Lowering Rf Noise Floor With Dsp

Whether for use at microwaves or lower frequencies this rf amplifier is the chief element in determining the performance of the whole receiver.

Lowering rf noise floor with dsp. What i don t quite get is how lowering the rf gain can help dig a weak signal out of the noise. In signal theory the noise floor is the measure of the signal created from the sum of all the noise sources and unwanted signals within a measurement system where noise is defined as any signal other than the one being monitored. Vhf fm broadcast outside the band of interest which is hf 30mhz. Written by admin posted in amateur radio hf rtl sdr tagged with hf noise floor rtl sdr rtl2832 rtl2832u 10 comments.

The use of a low noise amplifier at the front end of the receiver will ensure that its performance will be maximised. January 24 2017 1 24 pm drone. The next most important element is the first mixer. Quickly sorted it out and pin pointed the problem to the 12v power.

Thus the phase noise from the lo must be lower than 108 dbm with an offset of 200 khz. But it will also lower the signal as well. However the noise temperature of a low noise 1st stage amplifier such a noise figure of such a device may well be. It may be the case that a 1st stage rf amplifier with a lower noise temperature say 150kelvins or a noise figure of 1 8db would bring the signal advantages of the lower signal value while still operating at room temperature.

The better shielded coax may masking a bigger problem with the overall system. Drake s specs imply that for a 6 khz bandwidth the noise floor should be below 118 dbm with the preamp off. Lowering the rf gain will lower the noise floor. Radio receiver noise floor.

Considering all of the uncertainties the numbers hold together remarkably well better than the likely accuracies in this case just dumb luck. Assuming that noise at the mixer is the same as at the antenna 121 dbm noise in 200 khz at the antenna p a ktb can be used. There is an extra section on bhi s website addressing these issues. Only problem i had was tx rf finding its way to the speakers through the compact in line.

A weak signal just means that it s not much stronger than the noise floor. Averaging causes a reduction in the noise floor by 2 51 db. Really suprised by how the dsp cuts out the noise floor when signals are weak. The better shielded coax may be attenuating high power higher frequency signals e g.

This reduction essentially differentiates danl from nf. You really have to hear it to believe it. For the measurements quoted in my previous message the receiver s noise floor is 119 dbm.