VHF Tag Registration

From $1

    Version as of 05:29, 16 Feb 2019

    to this version.

    Return to Version archive.

    View current version

    SensorGnome users: deployment without registration is futile - always do this step before deploying tags!

    Lotek receiver users: registration lets SensorGnome users detect your tags in their data.

    To register a tag, you need to make a short recording of its output using a funcubedongle attached to a PC, or from the headphone jack of a Lotek receiver.

    Use the appropriate hook-up procedure, then register your tags!

    Hook-up for SensorGnome Users

    1. remove a funcubedongle from a SensorGnome, and attach it to a computer USB port, ideally via a USB extension cable
       
    2. determine whether you have a funcubedongle Pro (wrapped in copper if from Acadia U.) or Pro Plus (wrapped in aluminum if from Acadia U.)
      (The SensorGnome web interface will show you which model(s) you have if they are plugged into the USB hub.)
       
    3. if possible, attach a VHF antenna to the BNC jack on the funcubedongle (or be sure to hold the tag close to the funcubedongle).
       
    4. place the funcube flat on a printout of the attached layout so that the funcube's edges line up with the tracing on the layout.  The layout also has a position for the tag antenna and tag base - this is where you should place each tag when recording its registration file.  Standardizing the layout like this will help us notice when tags are transmitting at unduly low power levels, as might happen if the battery is low or due to a manufacturing defect.
       
    5. tune the funcubedongle receiver to the frequency 4 kHz below your tag's nominal frequency.  For example, if your tag is supposed to broadcast at 166.380 MHz, tune to 166.376 MHz.  This will require one of these programs:
      • Windows users:  use QTHID-4.1 for funcubedongle Pro Plus, and QTHID-4.0 for the original funcubedongle Pro.
         
      • Mac OS/X users:  use QTHID-4.1 for funcubedongle Pro Plus, and QTHID-4.0 for the original funcubedongle Pro.

      • Funcube not recognized by your computer?:  if your funcubedongle Pro+ has been
        attached to a SensorGnome with post July-2015 software, you'll need to use the
        FCHID
        program to set its frequency when registering tags.  The QTHID programs do not recognize
        funcubedongles with the updated firmware they obtain from recent SG software.
        Unfortunately, this is a windows-only solution, at the moment.

        You get  "audacity error opening sound device" when you hit record?  You might need to delete
        the drivers for the funcube (Windows).  With the funcube plugged in, go into
             Control Panel | Device Manager | Sound, video and game controllers
        then right click on the entry for FUNcube Dongle and choose uninstall.
         
        Remove the funcubedongle, wait a few seconds, re-insert, then wait for drivers to reinstall.


         
    6. The QTHID program allows you to change other parameters - don't do this - use the default values which are shown below.  In particular, make sure LNB is 0.000 MHz!    Changing LNB will change your frequency, so go back and reset the frequency directly if this happens.   Set the frequency in MHz by typing it into wide frequency box with the black background (aka odometer).  You can point the mouse at individual digits in the odometer and use the mousewheel to dial them up or down (but note that it changes the preceding digit when it wraps).  You can also point at an odometer digit and type its replacement.

      Here is what the settings should look like in both versions of the program (for tags at 166.380 MHz):

                 
                        qthid 4.1 settings for Funcube Pro Plus                                                  qthid 4.0 for Funcube Pro
                        (LNA is on and Mixer gain is On, but set to 0 dB)

    Hook-up for Lotek receiver Users

    Warning:  turn off all echo cancellation and noise reduction controls, both on the Lotek receiver and on your computer's audio input jack.  Failure to do so may result in distorted or even unusable registration .WAV files

    1. turn the volume all the way down on your Lotek receiver
    2. connect the headphone jack of your Lotek receiver to the line-in jack of your computer.  If your computer does not have a line-in jack, you may be able to use the microphone-in jack, but you do so at your own risk - we cannot be responsible for damage to your computer's audio hardware.  For the Lotek SRX-600, this connection will require a 1/4" plug to 1/8" jack adapter, or some other way to join the 1/8" jack on the receiver to the 1/4" jack on your computer.
    3. set the Lotek receiver to listen on the appropriate frequency
    4. activate a tag
    5. watching the microphone levels meter in Audacity (see screenshot below), slowly turn up the volume on the Lotek receiver until you red bars bouncing to the right every time the tag emits a burst.  The peak levels are persistent, and should be kept away from the extreme right end of the meter by lowering the volume or microphone input level if necessary.
    6. de-activate the tag (this activation was just to get the volume set correctly)

    Register a tag - SensorGnome and Lotek

    1. start recording stereo audio from the funcubedongle (SensorGnome) or line in / microphone (Lotek receiver) at 48000 Hz using audacity.
      You will probably find it helpful to set your default sample rate to 48000 Hz using the Edit | Preferences menu like so:

      audacity_quality_default_sample_rate.png
       
    2. activate your tag with the Lotek activator (you'll see an activation spike and the first burst of 4 pulses in the audacity window):
      1. lower your tag into the hole in the activator unit a few mm below the surface of the unit, with the label facing the "Label->" marking on the unit
      2. press the Start button
      3. this should light up the green LED on the activator for a 1-2 seconds.  While the green LED is lit, further presses of the Start button are ineffective.
      4. if this doesn't immediately show large spikes in audacity, move the tag a little bit up or down, then repeat from step 2.
    3. record at least 3 consecutive bursts from the tag  (e.g. if the burst interval is 10 seconds, your recording will be at least 31 seconds or so)
    4. de-activate your tag with the Lotek activator (you'll see a deactivation spike in the audacity window, then wait at least 1 burst interval to ensure the tag is off).   If you don't de-activate, we can't guarantee that your registration file will be usable.
    5. Use File | Export... to save the recording to a file named tagXXX.wav, e.g. tag435.wav. If there are duplicate tagIDs with different burst intervals use the addition of ".1" for duplicates; eg. tag123.wav and tag123.1.wav could be present if there were two tag IDs 123 with different burst intervals.
      • XXX is the Lotek tag ID - you must include this in the name
         
    6. make sure the recording has at least 3 consecutive bursts from your tag.  These will be visible as sharp vertical spikes in the audacity window, separated by the burst interval for your tag (e.g. 5 seconds).  When you zoom into each burst in audacity, you should see 4 sharp spikes in each burst.
    7. make sure the tag you are registering is the only one active in the vicinity of the funcubedongle
    8. repeat this procedure for every tag you will deploy, even if it has the same ID as another tag you are deploying or have deployed.  Even tags with the same ID, burst interval, and nominal frequency can vary somewhat in detailed signal characteristics, and this information is useful for later data processing. 
    9. make sure to do File | New or close the track between recordings, so that each recording starts with an empty track - please don't overlay different tags in the same recording.
    10. Create a .txt file called tagreg.txt (file available for download below) to record the following tag information:
      • motusProjID: XXX (numeric project ID)
      • tagModel: NTQB-??? (as given on the Lotek invoice)
      • nomFreq: 166.38 (nominal tag frequency, in MHz)
      • species: XXXXX (optional 4-letter code or motus numeric species ID)
      • deployDate: YYYY-MM-DD (earliest likely deployment date for any tags)
         
    11. create a .ZIP or other archive of your WAV files AND the tagreg.txt file and store it somewhere safe.
    12. upload the .ZIP file to https://sensorgnome.org/Sending_Data_for_Automatic_Processing, this requires sensorgnome.org login credentials (email jbrzusto AT fastmail DOT fm to obtain them).

    SensorGnome users: don't forget to re-install the funcubedongle in your SensorGnome.

    What registration looks like in Audacity

    Here's a screen capture of Audacity after recording the first three bursts from a tag.  Here, we also capture the "start" and "end" pulses from the tag being turned on and off, but this is not necessary for registration recordings. 

    tag_registration_in_audacity.png
    The bursts should each consist of four spikes that span the vertical scale in the range [-0.2, 0.2] or greater.
    The ones here span approximately [-0.6, 0.6]:
    tag_registration_zoom_into_first_burst.png

    NOTE: Deactivate each tag after you register it; start each recording in a new track window

    If you don't do this, all active tags contribute to the registration recording, and it becomes nearly
    impossible to identify the signature of the tag being registered (note the x-axis scale, which is in seconds):

    This recording shows at least 10 active tags.  The same problem occurs if you record different tags without closing the track
    or doing File | New between consecutive tags. 

    Beware of Bad Pulses (SensorGnome users only)

    The registration procedure is usually straightforward, but occasionally, the match between the tag's
    actual transmit frequency and the listen frequency on the funcubedongle is too(!) good, which can lead
    to wonky-looking pulses because the funcubedongle has trouble staying locked on the tag's frequency
    (this issue is not unique to the funcubedongle).
    The symptom is pulses with missing top or bottom legs, such as the second in this burst:

    tag_registration_showing_bad_pulse.png

    If you see this, try re-tuning the funcubedongle frequency to 2 kHz (rather than 4kHz)
    below the nominal tag frequency (e.g. 166.378 MHz for a nominal 166.380 MHz), then re-record
    the bursts.  Repeat this procedure in 2 kHz steps until you get a set of bursts with symmetric
    spikes for all pulses.
    Make note of this by changing the filename so it includes a second '@FFF.FFF' portion indicating
    the frequency to which the funcube was tuned when you recorded the tag.  e.g.:
    If the original name would have been:

    Fundy2013_tag435@166.380.wav
    

    then the new name should be:

    Fundy2013_tag435@166.380@166.378.wav

    to indicate that the funcube was tuned to 166.378 when the tag was re-recorded.  Without the
    second @FFF.FFF portion, it is assumed the funcube was tuned 4kHz below the nominal tag frequency.


     
    Powered by MindTouch Core