Re: Looking for a way to plot V_LSR vs intensity in GNU Radio

On 07/24/2020 12:17 PM, Marcus Müller wrote:
> Hi Ellie,
>
> being not versed in radioastronomy, I need to guess a bit here, but:
> Is what you want essentially "how much power is there for any Doppler
> shift"?
>
> If that's the case, and you're observing some known-frequency emission
> (say, a Hydrogen line) would that basically amount to:
>
> 1. Frequency-Shifting so that the zero-doppler frequency ends up at 0 Hz
> 2. transforming your time domain observation to frequency domain
> 3. labeling the frequency axis so that it tells velocity?
>
> In that case, the Qt GUI frequency case would be a way to go. You can
> set the center frequency to do 1., it inherently does 2. and 3. can be
> achieved (ignoring wrong physical unit labels) by adjusting the
> bandwidth parameter.
>
> Cheers,
> Marcus
>
In spectro_radiometer, I use the Qt Vector plotter, and use some math to
display km/sec on what would normally be the frequency axis. This
calculation doesn't account for the VLSR, but it certainly could.