Lab 6.6 - Zynq RX-only observation on the clean image¶

Goal¶

Capture the first receive-only CI16 IQ artifact from the clean stock Pluto-like image on the Zynq-7020 + AD9361 board and compare its FM-band spectrum with the earlier RTL-SDR observation.

This lab answers the practical question:

Can the cleaned-up board image already produce a reproducible host-side RX capture package before any TX work or attenuator-based loopback is available?

Why this lab matters now¶

At the current stand stage:

no attenuators are available yet;
TX remains intentionally conservative under the course-clean overlay;
antennas are connected to RX1 on the Zynq board and to the independent RTL-SDR path.

That makes RX-only the correct next hardware step. It validates:

clean image bring-up;
network IIO access;
AD9361 RX configuration from the host;
CI16 dataset generation;
offline replay through the Block 9 tooling;
qualitative cross-receiver comparison on the same FM broadcast band.

Executable files¶

File	Purpose
`blocks/block_06_rf_frontend_and_ad9363/python/lab_6_6_capture_zynq_rx_only.py`	configure RX, capture CI16 IQ, write manifest
`blocks/block_06_rf_frontend_and_ad9363/python/lab_6_6_compare_receivers.py`	overlay Zynq and RTL-SDR FM spectra
`datasets/lab6_6_zynq_rx_observation/manifest_fm_103119454.yaml`	first curated clean-image RX dataset
`datasets/lab6_6_zynq_rx_observation/manifest_fm_103119454_live_20260622.yaml`	repeated live RX-only dataset captured on 2026-06-22

Live capture command¶

Run from the repository root:

python blocks/block_06_rf_frontend_and_ad9363/python/lab_6_6_capture_zynq_rx_only.py \
  --uri ip:192.168.40.1 \
  --center-frequency-hz 103119454 \
  --sample-rate-hz 2400000 \
  --rf-bandwidth-hz 2000000 \
  --gain-control-mode manual \
  --rx-hardwaregain-db 50 \
  --rf-port-select A_BALANCED \
  --sample-count 262144 \
  --out-iq datasets/lab6_6_zynq_rx_observation/raw/zynq_rx_fm_103119454Hz.ci16 \
  --manifest-out datasets/lab6_6_zynq_rx_observation/manifest_fm_103119454.yaml

The capture script:

connects to the remote IIO context;
snapshots the current RX state;
applies a short receive-only FM observation setup;
captures interleaved CI16 I/Q samples from cf-ad9361-lpc;
restores the previous RX state;
writes the CI16 file and a dataset manifest with checksum and capture metadata.

Offline analysis¶

Analyze the captured CI16 package through the generic Block 9 reader:

python blocks/block_09_recording_and_analysis_tools/python/lab_9_2_read_ci16_iq_and_analyze.py \
  --manifest datasets/lab6_6_zynq_rx_observation/manifest_fm_103119454.yaml

This writes:

docs/assets/lab92_lab6_6_zynq_rx_fm_103119454_spectrum.png
docs/assets/lab92_lab6_6_zynq_rx_fm_103119454_time_preview.png
docs/assets/lab6_6_zynq_rx_fm_103119454_metrics.json

Cross-receiver comparison¶

Overlay the Zynq RX dataset and the existing RTL-SDR FM observation:

python blocks/block_06_rf_frontend_and_ad9363/python/lab_6_6_compare_receivers.py \
  --zynq-manifest datasets/lab6_6_zynq_rx_observation/manifest_fm_103119454.yaml \
  --rtl-manifest datasets/lab1_0_rtl_sdr_observation/manifest_fm_103119454.yaml

This writes:

docs/assets/lab66_lab6_6_zynq_rx_fm_103119454_vs_lab1_0_rtl_sdr_fm_103119454_spectrum.png
docs/assets/lab66_lab6_6_zynq_rx_fm_103119454_vs_lab1_0_rtl_sdr_fm_103119454_metrics.json

Latest measured rerun¶

The repository also keeps a repeated live rerun captured on 2026-06-22:

datasets/lab6_6_zynq_rx_observation/manifest_fm_103119454_live_20260622.yaml
docs/assets/lab92_lab6_6_zynq_rx_fm_103119454_live_20260622_spectrum.png
docs/assets/lab92_lab6_6_zynq_rx_fm_103119454_live_20260622_time_preview.png
docs/assets/lab6_6_zynq_rx_fm_103119454_live_20260622_metrics.json
docs/assets/lab66_lab6_6_zynq_rx_fm_103119454_live_20260622_vs_lab1_0_rtl_sdr_fm_103119454_spectrum.png
docs/assets/lab66_lab6_6_zynq_rx_fm_103119454_live_20260622_vs_lab1_0_rtl_sdr_fm_103119454_metrics.json

That rerun used:

103.119454 MHz center frequency;
2.4 MS/s sample rate;
2.0 MHz RF bandwidth;
manual 45 dB RX gain;
passive RX-only OTA reception.

What should be recorded¶

At minimum, keep:

context URI and firmware/model strings from the clean image;
center frequency, sample rate, RF bandwidth, gain mode and gain;
RF port selection (RX1 path assumptions);
CI16 file checksum;
FFT plot and time preview;
one short comparison note against the RTL-SDR observation.

Interpretation notes¶

This is a receive-only baseline, not an absolute calibrated measurement.
The overlay plot should be interpreted by spectral shape and occupancy, not by absolute amplitude.
Wideband FM is not a narrow single-tone test, so peak-bin location is only a quick sanity check.
The next engineering step after this lab is a controlled RX gain/overload table, not TX loopback.

Report checklist¶

[ ] State that TX remained in the safe course-clean default state.
[ ] Attach the Zynq CI16 manifest.
[ ] Record the exact RX gain mode and hardware gain.
[ ] Include the offline spectrum plot from the CI16 reader.
[ ] Include the receiver comparison overlay.
[ ] State whether the Zynq clean-image RX path is ready for future Block 6/7 labs.

Engineering conclusion template¶

The clean-image Zynq board was observed in receive-only mode at ____ MHz with
sample rate ____ MS/s, RF bandwidth ____ MHz, gain mode ____ and RX gain ____ dB.
The capture was saved as CI16 with checksum ______ and replayed through the
Block 9 reader. Compared with the earlier RTL-SDR FM observation, the Zynq
capture does / does not show a consistent occupied FM-band shape because ______.
This means the clean-image RX path is / is not ready for the next hardware lab because ______.