Wildlife Acoustics | Bioacoustic monitoring systems for research, science, industry and governments.

You can easily convert full spectrum recordings to ZC files using Kaleidoscope, which can be downloaded for free from our website. No software license is necessary to use this feature.

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We do not support the use of Micro SD cards with our Song Meter recorders, even with the use of standard SD card-size adapters. Micro SD cards do not perform as reliably as standard size cards, and are more likely to experience file corruption.

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It is possible to program an SM3Bat to record both triggered ultrasonic recording and continuous sonic recording. However, there are limitations to this that are fully discussed in this whitepaper.

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Our microphones are built specifically to work with our recorders, and vice-versa, and use a proprietary cable connection. We are unable to provide support for any use of our recorders with third-party microphones or vice-versa. Similarly, we do not support use of third-party external power cables.

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Our recorders and accessories are rated for use to -20 °C (-4 °F). Temperatures below this may damage the equipment. At temperatures below freezing you can expect the display to become sluggish, have low contrast or go out altogether. Batteries will have a greatly reduced life at colder temperatures; check the datasheet for the batteries you are using for an estimate of the magnitude of this reduction.

For terrestrial recorders, storing the unit in an insulated cooler or even burying it will help protect against short-term temperature swings, but not against sustained temperatures below -20 °C.

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When using a recorder with two microphones, recording from both microphones simultaneously means recording a single stereo file. A stereo file has two channels of audio data that can be played back simultaneously. In the case of recorded music, this would mean one channel being played in your left ear, one in your right ear.

After they are retrieved from your recorder, stereo files can be split into separate mono (single-channel) files using Kaleidoscope's free file conversion features. Under "OUTPUTS," simply check the box to include WAV files and select "Split channels" prior to processing your batch.

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For the best performance with SD cards, we recommend formatting your cards before each deployment. On SM3 and SM4 series recorders, this can be done directly from the recorder's Utilities menu. For SM2 recorders, we recommend instead using the SD Association's Formatter. Regularly formatting your cards can prevent glitches and dropped audio.

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Avoid mounting microphones on tall plastic masts (e.g. fiberglass, nylon, etc.) for deployments in dry conditions because a breeze flowing over the plastic can build up a sizeable electrical charge much like rubbing a balloon. Eventually, the electric charge will be strong enough to discharge with an attraction to the mass of metal in the mic cable, resulting in a spark that could damage the microphone or recorder. Instead, use wood or metal masts.

If electrical storm activity is a possibility, you need to protect the microphone and equipment from damage from electrical discharge. If the best path to ground is through the microphone and/or Song Meter, then the microphone and/or Song Meter can be severely damaged. To protect against this, like a lightning rod, you need to create a better and safer alternate path to ground. One way to do this is to use a pipe clamp to clamp a heavy gauge (18AWG) wire from the microphone to ground (e.g. by securing the other end of the wire to the metal frame of a grounded tower structure, or securing the wire to a metal pipe planted 2 meters into the earth). The connections must be electrically strong, with low resistance. A local electrician might be able to help you with a specific installation. Additionally, it is better to not ground the Song Meter or its power source so there is not a clear path to ground through the Song Meter.

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Non-Triggered Recordings

If you use Kaleidoscope to split stereo recordings into pairs of mono recordings, Kaleidoscope will add a channel indicator to the file names of the mono recordings. For example, the stereo file SN_DATE.wav will be split into the mono files SN_0_DATE.wav, from channel 0, and SN_1_DATE.wav, from channel 1.

Triggered Recordings

The recordings produced by your SM2Bat+ or SM3Bat are marked by what channel prompted the Song Meter to start recording. For example, SN_0_DATE.wav is a stereo recording that was triggered by a signal detected on channel 0. If you use Kaleidoscope to split this stereo recording into two mono recordings, it will add an additional indicator telling you which channel's data each recording represents. For example, the stereo file SN_0_DATE.wav will be split into the mono files SN_0_0_DATE.wav, from channel 0, and SN_0_1_DATE.wav, from channel 1.

SN_0+1_DATE.wav is a stereo recording that was triggered by signals detected on both channel 0 and channel 1. When this file is split into mono recordings, they will be labeled SN_0+1_0_DATE.wav and SN_0+1_1_DATE.wav.

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If you only need to use the GPS accessory to quickly set your recorder's clock and location, you can connect the GPS puck to the recorder until it finds a signal, then disconnect it, and your time and location settings will be saved. You can use a single GPS puck to quickly adjust these settings for multiple recorders.

If you want to use a GPS puck to record location data over the course of a moving transect, or you want to maintain synchronization between an SM3/SM3Bat and GPS time, the GPS puck will need to be attached and receiving a GPS signal for the full recording period.

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The storage space taken up by an uncompressed, full-spectrum audio recording is a product of four factors:

  1. The length of the recording, in seconds
  2. The sample rate of the recording, in samples per second or Hertz
  3. The bit depth of the recording, in bits per sample
  4. The number of recording channels

All of our recorders produce .wav files with a 16-bit depth, except for our marine units, which can optionally be configured to record with a 32-bit depth. The sample rate of our recorders is user-configurable.

You can use our free Song Meter Configurator software to estimate when SD cards of any size will fill up based on your recording schedule and audio settings.

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According to the sampling theorem, it is impossible for a digital recorder to properly record any frequency higher than half of the recorder's sampling frequency (called the Nyquist frequency). Any information above the Nyquist frequency is therefore removed in the process of recording.

Note that the file size of recordings scales directly with sampling rate, so it's not necessarily a good idea to choose the highest sampling rate available on your recorder. Determine the highest frequency you are interested in among your species of interest, including harmonics, and choose the lowest sampling rate greater than twice that frequency in order to save on storage space.

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The SM3 and SM4 configurators can estimate how long your recorder will last based on your settings and schedule, as well as the energy capacity of the batteries you will be using. Under "Deployment Scenario," you can enter the energy capacity of the power source you will be using to get a rough idea of when the recorder will run out of battery.

To calculate the energy capacity in Watt-hours, you need to know the battery's voltage, measured in Volts, and its charge capacity, measured in amp-hours or milliamp-hours (1000 mAh = 1 Ah). These figures can typically found on any battery's data sheet. Note that charge capacity typically decreases as more power is drawn from them. The typical power draw level for your recorder can be found in its user guide.

If we are powering an SM4 using an external golf cart battery that has a voltage of 6 V and a charge capacity of 215 Ah when enough power is drawn from it to completely discharge it in 20 hours. The SM4 uses much less power than that, so the figure of 215 amp-hours should be a safe, rough estimate. Therefore, our estimated energy capacity would be 6 V x 215 Ah = 1290 Wh.

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If you use rechargeable batteries, this may be due to the tendency of rechargeable batteries to lose their energy capacity over their lifetimes. Alkaline batteries from a reputable manufacturer will consistently allow longer deployments than standard rechargeable batteries, even brand new ones. If you do use rechargeable batteries, please refer to the manufacturer of the batteries for the best way to extend their lifespan.

Also keep in mind that different brands or even batches of batteries may perform differently, and temperature differences have major effects on battery efficiency. If you are planning for a deployment in a very hot or cold climate, check the data sheet for your batteries to see how their capacity changes with temperature.

There can also be some variability in how much power SD cards draw, between among different brands or even among different individual cards. For the SM4 series, in which power drawn by SD cards represents a significant fraction of the total power consumption, this can be more noticeable than on other recorders. In our experience, SanDisk cards show the most consistent power usage among different cards.

If you see any white, powdery residue inside your recorders, or a brand new set of batteries or SD cards does not correct the problem, please contact Wildlife Acoustics support.

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If you have any product in the SM3 or SM4 line and it will not turn on, please check/try the following:

  • Install brand new alkaline D batteries.
  • Make sure the power switch is in the correct position (down for internal power).
  • Press and hold the "Stop Program" button for a couple of seconds.

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If an SM3 or SM4 series recorder detects a problem with an SD card, it will mark the card as "Dirty" and no longer use that card, to avoid corrupting any further data. This can happen if a recorder momentarily loses power in the middle of writing a file. When it wakes back up and sees a half-written audio file, it suspects that the SD card may be corrupted, so it will mark the card as "Dirty."

Dirty cards can be used again after they are formatted, either using the Format Cards utility on the SM3 or SM4, or by using the SD Association Formatter.

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Rather than representing the full waveform, or shape, of sound information in the way that most conventional, full-spectrum audio recordings in any application do, zero-crossing is a compact way of representing only the most prominent frequency in a recording by noting the points in time at which a sound wave has crossed a reference amplitude a certain number of times.

Because the zero-crossing format is only able to represent one frequency at a time, full-spectrum is particularly preferable for recording multiple sources of sound simultaneously, such as multiple bats vocalizing in the same area, or a single bat in a noisy environment.

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Performing triangulation of sound sources based on time-of-arrival distances requires multiple recorders precisely synchronized to the same clock, as small differences in time can translate to large inaccuracies in distance. The SM2, SM2Bat, SM3, and SM3Bat all contain hardware that, when paired with an external GPS accessory, allow them to maintain synchronicity with GPS time to within 1 millisecond, making them suitable for this kind of work.

The SM4 and SM4Bat FS/ZC do not have the hardware necessary for continual synchronization with GPS time and therefore cannot be used for triangulation.

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Overview

A channel is a representation of sound coming from or going to a single point. A single microphone can produce one channel of audio, and a single speaker can accept one channel of audio, for example.

A digital audio file can contain multiple channels of data. Music that is mixed for headphone listening is saved as a file with two channels - one sent to the left ear, one sent to the right, while surround-sound movie audio is often mixed for 6 channels.

What does this have to do with my recorders?

Many of our recorders have the ability to record on two separate channels, including all SM2s, all SM3s, and the SM4 (non-ultrasonic). These channels are marked as channel 0, or the left channel, and channel 1, or right. When you configure these units to record in stereo, the recordings it saves will contain two channels. If you listen to these files in a conventional audio player, you will hear both channels simultaneously from your left and right speakers. If you open the files in Kaleidoscope, you can switch between viewing and hearing the left and right channels. Using Kaleidoscope, you can also split these stereo files into two mono, single-channel files.

Because the Song Meters listed above can only record on two channels maximum, plugging in an external microphone will override one of the internal microphones on an SM3 or SM4. If you plug one SMM-A2 into channel 0 of an SM4, the left channel will be recorded from that SMM-A2, and the right channel will be recorded from the right-hand built-in microphone if the recorder is configured for stereo recording.

The following recorders only have one recording channel, and will always produce mono files: SM4Bat FS, SM4Bat ZC, Echo Meter Touch, Echo Meter EM3, SMZC.

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This is a very difficult question to answer. The factors that determine how far a sound travels include humidity, temperature, the source volume and directionality, and surrounding clutter. Additionally, no two microphones have exactly the same sensitivity, even brand new.

This white paper discusses all of the factors involved in much greater detail.

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All recorders

All cards should have a speed class of 4 or higher, and we strongly recommend SanDisk cards, though PNY and Kingston cards will also work.

SM2 Series

The SM2 series of recorders was produced prior to the introduction of the SDXC card standard, which raised the maximum size of an SD Card from 32 GB to 2048 GB. Using SDHC cards, with a maximum size of 32 GB, is the most reliable option when using an SM2, as using SDXC cards can lead to dropped audio and unreliable file transference.

SM3 & SM4 Series

The SM3 and SM4 lines of recorders support both the SDHC and SDXC card standards, meaning they can use cards up to 2048 GB in size.

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All Song Meter models predict when the sun will rise and set based on the internal clock, latitude and longitude, and the time zone. The internal clock and latitude/longitude values can be set manually or by attaching a Wildlife Acoustics GPS accessory for long enough for the Song Meter to sync these values to a GPS signal. Note that because time zones are determined by national and state/provincial boundaries as well as local conventions regarding Daylight Savings Time, the recorder's time zone must always be set manually.

If you notice that your Song Meter is incorrectly predicting the times of sunset and sunrise, here are some settings you should double-check:

  • Make sure that the date and time settings are accurate to local time.
  • Check that the recorder's latitude and longitude settings are approximately accurate for the recorder's location. Note that Song Meters do not use negative latitude or longitude values to denote the Southern and Western hemispheres, but instead use N/S and E/W characters. For example, rather than noting the location of São Paulo, Brazil as (-23.6,-46.6), you would enter it as (23.6 S, 46.6 W).
  • Confirm that your UTC offset is set accurately for your timezone. With a few exceptions near the prime meridian and antimeridian, regions in the Eastern hemisphere have positive UTC offsets, and regions in the Western hemisphere have negative UTC offsets. Note that if your region observes Daylight Savings Time, there will be two different UTC offsets depending on time of year (see note on DST below).

Daylight Savings Time

When a region is observing daylight savings time, the UTC offset for the region is increased by (usually) 1 hour, and the clock is adjusted to match the new offset. For example, US Eastern Standard Time is UTC -5:00, and US Eastern Daylight Time is UTC -4:00. If DST starts or ends in the middle of your deployment, your Song Meter will not automatically adjust its UTC offset or clock, since it has no way to know if or when your region observes DST.

If your Song Meter is scheduled to start recording at sunrise, it will continue to do so accurately, but all time stamps will be relative to the UTC offset programmed into the recorder. For example, if sunrise is supposed to be at 07:30 US Eastern Daylight Time (UTC -4:00), but the recorder is still on US Eastern Standard Time (UTC -5:00), then it will wake up at 06:30 according to its internal clock. Even though the timestamp is off by an hour, the recorder is still waking up when the sun rises.

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When batteries start to die, a recorder might lose and regain power multiple times before finally shutting off. When this happens, the recorder detects something is wrong and writes dump files to aid with later troubleshooting. In most cases, this is simply a sign that you need to replace your batteries.

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