Attachment 3 - First Article - System Test Procedures for ASDE-3 DTO Procurement.pdf

Test Procedures

May 19, 2017

SYSTEM TEST PROCEDURES

FOR

ASDE-3 Digitally Tuned Oscillator Procurement

ASDE-3-2016-003738-ES

5/8/2017

Prepared By:

Radar Systems Engineering Branch, AOS-230

Oklahoma City, OK 73125

APPROVAL SIGNATURE PAGE

APPROVAL SIGNATURES

NAME DATE PARTICIPANT

Team Manager, AJW-148 7-26-2017

REVISION RECORD

REVISION

LETTER DESCRIPTION DATE ENTERED BY

A INITIAL PROCEDURES 5/8/2017 B. RAY

B ADDED SPECTRAL PURITY 5/19/17 B. RAY

TABLE OF CONTENTS

1 Scope

2 Referenced documents

3 Test Preparations

3.1 Test

4 Test Cases

4.1 Validation of Absolute and Incremental Accuracy

4.2 Validation of Output Power and Output Power Variation

4.3 Validation of Short Term Stability

4.4 Validation of Spectral Purity

5 Requirements traceability – see test cases

1 Scope.

Internal test procedures for ASDE-3 Digitally Tuned Oscillator . This oscillator is a component of the ASDE-3 Exciter Assy. (Ref Des 3A6, 21877 DWG 187509-1). Devices will be tested at the

FAA facility for verification that they satisfy the requirements defined in DTO 189970 Technical

Requirements Document Rev C.

2 Referenced documents.

• DTO 189970 Technical Requirements Document Rev D

• Maintenance of Airport Surface Detection Equipment (ASDE-3) Collocated with

Airport Movement Area Safety System (AMASS) – 6330.5C

3 Test Preparations.

3.1 Test.

All testing will be done on devices seeking to meet the DTO 189970 Technical Requirements

Document Rev D. These devices may or may not be a Digitally Tuned Oscillator (DTO) but for the purposes of this document they will be referred to as DTOs.

3.1.1 Hardware Preparation.

Validation of frequency accuracy must be done with the DTO installed in the exciter (187509) and the exciter installed in the transmitter/receiver (T/R). Best results may be achieved after the DTO is allowed to heat up for more than 10 minutes.

Freq No. Agility Sequence No. Freq (GHz)

F0 16.950

F1 16.975

F2 17.000

F3 16 17.025

F4 8 17.050

F5 3 17.075

F6 11 17.100

F7 6 17.125

F8 14 17.150

F9 9 17.175

F10 1 17.200

F11 12 17.225

F12 4 17.250

F13 15 17.275

F14 7 17.300

F15 2 17.325

F16 10 17.350

F17 5 17.375

F18 13 17.400

F19 17.425

F20 17.450

Table 1

3.1.2 Software Preparation.

none

3.1.3 Other pre-test Preparations.

none

4 Test Cases.

4.1 Validation of Absolute and Incremental Accuracy.

After the DTO/exciter has been installed and initialized, the rigid coax connected to the Down

Conv LO (J3) port should be removed. Connect an appropriate 50 ohm cable to J3. The other end of the cable should connect (perhaps through 10dB atten) to a frequency counter (eg HP

5350B). With WinPMT, turn off frequency agility. By default, control of the DTO will be set to F10 and the frequency counter will show the measured frequency.

Record the F10 value and set the control for F15 by actuating the Freq Step WinPMT button.

Each time the Freq Step button is pressed the control will go to the next value according to its associated agility sequence number (see Table 1).

Record the F15 value, increment agility sequence number, and record associated frequencies until all 16 values are measured.

To pass the absolute accuracy requirement, the values recorded for each frequency should be within +/- 10MHz of the FREQ values in Table 1. For example, for F10 the allowable frequency range will be 17.190 -17.210 GHz. For F17 the allowable range will be 17.365 -

17.385 GHz.

To pass the incremental accuracy requirement, the difference between any two adjacent frequencies must be 25 +/- 4MHz (or 21 - 29MHz). For example if F10 is 17.2 GHz then F11 will need to be 17.225 +/- .004 or 17.221 - 17.229 GHz. If F10 is 17.203 GHz then F11 will need to be 17.224 - 17.232 GHz.

4.2 Validation of Output Power and Output Power Variation

Validation of the output power and output power variation must be done with the DTO

(187828) installed in the exciter (187509) and the exciter installed in the transmitter/receiver

(T/R). Best results may be achieved after the DTO is allowed to heat up for more than 10 minutes.

The power will be measured at the Down Conv LO (J3) of the exciter with the Gigatronics

8502A peak power meter (or equivalent) at each of the 16 (F3 - F18) frequencies of the DTO.

However, before the measurements can be used to determine the condition of the DTO they must first be corrected for known losses in the exciter and measurement connections. In order to determine the losses of the exciter, a signal generator (HP 8373A or equivalent) will be set up to generate 12dBm of power at 17.2GHz at the end of a low loss 50ohm coax cable. To do this, attach the low loss cable to the signal generator and set up the signal generator for 17.2GHz and approximately 12dBm of power. Attach the power measurement head of the peak power meter to the loose end of the low loss cable. Setup the peak power meter to measure CW (press CW button on front of meter) power. Set the center frequency of the measurement (press FREQ button on front of meter and enter center frequency) for 17.2GHz. Enable or turn on the RF of the signal generator and readjust the signal generator power until the peak power meter reads

12dBm. Typically the signal generator will be at about 16dBm.

After the signal generator power output is set such that measured power at the output of the low loss cable is at 12dBm, connect the low loss cable to the rigid coax inside the exciter assembly that would normally attach to the DTO RF Output J2. Attach the peak power meter to the Down

Conv LO J3 of the exciter assembly. With the peak power meter still in CW mode, measure the power at the exciter output (at 17.2GHz) when the signal generator is attached and RF on.

Record the difference between 12dBm and the value displayed on the peak power meter as the exciter loss incurred by an isolator and directional coupler.

Once the exciter loss is known, the DTO will be put into the exciter and the exciter assembly put into service in the TR. After the exciter assembly has been powered up for more than

10min, the power of the DTO can be measured. To measure the DTO power, the peak power meter must be attached to the exciter Down Conv LO J3. In addition, frequency agility must be turned off. The power of the LO is displayed on the peak power meter. By default, control of the

DTO will be set to F10 and the peak power meter will show the measured frequency. Record the F10 value and set the control for F15 by actuating the Freq Step WinPMT button. Each time the Freq Step button is pressed the control will go to the next value according to its associated agility sequence number (see Table 1). Record the F15 power value, increment agility sequence number, and record associated frequencies until all 16 values are measured. A frequency spectrum analyzer can be attached to the 50dB directional coupler on the top of the TR and set up to confirm the frequency being measured. It will be necessary to know that the transmitted frequency is 1.25GHz below the frequency of the DTO as measured on the LO port of the exciter.

After all power measurements have been made the exciter loss value derived earlier should be added to the measurements to correct for losses of the exciter.

To pass the output power requirement the values recorded for the DTO output must be within

+/- 1.5dB of 12dBm.

To pass the output power variation the difference between the maximum and minimum DTO output must be less than 2dB.

4.3 Validation of Short Term Stability.

Short term stability is the specification of how quickly the DTO switches frequency and how well it keeps it on the new frequency. To monitor the DTO's frequency during the switch, the procedure will use the ASDE downconverter and IF detector. The procedure will disable the transmitter and send a continuous wave (CW) of a frequency near the transmitted frequency through the directional coupler (50 dB) at the top of the TR to the downconverter. As the system switches frequencies it will eventually get to one of the frequencies that is 1.25GHz above the injected signal. When this happens the downconverter will send a 1.25GHz signal to the IF detector and the video signal on the output of the IF detector will be proportional to the frequency of the DTO.

Setup of the frequency measurement system

Remove the IFSTC cable from the top of the triggers card and supply a 5V DC supply to the cable. This will take out the IFSTC profile yet give a fixed level of attenuation to the IF detector.

Turn off the high voltage (at RMSi w/ WINPMT). This keeps the 40ns Tx pulse out of the waveguide.

Remove the RFSTC cable from the top of the triggers card. This removes attenuation at the beginning of the frame.

Disable the RFTT by removing the rigid coax SMA at the bottom of the A8AT3. Connect a signal generator (capable of 15-17GHz at -10dBm) to the -50dB directional coupler at the top of the cabinet with a low loss cable.

Attach the AZ count and AZ reference to a couple of channels of the oscilloscope. Attach the video signal (also available on the TR front panel).

Set the signal generator for 15.95GHz and -10dBm output level. Turn on the RF output of the signal generator.

Adjust the IFSTC voltage.

With the 'scope timebase set to 200us/div, trigger on the Azimuth Reference Pulse (ARP) available on the front of the TR cabinet.

Adjust the frequency either up or down until one of the sixteen 61us pulses of the video signal is at a maximum amplitude. It will be useful to average 10 or more sweeps of the video signal.

The maximum will be around 1V. Adjust the IFSTC power supply until the video output swings from a minimum of -1V to a maximum of 1V. Sweep through the range of the Tx frequencies (15.75 - 16.15GHz) and check that at the setting of IFSTC voltage all 16 video pulses will change amplitude through the +/- 1V range.

Determine the measurement frequencies.

At each frequency that a video burst is at maximum amplitude there are two adjacent frequencies at which amplitudes are roughly at 0.5V. Sweep through the range of Tx frequencies and record the frequencies at which two video pulses are equal and at this ~0.5V level. There will be two such frequencies for each pulse and they will be separated by about

50MHz.. The frequencies will be very close to the operating frequencies of the DTO (minus

1.25GHz) and spaced 25MHz.

Setup oscilloscope for delay by event triggering.

Typical digital storage oscilloscopes (DTOs) can be set up to trigger or delay on some number of B events after an A trigger. Trigger the A with the ARP and then setup B to trigger on the nth event of an Azimuth Change Pulse (ACP). In addition to the event delay add an additional 51us delay to the trigger. In this way the End of Live Time (ELT) can be placed on the DSO screen at the trigger location and at a timebase that will allow for closer inspection of the video signal. It is at the ELT the DTO is commanded to change frequencies. Setting the timebase at 1us/div will allow validation of the switching behavior of the DTO.

Use the delay by events to focus attention on each of the 16 frequencies starting at n = 15. At n

= 15 the two frequencies that can be measured are near 15.925GHz and 15.975GHz. At n = 16 the two frequencies that can be measured are near 16.05GHz and 16.1GHz.

To pass the short term requirements, the DTO frequency must switch to within 3MHz (+/-

200mV) of the new frequency 1.5us after the ELT and not deviate from it for 50us.

4.4 Validation of Spectral Purity

This test is based upon the 6330.5C MTHB procedure 5-8. Transmitter Center Frequency

Measurement and RF Spectrum Procedure. It is an effort to confirm that the DTO Phase

Noise and Spurious Outputs has no adverse affect on a commonly performed system procedure.

Test Equipment Required.

(1) Spectrum analyzer, Hewlett-Packard model 8563A or equivalent.

(2) Cable, low loss, SMA, male-to-male, Flexco FC182 6060 0840 A6B, NSN 6150-01-

423-7818 or equivalent.

d. Detailed Procedure.

(1) Perform paragraph 5-41, T/R to Standalone Mode Procedure.

(2) Set the spectrum analyzer to a center frequency of 15.95 GHz.

(3) Set the spectrum analyzer for a 500-MHz span.

(4) Set up the spectrum analyzer to measure amplitude of 0 dBm (zero dBm):

(5) Set the spectrum analyzer sweep period to 700 milliseconds.

(6) Using a low loss cable, connect the spectrum analyzer to the minus 40 dB (-40 dB) forward power port of the directional coupler on top of the T/R cabinet being aligned.

(7) On WinPMT for the standalone T/R, perform the following commands:

(a) Confirm high voltage is on. If not, select HV ON and submit. Confirm the HV INHB red LED on the RF Filter Box assembly, A1, is OFF.

(b) Confirm triggers are on. If not, select Triggers ON and submit. Confirm the RAD

PWR ON green LED is ON.

(c) Confirm Frequency Agility is on. If not, select Freg Agility ON and submit.

(8) On the spectrum analyzer, place marker on the center frequency

(9) On WinPMT for the standalone T/R, perform the following commands:

(a) Select Frequency Agility OFF and submit. There should be one primary peak now displayed at or near the center vertical graticule on the spectrum analyzer; and if so, proceed to step (10).

(b) If the peak of the signal is NOT at or near the center vertical graticule of the spectrum analyzer, on WinPMT, select Frequency Agility ON and submit. Next, select

Frequency Agility OFF and submit. Check the signal peak on the spectrum analyzer screen again, it should now be at or near the center graticule of the spectrum analyzer screen. If not, perform this step again until it does.

(10) On the spectrum analyzer:

(a) Press the PEAK SEARCH key under the Marker section. This will automatically locate the frequency of the peak amplitude.

(b) Press the MARKER→CF soft key. Note the frequency reading at the top of the spectrum analyzer screen. Confirm the center frequency is between 15.911 GHz and 15.989

GHz. Record the actual transmitter center frequency.

(c) Press the MARKER DELTA menu soft key.

(d) Using the keypad, enter 210.

(e) Press the MHz data key and record dB reading on display.

(f) Using the data keypad enter -210.

(g) Press the MHz data key and record dB reading on display.

(h) Verify the amplitude (dB) readings are at least 40 dB down (-40 dB) at ±210 MHz from center frequency. If readings are less than 40 dB down ±210 MHz from center frequency perform paragraph 5-20, Transmitter Pulse Width Adjustment Procedure.

(11) On WinPMT for the standalone T/R, perform the following command. Select Freq

Agility On and submit. Verify the spectrum analyzer display shows the 16 discrete frequencies.

5 Requirements traceability – see test cases.