Frequently Asked Questions

Thank you for visiting the FAQ section of our website. We will continue to add and update information on the FAQ as appropriate. If after reviewing the FAQ, you still have further questions, be sure to call us toll-free at 888-733-0200 or +1-978-369-5225 or email .

ANSWERS

GENERAL QUESTIONS

Question: Is it possible to start/stop recording of the SM2BAT only if a bat call is detected?
Answer: The SM2BAT should be set up to record with adaptive triggers. We recommend a 12dB setting. This will only start recording when an event occurs 12dB in amplitude above a rolling average of ambient conditions. We also recommend recording in our compressed WAC format. Triggered events are contained within a WAC, the length of which is programmable. The WAC file can be opened natively in our Song Scope analysis software or converted to WAV or zero cross format using our free WAC2WAV utility. This will make an individual WAV or zero cross file for each triggered event which can then be analyzed in AnaLookW®, SonoBat®, Bat Sound, etc. More details are in the SM2 Users Guide and SM2BAT Supplement found at Documentation.

Question: Do you have any rough guesses on the range of detectability of a bat call?
Answer: Detection distance for bats is extremely variable. It is affected by atmospheric attenuation (which changes quite a bit with humidity, temperature, air pressure and most of all with frequency), the frequency of the bat call, vegetation, obstacles, wind, frequency and amplitude of the bat, the loudness of the bat and the directionality of the bat call itself. Higher frequencies are absorbed more than lower such that the detection distance is quite different for a silver hair and a myotis. Our ultrasonic sensor is omnidirectional so you would pick up bats in all directions but quantifying the detection distance is difficult. A guestimate is that most bat species can be detected well over 30m, with a likely maximum of about 100m. With recommended settings, the limiting factor is the bat and the atmospheric absorption not the ultrasonic microphone.

Question: What is the trigger window?
Answer: The trigger window is how long the unit continues to record after the last “re-trigger”. The Song Meter will keep recording as long as it is triggered such that if a bat were flying in a small circle around the recorder it would just keep recording. When the bat finally leaves it will continue recording for the trigger window length of time. If the bat just echo locates once and it triggers the recording, that triggered recording will just be the length of the trigger window. Note, longer windows will fill the card faster since each triggered recording is longer.

Question: Do I have to use compression with triggers?
Answer: The triggers are designed to work with compression. If you don’t use compression, the Song Meter will record continuously (triggers still work if monitoring with headphones).

Question: What is real-time expansion?
Answer: Real Time Expansion (RTE) is a technology that allows a maximum amount of spectral and temporal information of a bat echolocation to be delivered to your ears. The ultrasound is expanded at whatever division ratio is selected, but it is done on a microsecond scale such that no information is missed. The bat pulse is actually expanded into the empty space between the calls.

Question: What is a sample rate?
Answer: A digital recording takes “samples” at some rate. The bat recordings for example are at 192 kHz. This means the Song Meter is taking a digital reading of the voltage at the microphone 192,000 times per second! CD’s are generally sampled at 44.1 kHz. There is something called the nyquist theorem which states that you can only resolve frequencies up to half of your sample rate. So the ultrasonic recordings for example at 192 kHz can record bats up to half of that or 96 kHz. A CD can resolve up to 22.05 kHz (humans can only hear up to 20 kHz). The advantage of high sample rates is that you can record high frequencies. The disadvantage of a high sample rate is that it fills the flash cards faster since you are writing more digital samples per second. So the trick is to take the highest frequency you want to record and double that. Select the next sample rate up from there. The choices in kHz are 192,000 48,000, 44,100, 32,000 24,000 22,050 16,000 8,000 and 4,000.

WAC, WAV, AND WAC2WAV AND OTHER FILE FORMAT QUESTIONS

Question: With the new WAC2WAV we are occasionally seeing .tmp files being generated. They range in size from 1-4MB. What are these files, and do we have to be concerned with them?
Answer: For each file that wac2wav starts to write (e.g. for each trigger on each channel), it starts as a temp file. Then, at the very end, it is either (1) renamed to the final file name or (2) deleted if we decide it’s noise and you didn’t check the keep noise files box. If you abort wac2wav while the utility is running, it may leave the temp file lying around. Also, sometimes a remaining temp file will result from a file that was being recorded when the battery died. Often a battery will die and ruin the last file and then come back to life after some rest and do it again so you can end up with a few.

Question: How do I convert my calls to zero crossing?
Answer: If you record using SM2BAT in the “WAC” format with triggers as recommended in the documentation, then you have a choice in post-processing of either retaining full spectrum information or converting to AnaBat®-compatible zero-crossing file. Full spectrum recordings can be converted to zero-cross but with all the inherent disadvantages of that technology (no harmonic information, no spectral power information, etc.). The WAC2WAV software is available as a free download from the “downloads” section of our website. The help section of the software should get you going but don’t hesitate to contact us with questions.

Question: It is not readily apparent how to tell from a *.wac file what time the recording started or ended? They all seem to start with 0.00. Is there any type of date and time stamp? I see the date in the file name, but not sure about the time.
Answer: The file name has the format Prefix_YYYYMMDD_hhmmss.wav, where Prefix is the prefix specified here, YYYY is the year, MM is the month, DD is the day, hh is the hour, mm is the minute, and ss is the second at which the recording was started. If you are using Song Scope, the time on the axis is the time from the beginning of the recording so you can add that to the time in the file name for absolute time

SET UP QUESTIONS

Question: What if I want to connect my acoustic microphone for lengths longer than 100m?
Answer: At 100 meters, you begin to see 3dB attenuation at 120kH. If you go to 120 meters, you can expect to see the 3dB attenuation point move to about 100 kHz. At 150m, you would see or -3dB at around 80 kHz. The capacitance in the cable (proportional to length) works with the impedance of the microphone to form a single-pole low-pass filter. The “knee” of the filter is considered the -3dB point. After that, you’re looking at a slope of 6dB per octave. So, for example, if you use a 200 meter cable, the knee would be at half of the 100 meter cable, or about 60 kHz. Then, if you cared about a 120 kHz signal (one octave), it would attenuate an additional 6dB for a total of 9dB attenuation. The signal may still be detected, but it will be weaker.

Question: I want to record both birds and bats with our SM2BAT ultrasonic recorder. How can I do this?
Answer: This can be done in one of two ways:

(A) You can record at 192 kHz at a scheduled time with the SMX-US ultrasonic microphone and then record at a lower acoustic sample rate at a different scheduled time with the SMX-NFC acoustic microphone.

(B) You can record simultaneously with both microphones at 192 kHz. In this case you configure the digital filters on the SM2BAT to filter out acoustic sounds on the SMX-US with a high pass filter and filter out ultrasonic sounds on the SMX-NFC with a low pass filter. Basically you will have an acoustic recording that is oversampled. This recording can be down-sampled in Song Scope or other audio software or left as is. The upside of doing this is the huge flexibility the SM2BAT offers in one box. The downside is that the 192 kHz will use up more card space than a lower sample rate and the SM2BAT has lower battery longevity then the SM2 acoustic recorder.

MEMORY QUESTIONS

Question: What do you recommend for memory cards?
Answer: We recommend Kingston, Sandisk or PNY Class 4 SDHC cards. There is no advantage to higher classes except it will upload to your computer a bit faster. Also, most 2GB cards are NOT SDHC cards. Please, use a reputable brand and be careful of counterfeits being sold on the web that do not operate to specification.

Question: When the SDHC card in slot A fills, does the Song Meter automatically continue recording on the next slotted card?
Answer: Yes, the Song Meter will continue to attempt to record in sequence slots A through D.

Question: Does it make any difference in what combination of memory cards we use, for example, two 8 GB, or one 16 GB, or any other combination up to the128 GB?
Answer: Mix and match as you please.

MICROPHONE/HYDROPHONE QUESTIONS

Question: Are my acoustic and ultrasonic microphones weatherproof?
Answer: These microphones are designed to be placed in the elements without protection. If you expect constant rain, you might want to shield the microphone just so the windscreen is not constantly saturated as this will cause some attenuation of the signals. An important caveat to our weatherproofing is that if the microphone is pointed skyward water can collect on the inner waterproof membrane. With time gravity will pull the moisture through, so as long as you are pointed horizontal or lower, you will be fine (the microphones are omnidirectional and do not need to point towards source).

Question: Can I use my ultrasonic microphone in a buoy?
Answer: You may want to protect them from splashing. The waterproof membrane is rated for salt water use, but having a constantly saturated windscreen will cause ultrasonic attenuation

Question: The manual recommends setting the microphone on the Left side of the Song Meter. Is it fine to set the microphone on the right side when using mono?
Answer: You can use the right channel if you specify stereo or mono-r; but if you have an SM2BAT384, you can only use the left channel for ultrasound.

Question: How will the sun affect my microphone?
Answer: The microphone cover will break down eventually in direct sun, though it will last quite some time after it has turned brown. We suggest that customers stock up on wind screens as after a field season or two, it is likely that some screens will have degraded or been eaten.

Question: How is the microphone affected by the cold?
Answer: The cold will be no problem in regards to the microphone, but expect diminished battery life if using alkaline or external lead acid batteries

Question: How will the SMX-NFC night flight call microphone be affected by snow?
Answer: Snow will definitely affect the performance of the microphone. Snow is excellent at absorbing sound and will absorb reflections and the microphone will no longer be as directional. The sounds from below will likely be nicely absorbed, but sounds from above will no longer experience the PZM effect of the plate. If the snow covers the entire microphone element, you will have all sounds attenuated and risk moisture damage to the microphone element if the snow is wet and seeps through the weather proof membrane.

SONG SCOPE QUESTIONS

Question: In Song Scope, can I run multiple recognizers as the same time?
ANSWER: You can run multiple recognizers at once if the recognizers are all in the same recognizer group – meaning – they are built with identical parameters e.g. sample rate, fft size, detector parameters, etc.

Question: I see that you have a “floating seat license” for SongScope. How does this work?
ANSWER: We offer a 10 seat for the price of 5 as the entry level floating license, at $2500. This is one time and includes updates for one year. There is a license manager you would have to install on a server on the network, and the licenses are only available to machines connected to the network. The recommended server configuration would be a Linux x86 e.g. RedHat machine. It runs reasonably well on a Mac. For Windows, it runs as a background process, but not technically as a “service”, and would require that someone is actually logged in on the Windows machine for the license manager to run.

Question: Is optimal to use Song Scope to record known calls if they are to be used as training data? Why is this? None of my known calls are from Song Meter recording devices and I was wondering if this had anything to do with my lack of success in getting results?
ANSWER: You can use training data from any source. The dynamic range control in Song Scope can be used to correct for differences in signal to noise ratio between your training data and field recordings.

Question: Can I make only one recognizer in Song Scope for multiple calls?
ANSWER: You should make different recognizers for calls that are significantly different, especially with limited training data. With a small data set and significant variation in call types, you are likely to create a recognizer that will only look for a very close match to each variation; the new recording is unlikely to fit within any one of the tight definitions and thus will fail to match.

Question: Can I use training data from one individual to make a recognizer in Song Scope?
ANSWER: If you use only data from one individual, you are telling Song Scope that a large number of individuals have very little variation in their calls. Song Scope will reject calls that aren’t nearly identical to this individual’s calls. The solution is much more training data, preferable from different sites at different times and conditions to be sure that a dozen or so individuals are present. This will reflect the broadest range of variations present and avoid model segmentation.

Question: I recently got a new computer, and have tried to activate Song Scope. My serial number doesn’t appear to work? What can we do?
ANSWER: You will want to enter your original 16-digit serial number and then select “automatically install a new activation code”. Make sure to use your serial number and not your activation code. The activation codes are 16 digits but are only good for the computer they were generated.

GENERAL QUESTIONS

WAC, WAV, AND WAC2WAV AND OTHER FILE FORMAT QUESTIONS

SET UP QUESTIONS

MEMORY QUESTIONS

MICROPHONE/HYDROPHONE QUESTIONS

SONG SCOPE QUESTIONS

ANSWERS

GENERAL QUESTIONS

WAC, WAV, AND WAC2WAV AND OTHER FILE FORMAT QUESTIONS

SET UP QUESTIONS

MEMORY QUESTIONS

MICROPHONE/HYDROPHONE QUESTIONS

SONG SCOPE QUESTIONS

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