Data Export Commands

Commands for exporting measurement data and screen captures.

data

Output measured S-parameter data.

Syntax

data [channel]

Parameters

Array	Description
0	S11 (CH0) — measured or calibrated reflection
1	S21 (CH1) — measured or calibrated transmission
2	Calibration: Directivity (ED)
3	Calibration: Source Match (ES)
4	Calibration: Reflection Tracking (ER)
5	Calibration: Transmission Tracking (ET)
6	Calibration: Isolation (EX)

Output Format

One line per sweep point, real and imaginary parts:

<real> <imaginary>

Examples

ch> data 0
0.998234 -0.023456
0.997234 -0.024567
0.996234 -0.025678
...

ch> data 1
0.012345 0.001234
0.012456 0.001345
...

Notes

• Values are linear complex pairs (not dB)
• Arrays 0–1 reflect current calibration state (corrected if cal on)
• Arrays 2–6 contain raw calibration error terms — useful for custom post-processing
• For uncalibrated measurement data, disable cal first: cal off
• Number of lines equals sweep_points (query with sweep)

Converting to dB

import math
magnitude_dB = 20 * math.log10(math.sqrt(re**2 + im**2))
phase_deg = math.degrees(math.atan2(im, re))

---

frequencies

Output frequency list for current sweep.

Syntax

frequencies

Output Format

One frequency per line in Hz:

1000000
2000000
3000000
...

Example

ch> frequencies
1000000
1990099
2980198
...

Notes

• Frequencies are the actual sweep points
• Number of lines equals sweep_points
• Use with data to get frequency-indexed measurements

---

capture

Capture screen as binary data. Supports raw RGB565 and an RLE8 palette-compressed format.

Syntax

capture [rle8]

Output Format

Binary RGB565 pixel data, row by row from top-left:

• 320x240 display: 153,600 bytes (320 * 240 * 2)
• 480x320 display: 307,200 bytes (480 * 320 * 2)

RGB565 Byte Order

Each pixel is 2 bytes, little-endian RGB565:

Byte 0: GGGBBBBB (low byte)
Byte 1: RRRRRGGG (high byte)

Example Usage (Python)

import serial
from PIL import Image

ser = serial.Serial('/dev/ttyACM0', 115200)
ser.write(b'capture\r')

# For 320x240 display
data = ser.read(320 * 240 * 2)

# Convert to image
img = Image.new('RGB', (320, 240))
pixels = []
for i in range(0, len(data), 2):
    rgb565 = data[i] | (data[i+1] << 8)
    r = ((rgb565 >> 11) & 0x1F) << 3
    g = ((rgb565 >> 5) & 0x3F) << 2
    b = (rgb565 & 0x1F) << 3
    pixels.append((r, g, b))
img.putdata(pixels)
img.save('capture.png')

RLE8 Compressed Format

When rle8 is specified (requires __CAPTURE_RLE8__), the output uses palette-based RLE compression for significantly smaller transfers:

Header:

Field	Type	Description
magic	uint16_t	0x4D42 (BMP signature)
width	uint16_t	Display width
height	uint16_t	Display height
bpp	uint8_t	8 (bits per pixel)
compression	uint8_t	1 (RLE8)

Palette block:

Field	Type	Description
size	uint16_t	Palette data size in bytes
palette	uint16_t[]	RGB565 color palette entries

Row data: Each row is PackBits-compressed with a uint16_t length prefix followed by the compressed bytes.

Note

The capture command pauses sweep during data transfer to ensure a consistent image.

---

dump

Dump raw ADC sample data (requires ENABLED_DUMP_COMMAND).

Syntax

dump

Output Format

Binary raw ADC samples from the TLV320AIC3204 codec.

Usage

For debugging audio codec and signal processing:

1. Connect known signal
2. Run dump command
3. Capture binary output
4. Analyze in external tool

---

sample

Select the sample acquisition function used by the gamma command (requires ENABLE_SAMPLE_COMMAND).

Syntax

sample <mode>

Modes

Mode	Function	Description
gamma	calculate_gamma	Compute complex gamma from I/Q samples (default)
ampl	fetch_amplitude	Raw amplitude from measurement channel
ref	fetch_amplitude_ref	Raw amplitude from reference channel

Examples

ch> sample gamma
ch> sample ampl
ch> sample ref

Notes

• Debug command for characterizing signal path behavior
• Changes what the gamma command returns
• Default mode is gamma (complex reflection coefficient calculation)

---

gamma

Take a single-point measurement and return the raw gamma (reflection coefficient) value. Requires ENABLE_SAMPLE_COMMAND.

Syntax

gamma

Output

Two integer values representing the real and imaginary parts of gamma:

ch> gamma
12345 -6789

Notes

• Pauses the sweep, acquires DSP samples, and computes gamma
• The acquisition function can be changed with the sample command
• Useful for real-time monitoring of a single frequency point
• Values are integer-scaled (not the 0.0–1.0 float range of data)

---

measure

Output measurement module results (requires __VNA_MEASURE_MODULE__).

Syntax

measure [type]

Measurement Types

Type	S-param	Compile Flag	Description
none	—	(always)	Disable measurement display
lc	S11	__USE_LC_MATCHING__	L/C matching network values
lcshunt	S21	__S21_MEASURE__	Shunt LC component extraction
lcseries	S21	__S21_MEASURE__	Series LC component extraction
xtal	S21	__S21_MEASURE__	Crystal motional parameters
filter	S21	__S21_MEASURE__	Filter characterization (BW, loss, ripple)
cable	S11	__S11_CABLE_MEASURE__	Cable length and loss
resonance	S11	__S11_RESONANCE_MEASURE__	Resonance frequency and Q

Examples

ch> measure cable
Length: 1.234 m
Loss: 0.5 dB

ch> measure resonance
Frequency: 145.000000 MHz
Q: 125.3

ch> measure off

Output Fields

Depends on measurement type:

Cable:

• Length in meters
• Loss in dB

Resonance:

• Frequency
• Q factor
• Bandwidth

LC Components:

• Inductance (H)
• Capacitance (F)
• Quality factor

Crystal:

• Series resonance
• Parallel resonance
• Motional parameters

Filter:

• Passband ripple
• 3dB bandwidth
• Insertion loss

---

Data Processing Examples

Export to Touchstone S1P

import serial

ser = serial.Serial('/dev/ttyACM0', 115200)

# Get frequencies
ser.write(b'frequencies\r')
freqs = []
while True:
    line = ser.readline().decode().strip()
    if not line or line.startswith('ch>'):
        break
    freqs.append(float(line))

# Get S11 data
ser.write(b'data 0\r')
s11 = []
while True:
    line = ser.readline().decode().strip()
    if not line or line.startswith('ch>'):
        break
    re, im = map(float, line.split())
    s11.append((re, im))

# Write S1P file
with open('output.s1p', 'w') as f:
    f.write('# Hz S RI R 50\n')
    for freq, (re, im) in zip(freqs, s11):
        f.write(f'{freq:.0f} {re:.9f} {im:.9f}\n')

Export to CSV

import serial
import csv

ser = serial.Serial('/dev/ttyACM0', 115200)

# Collect data (similar to above)
# ...

with open('output.csv', 'w', newline='') as f:
    writer = csv.writer(f)
    writer.writerow(['Frequency (Hz)', 'S11 Real', 'S11 Imag', 'S21 Real', 'S21 Imag'])
    for i, freq in enumerate(freqs):
        writer.writerow([freq, s11[i][0], s11[i][1], s21[i][0], s21[i][1]])

---

Source Code Reference

Data export commands in main.c:

• cmd_data: line 738 — array index 0–6 selects measured[] or cal_data[]
• cmd_frequencies: line 2354
• cmd_capture: line 789 — RLE8 variant at line 758
• cmd_dump: line 1238 (conditional: ENABLED_DUMP_COMMAND)
• cmd_sample: line 828 (conditional: ENABLE_SAMPLE_COMMAND)
• cmd_gamma: line 810 (conditional: ENABLE_SAMPLE_COMMAND)
• cmd_measure: line 582 (conditional: __VNA_MEASURE_MODULE__)