50P-2014 USB controlled programmable attenuator

What is a step attenuator?

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A step attenuator is a variable attenuator that can have its attenuation setting varied over an attenuation range by a specific dB step size.  All attenuation settings are referenced to the insertion loss.  This means that the minimum setting (0dB) is the insertion loss state of the step attenuator.  For example programmable attenuator model 50P-1857 has range 0-95dB x 1dB and is a solid-state type of step attenuator.  The 95dB setting is the maximum attenuation setting.  The 0dB setting (i.e. insertion loss state) is the minimum setting.  It can be set at any 1dB increment between 0dB and 95dB.

Step Attenuator Characteristics:

    • Attenuation Range
    • dB step size
    • Frequency range
    • RF input power
    • Switching speed
    • Lifetime

When selecting a step attenuator first determine how you want to control it.  There are several different control types for step attenuators:  manually control, TTL control, USB control, Ethernet control.

Manual Control50 Ohm dual knob manual attenuator with BNC female connectors and attenuation range 0 to 30dB by 1dB steps

Manually controlled step attenuators are passive devices that require no external power source.  Just turn the knobs to set the desired attenuation.  JFW model 50DR-055 is an example of a manual attenuator with attenuation range 0-30dB by 1dB steps.  It has two rotary knobs used to set the attenuation.  It has a 1dB step knob and a 10dB step knob.  The attenuation setting is the combination of both knob settings (22dB = 2dB + 20dB).

TTL ControlSolid State Programmable Attenuator

JFW model 50P-1857 SMA is an example of a TTL controlled 50 Ohm step attenuator.  It has attenuation range of 0-95dB by 1dB steps.  This step attenuator is comprised on several individually controlled attenuation steps:  1, 2, 4, 8, 16, 32 and 32dB.  Each of the attenuation steps has its own TTL control line for a total of 7 control lines.  TTL high turns on the step.  TTL low turns off the step.  Set multiple control lines to TTL high to create combinational dB settings.  For 7dB of attenuation, turn on the 1, 2, and 4dB control lines.

USB Control50P-2014 USB controlled programmable attenuator

JFW model 50P-2014 SMA is also a step attenuator with range 0-95dB by 1dB steps but with USB control.  It is similar to the TTL controlled example in that It also has individual attenuation steps:  1, 2, 4, 8, 16, 32 and 32dB.  But since it is USB controlled, you don’t have to worry about setting the individual attenuation steps.  Just send the USB attenuator remote commands at it automatically sets the attenuation for you.  You can control the USB attenuator using the JFW provided test software or control it using with a Python test script.  We have a Python library with examples that we can email to you.

Ethernet Control50PA-128-08 SMA eight channel attenuator assembly with Ethernet and serial remote control

JFW model 50PA-128-XX is another step attenuator with range 0-95dB by 1dB steps but with Ethernet control.  It is actually an assembly that can contain up to 8 individually controlled step attenuators in a single 19 inch rack mountable chassis.  To set the attenuation just send the Set Attenuator remote commands at it automatically sets to the desired dB value.  You can control an Ethernet attenuator using the JFW provided test software or control it using with a Python test script.  We have a Python library with examples that we can email to you.