The Pettersson U384 & U256
Ultrasonic microphones for your phone or tablet
Works with Windows, OS X, Android, iOS & Linux (microUSB)
Call me on 0333 9000 927 for a chat
The U384 & U256 have my 60 day 100% Satisfaction Guarantee & extra year's warranty

Hi there,

What can I say about the Pettersson U384 & U256?

If you're looking for an ultrasonic microphone to plug into your device, the Pettersson U384/U256, Pettersson M500Pettersson M500-384 and Echo Meter Touch 2 are the ones to consider.

They all record bat calls very efficiently, but the main consideration is going to be which device you want to plug it into. The U384 & U256 now have a USB type C connector, the M500 & M500-384 use a USB connector, the Echo Meter Touch 2 for Android uses a USB type C connector.

I want you to be 100% happy with your purchase so please call me on 0333 9000 927 for advice.

Warm Regards,


U256 @ £275
  • Weight: 25g
  • Dimensions: 43 x 35 x 13 mm
  • Current consumption: 26 mA
  • Frequency range: 1kHz - 128 kHz
  • Recording format: 256 kHz / 16 bits
  • Anti-aliasing filter: Yes
U384 @ £360
  • Weight: 25g
  • Dimensions: 43 x 35 x 13 mm
  • Current consumption: 28 mA
  • Frequency range: 1kHz - 192 kHz
  • Recording format: 384 kHz / 16 bits
  • Anti-aliasing filter: Yes
Pettersson U384/U256 comes with my 60 day 100% Satisfaction Guarantee and my exclusive 2 year warranty. Prices include UK delivery & VAT
(EU delivery is included and if you are outside the UK, we can supply without VAT)
For orders to be shipped outside the UK, please email to get prices.

Compact, lightweight, single-channel bat detector and recorder.

Developed specifically for bat research, the SM4BAT recorders combine innovative design with a new low-power processor and easy-to-use scheduling features. Available in full-spectrum and zero-crossing models, the SM4BAT will make bat research simpler, faster, less costly and more reliable. The SM4BAT FS creates high-quality, full-spectrum recordings that can be easily converted to zero-crossing recordings using free Kaleidoscope conversion software. The SM4BAT ZC creates zero-crossing files that optimize power and data storage.

Small, secure and weatherproof.

Designed around the footprint of 4 D-size batteries and made of rugged polycarbonate, the SM4BAT is less than half the weight and size of the SM3BAT. The integrated mounting bracket and weatherproof security cover keep the unit safe and dry in the most punishing environments.

Longest deployment times available.

The new, low-power microprocessor, combined with 4 D-size batteries, enable the longest deployment times of any other bat recorder available. The SM4BAT FS has a recording run time of 300 to 500 hours depending on bat activity and other factors. The SM4BAT ZC run time is even longer. See Specifications for details.

Easy to program.

To get you started quickly, the SM4BAT features a brand new, easy-to-use, Quick Start menu and Scheduler. Use built-in schedules, or customize them for your specific recording needs.

Available GPS accessory to set clock and location.

When deploying multiple recorders, use a single GPS accessory to automatically set the date, time and location settings of all recorders. The GPS accessory can also be attached to log the recording locations and path for mobile transects.

Recording Technology: Single-channel

SM4BAT FS: 16-bit .wav

SM4BAT ZC: Zero-Crossing

Sample Rates: Full-Spectrum, single-channel, 256kHz, 384kHz, 500kHz

Run-Time: SM4BAT FS: 300-500 hours, depending on bat activity, SM4BAT ZC: 500 hours (NOTE: SM4BAT FS and ZC run times can vary by as much as 50% depending on the characteristics of specific brands and models of flash cards, the kind and quality of batteries used (alkaline versus rechargeable), temperature and configuration. We recommend SanDisk brand SDHC/SDXC cards.)

Power Options: Internal power using 4 D-size alkaline (included) or NiHM batteries; External power via optional SM3/SM4 Power Cable

Storage: 2 SDHC/SDXC flash card slots (Class 4 or greater)* More than 1 terabyte total capacity using 2 512GB SDXC cards* (I recommend using SanDisk SDHC/SDXC cards and I include 2 128GB SDXC cards in the complete bundle).

Height: 8.6"/21.8 cm; Width: 5.9"/ 15.0 cm; Depth: 2.8/7.1 cm; Weight: 1.4 lbs./.64kg without batteries, 2.7 lbs./1.2kg with batteries

Enclosure Material: Polycarbonate

Operating Temperature: -4°F to +122°F or -20°C to 50°C

Warranty: 3 years (4 years if you buy from me)

If you're not sure whether the SM4BAT FS is the one for you, just give me a call on 0333 9000 927 and I'll loan you mine to see if you like it.

Download SM4BAT FS User Guide - English - Spanish (Manual de usuario) - German (Bedienungsanleitung) - Chinese (用户指南)French (Guide de l'utilisateur)Japanese

The SM3BAT and SM4BAT FS implement a serial communications interface in support of wind energy SCADA systems to report possible bat activity. With firmware version 1.3.3 and later of the SM3BAT, or SM4BAT FS recorders produced with serial numbers greater than S4U06942 (shipped on or after March 12, 2019), the recorder responds to serial requests with information including cumulative number of bat passes and pulses detected as well as timestamp, voltage, temperature, and flash card capacity information.

Download more information

New Products to protect your Song Meters and the SMM-U2 microphone from electrical surges! 
o   The Song Meter Surge Suppressor protects SM4/SM4BAT and SM3/SM3BAT recorders from power surges that could harm your recorders. This accessory should be used wherever microphones are mounted at elevation.

o   If you’ve mounted your SM4BAT and SMM-U2 to a metrology tower, wind turbine or some mounting point several feet off the ground, the SMM-U2 Grounding Bracket protects the SMM-U2 microphone from electrical surges that could damage the microphone and recorder.

1. Quick Start
2. Overview
3. Audio Settings
4. Settings Part Two
5. Daily Recording Schedules
6. Advanced Recording Schedules
7. SM4 Configurator Software
8. SM4BAT Utilities
Select the type of bat/bird detector you're looking for below
Passive Bat Detectors

Recorders to be left out on site and producing full spectrum files.

Active Bat Detectors

Hand-held recorders that can record full spectrum files and most of them log GPS co-ordinates.

Acoustic Recorders

Hand-held recorders that can record birds, frogs and other audible species. Some also record bats.

Comment from a client:

"My bat detector microphone failed during a dawn survey and knew that I had a group of dusk surveys starting in two days time. I was not in a good place as I did not have a spare, but my equipment was less than a year old.

After my survey I contacted Martin by email and he called me back on the same day, a few hours later, after a quick nap. He told me he did not have a part in stock, but had already contacted the supplier on my behalf.

The next day I received a replacement part, free of charge and express delivered from Switzerland. I thought it was amazing, and could not believe it was resolved so quickly.

Due to Martin's exceptional service I was good to go with the surveys, and I really would like to thank Martin and Wildlife Countryside Services for making the dusk surveys happen." 

David Kent

© 2015 Bat Detectors UK, part of Wildlife & Countryside Services