Usually 3KHz for 25KHz channel spacing and 1.5KHz for 12.5KHz spacing.
level. Usually 3KHz for 25KHz channel spacing and 1.5KHz for 12.5KHz spacing.
10. Set the VF level to the standard input level (-10dBm) and adjust the compress Tx VF Gain to just compress.
11. Go to the Channel Info screen and click on the channel number to be allocated to the calibration results. Click
on Get Defaults, then OK.
on Get Defaults, then OK.
12. Go to the next channel and load defaults. Key in the appropriate RF frequencies and set the VCO Level for the
same deviation as in step 9. Repeat this step for all the channels required. Note that a small error will result in the
calibration of the "Ref Level" as in step 6 if the next channel frequency varies greatly from the original cal
frequency. Recalibrate the "Ref Level" if necessary.
same deviation as in step 9. Repeat this step for all the channels required. Note that a small error will result in the
calibration of the "Ref Level" as in step 6 if the next channel frequency varies greatly from the original cal
frequency. Recalibrate the "Ref Level" if necessary.
Caution:
Due the high degree of adjustment available in the SR35/50, check the PLL stability by
monitoring the PLL tune voltage with a CRO at the onset of PTT for minimal ringing.
monitoring the PLL tune voltage with a CRO at the onset of PTT for minimal ringing.
Description of Program Functions
Synthesizer Control
The SR35/50 Base Station has the facility for precise software control of the PLL characteristics. This provides user
with additional flexibility and capability for specialized or precise setting. The following program functions allow for
control of the fractional-N synthesizer and are described as such:
with additional flexibility and capability for specialized or precise setting. The following program functions allow for
control of the fractional-N synthesizer and are described as such:
PLL Correction Factor: Controls the relative amount of charge current into the PLL charge - pump circuit. The
value for the PLL Correction Factor is loaded into the receiver and exciter synthesizer during normal operation. It is
primarily used to control the dynamic PLL settling characteristics. A value of 0 will provide a minimum current and
hence a slow and under damped loop response. A value of 255 will provide the maximum current and hence a fast
and overdamped loop response.
value for the PLL Correction Factor is loaded into the receiver and exciter synthesizer during normal operation. It is
primarily used to control the dynamic PLL settling characteristics. A value of 0 will provide a minimum current and
hence a slow and under damped loop response. A value of 255 will provide the maximum current and hence a fast
and overdamped loop response.
Bin Accel Main: Same as PLL Correction Factor except that the value for the Bin Accel Main is only loaded into
the exciter synthesizer during the transmitter modulation period. It is primarily used to control the static PLL
characteristics. This will allow adjustment for a maximally flat modulation response near the cutoff frequency of the
PLL. A value of 0 will provide a minimum current and hence an under damped response. A value of 255 will
provide the maximum current and hence an overdamped response.
the exciter synthesizer during the transmitter modulation period. It is primarily used to control the static PLL
characteristics. This will allow adjustment for a maximally flat modulation response near the cutoff frequency of the
PLL. A value of 0 will provide a minimum current and hence an under damped response. A value of 255 will
provide the maximum current and hence an overdamped response.
Modulo: A modulo value of 8, sets the synthesizer comparison frequency to 8 times that of the Channel Spacing
(synthesizer step size). A value of 5 is 5 times respectively.
(synthesizer step size). A value of 5 is 5 times respectively.