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jj1bdx /
Last active Apr 15, 2019
Calibrating frequency of Airspy HF+ and Airspy R2 (and probably Mini)
jj1bdx /
Created Apr 4, 2019
sox examples for macOS coreaudio
# equivalent to `play`
sox -t raw -esigned-integer -b16 -r 48000 -c 2 -q - -t coreaudio "default"
play --buffer=1024 -t raw -esigned-integer -b16 -r 48000 -c 2 -q -
# check macOS devices
sox -V6 -n -t coreaudio nonexistent
jj1bdx / cidr-cheat-sheet
Created Mar 25, 2019 — forked from charlesgreen/cidr-cheat-sheet
View cidr-cheat-sheet
Netmask Netmask (binary) CIDR Notes
_____________________________________________________________________________ 11111111.11111111.11111111.11111111 /32 Host (single addr) 11111111.11111111.11111111.11111110 /31 Unuseable 11111111.11111111.11111111.11111100 /30 2 useable 11111111.11111111.11111111.11111000 /29 6 useable
jj1bdx / duolingo-swedish-fur-pret.txt
Last active Apr 4, 2019
Duolingo Swedish example text for Future Perfect
View duolingo-swedish-fur-pret.txt
När vi skulle åka till sjukhuset gick bilen sönder.
De skulle åka till Frankrike på semester.
Filmen skulle precis börja när allt blev svart.
När vi skulle åka upptäckte vi att bilen var stulen.
Hon gick tidigare, eftersom hon skulle träffa sin syster.
Vi skulle börja med att spela fotboll, men han hade glömt bollen hemma.
Jag hoppades att du skulle komma.
Hon skulle komma efter honom.
Mannen skulle träffa sin fru när han kom ihåg att han hade glömt hennes väska.
Han såg ut som om han skulle börja gråta.
jj1bdx /
Created Mar 1, 2019
Scripts to retrieve MPX (FM demodulated) output for FM broadcasting with RTL-SDR / Airspy and csdr
# 88.1MHz (10Msps, Set 500kHz upper freq)
# CF32 IQ signal decimated to 768kHz first,
# FM decoded to real signal,
# then decimate by 4 to 192kHz CF32 output
airspy_rx -r/dev/fd/1 -p0 -f88.6 -a10000000 -t0 -g7 | \
csdr shift_addition_cc 0.05 | \
csdr fir_decimate_cc 13.028333333333 0.05 HAMMING | \
csdr fmdemod_quadri_cf | csdr fractional_decimator_ff 4
jj1bdx /
Created Feb 25, 2019
RFワールド No.1-32のキーワード

2015年11月にRFワールド No.1 ~ No.32 を手放すことにしたときのキーワードを列挙しておいたので書いておく。

  • 920MHz ARIB STD-T108 受信距離を伸ばすにはビームアンテナで
  • 技適: TELECホームページの特定無線設備の手引書
  • 74AHCU04 より高速なアナログ増幅器
  • GNU radio, USRP
  • 小型アンテナ / 携帯やスマホ用
  • Time-Domain Reflectometer
  • ISA100.11a (ISA100WCI)
  • 40kHz/60kHz SDR

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jj1bdx / getroot.c
Created Jan 23, 2019 — forked from hikalium/getroot.c
Compute (inaccurate) square root (2012)
View getroot.c
#include <stdio.h>
#include <stdlib.h>
typedef struct MATH_BIGNUMBER {
unsigned int size_word; //value size in unsigned short(word).
unsigned short *value; //pointer to value array in unsigned short.
} MATH_BigNumber;
typedef union MATH_BIGNUMBER_WORK32 {
jj1bdx /
Created Jan 1, 2019
rtl_fm example for listening to monaural FM
# deemp: 75usec, treble +6 for compensating over-deemphasis
# sinc filter required to kill the 19kHz output
rtl_fm -f 76.5M -g 8.7 -M fm -s 192k -A fast -F 1 -r 48k -l 0 -E deemp | \
play -t raw -esigned-integer -b16 -r 48000 -c 1 -q - sinc -16k treble +6 spectrogram
jj1bdx /
Last active Jan 22, 2019
Mac mini migration from Late 2012 to 2018

Mac mini migration memo from Late 2012 to 2018

How to migrate

  • Used the Migration Assistant over Ethernet

Homebrew glitches

  • Homebrew got broken during the migration
  • Not all files were copied under /usr/local
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