Effective DANL Option NFE/NF2 Functional Test

This test applies to the following models with Option NFE or NF2:

  • Option NF2 will be functionally tested to a limit that is 3 dB below the DANL specification. Option NFE will be tested to the specification as listed in the “Version-Dependent Backdated Specifications” chapter of the PXA Specifications Guide.

  • If the Effective DANL test should fail, Option NF2 requires a manual noise floor characterization. To do this, press System > More > Advanced > Characterize Noise Floor. For Option NFE, refer to the Effective DANL Adjustment .

Option NFE/NF2 provides noise corrections which will allow the signal analyzer to measure signals close to the noise. The corrections will essentially compensate for the known conversion loss of the signal analyzer RF front-end.

The noise floor improvement is inferred from amplitude measurements made on a signal close to the noise floor. The test is actually three measurements that are performed at each test frequency. The choice of test frequency was center of the band offset by 100 MHz times Pi. This frequency offset was done to avoid measuring residuals.

Measurement 1 (M1) — This is a DANL measurement made in a 300 kHz resolution bandwidth. The goal of this measurement is to baseline the noise of the DUT. The test signal amplitude will be placed approximately 5 dB above the measured noise floor.

Measurement 2 (M2) — The test signal amplitude is calculated from the DANL measurement. This step measures the amplitude of the test signal in the 30 Hz resolution bandwidth. The 30 Hz resolution bandwidth will provide a 40 dB improvement in SNR. The goal of this measurement is to baseline the true amplitude of the test signal.

Measurement 3 (M3) — The resolution bandwidth is set to 300 kHz and the amplitude of the signal (plus noise) is measured with the noise corrections set to On. The 300 kHz resolution bandwidth causes the SNR to be around 5 dB. The amplitude difference relative to the M2 measurement is the noise contribution.

The "effective noise, Neff" can be calculated from the results of these three measurements:

M1 = Uncorrected Noise (in watts) = N

M2 = Amplitude of signal with high SNR (in watts) = A

M3 = Amplitude of signal with low SNR (in watts) = A + Neff

Neff = A – (A + Neff)

Neff = M2 – M3

Let’s state this as a ratio because then we can easily calculate the relative improvement in terms of dB:

Noise Improvement (Linear) = Neff/N = (M2-M3)/M1

Noise Improvement (dB) = 10 x LOG(Neff/N) = 10 x LOG [(M2-M3)/M1]

The Effective DANL can be calculated by the following equations:

Effective DANL (dBm/Hz) = Uncorrected Noise (300 kHz RBW) + Noise Improvement (dB) + 1 Hz RBW Normalization

Effective DANL (dBm/Hz) = 10 x LOG(M1/.001) + 10 x LOG [(M2-M3)/M1] + 10 x LOG (300000)

Where: 10 x LOG (30000) normalizes the result to a 1 Hz resolution bandwidth.

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Required Test Equipment

Test Equipment

Recommended Model Number

Microwave Signal Generator #1

PSG Models
(see equipment list)

BNC Cable

8120-1840 

Coaxial Cable, 3.5 mm

11500E

Coaxial Cable, 2.4 mm

8120-6164

3.5 mm (f) to 3.5 mm (f) adapter
(for 3.5 mm source)

83059B

Type-N (m) to 3.5 mm (f) adapter

1250-1744

2.4 mm (f) to 3.5 mm (f) adapter
(for 2.4 mm source)

11901B

Connection Setups

Effective DANL Test Setup