This is the "Elephant in room" for me, designing and building the analog part of the front end. I know the theory I can apply some intuition on top but in the end is open to experimentation. Because I took the "brilliant" decision not to have a mixer in the front end and directly sample (actually under sample) the RF now I have to deal with larger frequencies (the opposite of simple) and I saved the cents to spend the dollars. The VGA (variable gain amplifier) in front of the

Next step in building the radio is to prepare to interface with the ADC (LTC2314-14) which is sending the samples in serial stream very much like SPI but has timing requirements in order to trigger the conversion and give sufficient time to complete the conversion. The datasheet is showing three timing diagrams two are pushing the timing to the limits and the third is more relaxed and easier to implement. The whole conversion cycle is taking 20 clk cycles, 16 cycles to transf

In order to make experiments we need to be able to hear the audio and I found a PMOD module in one of my boxes which fits perfectly my FPGA board. The module is question is pictured below PMOD AMP3 link to the manual https://digilent.com/reference/pmod/pmodamp3/reference-manual This module is using a I2S digital interface and master clock (MCLK) from the FPGA and can be used with i2C control or standalone (jumpers) I'm using without I2C for the time being in default settings

A short analysis of the HAM Radio HF bands led me to the idea of under sampling the incoming signal and eliminate the mixer altogether here is my rationale The HAM Radio bands are quite narrow in comparison to my ADC Nyquist band (0-Fs/2) Checking the datasheet of LTC2314-14  it seems that is suited for under sampling because it has good full power bandwidth, so in theory is should be feasible to use aliasing in our favor and make the band limited signal to fall in our Nyquis

This is an old idea that I keep recycling in my brain (what's left of it) - to build a simple radio made of two major components (two PCBs) - an analog front end and a digital processing board (the Spartan7 FPGA board that I designed previously) So brace yourself for a series of unfortunate events and silly mistakes that I'm going to make along the way. I will publish everything with good and bad with the obvious risk to look like a fool (I got to a stage in life when I don't

Last year I made a Sinclair Spectrum from scratch on the S7 Retro Board (actually was on a Zed Board which is out of reach for many hobby...

I always wanted to build a ADC and DAC board for my hobby experiments mainly in the digital radio domain. so here it is in a form of...