miri_fm(1)

✨ miri_fm ✨

okay so bestie, you know miri_fm(1) from the User Commands corner of the manual? yeah. this is that. a whole lil program, and honestly? she's iconic. 💅

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🌸 NAME 🌸

miri_fm — a simple narrow band FM demodulator for Mirics based receivers 🎀

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🦋 DESCRIPTION 🦋

So basically: this is software for the Mirics MSi2500 + MSi001 SDR platform. ✨

And the lore? The reason she exists at all? People literally could not do real time FM demod on Atom hardware with GNU radio based on rtl_sdr.c and rtl_tcp.c. So she got written. main character energy, no cap. 👑

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💜 USAGE 💜

This program captures information from a band of frequencies and outputs the data in a form useful to other software radio programs. that's the whole vibe, that's the whole job 🫶

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⭐ SYNOPSIS ⭐

miri_fm [-f freq] [OPTIONS] [output file]

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💖 OPTIONS 💖

• -f frequency_to_tune_to [Hz] — pick the frequency, bestie. in Hertz.
  • use multiple -f for scanning (requires squelch) 👀
  • ranges supported, like -f 118M:137M:25k
• -M modulation (default: fm) — choose your modulation flavor
  • fm, wbfm, raw, am, usb, lsb
  • wbfm == -M fm -s 170k -o 4 -A fast -r 32k -l 0 -E deemp (it's literally just a shortcut, slay)
  • raw mode outputs 2x16 bit IQ pairs
• -s sample_rate (default: 24 kHz) — the sample rate, she's giving 24 kHz by default ✨
• -d device_index (default: 0) — which device, index style
• -T device_type device variant (default: 0) — tell her what kind of device you got
  • 0: Default
  • 1: SDRPlay
• -g tuner_gain (default: automatic) — gain, and by default she's just gonna figure it out herself
• -m sample format (default: auto) — the format of the samples, and yes these numbers matter
  • 504: S8 (fastest) 🔥
  • 384: S10 +2bits
  • 252: S14
• -e USB transfer mode (default: 1) — how the USB does its thing
  • 1: Isochronous (maximum 196.608 Mbit/s)
  • 2: Bulk (maximum 333Mbit/s, depends on controller type)
• -i IF mode (default: ZERO) — intermediate frequency mode, pick your poison
  • 0: ZERO
  • 450000: 450 kHz
  • 1620000: 1620kHz
  • 2048000: 2048kHz
• -w BW mode (default: 8MHz) — bandwidth mode, so many choices omg
  • 200000: 200kHz
  • 300000: 300kHz
  • 600000: 600kHz
  • 1536000: 1536kHz
  • 5000000: 5MHz
  • 6000000: 6MHz
  • 7000000: 7MHz
  • 8000000: 8MHz
• -l squelch_level (default: 0/off) — squelch level, off unless you say otherwise
• -o oversampling (default: 1, 4 recommended) — bestie, they literally recommend 4. just saying. 💅
• -p ppm_error (default: 0) — your ppm error, fix that clock drift
• -E enable_option (default: none) — turn stuff on
  • use multiple -E to enable multiple options (stack 'em, queen)
  • edge: enable lower edge tuning
  • dc: enable dc blocking filter
  • deemp: enable de-emphasis filter
  • direct: enable direct sampling
  • offset: enable offset tuning
• filename ('-' means stdout) — where the output goes
  • omitting the filename also uses stdout 🫶

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🧚 EXPERIMENTAL OPTIONS 🧚

these ones are literally labeled experimental. proceed with the cute caution energy. 🙈

• -r resample_rate (default: none / same as -s) — resample rate, defaults to whatever -s is
• -t squelch_delay (default: 10) — squelch delay
  • +values will mute/scan, -values will exit ⚠️ (yes the sign changes the whole behaviour, pay attention bestie)
• -F fir_size (default: off) — enables low-leakage downsample filter
  • size can be 0 or 9. 0 has bad roll off 😭
• -A std/fast/lut choose atan math (default: std) — pick how you wanna do your atan math

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🌈 EXAMPLES 🌈

Produces signed 16 bit ints, use Sox or aplay to hear them. ✨

miri_fm ... | play -t raw -r 24k -es -b 16 -c 1 -V1 -
            | aplay -r 24k -f S16_LE -t raw -c 1

• -M wbfm | play -r 32k ...
• -s 22050 | multimon -t raw /dev/stdin

If the device can't be opened, make sure you have the appropriate rights to access the device (install udev-rules from the repository, or run it as root). 🫡

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👑 SEE ALSO 👑

miri_sdr(1)

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🎀 AUTHOR 🎀

This manual page was written by Maitland Bottoms for the Debian project (but may be used by others). 💖

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📜 COPYRIGHT 📜

Copyright (c) 2023 A. Maitland Bottoms <bottoms@debian.org>

This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 2 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

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okay that's the whole page bestie, and the vibe check at the very bottom is: MiriSDR version 2.0.0, filed under miri_fm(1). go demodulate something, you absolute icon 🌸💅✨