PNM Operations - Downstream OFDM RxMER¶

Deep Visibility Into Downstream OFDM RxMER At The Subcarrier Level.

Overview¶

CmDsOfdmRxMer validates that the input PNM payload is an RxMER file, unpacks header fields, decodes per-subcarrier RxMER in quarter-dB steps, and provides a typed model (CmDsOfdmRxMerModel) with statistics and Shannon-based modulation metrics.

Endpoint¶

POST /docs/pnm/ds/ofdm/rxMer/getCapture

Request¶

Refer to Common → Request. Deltas (Analysis-only additions): the request accepts optional analysis, analysis.output, and analysis.plot.ui controls.

Delta Table¶

JSON path	Type	Allowed values / format	Default	Description
`analysis.type`	string	`"basic"`	`"basic"`	Selects the analysis mode used during capture processing.
`analysis.output.type`	string	`"json"`, `"archive"`	`"json"`	Output format. `json` returns an inline body under `data` (`analysis`, `primative`, `measurement_stats`). `archive` returns a downloadable ZIP (CSV exports and Matplotlib PNG plots).
`analysis.plot.ui.theme`	string	`"light"`, `"dark"`	`"dark"`	Theme hint for plot generation (colors, grid, ticks). Does not affect raw metrics/CSV.
`pnm_parameters.capture.channel_ids`	array(int)	Channel IDs	omitted	Optional list of OFDM channel IDs to capture. Omitted or empty means all available channels.

Notes¶

When analysis.output.type = "archive", the HTTP response body is the file (no data JSON payload).
The primative section is a normalized representation of the raw PNM file with added statistics (e.g., mean, std, kurtosis).
The measurement_stats section summarizes one-shot SNMP statistics collected at capture-time (useful for dashboards).
When pnm_parameters.capture.channel_ids is omitted or empty, RxMER captures all available OFDM channels.
For TFTP and SNMP overrides, use null to request system.json defaults; blank strings are rejected.

Example Request¶

{
  "cable_modem": {
    "mac_address": "aa:bb:cc:dd:ee:ff",
    "ip_address": "192.168.0.100",
    "pnm_parameters": {
      "tftp": {
        "ipv4": null,
        "ipv6": "2001:db8::10"
      },
      "capture": {
        "channel_ids": [193, 194]
      }
    },
    "snmp": {
      "snmpV2C": {
        "community": null
      }
    }
  },
  "analysis": {
    "type": "basic",
    "output": { "type": "json" },
    "plot": { "ui": { "theme": "dark" } }
  }
}

Response¶

Standard envelope with payload under data.

When `output.type = "json"`¶

"output": { "type": "json" }

Abbreviated Example¶

{
  "mac_address": "aabbccddeeff",
  "status": 0,
  "message": null,
  "data": {
    "analysis": [
      {
        "device_details": {
          "system_description": {
            "HW_REV": "1.0",
            "VENDOR": "LANCity",
            "BOOTR": "NONE",
            "SW_REV": "1.0.0",
            "MODEL": "LCPET-3"
          }
        },
        "mac_address": "aa:bb:cc:dd:ee:ff",
        "channel_id": 193,
        "subcarrier_spacing": 50000,
        "first_active_subcarrier_index": 148,
        "subcarrier_zero_frequency": 251600000,
        "carrier_values": {
          "carrier_status_map": { "exclusion": "0", "clipped": "1", "normal": "2" },
          "magnitude_unit": "dB",
          "frequency_unit": "Hz",
          "carrier_count": 3800,
          "magnitude": [],
          "frequency": [],
          "carrier_status": []
        },
        "regression": { "slope": [] },
        "modulation_statistics": {
          "snr_db_values": [],
          "bits_per_symbol": [],
          "modulations": [],
          "snr_db_min": [],
          "supported_modulation_counts": {
            "qam_2": 3800, "qam_4": 3800, "qam_8": 3800, "qam_16": 3798,
            "qam_32": 3787, "qam_64": 3778, "qam_128": 3762, "qam_256": 3469,
            "qam_512": 2733, "qam_1024": 2362, "qam_2048": 2019, "qam_4096": 1467,
            "qam_8192": 883, "qam_16384": 60, "qam_32768": 0, "qam_65536": 0
          }
        }
      }
    ],
    "primative": [
      {
        "status": "SUCCESS",
        "pnm_header": {
          "file_type": "PNN",
          "file_type_version": 4,
          "major_version": 1,
          "minor_version": 0,
          "capture_time": 1761238473
        },
        "channel_id": 193,
        "mac_address": "aa:bb:cc:dd:ee:ff",
        "subcarrier_zero_frequency": 251600000,
        "first_active_subcarrier_index": 148,
        "subcarrier_spacing": 50000,
        "data_length": 3800,
        "occupied_channel_bandwidth": 190000000,
        "value_units": "dB",
        "values": [],
        "signal_statistics": {
          "mean": 32.80559210526316,
          "median": 34.0,
          "std": 6.398852563006556,
          "variance": 40.94531412309557,
          "power": 1117.1521875,
          "peak_to_peak": 32.0,
          "mean_abs_deviation": 5.666524757617728,
          "skewness": -0.25361308425026813,
          "kurtosis": 1.883937273853999,
          "crest_factor": 1.3089464730216689,
          "zero_crossing_rate": 0.0,
          "zero_crossings": 0
        }
      }
    ],
    "measurement_stats": [
      {
        "index": 3,
        "channel_id": 3,
        "entry": {
          "docsPnmCmDsOfdmRxMerFileEnable": true,
          "docsPnmCmDsOfdmRxMerFileName": "ds_ofdm_rxmer_per_subcar_aabbccddeeff_193_1761514136.bin",
          "docsPnmCmDsOfdmRxMerMeasStatus": "sample_ready",
          "docsPnmCmDsOfdmRxMerPercentile": 0.02,
          "docsPnmCmDsOfdmRxMerMean": 33.21,
          "docsPnmCmDsOfdmRxMerStdDev": 6.29,
          "docsPnmCmDsOfdmRxMerThrVal": 0.93,
          "docsPnmCmDsOfdmRxMerThrHighestFreq": 319500000
        }
      }
    ]
  }
}

When `output.type = "archive"`¶

"output": { "type": "archive" }

The response is a downloadable ZIP file containing:

CSV export of RxMER per subcarrier.
Matplotlib PNG plots of RxMER vs. Subcarrier Index.

DARK	Light	Description
RxMER (Ch 193)	RxMER (Ch 193)	RxMER vs. Subcarrier Index — Channel 193
Modulation Counts (Ch 193)	Modulation Counts (Ch 193)	Modulation Counts — Channel 193
RxMER (Ch 194)	RxMER (Ch 194)	RxMER vs. Subcarrier Index — Channel 194
Modulation Counts (Ch 194)	Modulation Counts (Ch 194)	Modulation Counts — Channel 194
RxMER (Ch 195)	RxMER (Ch 195)	RxMER vs. Subcarrier Index — Channel 195
Modulation Counts (Ch 195)	Modulation Counts (Ch 195)	Modulation Counts — Channel 195
RxMER (Ch 196)	RxMER (Ch 196)	RxMER vs. Subcarrier Index — Channel 196
Modulation Counts (Ch 196)	Modulation Counts (Ch 196)	Modulation Counts — Channel 196
RxMER (Ch 197)	RxMER (Ch 197)	RxMER vs. Subcarrier Index — Channel 197
Modulation Counts (Ch 197)	Modulation Counts (Ch 197)	Modulation Counts — Channel 197
Signal Aggregate	Signal Aggregate	Aggregate Signal Statistics (All Channels)

Field Tables¶

Payload: data.analysis[]

Field	Type	Description
device_details.*	object	System descriptor captured at analysis time.
mac_address	string	MAC address (`aa:bb:cc:dd:ee:ff` format).
channel_id	int	OFDM downstream channel ID.
subcarrier_spacing	int (Hz)	Subcarrier spacing.
first_active_subcarrier_index	int	Index of first active subcarrier.
subcarrier_zero_frequency	int (Hz)	Subcarrier 0 frequency.
carrier_values.*	object	Frequency-aligned magnitude and status arrays.
regression.slope	array(float)	Optional regression slope values.
modulation_statistics.*	object	Shannon-based metrics and counts by QAM order.

Payload: data.primative[]

Field	Type	Description
status	string	Result for this capture (e.g., `SUCCESS`).
pnm_header.*	object	PNM file header (type, version, capture time).
channel_id	int	Channel ID.
mac_address	string	MAC address.
subcarrier_zero_frequency	int (Hz)	Channel zero frequency.
first_active_subcarrier_index	int	Index of first active subcarrier.
subcarrier_spacing	int (Hz)	Subcarrier spacing.
data_length	int	Number of RxMER samples.
occupied_channel_bandwidth	int (Hz)	Occupied bandwidth.
value_units	string	Units for `values` (e.g., `dB`).
values	array(float)	RxMER values per subcarrier.
signal_statistics.*	object	Aggregate statistics (mean, std, variance, etc.).

Payload: data.measurement_stats[]

Summarized SNMP snapshot for each channel at capture time.

Field	Type	Description
index	int	SNMP table row index (per device).
channel_id	int	OFDM downstream channel ID.
entry.docsPnmCmDsOfdmRxMerFileEnable	boolean	Whether CM capture-to-file was enabled.
entry.docsPnmCmDsOfdmRxMerFileName	string	Device-side filename of the PNM RxMER sample.
entry.docsPnmCmDsOfdmRxMerMeasStatus	string	Measurement state (e.g., `sample_ready`).
entry.docsPnmCmDsOfdmRxMerPercentile	number	Percentile requested for percentile capture (0.00-1.00).
entry.docsPnmCmDsOfdmRxMerMean	number	Mean RxMER (dB) reported by CM.
entry.docsPnmCmDsOfdmRxMerStdDev	number	Standard deviation (dB).
entry.docsPnmCmDsOfdmRxMerThrVal	number	Threshold value dependent on vendor implementation.
entry.docsPnmCmDsOfdmRxMerThrHighestFreq	int (Hz)	Highest frequency associated with threshold metric.