Asking the fleet what it is doing…
monad-knowledge Wi-Fi sensing lab · FIIT STU

The capture format

Two captures, aligned.

Put two photographs of the same room side by side and the differences jump out. This page does that with two real capture files from the archive: every difference below is between the files themselves, not between two descriptions of them.

In plain words A capture is a binary file, and a binary file is readable exactly when you can put a finger on a byte and be told what it is. This is that finger: a real file from the archive on the left, its bytes in the middle, and the meaning of what you point at on the right. Point your own reader at the same file and compare.

Fact 5 GHz · HT20 · csid 0.2.0 2.4 GHz · HT20 · csid 0.2.0
Session monad05_exp-chan-36_20260901-012425 monad04_rate-ladder-sweep_20260830-235235
Band 5 2.4
Channel 36 11
Declared width HT20 HT20
Envelope in the archive csiq.zst csiq.zst
csid version 0.2.0 0.2.0
Writer modern modern
Quarantined False False
Records in the archive 57996 879244
Records in this slice 2000 2000
Slice bytes 1666473 1667043

What each writer recorded

Two captures can both stamp format version 1 and differ by five type codes. Adding a type code is not a version bump, because a reader skips what it does not know — so this table, and not the header, is the version answer.

Field 5 GHz · HT20 · csid 0.2.0 2.4 GHz · HT20 · csid 0.2.0
MONO_US (0x12) recorded recorded
BW_ANTSEL (0x11) recorded recorded
VENDOR_HDR (0x14) recorded recorded
NODE_* (0x40–0x43) not recorded not recorded
NODE_NIC_TEMP_C (0x44) not recorded not recorded
RSSI (0x0C) not recorded not recorded
PHY (0x05) not recorded not recorded
SRC_MAC (0x09) not recorded not recorded

What the records themselves say

Measured 5 GHz · HT20 · csid 0.2.0 2.4 GHz · HT20 · csid 0.2.0
Width code in the record HT20 HT20
Tones 52 52
Bandwidth 20 MHz 20 MHz
Tone spacing 312.5 kHz 312.5 kHz
Chains 2 2

Received power, and the sentinel

Over the slice 5 GHz · HT20 · csid 0.2.0 2.4 GHz · HT20 · csid 0.2.0
Chain readings 4,000 4,000
Measured range -96 to -58 dBm -70 to -57 dBm
−127 sentinels, counted apart 0 0

How each one reads its own matrix

The causality statistic separates the correct coefficient order from the swapped one. It is printed for both captures because four of the ten catalogue samples invert the specification's result, and the difference between two files is one of the places that shows.

Capture Imaginary first Real first Verdict
2.4 GHz · HT20 · csid 0.2.0 14.74 0.069 as specified
5 GHz · HT20 · csid 0.2.0 26.59 0.058 as specified

Every sample is a byte-preserving slice of a real capture from this project's archive. Record framing and lengths are bit-identical to the original. The only bytes that changed are the six-byte MAC addresses, relabelled into the RFC 7042 documentation range — in the SRC_MAC field, in the session block, and inside the 272-byte driver header that keeps its own copy of the source address. Hostnames are not redacted: this site publishes node names already, and stripping them would remove the provenance these files exist to demonstrate.

Back to the format explorer