Hardware Verification¶

It is important to verify that the system is operating nominally before deployment and regular operations. We recommend that you run at least the tests below.

GPS and Reference signal tests¶

Test for GPS lock on the GPS Octoclock.
- Connect a GPS antenna to the Octoclock and place the antenna in a location where it can receive a good signal, such as near a window.
- Plug in the power connector for the Octoclock.
- Ensure that the switch of the left side of the Octoclock face is switched to “internal” reference this indicates that the Octoclock is generating its own 10 MHz and 1 PPS signals, not being disciplined by external signals.
- Wait for a while until the green “GPS Lock” LED on the front face of the Octoclock is lit. This may take up to a half hour. Alternatively, you can write a script using the UHD API to query the device for GPS lock. See https://files.ettus.com/manual/classuhd_1_1usrp__clock_1_1multi__usrp__clock.html for more details on how to do this.
Test synchronicity of multiple Octoclock arrangement.
- Set the GPS Octoclock to internal reference, and the other two Octoclocks to external reference - these will be disciplined by the GPS octoclock.
- Using cables of equal electrical length, connect the input 10 MHz and input 1 PPS channels for each non-GPS octoclock to output 10 MHz and 1 PPS channels of the GPS Octoclock. Equal electrical length cables are required to keep the non-GPS Octoclocks synced as closely as possible.
- Use an oscilloscope to compare 10 MHz and 1 PPS channels between the two disciplined Octoclocks, and between output channels on the same Octoclock. Ideally all channels should be no more than 10 nanoseconds different.
Test that N200 REF and PPS LEDs are operating correctly.

Transmitter interface testing¶

Follow the testing procedure below to run a simple test of the TXIO inputs and outputs. There are two types of tests, a single ended output test which tests the SMA outputs and LEDs, and a loopback test which tests the differential signal outputs and inputs without an expensive differential probe. Reference the above image of the rear of the N200 for pinouts.

Connect a needle probe to channel one of your oscilloscope and set it to trigger on the rising edge of channel one.
Connect a needle probe to channel two of your oscilloscope, to be used in later tests.
Run test_txio_gpio.py located in borealis/tests/test_rx_tx/test_txio_gpio/. Usage is as follows (assuming the default IP address):
```
python3 test_txio_gpio.py 192.168.10.2
```
When prompted to enter the pins corresponding to the TXIO signals, press enter to accept the default pin settings. This will begin the tests.

Insert the needle probe into the SMA output corresponding to RXo, this should be the right-most SMA output when facing the N200 from the back.
- Verify that the GREEN LED is flashing, and all others are unlit.
- Verify that the scope signal is the inverse of the pattern flashed by the GREEN front LED.
- Proceed to the next test (CTRL+C, then enter “y”).
Insert the needle probe into the SMA output corresponding to TXo, this should be the second SMA output from the left when facing the N200 from the back.
- Verify that the RED and BLUE LEDs are flashing together, and both others are unlit.
- Verify that the scope signal is the inverse of the pattern flashed by the RED and BLUE front LEDs.
- Proceed to the next test (CTRL+C, then enter “y”).
Insert the needle probe into the SMA output corresponding to TR, this should be the left-most SMA output when facing the N200 from the back.

Note

You will not move on to the next test until you verify the SMA TR, TR+, and TR- signals on the oscilloscope.
- Verify that the BLUE and GREEN LEDs are flashing together, and both others are unlit.
- Verify that the scope signal is the inverse of the pattern flashed by the BLUE and GREEN front LEDs.
Insert the needle probe into the hole corresponding to pin 7 of the D-Sub connector (TR+, yellow wire, J2 pin 10).
- Verify that the scope signal is following the pattern flashed by the BLUE and GREEN front LEDs.
Insert the needle probe into the hole corresponding to pin 2 of the D-Sub connector (TR-, orange wire, J2 pin 8).
- Verify that the scope signal is the inverse of the pattern flashed by the BLUE and GREEN front LEDs.
- Proceed to the next test (CTRL+C, then enter “y”).
Insert the needle probe into SMA output corresponding to IDLE, this should be the third SMA output from the left when facing the N200 from the back.
- Verify that the YELLOW LED is flashing, and all others are unlit.
- Verify that the scope signal is the inverse of the pattern flashed by the YELLOW front LED.
- Proceed to the next test (CTRL+C, then enter “y”).
Insert the needle probe into the hole corresponding to pin 8 of the D-Sub (TM+, green wire, J2 pin 4) Insert the needle probe from the oscilloscope channel two into the hole corresponding to pin 3 of the D-Sub (TM-, blue wire, J2 pin 2).
- Verify that the scope signals for channel 1 and 2 are showing opposing pulses approximately 1 second in width, with a 2 second period (50% duty cycle). In other words, they are 180 degrees out of phase.
- Proceed to the next test (CTRL+C, then enter “y”).
To properly perform the loopback tests of the differential signals, connect the D-Sub pins to each other in the following configuration:
- Pin 6 to pin 7 - AGC+ to TR+, Red wire to Yellow wire
- Pin 1 to pin 2 - AGC- to TR-, Brown wire to Orange wire
- Pin 8 to pin 9 - TM+ to LP+, Green wire to Purple wire
- Pin 3 to pin 4 - TM- to LP-, Blue wire to Grey wire
The first test is a loopback test which uses the TR differential signal output to test the AGC status input. If this test passes you can be confident that the entire path through the differential driver and receiver works properly. It will alternate between setting and clearing the TR signal.
- Verify the hex digit printed by the script is 0x20 when the output pin is high.
- Verify the hex digit printed by the script is 0x800 when the output pin is low.
- If you see 0xa20 or 0xa00 during this test, verify the loop-back connections are in place.
- Proceed to the next test (CTRL+C, then enter “y”).
The second test is a loopback test which uses the TM differential signal output to test the Low Power (LP) status input. If this test passes you can be confident that the entire path through the differential driver and receiver works properly. It will alternate between setting and clearning the TM signal.
- Verify the hex digit printed by the script is 0x2000 when the output pin is high.
- Verify the hex digit printed by the script is 0x200 when the output pin is low.
- If you see 0x2a00 or 0xa00 during this test, verify the loop-back connections are in place.
- Press CTRL+C, then enter “y” to end the tests.

This concludes the tests! If any of these signal output tests failed, additional troubleshooting is needed. To check the entire logic path of each signal, follow the testing procedures found in the TXIO notes document.

Finally, install the enclosure cover lid back in place, ensuring that no wires are pinched.

N200 Output Testing¶

Test bandwidth and amplitude of TX waveforms from N200s across the output bandwidth
Test Timing stability of GPIO from TXIO board in N200s
pulse width
- ATR width
- long-term stability in timing. Use a Logic analyzer to measure this over a long time period (days)
- A Log-Amp circuit can give a TTL signal (same as the EPOP trigger) when a high output power is detected from the transmitter (i.e. TX on) and measure relative timing between TX and ATR, and widths of both signals.
Loopback tests at boresight. This test allows you to see the differences in channel power after digitizing. It verifies that N200s are synchronized, this is due to boresight steering having no phase offset so with all equal cable lengths the phase output on all antennas should be the same (check with rawrf and antennas_iq) - scripts are available under tools/testing_utils/plot_borealis_hdf5_data/
Long-term reliability tests of software
Scope output tests
- verify pulse shape of TX out
- verify GPIO signals (T/R)
- verify pulse distances