software-controlled RF digital step attenuators

(Downloads: Data Sheet, Manual)


The sysmoRFDSATT family is a product family of digitally controlled / programmable RF step attenuators. The initial product within this family is the sysmoRFDSATT-4-62 with:

  • 4 independent RF channels

  • 0 .. 62 dB nominal attenuation per channel.

This kind of device can be very useful in any kind of laboratory or test setup where RF signal strength must be adjusted programmatically. A classic use case is e.g. the testing of power-based hand-over within lab setups of cellular radio network, such as GSM BTS, UMTS NodeB, LTE eNodeB or 5G gNodeB.


The sysmoRFDSATT-4-62 is available in three variants:

  • PCBA only, for integration into custom projects

  • 3U Component Carrier

  • Desktop Enclosure

Software Integration

The full firmware stack, from boot loader up to the application firmware is Open Source Software. This means any user can be modified to accommodate any specific requirements.

For example, the following modifications are easily possible:

  • support of the SCPI protocol for integration into existing lab software solutions

  • support of any application-specific control protocol

  • support of autonomous execution of entire scenarios, like ramping attenuation with certain slope

Technical Data

Mechanical / Electrical Specification


Desktop Enclosure

3U Component Carrier

Dimensions (W x H x D)

105 x 44 x 104 mm (excl. SMA) 105 x 44 x 113.5 mm (incl. SMA)

35.3 x 128.2 x 82.5 mm (excl. SMA) 35.3 x 128.2 x 92 mm (incl. SMA)



7 HP wide 3U module IEC 60297-3-101

Maximum RF Power

+24 dBm >= 50MHz; +11 dBm >= 1 MHz

Absolute maximum RF power

+30 dBm

Attenuation Range (nominal)

0 .. 62 dB per channel; step size 1 dB

Insertion Loss (typical)

3.5 dB @ 1 GHz; 5.4 dB @ 2 GHz, 6 dB @ 3 GHz

UART Connector

3.3V UART on 2.5mm stereo jack, front-facing; 115200 bps

RF Connectors

8 x SMA, female, front-facing

Input Voltage

5V DC via 5.5/2.5mm barrel connector

barrel connector (see left) or 2.54mm pitch header

Software / Logical Specification


  • OpenBLT bootloader

  • application firmware built on libopencm3 + librfn

UART Protocol / Interface

  • human-readable text commands on command line interface

Firmware Upgrade

  • field-upgradable over UART without any special adaptre

Block Diagram

sysmoRFDSATT-4-62 block diagramsysmoRFDSATT-4-62-PCBA