See the [blog post](https://blog.porucha.net/2024/pico-sdr/) for more information. Older code the article is mostly referring to can be found in the branch `old` and a more up-to-date approach in the branch `master`.
This branch contains code to use RP2040 and some passives as a superheterodyne receiver. It is still very much work in progress.
Please refer to [the simulation](https://www.falstad.com/circuit/circuitjs.html?ctz=CQAgjCBMB0CsCmBaMAGEAOW0AsLboHYA2SWSIsWMIkAtFaFFCWNBZMAKEoE5wV06ENiE8ekYULZpUTOfM4BzfoMnhU2NfU4AlED2ybERTeh41jmmfpHyZ0IrHAOn9OJ0goC4AMyQhiOa+RGiBNE4AkgBi3ESihiBh-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).
5. Alternatively [gqrx](https://www.gqrx.dk/) works fine with `rtl_tcp` input mode. Maximum sample rate seem to be 400 ksps, above that the samples are dropped. Make sure to set LNA gain to 0, gain control is digital and does not provide any benefits unless you lower your sampling rate significantly.