Range Limit Block

[chefravioli]

Added the Range Limit Block, which allows you to limit the range of data collected by the radar in meters, as well as add a multiple of the waveform length to the end of the range for matched filtering.

Features:

• Limits the minimum and maximum range of a PDU containing radar data, as well as allowing a waveform multiple to be added to the end for matched filtering.
• Detects if the entered maximum range is above the maximum range collected by the radar, and will automatically adjust the limit and metadata values.
• Places metadata for the minimum range (radar:min_range), maximum range (radar:max_range), and waveform multiplier (radar:range_mult). These names can be changed in the block parameters under the Metadata tab.

Block Parameters:
Minimum Range: Minimum range of data in meters
Maximum Range: Maximum range of data in meters
Use Absolute Maximum Range: If set to true, ignores the maximum range parameter and gets all radar data from the minimum to the end of the data.
Multiplier: Adds a multiple of the waveform length to the end of the data, set to 0 to disable.

Testing:

With given parameters, we expect that the Linear FM source will output a PDU size of 1600 bytes (200 complex floats * 8 bytes per complex float) and the range limit will output a PDU size of 432 bytes (54 complex floats * 8 bytes per complex float). This is seen in the results, and the time sinks show the limited waveform.

Linear FM PDU:

Range Limit PDU:

Time Sink Output:

Further testing on radar data may be needed.

The block has successfully been tested on a fresh install of Ubuntu 22.04 and GNURadio.

[ShaneFlandermeyer]

In general, this looks good and functions as expected! While looking over it, I had an idea for how we could expand this block into a general-purpose PDU slicer where the user computes/provides the start and stop samples directly. We can talk about it more tomorrow if you'd like, but I think it would be pretty easy given the code in this PR.