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.
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.
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.
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.
The storage space taken up by an uncompressed, full-spectrum audio recording is a product of four factors:
- The length of the recording, in seconds
- The sample rate of the recording, in samples per second or Hertz
- The bit depth of the recording, in bits per sample
- 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.
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.
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.
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.
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.
In order to maximize battery life, our recorders go to sleep after each recording period and wake up some time (30 seconds for terrestrial units, 3.5 minutes for marine units) prior to the next recording period in order to prepare for recording. Additionally, our recorders will not sleep for periods of 30 seconds or less.
It is important to keep this in mind when scheduling on/off recording cycles. The more on cycles the recorder has in a given day, the more times it will have to wake up prior to recording, adding additional "active" time that drains the batteries more than sleep does. It is possible to schedule recordings in such a way that the recorder does not sleep at all, even when not recording.
For example, an SM3M unit with a 2 minutes on/4 minutes off duty cycle will never go to sleep. Marine units must wake up 3 minutes and 30 seconds prior to the next recording period in order to "warm up" their hydrophones, and the recorder will not bother falling asleep for 30 seconds or less. To keep the same ratio of recorded time to unrecorded time while improving battery life, use a longer cycle, such as 10 minutes on/20 minutes off.
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.
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.
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.
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.
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.