Song Meter SM2BAT 192kHz Stereo or 384kHz Mono
Contents
1. SMX US Microphone windscreen and instead implement your own weather protection to protect the membrane from wind blown rain Again we recommend that you aim the microphone horizontally or downward not upward to reduce the risk of damage should weatherproofing fail Directionality and Frequency Response The SMX US is an omnidirectional microphone and is therefore ideally suited to unattended monitoring in which the precise direction of bat activity may not be known in advance The following graph illustrates the typical pick up pattern SMX US Directionality 40khz 30kHz 120KHz 3 Song Meter SM2BAT Copyright 2009 2010 SMX US Microphone The SMX US is sensitive to frequencies up to 190kHz with some attenuation above 60kHz The graph shows the typical frequency response 110 000 100 000 90 000 80 000 70 000 60 000 Hz Sensitivity Noise Floor SMX US Frequency Response 50 000 40 000 30 000 20 000 o o o o o o o of al roo ry al l 5 e 9 y x i 5 7 ed Aap Copyright 2009 2010 Song Meter SM2BAT 4 Power Consumption Cables The SMX US is a powered microphone with low impedance and can drive cables up to 100 meters without a preamplifier and without any noticeable loss at frequencies up to 120kHz The SMX US microphone can be either connected directly to the SM2 enclosure without any cable or extende2. a device specific prefix For stereo ultrasonic recordings you can configure Song Meter to use both channels and install a second SMX US microphone Refer to the one channel recording settings above The Settings gt Audio gt Channels should be set to STEREO to enable both channels and you will want to set the digital high pass filter and triggers for the right channel as well Stereo recordings with compression and triggering consume about 30 more power and will use twice as much flash storage as single channel recordings The triggers act independently so each channel is compressed efficiently Mixed Ultrasonic and Acoustic Recording The 192kHz stereo board permits two channels to simultaneously record conventional audio on one channel and ultrasonic activity on the other by using an SMX II acoustic microphone on one channel and an SMX US ultrasonic microphone on the other The 384kHz mono board permits the recording of conventional audio on one channel on one schedule and ultrasonic activity on the other channel on a different schedule but not simultaneously Stereo Mixed Recordings One way to make a mixed recording is to sample both channels with SM2BAT stereo 192kHz board at the same time to make a stereo recording But you can then use the digital low pass filters to set a cut off frequency on the acoustic side to filter out the ultrasonic sounds and improve compression ratios For example setting a digital low pa
3. at 384kHz mono and 192kHz stereo or 93 2 minutes at 192kHz mono If you use one hour periods instead of half hour periods for 384kHz mono or 192kHz stereo recordings would be split into alternating 46 6 and 13 4 minute recordings which may be confusing Audio Settings The audio settings should be set as follows Sample rate 192000 or 384000 Channels MONO L Compression WAC4 for 192kHz model for 384kHz model for left channel lossy compression a Ss ee Note that the 384kHz model can only be used with the left channel Song Meter SM2BAT Copyright 2009 2010 Using SM2BAT to monitor Bats The WAC4 compression format drops the least significant 4 bits of the 16 bit audio samples resulting in a dynamic range of 72 2dB Given the noise floor of the SMX US microphone is no worse than 106dBV and assuming preamplifier gain of 48dB the noise floor is 106 48dBV 58dB This dynamic range can be resolved in 10 of the 16 bits so the lower 6 bits are below the noise floor and contain only random noise and no real signal information We have found that in many applications even better compression can be achieved with little noticeable loss in audio quality with WACS or WAC6 compression formats However with so much storage available it is better to use a lower compression ratio unless storage becomes a limiting factor to deployment duration The advanced settings should be set as follows Dig HPF Left fs 12 16
4. 09 2010 Song Meter SM2BAT 10 Using SM2BAT to monitor Bats 11 The Song Scope software can open WAC files natively To quickly locate and review potential bat echolocation calls in a long triggered recording you can set up Song Scope band pass and detector parameters and use the batch scan feature The WAC2WAV utility available at no charge on our web site can convert the WAC files into standard WAV files for analysis by other programs Usually it is best when processing triggered ultrasonic recordings to use the Split Triggers feature This will take a mono or stereo WAC file containing possibly many individual triggered events e g bat passes and break them out into many individual WAV files for analysis The max duration and min spacing parameters let you selectively restrict the duration of each created wav file and to optionally ignore detections to satisfy the desired spacing in order to fit whatever monitoring protocol you may be used to For example if you are accostomed to using Time Expansion detectors that only record for 5 seconds and then pause for 50 seconds while the time expansion buffer is recorded you could select a max duration of 5 seconds and a min spacing of 50 seconds to simulate this behavior By default all detections are included in their entirety The compensation filter may be selected to digitally alter the signal to compensate for the SMX US microphone by effectively altering the frequenc
5. GB flash cards you should have enough storage to last 50 250 nights depending on conditions Jumper Settings You should configure the preamplifier jumpers with the analog high pass filter set to kHz and the gain set for 48dB Refer to the Song Meter SM2 User Manual for details In some cases depending on your ambient noise environment you may want to increase the gain to 60dB to better detect quieter or higher frequency bats The SMX US microphone does not need the 2 5V 2 2K bias but will work with or without the bias jumper present Note that the jumper is required for the SMX II acoustic microphones Copyright 2009 2010 Song Meter SM2BAT 6 Using SM2BAT to monitor Bats Schedule You can configure the Song Meter to record only from sunset to sunrise each day in half hour segments as follows First configure your latitude longitude and UTC offset in the Location settings Next enter the following advanced schedule 01 AT SSET 00 00 00 02 DO 03 RECORD 00 30 00 recommended for 384kHz 03 RECORD 01 00 00 recommended for 192khz 04 GOTO LINE 03 00X 05 UNTSRIS 00 00 00 06 GOTO LINE 01 00X The schedule above will wait for sunset then record back to back one hour or half hour segments until sunrise the last segment will end early at sunrise and repeat daily You can modify this example to suit your own needs Note that the maximum uncompressed file length is 2GB which works out to 46 6 minutes
6. SM2 2BAT Song Meter SM2BAT 192kHz Stereo or 384kHz Mono Ultrasonic Recorders Wildlife Acoustics Inc www wildlifeacoustics com Copyright 2009 2010 Wildlife Acoustics Inc Rey 8 13 10 All rights reserved Wildlife Acoustics is registered in the U S Patent and Trademark Office Song Scope Song Meter SM1 SM2 SM2BAT SMX and WAC are trademarks of Wildlife Acoustics Inc All other trademarks are the property of their respective owners Patents pending About This Document Overview c0cccceee SMX US Microphone Po cccccccccccccccccccccececccccececceececccoeoececcoooecee Co cccccccccccccccccccccccccccccececccececceececoocooooecee Co cccccccccccccccccccccccecccccececceece ccc ceecceccocoecle Notes on Weatherprooting cs aiesseecie flied ee cesreewton Directionality and Frequency Response eeeeeeeeeee Cables Power Consumption Cocccccccccccccccccccccccccccccececceececceececoooocoeocee Using SM2BAT to monitor Bats cccsccsssscsssscessccsees Simple One Channel Configuration ee eeeeeeeeeeeee Jumper Settings Schedule Audio Settings Stereo Ultrasonic Recording 00 0 eeeeeeeeceseeeeeeeeeeneeeees Mixed Ultrasonic and Acoustic Recording 006 Stereo Mixed Recordings jd giasciets eek Scheduled Mixed Recordings ccccesceeeseeeeeeeeeees Post Processing Copyright 2009 2010 Song Meter SM2BAT iii About This Documen
7. SM2 automatically detects the presence of the SM2BAT daughter card If present the 192 000 or 384 000 Hz sample rate choice is added to the list of possible sample rate settings In addition the SET advanced scheduling command can also configure the 192 000 or 384 000 Hz sample rate as part of an advanced schedule When 384 000 Hz sample rate is selected the SM2BAT 384kHz mono daughter card is used to sample the audio stream from the left channel When the 192 000 Hz sample rate is selected the SM2BAT 192kHz stereo daughter card is used to sample the audio stream from the left and right channels Otherwise the SM2 uses its on board codec to sample at audio rates up to 48 000 Hz 1 Song Meter SM2BAT Copyright 2009 2010 SMX US Microphone SMX US Microphone The SMX US is an ultrasonic microphone designed for terrestrial monitoring applications specifically for recording the echolocation calls of bats Notes on Weatherproofing The transducer inside the SMX US microphone can be permanently damaged if it is exposed to water in the event that the weatherproofing fails To protect the transducer there are trade offs between ultrasonic sensitivity and weatherproofing The SMX US features several layers of protection First a porous membrane transparent to ultrasound prevents unpressurized liquid water from entering the microphone However the membrane is rated to only 0 07 Ibs in or 5g cm This is easily exceeded by wind blown
8. d on one or more lengths of our standard one meter ten meter and fifty meter cables up to the maximum Power Consumption The following table illustrates the typical power consumption for different configurations and settings Note that actual consumption may vary depending on flash cards variation in electronic components and other variables Bae aud Uncompressed Compressed Compressed Channels w Trigger 192kHz x 1 192khz x 2 384kHz x 1 High quality Alkaline D cells can deliver about 14 000mAh capacity at 20 C With compression and triggers this translates to about 95 hours record time with 192kHz mono 70 hours record time with 192kHz stereo and 75 hours record time with 384kHz mono Longer deployments are possible with larger external batteries using the Song Meter SM2PWR power adapter sold seperately When the SM2BAT daughter card is not being used for example when the Song Meter SM2 is configured for sampling rates at or below 48kHz it will still consume some additional current when recording compared to an SM2 without the SM2BAT card installed In the case of the 192kHz stereo card 25mA of additional current is used In the case of the 384kHz mono card 15mA of additional current is used When the Song Meter is sleeping between scheduled recording events the SM2BAT is also powered down and total current consumption is typically less than one milliamp 5 Song Meter SM2BAT Copyright 2009 2010 U
9. kHz for 192kHz or fs 24 16kHz for 384kHz Dig LPF Left Off low pass disabled Trg Lvl Left 6SNR adaptive 6dB Trg Win Left 0 5s The digital high pass filter shown above is set to either 1 12th of the sample rate for 192kHz 12 16kHz or 1 24th of the sample rate for 384kHz 24 16kHz This will filter out frequencies below 16kHz You could also choose different settings to suit your needs Song Meter will measure the rolling average power spectrum in the frequency band above 16kHz in the above example for periods of 0 5 seconds and if an onset of signal is detected that exceeds this threshold by 6dB a trigger event is started Recording will continue until no trigger is detected for a 0 5 second period of time You can reduce the false trigger rate by increasing the threshold but this may also reduce the detection rate More information on triggers can be found in the Song Meter SM2 User Manual Stereo Ultrasonic Recording The 192kHz stereo board allows for stereo ultrasonic recording The configuration described below is available as an example configuration in the Song Meter Configuration Utility distribution SM2BAT 192 STEREO SET For the SM2BAT to be able to determine your location s Copyright 2009 2010 Song Meter SM2BAT 8 Using SM2BAT to monitor Bats sunrise and sunset times it is necessary to input your latitude longitude and timezone These are found under location settings You may also want to set
10. rain The foam windscreen provides a critical second layer of protection to absorb the impact of wind blown rain so that only unpressurized water reaches the membrane effectively protecting the transducer When dry the foam windscreen is almost transparent to ultrasound with a loss of only 2dB However the loss increases with frequency when wet and will effectively block ultrasound if it then freezes The membrane is also fragile The foam windscreen adds a layer of protection against insects rodents and birds who will tend to nibble on the windscreen instead of the membrane We strongly recommend operating the SMX US with the windscreen and replacing the windscreen if it becomes fully or partially eaten We also recommend positioning the microphones so that they point parallel to the ground or even slightly downward In this configuration even if the windscreen is absent and water penetrates the membrane the water should not collect in sensitive areas inside the microphone and there is a good chance that the transducer will survive If you suspect that water may have entered the microphone you should avoid handling it until it has completely dried out Otherwise water could change position and come in contact with the transducer resulting in damage If you are deploying the SM2 in field conditions expected to remain wet or frozen you may want to operate the SMX US microphone without its foam Copyright 2009 2010 Song Meter SM2BAT 2
11. sing SM2BAT to monitor Bats Using SM2BAT to monitor Bats Simple One Channel Configuration The configuration described below is available as an example configuration in the Song Meter Configuration Utility distribution SM2BAT 192 MONO SET for the 192kHz stereo model or SM2BAT 384 MONO SET for the 384kHz model For the SM2BAT to be able to determine your location s sunrise and sunset times it is necessary to input your latitude longitude and timezone These are found under location settings You may also want to set a device specific prefix The SM2 Terrestrial Ultrasonic Packages come with one SMX US ultrasonic microphone The easiest set up is to connect the microphone directly to the left microphone connector on the SM2 enclosure and mount the SM2 on a tree or post at the field site You can also extend the microphone on a cable up to 100 meters away from the enclosure With one channel using compression and triggering you can get about 95 hours of record time at 192kHz or 75 hours at 384kHz out of the internal four D alkaline batteries over one week of night time monitoring In a typical night with bat activity and no rain or gusty wind you will need less than 0 5GB per night But even with gusty wind causing false triggers you will probably only need about 2GB per night Therefore a single 32GB card should easily last for 2 8 weeks For longer deployments you can use a larger external power source With 4x32
12. ss filter to fs 24 will filter out sounds above 8kHz An example of this is available in the Song Meter Configuration Utility distribution SM2BAT 192 MIXED STEREO SET 9 Song Meter SM2BAT Copyright 2009 2010 Scheduled Mixed Recordings Using SM2BAT to monitor Bats Another way to make mixed recordings is to use the Song Meter advanced schedule SET command to make ultrasonic recordings at some times and conventional recordings at other times An example of this configuration is available in the Song Meter Configuration Utility distribution SM2BAT 192 MIXED SCHED SET For example the following schedule would make ultrasonic recordings on the left channel at 192kHz at night and then a 24kHz recording on the right channel to record the dawn chorus for an hour after sunrise 01 02 03 04 05 06 07 08 09 SET192000xMONO L AT SSET 00 00 00 DO RECORD 01 00 00 GOTO LINE 04 00X UNTSRIS 00 00 00 SET 24000xMONO R RECORD 01 00 00 GOTO LINE 01 00X A similar example for 384kHz can be found in SM2BAT 384 MIXED SCHED SET 01 02 03 04 05 06 07 08 09 SET384000xMONO L AT SSET 00 00 00 DO RECORD 00 30 00 GOTO LINE 04 00X UNTSRIS 00 00 00 SET 24000xMONO R RECORD 01 00 00 GOTO LINE 01 00X Post Processing A WAC file is created for each scheduled recording segment In the advanced program above for example a WAC file would be created every hour from sunset to sunrise Copyright 20
13. t About This Document This document describes the use of the SM2BAT 192kHz stereo and SM2BAT 384kHz mono daughter cards for the Song Meter SM2 acoustic monitoring and data logging platform Refer to the Song Meter SM2 User Manual for detailed information on using the Song Meter SM2 platform This document is intended as a supplement and assumes you are already familiar with the Song Meter s operation You will also want to download and install the latest Wac2 Wav postprocessing software and Song Meter Configuration Utility software from the downloads section of our website at www wildlifeacoustics com Overview The SM2BAT 192kHz stereo or 384kHz mono daughter card is installed on the back of the SM2 motherboard and provides a high speed 16 bit digital sampling capability The audio input to the SM2BAT comes from the output of the two stage preamplifier on the SM2 Refer to the section on Amplifier Configuration Jumpers in the Song Meter SM2 User Manual for more information about configuring the analog high pass filters and gain settings Note that the SM2BAT audio signal is not routed through the third stage amplifier configured by the left and right gain parameters in the settings menu Therefore the gain is configurable only with the SM2 jumpers to 0 12 24 36 48 or 60dB and the third stage gain settings will have no effect For monitoring bats with the SMX US ultrasonic microphone the 48dB setting is recommended The
14. y response to match approximately a 240X This may be helpful for analysis by automated classification software that relies on the frequency response of the 240X to match known bat recordings The Skip Noise feature can be used to further analyze each candidate trigger to determine if it contains actual bat echolocation calls or other biological activity rather than just noise The algorithm looks for the presence of narrowband energy in the specified frequency band with at least the minimum specified duration Files that do not meet this criterion are still split out as WAV files but the filename is prepended with the prefix NOISE_ so they can be set aside Finally if you prefer zero crossing analysis over full spectrum recordings you can select Output ZCA to create zero crossing files instead of WAV files In this way the SM2 is like having a full spectrum recorder and a zero crossing recorder in one device The division ratio can be specified as well as the sensitivity The sensitivity is specified in dB relative to a full scale signal Song Meter SM2BAT Copyright 2009 2010
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