Setup Tab (Bluetooth Spectrum)
The tab of the dialog box selects the test purpose, configures how per-channel power is computed, and holds the specification limits the emissions test is run against.
The signal-description settings in the section above the tabs (, , , and ) are shared by both Bluetooth measurements and are described in Common Properties.
The tab's groups can be collapsed. Which groups and which rows appear depends on the selected Test Purpose: a setting that the active test purpose does not read is hidden rather than offered, so that entering a value that cannot affect the result is not possible.
Test
Test Purpose - Selects which Bluetooth spectrum transmitter test the measurement performs. Selecting a purpose re-profiles the acquisition (span, resolution bandwidth, video bandwidth, detector, and averaging style) to the values the corresponding conformance test specifies.
LE In-band Emissions - Measures the power in each 1 MHz Megahertz: A unit of frequency equal to one million hertz or cycles per second. band across the LE grid and tests it against the in-band emissions mask.
Default: LE In-band Emissions
Choices: LE In-band Emissions
The list offers only the test purposes the selected PHY Family can run. Because only LE can be selected in this release, LE In-band Emissions is the only test purpose available.
Channel Power
Power Calculation - Sets the basis of the per-channel and per-band power results.
Integrated Power - Each channel or band reports its total integrated power, in dBm deciBels referenced to a milliWatt: dB relative to 1 milliwatt dissipated in the nominal input impedance of the analyzer.
PSD Power Spectral Density: See power spectral density. - Each channel or band reports its mean power spectral density, in dBm/Hz.
This setting does not change the Spectrum trace, whose bins are always reported on the integrated-power basis.
Default: Integrated Power
Choices: Integrated Power, PSD
Detector - Sets the spectrum detector used for the power measurement. Selecting a detector also enables it on the acquisition, because the spectrum measurement computes only the detectors that are enabled.
Default: Average
Choices: Average, Peak
Interpolate channel-edge bins - When selected, spectrum bins that straddle a channel edge contribute proportionally to the channels on both sides, rather than being assigned wholly to one channel. This reduces the sensitivity of the per-channel power to the exact FFT Fast Fourier Transform: A mathematical operation performed on a time-domain signal to yield the individual spectral components that constitute the signal. See Spectrum. bin alignment.
Default: Selected
Limits
The specification limits the emissions test is run against, one value per limit tier. Only the tiers the selected Test Purpose evaluates are shown. The defaults are the values the conformance specification states, so a preset measurement reproduces the specification verdict with nothing entered.
Limits are applied on the 1 MHz measurement-band grid, and each band's limit is selected by that band's frequency offset from the carrier. The resulting per-band limits, margins, and verdicts appear in the Band Table trace.
Freq Offset 2 MHz - The in-band emissions limit applied at ±2 MHz from the carrier. Used on the LE 1M and LE Coded PHY Physical Layer rates. On LE 2M the ±2 MHz band falls inside the signal's own width and is not tested.
Default: -20 dBm
Freq Offset 4 MHz - The in-band emissions limit applied at ±4 MHz from the carrier. Used on the LE 2M PHY rate only, where the mask shifts outward with the wider signal.
Default: -20 dBm
Freq Offset 5 MHz - The in-band emissions limit applied at ±5 MHz from the carrier. Used on the LE 2M PHY rate only. It is a separate tier from Freq Offset 4 MHz because the specification states the two independently, even though both have the same default.
Default: -20 dBm
Far Limit - The in-band emissions limit applied beyond the near offsets: from ±3 MHz on LE 1M and LE Coded, and from ±6 MHz on LE 2M. This is the tier the specification's exception allowance applies to, so a limited number of bands may exceed it and the measurement still pass. The Exception Bands row reports how much of that allowance was used.
Default: -30 dBm
All three rows are shown for LE in-band emissions regardless of the selected PHY Rate. The rate selects which of them the test reads; a tier that the current rate does not use has no effect on the result until the rate selects it.
See Also
