Radio Oceanography Laboratory Support

RADCELF TEST

This is to test a D-Tacq stack consisting of ACQ1001 base board, ACQ435 ADC board, RADCELF DDS board, and UBlox F9T GNSS board. You need a NUC or laptop configured as a host computer with the standard GHFDR release software, and an OCXO installed in the socket.

A 12V power supply with center + is required. Verify that the center connector as 12V, CAUTION! some laptops have identical connector but 19V, which would irremediably damage the D-Tacq regulators. Connect the power supply to the D-Tacq base board.
Connect the micro-USB port of the D-Tacq to the host computer. Login into the D-Tacq over USB (you may need to be root):

 $ sudo su
 # screen /dev/ttyUSB0 115200
 acq1001-xxx login: root
 Password: d-t1012q

Connect the Ethernet port of the base board to the local network, assumed to provide dhcp service.
Verify IP address of the D-Tacq and make sure that it is on the same network as the host computer:

 acq1001-151> ifconfig
 eth0 inet addr:172.16.1.238  Bcast:172.16.255.255  Mask:255.255.0.0

If erroneous IP, you may need to reset it to dhcp by removing eth0 configuration file:

 acq1001-151> rm /mnt/local/ifconfig
 acq1001-151> reboot

 $ ssh root@172.16.1.238
 Password: d-t1012q

If there is no dhcp server, the D-tacq can be set manually to a fixed IP in the eth0 configuration file:

 acq1001_151> cat /mnt/local/network
 ifconfig eth0 172.16.1.238

Once communication is established using either micro-USB or Ethernet, check that the release version of the D-Tacq is exactly 473; if not prepare off-line a new SD-card with version 473, power off and restart with new card:

 head-1 /mnt/RELEASENOTES

Files radcelf_ini.sh and radcelf_ini_cal.sh must be in /mnt/local/. We’ll check that the Crystal has a frequency of 100 MHz. Connect the INS OSC (p4) to spectrum analyzer, using 20 dbm of attenuation as safety.

First press the button auto, you’ll be able to see the signal. Then configuration the frequency of spectrum analyzer between 98 MHz and 102 MHz, bandwidth (BW) to 1 Khz and Trace to max hold.

If you don’t have a signal or the frequency is different of 100 Mhz , the crystal isn’t working properly. The output in dBm could change depending on the crystal’s manufacturer. Figure 2 shows the output for the crystal, the frequency is 100 MHz and the output in dbm is -24.23 dBm.

Connect the TTL CLK (p6) to spectrum analyzer. We’ll check the frequency of DDS-C. It has to be ~ 24.19790769MHz. Use the same configuration in the spectrum analyzer as the previous step, but adjust the range of frequency to 23 MHz to 25.5 MHz. Figure 3 shows the output that we get for DDS-C. In the script radcelf_ini.sh we set up this frequency.

When DDS is in chirp mode, the frequency of DDS-B must be zero and in DDS-A we’ll have a frequency sweep. Connect DDS-A-Q (P21) or I (P19) to spectrum analyzer, if you use the same configuration as the previous step, you can see the bandwidth of your signal, just adjust the range of frequency to the frequency that you set up. Use delta market to measure the bandwidth. Figure 4 shows the bandwidth for a frequency sweep of 50 Khz.

To check the output of Q/I of DDS-A and DDS-B, use the oscilloscope. Use DDS in calibration mode but you have to change the frequency of DDS-B to be the same of DDS-A. Make a copy of script radcelf_ini_cal.sh and edit the following:

Comment the line of the frequency of DDS-B:

/usr/local/bin/set.ddsB FTW1 0E31A999999A

Add the following line. We’re setting the same frequency for DDS-A and B. Note that this frequency corresponds with the frequency desire that we set up. /usr/local/bin/set.ddsB FTW1 0E3CF71C71C7

Execute the new radcelf_ini_cal.sh and connect all 4 output to oscilloscope. Adjust all the channels to the same position and scale, acquisition mode = average and coupling =DC.

All 4 channels should have the same amplitude. If there is difference between DDS-A and B, with the little potentiometer you can adjust the output. Figure 5 shows the signals of the 4 channels and voltage peak-peak of signal. The output of DDS should be ~ 5.5 dbm ( ~1.128 V).

ADC BOARD

To test an ADC board we need to configure a signal of ~100 Hz that goes to a special little board and It to d-tacq.

Before getting an acquisition, use the oscilloscope to measure voltage of the signal that you generate. The signal in our case has an output of ~ 676 mV. Get an acquisition of 60 seg and process it. You should have the same amplitude and phase in all channels, make a plot of the last chirp to see if your board is working properly.

DTacqTest