megacode
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megacode [2014/12/28 19:49] – restructure kingkevin | megacode [2014/12/28 20:08] – [sdr] kingkevin | ||
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The first bit frame is used as sync frame and is always a 1. | The first bit frame is used as sync frame and is always a 1. | ||
It is followed by 20 system code bits and 3 data bits. | It is followed by 20 system code bits and 3 data bits. | ||
+ | |||
+ | ===== software defined radio ===== | ||
+ | |||
+ | This signal can be recorded using a software defined radio (SDR). | ||
+ | I used the inexpensive USB DVB stick [[https:// | ||
+ | |||
+ | First find the exact frequency at which the remote transmits using an FFT software, such as [[https:// | ||
+ | Use this frequency to record and demodulate the signal using [[https:// | ||
+ | < | ||
+ | rtl_fm -f 317.962M -M am megacode.pcm | ||
+ | </ | ||
+ | The recorded data can be view in audio editing tools such as [[http:// | ||
+ | |||
+ | The code can also be extracted using [[https:// | ||
+ | < | ||
+ | ./decode.rb megacode.pcm | ||
+ | </ | ||
+ | This decodes the transmissions and lists the 3 bytes values. | ||
+ | < | ||
+ | # egdes: 0 | ||
+ | # pulses: 0 | ||
+ | # groups: 1 (1) | ||
+ | # transmissions: | ||
+ | # values: 0 | ||
+ | # egdes: 1822 | ||
+ | # pulses: 167 | ||
+ | # groups: 9 (24, 24, 23, 13, 10, 24, 24, 24, 1) | ||
+ | # transmissions: | ||
+ | # values: 5 | ||
+ | values: | ||
+ | - value: 13178818 (0xc917c2), system code: 598776 (0x922f8), databits: 2 (0x2) | ||
+ | - value: 13178818 (0xc917c2), system code: 598776 (0x922f8), databits: 2 (0x2) | ||
+ | - value: 13178818 (0xc917c2), system code: 598776 (0x922f8), databits: 2 (0x2) | ||
+ | - value: 13178818 (0xc917c2), system code: 598776 (0x922f8), databits: 2 (0x2) | ||
+ | - value: 13178818 (0xc917c2), system code: 598776 (0x922f8), databits: 2 (0x2) | ||
+ | </ |
megacode.txt · Last modified: 2024/01/07 17:49 by 127.0.0.1