Freq Resp Below 250 kHz Option BBA Performance Test

This test applies to the following models with Option BBA:

The BBIQ Verification tests rely on the BBIQ Front Panel Alignment being run within 8 hours of running a verification test. If the alignment timestamp is greater than 8 hours from the current time, TME will run the BBIQ alignment. If the time difference between the DUT and the TME station clock is more than 8 hours, then TME will get stuck in an endless BBIQ alignment loop. To prevent this from happening, the DUT clock should be set to the local time. At the end of the adjustment cycle, set the DUT clock back to the customer's local time.

The Baseband IQ (BBIQ) hardware is a separate measurement path from the signal analyzer RF path. The BBIQ path is controlled through the IQ Analyzer Mode. The BBIQ hardware has four different input ports (or channels):

  • I (unbalanced)

  • I-Bar (balanced)

  • Q (unbalanced)

  • Q-Bar (balanced)

Each input port has 4 different amplitude ranges:

  • 1 Volt Peak (+10 dBm)

  • 0.5 Volts Peak (+4 dBm)

  • 0.25 Volts Peak (-2 dBm)

  • 0.125 Volts Peak (-8 dBm)

Each input has two impedance choices: 50 Ohm, and 1 Meg Ohm. There are potentially 32 different Input/Range/Impedance test variants that need to be tested.

This test measures the Baseband IQ (BBIQ) frequency response below 250 kHz. Frequency Response is defined as the amplitude difference at a test frequency compared to the reference amplitude at 250 kHz.

A function generator and DVM are used in this test. The DVM provides very accurate measurements below 250 kHz. In this test a DVM is placed in parallel to the DUT input. The source and DUT have a 50 Ohm characteristic impedance. The source is padded by 10 dB in order to present a known match to the DUT. The DVM has a 1 Meg Ohm input impedance so it won't load the system down. The DVM voltage is assumed to be the DUT input voltage.

This test will depend on the BBIQ IQ Cable Cal. The IQ Cable Cal is a frequency response calibration that is done manually on the signal analyzer. If the time since a IQ Cable Cal has been performed is more than 8 hours, the user will be prompted to perform an IQ Cable Cal.

 

BBIQ Frequency Response is described as a nominal specification. Generally nominal parameters are not tested. Frequency Response is tested because there is a minimum level of functionality that needs to be guaranteed. This level of functionality is especially true in the case of a field retrofit.

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Required Test Equipment

Test Equipment

Recommended Model Number

Function Generator

33622A

Digital Multimeter

3458A

10 dB Fixed Attenuator

8493C Option 010

BNC (m) Termination

1250-0207

BNC Cable
(4 ft, 3 required)

8120-1840 

BNC (f) to Type-N (m) adapter

1250-1476

BNC (m) to Type-N (f) adapter

1250-1477

BNC (f) to Dual Banana jack adapter

1251-2277

BNC Tee

1250-0781

Connection Setups

In the following setups, cables are designated as solid lines and direct connections are designated as dashed lines.

Freq Resp Below 250 kHz Option BBA
(non-Bar Inputs) Test Setup

 

Freq Resp Below 250 kHz Option BBA
(I-Bar Input) Test Setup

 

Frequency Response Below 250 kHz
(Q-Bar Input) Test Setup