Heading and velocity decoding on surface messages about pymodes

[junzis]

@markaif, thanks for the suggestion! I have implemented the surface velocity decoding now, however in a slightly different way. It is under now adsb.surface_velocity(), and also handled directly from adsb.velocity()

Implemented in commit: 15f2833

[marcaicart]

@junzis Thanks for the integration. However, i think that the adsb.surface_velocity() funcion should return a none even if ther's no velocity found. The way it tis, only return somenthing when a velocity is found.
I think the funciotn would be much more usable if allways returned something even if its a None.
An easy solution could be something like this:

    # heading
    hdg_status = int(msgbin[44])
    if hdg_status == 1:
        hdg = round(util.bin2int(msgbin[45:52]) * 360.0 / 128.0, 1)
    else:
        hdg = None

    # ground movment / speed
    mov = util.bin2int(msgbin[37:44])

    if mov == 0 or mov > 124:
        spd = None
    elif mov == 1:
        spd = 0
    elif mov == 124:
        spd = 175
    else:
        movs = [2, 9, 13, 39, 94, 109, 124]
        kts = [0.125, 1, 2, 15, 70, 100, 175]
        i = next(m[0] for m in enumerate(movs) if m[1] > mov)
        step = (kts[i] - kts[i - 1]) * 1.0 / (movs[i] - movs[i - 1])
        spd = round(kts[i - 1] + (mov - movs[i - 1]) * step, 2)

    return spd, hdg, 0, 'GS'

[junzis]

Hi @markaif, That's right. It was indeed a bug. I fixed it now in the new commit together with many other EHS updates. Thanks!