ZVx - attenuators

Several concepts of ICE /and or its Plugins/Tools.

ZVx - attenuators

Postby fransv » Wed Aug 03, 2011 2:25 pm

There are 2 concepts to keep in mind with respect to adding fixed attenuators.

--- Concept # 1 ---

Ideally the ZVA/T should have meas. receiver step attenuators at all ports.
When this is not the case (e.g. you don't have this step attenuator at port 1), the software will indicate the advised value of an external attenuator in order to have the same range for the reference and measurement receiver.
In case of a ZVA67 this will be 35 dB as shown below.

Dialog at startup when ICE detects missing step attenuator options
ReplacementOptionalStepAttenuators.JPG (10.49 KiB) Viewed 3133 times

It is important to notice that the dialog refers to a channel and not a port.
Channel 2 corresponds to the measurement receiver at port 1 (or port 3 if you created a 2-port RF analyzer using P3P4).

If you add 35 dB to channel 2 (B1 receiver), you will have about 11 dBm as port range for the B1 wave (meas. receiver) compared to 12 dBm for the A1 wave (ref. receiver).
If you add 20 dB instead, the port range is about -4 dBm, while the B1 wave will be about 6 dBm when the NM200-based HPR is applied.
In order to avoid the overrange warning during HPR calibration, you will need to use at least 30 dB of attenuation instead of 20 dB for B1.
Even at that moment, it may be that you will get an overrange warning because the actual port range is only roughly estimated (the exact port range can differ a few dB).
When you have added 30 dB attenuation, you may ignore the overrange indication during HPR calibration (if present).

The 20 (or 30) dB attenuator above is a replacement for the missing step attenuator option.

--- Concept # 2 ---

On top of that one can add a fixed attenuator (specified as gain, so please don't forget to specify -20 if you use a 20 dB attenuator) on top of the step attenuators (or the fixed attenuator used as replacement for the missing step attenuator option).
You can specify this value in the Fixed Gain section of the Ranging tab of the RF analyzer control GUI.
This is explained in the tutorial movies under ICE Functionalities - RF Analyzer - Ranging.
Again, please keep in mind that you have to select the port first and then you can specify the fixed gain (don't forget the minus sign in case of attenuation) for channel 1 (ref. receiver) and/or channel 2 (meas. receiver)

If you add 20 dB for the B2 receiver (on top of the 35 dB step attenuators), the actual B2 range is 31 dBm (beyond the 27 dBm that is specified as max
power for the ports).
At that moment you should not get any overrange indication for B2 if you stay below 27 dBm.

When you save the workspace and relaunch ICE, two dialogs will pop up.
The first one corresponding to concept #1 (see below) and refers to channels (not ports), so channel 2 corresponds to B1.

First dialog when loading ICE workspace in case of missing step attenuator options
ReplacementOptionalStepAttenuatorsWhenLoadingWorkspace.JPG (9.87 KiB) Viewed 3080 times

The second one corresponding to concept #2 (see below) and refers to channels (not ports), so channel 4 corresponds to B2.

Second dialog when loading ICE workspace in case fixed attenuators were added
FixedGainAdaptationWhenLoadingWorkspace.JPG (13.78 KiB) Viewed 3083 times
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