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M0LTE / pi-transceiver

An attempt to build a complete ham radio transceiver around a Raspberry Pi
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RF Attenuator before Lime SDR RX Input #29

Open ribbotson opened 2 years ago

ribbotson commented 2 years ago

Mike proposed a digital controlled attenuator befor the RX input of the Line SDR. This will allow the input level to be adjusted to keep the least significant bits at noise level an maximise the available dynamic range of the 12 bit ADC in the Lime SDR. Chip attenuators like PE4302/PE4312 or F1956 are possible candidates. The interface is usually either parallel or simple bit serial with clock, data,and latch

M0LTE commented 2 years ago

@G4CDF has suggested 2 bits parallel, might be simplest for now. Can always iterate. Though if anyone builds hardware we can easily drop in support for it!

G4CDF commented 2 years ago

There is a possible advantage of the software monitoring the signal entering the LimeSDR and using an attenuator to keep it within the ADC max limit. This would have to be done in real time. Not sure if this would work though in practice. Could use PIN attenuators as per IC7300/9700 although these are manually controlled.