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TX and RX from Pluto to itself Doppler Radar Lesson 8a: Transmit a tone and look at what is received. Tune to the same frequency. HW: Play with parameters like automatic gain control (AGC) and manual gains. Put manual TX and RX gains on sliders. Look for saturation. gallicchio.github.io/learnSDR/lesson08a.html All GNURadio flowgraphs are at: github.com/gallicchio/learnSDR Learn SDR with Profess...

I use an RTL-SDR and a cheap GPS antenna to see some some of the Global Positioning System (GPS) satellite transmissions. gallicchio.github.io/learnSDR/lesson23.html All GNURadio flowgraphs are at: github.com/gallicchio/learnSDR Learn SDR with Professor Jason Gallicchio

CORRECTION: In the last third of the video, I say that there is a new bit of data at 100 Hz, with each bit being 10 cycles of the 1023-bit Gold code. My memory was wrong. Bits are transmitted every 50 Hz, with each data bit XORed with 20 complete cycles of 1023 chips. Thank you to okan erturk for correcting me in the comments. Gold Codes are XORed combinations of taps from Linear Feedback Shift...

Pseudo-random numbers generated by a Linear Feedback Shift Registers (LFSRs) are useful in communications and are required-knowledge to see GPS transmissions. Wikipedia reference: en.wikipedia.org/wiki/Linear-feedback_shift_register gallicchio.github.io/learnSDR/lesson21.html All GNURadio flowgraphs are at: github.com/gallicchio/learnSDR Learn SDR with Professor Jason Gallicchio

Learn SDR with Professor Jason Gallicchio at Harvey Mudd College Lesson 20: Resolving the Phase Ambiguity and Differential Encoding First just look at the output for BPSK and see that sometimes it's inverted. For QPSK, explicitly decode all 4 possible phase shifts. I've sneakily avoided comparing TX to RX until now because of this issue. Option 1: sync word to determine which of 4. For packet d...

Learn SDR with Professor Jason Gallicchio at Harvey Mudd College Lesson 19: Carrier Phase Synchronization with a Costas Loop Reminder: Receiver antenna's r(t) = A cos(2πft ϕ) turns into SDR samples of z(t) = A e^iϕ e^(2πi(f-f0)t) (Phases are preserved through the frequency shifting down-conversion process.) The hardware clocks are never matched (in sync) Even if they were ticknig at the same ra...

First look at eye diagram of 16sps or more incoming signal real part We'll basically be describing the function of the "Symbol Sync" Block Timing Error Detector (TED) Time Lock Loop: nudge an internally-running numerically-controlled oscillator (NCO) slightly faster or slower. Interpolation to really nail down the right place to sample. This is done by selecting from a bank of filters, each of ...

Learn SDR with Professor Jason Gallicchio at Harvey Mudd College Lesson 17: Frequency Locked Loop (FLL) "FLL Band-Edge" Block Filter that takes advantage of the excess bandwidth and - to nudge frequency of a NCO. This filter needs to know about the excess bandwidth alpha. It doesn't need to take Fourier Transforms, just have an appropriately tailored impulse response, which is pre-computed once...

Learn SDR with Professor Jason Gallicchio at Harvey Mudd College Lesson 16: Constellation Modulator It does the Root Raised Cosine filtering Packed versus Unpacked Bytes HW: Look at QPSK and other built-in constellations. Don't bother trying to "decode" anything by hand this is very difficult before Timing and Carrier synchronization. HW: Try fewer samples per symbol. 2 is the absolute minimum....

Learn SDR with Professor Jason Gallicchio at Harvey Mudd College Lesson 15b: Pulse Shaping Matched Filter gallicchio.github.io/learnSDR/lesson15.html All GNURadio flowgraphs are at: github.com/gallicchio/learnSDR Learn SDR with Professor Jason Gallicchio

Lesson 14 Pulse shaping and Nyquist criteria (Nyquist ISI criterion) Each symbol must have zeros at the peaks of all other symbols. Raised-cosine filter is a popular choice, but we want a low-pass-like filter at the TX and a matched filter at the RX. Root-raised-cosine filter (RRC) on both TX and RX. There's a block. roll-off factor, beta (alpha in GNUradio), is a measure of the excess bandwidt...

Learn SDR with Professor Jason Gallicchio at Harvey Mudd College Lesson 13: QPSK naive with no pulse shaping (naive: 100x repeat with no pulse shaping) Chunks to Symbols You get 2x as much data in the same bandwidth, because the spectrum is no longer symmetric. The redundancy did buy you some tolerance for noise, so it makes sense for GPS, for example, to use PSK. Constellation Object Constella...

Learn SDR with Professor Jason Gallicchio at Harvey Mudd College Lesson 12 Binary Phase Shift Keying (BPSK) (naive rectangular pulses: 100x repeat with no pulse shaping) No pulse shaping just slow 1,-1 times the carrier. [0,1,0,1,0,0,0,1,1,0,0,0,1,1,1,1] Chunks to Symbols Really need to fine tune frequency. Ambiguity: Even when tuned, how do you ever tell apart 1 and -1? Relevant for communicat...

Learn SDR with Professor Jason Gallicchio at Harvey Mudd College Lesson 11: ASK amplitude shift keying from Pluto to SDR. gallicchio.github.io/learnSDR/lesson11.html All GNURadio flowgraphs are at: github.com/gallicchio/learnSDR Learn SDR with Professor Jason Gallicchio

Learn SDR 10: On-Off Keying (OOK) from Pluto to RTL SDR

Learn SDR 09: Pluto to RTL SDR

Learn SDR 08b: Doppler Radar with Pluto SDR

Learn SDR 07: Frequency Spectra and the Fast Fourier Transform (FFT)

Learn SDR 06: Sampling

Learn SDR 05: On-Off Keying (OOK) with 4 Button Remote

Learn SDR 04: What's Inside an SDR: Designing one from First Principles

Learn SDR 03b: Negative Frequency Question

Learn SDR 03a: Complex Numbers in SDR

Learn SDR 02: Signal Generator into RTL-SDR

Learn SDR 01: FM Receiver with RTL SDR

Optics Lab 4c HeNe Laser Cavity Longitudinal Modes

Optics Lab 4b HeNe Laser Cavity Beam Profile

Optics Lab 4a HeNe Laser Cavity Spatial Modes

Optics Lab 7 Diffraction