mossmann

What Lurks Below

Challenge Description

"This one seems to be straight forward, but there is no flag to be found! Sample rate = 1024k"

challenge.cfile

Decoding ASK

mossmann

mossmann

# for 13 August 2019 hardware
led=gf.gpio.get_pin("J1_P24")
sleep=gf.gpio.get_pin("J1_P8")
clock=gf.gpio.get_pin("J1_P16")
port=gf.gpio.get_port("J1_P25", "J1_P26", "J1_P21", "J1_P22", "J1_P20", "J1_P17", "J1_P18", "J1_P15")
port.all_output()
led.low()
clock.high()
sleep.low()
port.write(0)

mossmann

<?grc format='1' created='3.7.11'?>
<flow_graph>
<timestamp>Sun Jan 5 20:29:21 2020</timestamp>
<block>
<key>options</key>
<param>
<key>author</key>
<value/>
</param>
<param>

mossmann

#!/usr/bin/python

from greatfet import GreatFET
import time

gf = GreatFET()

# These values tune the ADF4360 to 2440.5 MHz (with a 12 MHz reference clock):
r = 24
#p = 16

mossmann

#!/usr/bin/python

import sys

from greatfet import GreatFET
gf=GreatFET()

# incomplete list of SPI commands
NOP         = 0xFF
SPI_MEM_WR  = 0x18

mossmann

%!
/c {closepath} bind def
/a {arc} bind def
/v {arcn} bind def
/n {newpath} bind def
/s {stroke} bind def
90 rotate
5 -5 scale
10 20 translate
2 setlinewidth

mossmann

from rflib import *
import sys
import bitstring

def manchester_decode(symbols):
    bits = []
    for dibit in symbols.cut(2):
        if dibit == '0b01':
            bits.append(0)
        elif dibit == '0b10':