New Experimental Capabilities

Simultaneous Full Field-of-View Imaging

Simultaneous Full Field-of-View (FOV) Imaging is now possible with Borealis! The current implementation uses phase modulation across the transmitting antennas of the main array. Two configurations are supported right now: transmission with all 16 main antennas, and transmission with 8 adjacent antennas of the main array. These two modes are implemented in the experiments and, respectively, with the latter using 8 antennas for each of two frequencies which transmit simultaneously.

To create your own Full FOV experiment using 8- or 16-antenna phase modulation, a utility function is present in To use this function, set

slice_dict['tx_antenna_pattern'] = scf.easy_widebeam

in your experiment slice dictionary.

More generally, you can define your own power- and phase-modulation across the transmitting antennas. Define a function with the following signature

def fn_name(frequency_khz, tx_antennas, antenna_spacing_m):
    """Defines the power and phase modulation for each transmitting antenna.

    frequency_khz: int
        Frequency in kHz.
    tx_antennas: list
        List of transmitting antennas for the slice.
    antenna_spacing_m: float
        Spacing between adjacent antennas in the main array, in meters.

    np.ndarray of shape (num_beams, num_main_antennas). Each element should be a complex number
    with magnitude <= 1.0 defining the power and phase for that antenna.

Then, assign the function to tx_antenna_pattern in your slice dictionary. It is important that the first dimension of the returned array matches the first dimension of rx_beam_order in your slice dictionary, and that num_main_antennas matches the number of main antennas in the config file.

Custom beamforming of the results measured during a full field of view experiment is possible through defining the rx_antenna_pattern field in the full field of view experiment. A custom function can be written in the experiment and passed to borealis

beamforming_function(beam_angle, freq, antenna_count, antenna_spacing, offset=0.0):


slice_dict['tx_antenna_pattern'] = beamforming_function

The function should expect to receive beam angles, operating frequencies, number of antennas, antenna spacing, and an offset. This function will be called for both the rx signals from the main array and the interferometer array. The return is expected to be the desired phase for beamforming each antenna, and should be of size [beam_angle, antenna_count]. The magnitude of each entry should be less than or equal to 1.

Bistatic Experiments

Bistatic experiments are now supported in Borealis. A multi-purpose bistatic experiment is defined in, and can be used at both transmitting and receiving radar sites. This experiment uses command-line arguments to control its behaviour, making it flexible and configurable.

By default, the bistatic_test experiment will transmit a full FOV pattern like on a single frequency. To operate a radar in a bistatic listening mode, the argument listen_to=[three-letter radar code] must be passed to the experiment handler via This will look something like this

radar@borealis~$ ./ bistatic_test release discretionary --kwargs_string "listen_to=rkn"

This invocation will trigger the radar to receive only, tuning to common-mode frequency 1 for RKN defined in Additionally, it will trigger an imaging mode, receiving signals on all 16 beams simultaneously. If the listening radar specified is the same as the radar that you are running the experiment on, the experiment will default to a listening-only mode on the radar’s common-mode frequency 1.

For further control over the transmitting characteristics, an additional keyword argument beam_order is supported. This controls the tx_beam_order field of the slice dictionary, and allows for traditional beams to be used. The beam_order value must be formatted as a list of numbers, such as 0,1,2,3-5,2,9, with ranges being parsed to include all numbers in between and both endpoints. Therefore, for this example, beams used would be 0, 1, 2, 3, 4, 5, 2 and finally 9. Repeated beams are valid.

The arguments beam_order and listen_to are mutually exclusive.

You can define your own bistatic experiment, with very few restrictions. It is highly recommended that the field align_sequences is set to True in your experiment slice dictionary, which will send out the first pulse in each sequence within 1us of each 0.1 second boundary. Without this field set in the experiments of both radars in the bistatic link, there is no guarantee of timing synchronicity and the data will likely be useless. Additionally, it is recommended that the experiments running at both the transmit and receive radars are both using the same scanbound. This will make it much easier to compare data from the transmit and recieve sites as the averaging periods should line up exactly. Lastly, it is recommended that you check the data files for both radars afterwards and ensure that the gps_locked flag is True for all times. If not, the clock may have drifted, and the sqn_timestamps field may be inaccurate.