Hi Ronald
You are absolutely correct, there is NO description of these features in the QuickStartGuide unfortunately, mea culpa, sorry :-(
As a general rule, when you hover the mouse over an item on the G8JCFSDR display, a text box should be displayed explaining what the control is for, and what actions are available to the Operator for that control.
NB stands for Noise Blanker, ie impulse type noise. There are 2 different types of algorithm implemented, hence why the operator can select A or B and hear which algorithm better suits their situation. For each algorithm the operator can select L(ow) M(edium) H(igh) preset strength of Blanking, or the operator can use the slider to manually adjust the strength of the blanking.
NR stands for Noise Reduction, tries to improve the SNR by reducing the background noise. There are 2 different types of algorithm implemented, hence why the operator can select A or B and hear which algorithm better suits their situation. For each algorithm the operator can select L(ow) M(edium) H(igh) preset strength of Noise Reduction, or the operator can use the slider to manually adjust the strength of the Noise Reduction. In addition, if the Operator right clicks on the On checkbox (hover the mouse over the On Check Box for text explanation), dialogue box is displayed enabling the Operator to have very fine grained control over the Noise Reduction algorithms - if you want to reset any of the values back to their default value, right click over the digits.
Notch stands for a deep notch in the receiving passband so as to null-out heterodyne or other annoying signals. In IF Mode, the Notch is applied at the IF frequency. In Mirror mode the Notch works in reverse, ie all of the passband is nulled apart from the notch frequency. In Auto Mode, the notch will automatically adjust in frequency to keep the interfering signal nulled out. If Auto Mode is unchecked you can manually adjust the notch frequency, and the width of the notch, a width of less that 100Hz doesn't usually change the quality of the AF output much.
IF Filter, aka Passband tuning", applies filtering to the incoming signal from the front-end, ie to the IF signal. Usually filtering is applied only to the demodulated signal, ie the base-band AF. The IF Filter can help sometimes when two very strong AM broadcast are very close, ie less than 5KHz, together. Operators of ICOM equipment should find this feature operates much like the Twin PBT feature on their receiver/transceiver - I'm sure Yaesu/Kenwood must have similar capability, but I have an ICOM IC7200.
AGC is Automatic Gain Control, and maintains the AF output within a narrow range despite huge differences in the strength of the RF signals. Normal operation is to have AGC always switched on. "Fast" AGC works well for strong AM stations, eg LW/MW band. "Normal" AGC works well for SW AM stations. "Slow" is designed for SSB reception, eg Amateur Radio, Volmet, Coastguard.The Fast/Normal/Slow settings control the Attack and Decay times of the AGC, ie how quickly/slowly the AGC algorithm adapts to changing signal levels.
Hopefully I've shed some light on these facilities, please free to ask further questions about any aspect of the G8JCFSDR.
Thanks for asking
73
Peter - GM8JCF
