PIDATV filter and modulator solution for SR100 to SR650

[F6DZP]

Hello,

I have found a solution for building an interface for the Raspberry Pi that can filter all SR values between 100kS/s and 650 kS/s, just using a potentiometer. This potentiometer will be changed by a digital potentiometer MAX5478-EUD+ ( Radio Spare) next week and the raspberry Pi will be able to setup via I2C the frequency we want for the SR chosen. We will be able to chose any SR we want below SR650 kS/s and the filter will be adjusted.
No PIC, no DAC, no processor, just the use of a little chip from Linear Technology : the LTC1569-7.

I have just plug the IQ output of my proto_filter in the end a a Digithin for using the U2970B already made and it works well, as it is only made on a veroboard ...

Perhaps Brian G4EWJ will be interested in adapting this idea for a new PiModulator pcb (?).

Result, and proto schematic can be found here :http://www.vivadatv.org/viewtopic.php?f ... 1352#p1352

I am not an electronic engineer, so sure the schema can be optimized... But this is a first solution that show that it can work well.

Jean-Pierre F6DZP

[G4KLB]

How low can we go!!!!!!!!!!
First test at SR125

SR-125s.jpg (196.07 KiB) Viewed 3788 times

[G4KLB]

Very usable at SR250

SR-250s.jpg (208.98 KiB) Viewed 3788 times