Create phase_down.py

[lmagnus]

@spassmoor @ludwigschwardt Please can you have a look over this new phase down ... better than trying to use the phase up script with the --reset option

[ajoubertza]

The kat object hasn't been assigned yet. Looks like this block needs to move down, after line 41.

[ludwigschwardt]

As below, I would suggest to follow calibrate_delays.py as a template. We have removed these explicit sources in the code and replaced them with the three_calib.csv file in the instruction set. The whole catalogue construction also moves down to after verify_and_connect as @ajoubertza suggests. I also pick only a single source as opposed to looping through a list containing one source.

[ajoubertza]

I know this check is used in other scripts, but it isn't very robust. E.g. for a user product like c856M32k4s or bec856M32kram. There is a CBF sensor that gives the number of channels, so suggest that is used instead. Think you can use it like this: channels = session.cbf.fengine.sensor.n_chans

@ludwigschwardt, please confirm that is the correct way to use the SessionCBFStream object.

[ludwigschwardt]

Indeed. My best suggestions would be to look at calibrate_delays.py as that is the most up-to-date cal/cbf-interacting script. There is a function that you can copy (and which should move into CaptureSession now that there is more than one user :-)):

# Default F-engine gain as a function of number of channels
DEFAULT_GAIN = {4096: 200, 32768: 4000}

def set_fengine_gain(session, gain):
    """Set F-engine gain to *gain* if positive, or automatic default if 0."""
    if session.kat.dry_run:
        gain = -1
    # Obtain default gain based on channel count if none specified
    if gain == 0:
        num_channels = session.cbf.fengine.sensor.n_chans.get_value()
        gain = DEFAULT_GAIN.get(num_channels, -1)
    if gain > 0:
        user_logger.info("Setting F-engine gains to %d" % (gain,))
        for inp in session.cbf.fengine.inputs:
            session.cbf.fengine.req.gain(inp, gain)

[ludwigschwardt]

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