Earthworm Modules:
PsnAdSend Version 2.6 for Earthworm 7.x Overview

Updated: December 21, 2014

Index:

Introduction:

PsnAdSend is a digitizing module similar to ADSend for Earthworm. This module runs under Windows (2000, XP, Vista or Win7) or Linux and produces demultiplexed data to one of the transport data rings. This program was designed to work with the Webtronics' 16-Bit 8-Channel PSN-ADC-SERIAL or PSN-ADC-USB Analog to Digital boards, PSN-ACCEL (our new strong motion board) as well as the VolksMeter Sensor. The 16-Bit ADC board can record 1 to 8 channels at sample rates of 10, 20, 50, 100, 200, 250 or 500 sample per second. At 500 SPS the maximum number of channels the board can digitize is 4. To use the board you will need one free RS-232 Comm port or use the USB version of the board. If the system only has USB ports, a USB to RS-232 converter can be used between the computer and the PSN-ADC-SERIAL board. Adapters based on the FTDI chip set are recommended. The PSN-ACCEL board has both RS-232 and USB ports and can record up to 4 channels at 15, 25, 30, 50, 60, 100, 120 or 200 samples per second.

The Windows version of the module was built using Microsoft Visual C++ 8.0 (Visual Studio 2005) and the Linux version is build and tested using OpenSuse 11.4. The program (PsnAdSend.exe) has been tested using Earthworm version 7.7. The PsnAdSend module uses the PSNADBoard.dll to interface between the program and the ADC board. See this page for more information on the DLL / Linux library. Under Windows this file must be in the same bin directory as PsnAdSend.exe and be DLL version 5.1 or higher. The Linux version does not need any other files other then the PsnAdSend executable. 

Addition Configuration File Information:

PsnAdSend Version 2 has some additional configuration file parameters; 

The ConsoleDisplay parameter is only used under Windows and controls how PsnAdSend displays status information on the screen.  If set to 1, the  program will clear the screen, reposition the cursor to the top of the window and display the status information.  When ConsoleDisplay = 0, status information will be appended to the end of the screen buffer.

The ControlCExit parameter controls how the module handles console event signals like Control-C. If the parameter = 1, PsnAdSend will exit, if 0, the program will ignore Control-C keyboard input.

The RefreshTime parameter is used to automatically display the module status on the screen. The number entered is in seconds. If the user enters 0 (zero) for this parameter no status information will be displayed on the screen.

CheckStdin is another Windows only feature. If set to 1, the program will pole the STDIN buffer using kbhit() for any user input. Currently only the 'c' key is used to clear the packet received counter, all other input will redisplay the module status information.

The Station/Component/Network/Location (SCNL) channel line format has been changed and the need for Nchan has been removed. The number of channels that the ADC board will record is now controlled by how many SCNL channel lines are found in the configuration file. Older versions of PsnAdSend required a index parameter per Channel line, this is no longer needed. The new SCNL line format looks like this:

     # Stat Comp Net Loc Bits Gain FltrDly Invert Send DcOffset
     # ---- ---- --- --- ---- ---- ------- ------ ---- --------
Chan   CH1  SHZ  PN  01   16    1     20      N     Y     0
Chan   CH2  SHN  PN  02   16    1     20      N     Y     0

Note #1: This parameter controls how many converter bits will be used from the ADC channel. For 16 bit boards this parameter can be in the range of 12 to 16. The VolksMeter and SDR24 boards use a 24 bit converter, so the range can be 12 to 24. 

Note #2: The Filter Delay parameter is used to compensate for the propagation delay of the signal through the low-pass filter connected between the sensor and the A/D card. This is done by subtracting time from the packet start time before sending the data to the EW ring. 

Additional Derived Channels:

Version 2.x of the PsnAdSend Module has a new feature that allows the user to create additional channels from one of the real ADC channels. This can be used with the new built in digital filters (see below for more information) to send both the filtered data and raw data to EW. The SCNL line is similar to the normal channel SCNL control line.

#       AdcCh Stat Comp Net Loc Bits FltrDly Invert Send DcOffset
#       ----- ---- ---- --- --- ---- ------- ------ ---- --------
AddChan   1    CH9  BHN  NC  02  16     0      N     Y     0

Data Time Stamping:

The PSN-ADC-SERIAL/PSN-ADC-USB boards and the PSNADBoard.dll can use various methods to time stamp the data. The most accurate timing (< 3 milliseconds) can be achieved using a GPS receiver connected to the digitizer. Currently the board supports the Garmin GPS 16, Garmin GPS 18x LVC Sensors or the older and now obsolete Motorola ONCORE receiver series.  If the system is running a program like the NTP, the user can expect an overall accuracy of around +-50 milliseconds. DLL/Linux Library version 2.0 and some of our ADC boards now support the Sure Electronics GPS Evaluation board. To use this GPS receiver the user must solder a wire from the GPS' 1-PPS signal to pin 1 of the RS-232 connector. To power the receiver from the ADC board the user can solder another wire from pin 5 of the RS-232 connector to the +5VDC buss on the GPS evaluation board. 

PsnAdSend version 2.4 and above now supports generic OEM GPS receivers running at 4800 or 9600 baud. The GPS receiver must have a 1 Pulse Per Second signal going to Pin 1 of the GPS connector on the ADC board. This signal must be a few milliseconds in duration to be detected correctly by the board. Use "HighToLowPPS 1" in the PsnAdSend configuration  file if the 1PPS signal has a high to low direction at the top of the second. This will need to be done if the 1PPS signal goes through an inverter before going into the A/D board.

Built-in Digital Filters:

The PsnAdSend module now has some basic digital filtering. Each channel, including the derived channels, can have one or more of the of the following filter types:

See http://www.seismicnet.com/epf/ for more information on the inverse filter. The Inverse Period Extending Software filter is based on work by Bob McClure.

TCP/IP Connection to ADC Board:

Version 2.x of the PsnAdSend now supports a TCP/IP connection to the ADC board through a TCP/IP to RS-232 bridge. This can be either wired or wireless based on the adapter type. We have been experimenting with WiFi adapter  that seems to work Ok. To use this feature set the "TcpMode" parameter in the PsnAdSend.d file to 1, set the "CommPortTcpHost" to the host IP address or host name of the adapter and "TcpPort" to the adapters port number. The RS-232 bridge must be configured as a server and listen for a connection from the host computer running PsnAdSend.     

New Features in Version 2.5:

A new parameter MUX_DATA_RING has been added to the configuration file. This parameter can be used to send raw multiplexed ADC data as well as log file messages to the specified transport ring. This parameter is option so it can be commented out, removed from the *.d file or set to 0 (zero) to disable this feature. The sending of the raw multiplexed data can be used by our Ew2Ws (Earthworm two WinSDR) module to send ADC data to our WinSDR datalogging program through Earthworm. Messages sent to the specified ring are sent with the TYPE_ADBUF message-type tag defined in the earthworm_global.d file. The user will need to use an unused transport ring or define a new one in the earthworm.d file.  Example:

Ring MUX_DATA_RING   1038      # multiplexed waveform data ring

You will also need to define and set the size of the ring in your startstop_*.d file. Example:

nRing 2
Ring WAVE_RING       2048
Ring MUX_DATA_RING   2048

Five other parameters, all optional, have been added to the configuration file. The first three are used to send time reference error messages to the StatMgr. They are;

SystemTimeError - Used to test the time difference between the ADC board time and the system time. This parameter is in seconds. If the time difference exceeds the specified amount an error message will be sent to the StatMgr. Setting this parameter to 0 will disable this test.

PPSTimeError - Used to test the time difference between the GPS receiver and the time on the ADC board. This parameter is in milliseconds. If the time difference exceeds the specified amount an error message will be sent to the StatMgr. A value greater then 10 milliseconds should be used for this parameter. Setting this parameter to 0 will disable this test.

NoLockTimeError - Used to test for a long unlocked time reference condition. This parameter is in minutes. If the ADC board becomes unlocked or never locks to the time reference in the specified time limit  PsnAdSend will send an error message to the StatMgr. 

The last two parameters are used to filter out some time reference log messages from going to the log file.

FilterSysTimeDiff - If the SystemTimeError feature is enabled the message below will be sent to the log file every 5 minutes. When the FilterSysTimeDiff  feature is enabled these messages will be blocked from going to the log file.

DLL: Time difference between A/D Board and Host Computer=-0.001 seconds

FilterGPSMessages - When the time reference type is set to one of the GPS receiver options PsnAdSend will log a status message every 5 minutes that looks like this from 24-Bit boards: 

DLL: GPSRef: Sts:1 Lck:1 Sats:10 LckTm:12 10:49 Vco:48% VcoChg:00:00/00:02 PPSDif:0

And this from 16-Bit boards:

DLL: GPSRef: Sts:2 Lck:1 Sats:12 AdjTm:23:45.6 A LckTm:13 12:18 MsAdj:-2 MsOff:-3 1PPSDif:-1

If the FilterGpsMessages option is enabled PsnAdSend will filter out messages indicating a good lock status. 

New Features in Version 2.6:

One new feature has been added to PsnAdSend version 2.6. This feature, controlled by the StartTimeError parameter in the configuration file, can be used to seed the system time when PsnAdSend first starts running. This is for systems like the Linux based BeagleBone or Raspberry Pi boards that do not have a Real-Time Clock (RTC) to set the system time after boot-up. This option may not be needed if the BeagleBone or Raspberry Pi board has access to a NTP time server. A system without a RTC, or NTP server access, will boot-up with the system time set to a date sometime in the past. 

When the StartTimeError parameter is used PsnAdSend will wait for the GPS receiver to lock onto UTC time and then set the system time to the current date and time. The StartTimeError feature is similar to but independent from the UpdateSysClock parameter. The StartTimeError only checks the system time once after GPS lock. If the error, in seconds, is greater then the number entered in the StartTimeError parameter PsnAdSend will set the system time. Once the system time is set or the time difference is below the StartTimeError number, PsnAdSend will stop performing the time test. The UpdateSysClock should be enabled to continuously monitor and set the system time if the time difference is greater then 50 milliseconds. Please note that this feature is not available on PsnAdSend built for Windows.    

Additional Information:

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