||Start/Stop Receiving, and close down the SDR software
||Set display size - See below for other display modes
||The AF output level is set as follows
- Mute - Click the Mute checkbox on to mute the AF output
- Slider left to attenuate the output; slider right to amplify the
- Volume knob counter-clockwise to decrease AF output level; clockwise
to increase AF output level
- Mouse scrollwheel over the dB digits to decrease/increase the AF
||The experimental noise reducer is a level
sensitive frequency filter. The spectrum of the received signal is
analysed, and any frequency whose amplitude is below the threshold set,
is zeroed - when switched on the NR does generate artifacts but I have
found that the brain is good at learning to ignore the
"twinkling" and pick out signals.
The SDR may be tuned using several mechanisms.
Move the mouse pointer over the digit you want to tune, eg if you
want to tune in steps of 100Hz then move the mouse pointer over the
100' Hz digit. When you tune a digit, eg 100Hz, all digits to the
right of that digit are set to zero. If you want to lock the tuning
rate, then RIGHT Click over the digit you want to lock the rate at, OR
LEFT click over the tuning rate indicator, ie the one showing x N KHz
If you click on the words MHz, KHz, or Hz, just under the main
frequency display, then the appropriate part of the frequency is set
to ZERO, ie click on KHz, and the KiloHertz portion is zeroed.
||1) Presets are SET by
holding down the SHIFT key, and simultaneously clicking the RIGHT mouse
button for a QUICK preset set.
2) Select a preset by LEFT mouse click.
3) You can edit a Preset by RIGHT clicking over the
preset you want to edit. (I will be extending this capability to editing
the band selectors soon).
4) Pressing the Ctrl key whilst over a preset will
toggle on/off the preset detail display panel
The Bandplans/presets are held in *.BPL files in the
same directory as the program. If you add another .BPL the SDR will
automatically find it the next time it starts up and add it to the list
if available Bandplans.
- AM selects Amplitude Demodulation
- BC selects an alternative AM demodulation mechanism which sometimes
sounds better for MW music stations
- USB selects Upper Sideband demodulation
- LSB selects Lower Sideband demodulation
- FM selects Narrow Band Frequency demodulation
- DRM tells the SDR to release the soundcard, & mute the output,
so as to enable the use of external s/w such as dream.exe to
demodulate the DRM signal - The tuning part of the G8JCFSDR is still
- Select the filter bandwidth appropriate for the demodulation mode
desired. 400Hz is good for CW, 2.0KHz is good for SSB, 3,4,5 kHz are
good for AM broadcasts.
- Click Music On for extended Bass response which is good for AM
- Click IF On for improved selectivity.
- Dyn is special kind of filter which automatically tracks the
greatest amplitude peak frequency of the received signal, and sets
the filter's centre to that peak in real-time.
- The G8JCFSDR provides fully adjustable filters. The adjustment
precision is 10 Hz. To adjust the High frequency cut-off, place the
mouse over upper Hz figures; use the mouse scrollwheel to roll the
HF cutoff frequency up or down. To adjust the Low frequency cut-off,
place the mouse over the lower Hz figures; use the mouse scrollwheel
to roll the LF cutoff frequency up or down.
- To reset the filters to their preprogrammed default pass-bands,
Right mouse-click over the cut-off adjust figures.
||The Notch facility allows you to notch out, over
-60dB suppression, an interfering signal. The notch facility is
particularly useful when two broadcast stations interfere and produce
that annoying heterodyne whistle. The Notch facility is implemented by a
- Off - Switch off the Notch filter
- Man - Switch on Notch filter in Manual mode
In Manual notch mode, the operator adjusts the notch centre
frequency using upper Hz figures (mouse scrollwheel), and the width
of the notch using the lower Hz figures (mouse scrollwheel). if the
Spectrum display is enabled, the notch frequency will be shown as a
red line, and if you select AFOut on the spectrum display, you will
see the affect of the width adjustment
- Auto - Switch on Notch filter in Automatic mode
In Automatic notch mode, the G8JCFSDR continuously and automatically
adjusts the notch centre frequency in real-time to notch out the
||The AGC, Automatic Gain Frequency, keeps the output level of
the G8JCFSDR at a uniform level - preset to a an output count of 16384.
The amount of Gain being applied by the AGC function is shown in the
lowest pane when Full display mode is selected. AGC is NOT a good thing,
but it is very convenient ! Try to adjust the DRT1's gain level
rather than relying on the AGC function if possible
- AGC is turned On/Off by clicking on the AGC Check Box
- N - Normal AGC time constants
- F - Fast AGC time constants
- S - Slow AGC time constants - Best for SSB reception
- You can adjust the AGC Attack and Decay time constants using the
upper and lower figure displays in the AGC box using the mouse
|The CONFIGURE button lets you configure the
A) Select audio devices
B) Set IF Frequency
C) Set DDS CLKIN
D) Calibrate DDS CLKIN
E) Select Parallel or Serial I/F to the h/w, Default is
Parallel - so uncheck it if you haven't got a parallel cable
F) Select the COM port for Serial mode
G) Select if you want to use the Intel SPL instead of
the G8JCF SPL (If you can find a copy of the iSPL to install)
||The G8JCFSDR has a built-in Oscilloscope, Spectrum Analyser
and Phase Angle display. Probably the most useful is the Spectrum Analyser
since it allows you to see the shape of the received signal, and also
activity around the received frequency.
- Freq - Select Spectrum Analyser mode
- Time - Select Oscilloscope mode
- Phase - Display Lissajous figures of Y1 and Y2, ie Y2 is used as the
- Filter - Display the filter passband as an overlay onto the received
signals (only applicable in Freq Mode)