import numpy as np, sys
fs=4e6; SPC=2  # samples per chip
C0='11011001110000110101001000101110'
def chips(s):
    b=[int(c) for c in C0]
    k=s&7
    b=b[-4*k:]+b[:-4*k] if k else b
    if s>=8: b=[v^(i&1) for i,v in enumerate(b)]
    return b
CH=[chips(s) for s in range(16)]
def modulate(chipseq):
    n=len(chipseq)
    L=(n+2)*SPC
    I=np.zeros(L);Q=np.zeros(L)
    p=np.sin(np.pi*np.arange(2*SPC)/(2*SPC))
    for i,c in enumerate(chipseq):
        v=2*c-1; st=i*SPC
        if i%2==0: I[st:st+2*SPC]+=v*p
        else: Q[st:st+2*SPC]+=v*p
    return I+1j*Q
def fdisc(x): return np.angle(x[1:]*np.conj(x[:-1]))
# templates of freq per symbol (64 samples), from symbol embedded in random context
rng=np.random.default_rng(1)
T=np.zeros((16,64))
for s in range(16):
    acc=np.zeros(64)
    for _ in range(20):
        a,b=rng.integers(16,size=2)
        seq=CH[a]+CH[s]+CH[b]
        f=fdisc(modulate(seq))
        acc+=f[64:128]
    T[s]=acc/20
T-=T.mean(1,keepdims=True)
Tn=T/np.linalg.norm(T,axis=1,keepdims=True)
def demod_from(f,st):
    syms=[];pos=st
    while pos+64+2<=len(f):
        best=None
        for d in (-1,0,1):
            p=pos+d
            if p<0: continue
            r=Tn@f[p:p+64]
            k=int(np.argmax(r))
            if best is None or r[k]>best[0]: best=(r[k],k,p)
        r,k,p=best
        if r<0.3*np.linalg.norm(f[p:p+64]): break
        syms.append(k);pos=p+64
    return syms
def parse(syms):
    for i in range(1,len(syms)-1):
        if syms[i]==7 and syms[i+1]==0xA and syms[i-1]==0:
            b=syms[i+2:]
            by=bytes((b[j]|(b[j+1]<<4)) for j in range(0,len(b)-1,2))
            if not by: return None
            L=by[0]&0x7f
            return by[1:1+L]
    return None
def demod_burst(x):
    f=fdisc(x); f=f-np.median(f)
    pre=np.tile(Tn[0],4)
    n=min(len(f),3500)
    c=np.correlate(f[:n],pre,'valid')
    c=c/(np.sqrt(np.convolve(f[:n]**2,np.ones(len(pre)),'valid'))+1e-9)
    cand=np.flatnonzero(c>0.7*c.max())
    tried=set();first=None
    for st in cand:
        st=int(st)
        if any(abs(st-t)<3 for t in tried): continue
        tried.add(st)
        fr=parse(demod_from(f,st))
        if fr is None: continue
        if first is None: first=fr
        if len(fr)>=2 and crc16(fr[:-2])==int.from_bytes(fr[-2:],'little'): return fr
        if len(tried)>40: break
    return first
def frames(path):
    raw=np.fromfile(path,dtype=np.int8).astype(np.float32)
    x=raw[0::2]+1j*raw[1::2]
    p=np.abs(x)**2
    e=np.convolve(p,np.ones(400)/400,'same')
    on=e>np.median(e)*10
    idx=np.flatnonzero(np.diff(on.astype(int)))
    for s,t in zip(idx[0::2],idx[1::2]):
        s=max(0,s-600);t=t+300
        yield s/fs,demod_burst(x[s:t])
def crc16(d):
    c=0
    for b in d:
        c^=b
        for _ in range(8):
            c=(c>>1)^0x8408 if c&1 else c>>1
    return c
if __name__=='__main__':
    for t,fr in frames(sys.argv[1]):
        if fr is None: print(f'{t:.4f} ??');continue
        ok=len(fr)>=2 and crc16(fr[:-2])==int.from_bytes(fr[-2:],'little')
        print(f'{t:.4f} {"OK " if ok else "BAD"} {len(fr):3d} {fr.hex()}')