CSP delay model 3.0
JSON schema and example for CSP Mid delay model
CSP delaymodel 3.0
Example JSON
{
"interface": "https://schema.skao.int/ska-mid-csp-delaymodel/3.0",
"start_validity_sec": 748656000.0,
"cadence_sec": 10.0,
"validity_period_sec": 30.0,
"config_id": "sbi-mvp01-20200325-00001-science_A",
"subarray": 2,
"receptor_delays": [{
"receptor": "SKA001",
"xypol_coeffs_ns": [750.0, 0.0046, -2e-06, -4.1e-12, 9e-16, -1.9e-19],
"ypol_offset_ns": -0.1
}, {
"receptor": "SKA002",
"xypol_coeffs_ns": [750.0, 0.0046, -2e-06, -4.1e-12, 9e-16, -1.9e-19],
"ypol_offset_ns": -0.1
}]
}
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object |
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properties |
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URI of JSON schema applicable to this JSON payload. |
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string |
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Time when delay model becomes valid (when Mid.CBF shall apply the new model), specified as the number of seconds since the 1999-12-31T23:59:28Z UTC (SKA epoch). Note: Delay models need to be published at least 5 seconds before the validity period starts Range: Non-zero positive number |
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number |
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The time in SI seconds of the planned validity period of the delay model, measured from start_validity_sec. Also indicates that the next delay model should be issued no more than cadence_sec later than the current delay model that was issued. This is a configurable field and may change during operations, but the expected value for Mid.CBF is 10 seconds. Mid.CBF will expect the next delay model it receives to have a start_validity_sec <= (current start_validity_sec + cadence_sec). If such a delay model does not arrive, Mid.CBF will continue to use the current delay model, up to the maximum acceptable validity period, which is validity_period_sec. At that point, if a new delay model still hasn’t arrived, Mid.CBF will stop processing (including outputting products) and will issue an error message. Range: Non-zero positive number |
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number |
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The maximum acceptable delay model validity period in SI seconds, starting at start_validity_sec. This is a configurable field and may change during operations, but the expected value for Mid.CBF is 30 seconds. If Mid.CBF has not received, as expected, a new delay model with a new start_validity_sec <= (start_validity_sec + cadence_sec), it will continue to use the current delay model for up to validity_period_sec seconds. At that point, if a new delay model still hasn’t arrived, Mid.CBF will stop processing (including outputting products) and will issue an error message. Range: Non-zero positive number |
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number |
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The configuration ID of the scan that this delay model applies to. Corresponds to “config_id” provided in the scan configuration. This field is used to ensure that the CBF does not use delay models from a previous observation at the start of a new observation. |
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string |
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The subarray to which the delay models apply. Range: Integer from 1-16 inclusive |
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integer |
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array |
items |
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additionalProperties |
True |
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delay_details_3.0
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object |
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The Receptor (Dish) ID to which the xypol_coeffs_ns and ypol_offset_ns apply. Valid receptor IDs include: SKA dishes: “SKAnnn”, where nnn is a zero padded integer in the range of 001 to 133. MeerKAT dishes: “MKTnnn”, where nnn is a zero padded integer in the range of 000 to 063. |
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string |
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The delay model for a receptor is specified as a set of coefficients for a 5th order polynomial. Coefficients of the polynomial are specified as an array. The Coefficients apply to both X and Y polarizations. The delay at time t, where t is measured with respect the beginning of the validity interval, is calculated as: d(t) = c0 + c1*t + c2*t^2 + c3*t^3 + c4*t^4 + c5*t^5 Units for coefficients c0,c1,…,c5: ns/s^k where: k=0,1,…,5 ns=nanoseconds s=seconds Type: 64 bit floating point number |
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array |
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items |
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number |
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Constant delay offset of polarization Y with respect to polarization X, in nanoseconds. Type: 64 bit floating point number |
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number |
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additionalProperties |
True |
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