Workshops/Workshops/RadarSystems2009/RadarSystems2009/openradar workshop tutorial digital receivers

Digital Receiver Tutorial

In this tutorial we will collect data remotely using several data systems which are part of the ISIS Array. Different groups will collect data using different systems. The systems used are part of nodes at MIT Haystack Observatory or Siena College.

Data collection is done remotely using command line tools to issue the needed collection requests and for simplicity we will use the wget tool to transfer data from the remote system's web server. It is possible to browse the data on the remote system using a web browser by clicking on the given link for the node. Once the data is collected and downloaded a simple script will be used to make several types of plots. These plots will be saved. As a group we can then compare the resulting plots and discuss what is seen at the different locations.

FM Radio signals will be used for the observations in this tutorial. The needed digital receiver configuration files have already been created and loaded onto the ISIS array nodes. Each node has different frequency tunings which are suitable for the local radio environment. The first data acquisition will obtain 7.2 MHz of RF bandwidth centered at 100 MHz. The second will select a single FM radio station at 150 kHz bandwidth.

The ISIS Nodes will be :

Steps :

  1. Login to your Linux tutorial workstation using the guest account and the provided password.

  2. Open a bash shell terminal window.

  3. In the terminal window, change directory to the digital_rx_tutorial. 

    • [guest@minos ~]$ cd tutorials/digital_rx_tutorial/

  4. There will be two data sets collected. Determine the data acquisition times. Choose times a few minutes ahead of the current time. The command ( date -u ) can be used to get the time in UTC. We prefer to work with UTC times to avoid confusion about time zones.

  5. Issue the following data collection commands. It will be necessary to substitute the URI for your group and also use a future UTC time. The commands are python scripts which communicate with the remote servers via XMLRPC. A configuration file name is provided for each data collection. A UTC time is provided as well as a URI that points at the remote isis system digital receiver daq_service script. Each data collection will be for a duration of 5 seconds. 

    • 
[guest@minos group1]$ python /usr/local/midas/bin/daq_remote_collect.py -c workshop_tutorial_1a.ini -d 5 -t "2009-05-25 20:15:00 UTC" -u http://snc-isis004.siena.edu/isis-rx40/cgi-bin/daq_service

Collect data http://snc-isis004.siena.edu/isis-rx40/cgi-bin/daq_service at 2009-05-25 20:15:00 UTC for 5 seconds.

Success for http://snc-isis004.siena.edu/isis-rx40/cgi-bin/daq_service at time 2009-05-25 20:15:00 UTC (1243282500)

[guest@minos group1]$ python /usr/local/midas/bin/daq_remote_collect.py -c workshop_tutorial_1b.ini -d 5 -t "2009-05-25 20:16:00 UTC" -u http://snc-isis004.siena.edu/isis-rx40/cgi-bin/daq_service

Collect data http://snc-isis004.siena.edu/isis-rx40/cgi-bin/daq_service at 2009-05-25 20:16:00 UTC for 5 seconds.

Success for http://snc-isis004.siena.edu/isis-rx40/cgi-bin/daq_service at time 2009-05-25 20:16:00 UTC (1243282560)

  6. While you wait for the data collection times to pass you can take a look at the digital receiver configurations in your web browser. The configuration files have some comments to help you understand the different parts. Setting up digital receivers can be complex. ctrl-click on the following links to open a tab to the appropriate files :

  7. Now that the data collections have occurred. Transfer the data using the command line wget tool. You must provide the appropriate location for the data and substitute the unix long second for the time. If the config file for the acquisition uses a different chip and channel, substitute the correct one. The daq_remote_collect program prints out the needed long second when an acquisition is successfully scheduled. There is a slight chance that the data collection will have had a problem or be offset by about a second. Seek additional help if the transfer doesn't work. It is possible to use the hyperlinks to the node web servers to look up the file names and cut and paste them into a wget command. 

    • 
[guest@minos group1]$ wget http://snc-isis004.siena.edu/isis-rx40/isis/2009-05-25/ecdr_chip00_chan00@1243282500.bin
--16:16:12--  http://snc-isis004.siena.edu/isis-rx40/isis/2009-05-25/ecdr_chip00_chan00@1243282500.bin
Resolving snc-isis004.siena.edu... 66.194.178.64
Connecting to snc-isis004.siena.edu|66.194.178.64|:80... connected.
HTTP request sent, awaiting response... 200 OK
Length: 80740352 (77M) [application/octet-stream]
Saving to: `ecdr_chip00_chan00@1243282500.bin'

100%[================================================================>] 80,740,352  3.70M/s   in 23s    

16:16:35 (3.41 MB/s) - `ecdr_chip00_chan00@1243282500.bin' saved [80740352/80740352]

[guest@minos group1]$ wget http://snc-isis004.siena.edu/isis-rx40/isis/2009-05-25/ecdr_chip00_chan00@1243282560.bin
--16:16:39--  http://snc-isis004.siena.edu/isis-rx40/isis/2009-05-25/ecdr_chip00_chan00@1243282560.bin
Resolving snc-isis004.siena.edu... 66.194.178.64
Connecting to snc-isis004.siena.edu|66.194.178.64|:80... connected.
HTTP request sent, awaiting response... 200 OK
Length: 3145728 (3.0M) [application/octet-stream]
Saving to: `ecdr_chip00_chan00@1243282560.bin'

100%[================================================================>] 3,145,728   3.07M/s   in 1.0s   

16:16:40 (3.07 MB/s) - `ecdr_chip00_chan00@1243282560.bin' saved [3145728/3145728]

8. Now the data can be plotted. To do this we will use a program called ecdr_plot.py which loads and displays data in different formats. It will be necessary to substitute the correct filename for each plot.

Each plot will display with a window that allows interactive zoom and pan over the data. The program also has the ability to save the output as a png file. When making each plot save a copy with the provided name for later comparison with the other groups (substitute your group's number for # below). To make the plot click the save icon and type the appropriate file name.

  1. Dataset 1 plot 1: FM Band Specgram (save as g#_d1_plot1.png)

9. Rejoin the other groups. We will now compare the signals collected at the different sites and discuss what the plots show.

last edited 2009-05-26 00:56:57 by FrankLind