Some users want to test the frequency response or tuning of a tag as shown in this recent question from an Impinj partner:
"The idea is to set the reader to a single frequency and increase the power level until a tag at a fixed distance begins to read. Then, move to the next frequency and increase the power until it reads. This shows the tuning of a tag. It does not look like I can use MultiReader to set the reader to a fixed frequency. Any ideas? Thanks"
This post will describe how to do this using Impinj MultiReader software and the Speedway Revolution RFID reader.
YES, you can use MultiReader to achieve this, though it is a bit of a different approach. The FCC does not allow for disabling frequency hopping in order to set the reader at a fixed frequency. So, rather than set one fixed frequency and increase power, MultiReader allows for sitting at a given power while the reader hops all available frequencies/channels and reports which frequencies it was able to read the tag and the tag's RSSI (returned power).
To do this:
1. Ensure you are using latest version of MultiReader. If not, install and use this version.
2. Click on 'Configure Settings'
3. Select 'Modes, RF, Power' menu - ensure desired antenna is checked and that Rx Sensitivity Max is checked.
4. Select the 'Run Mode' menu
5. From the Run Mode drop-down box, select 'Margin Test'.
6. Ensure that the On Time is at least 10 seconds (10000 ms) for FCC - reader hops ~ every 200ms across 50 frequencies/channels so in 10 seconds it will cover all available, I recommend 12 seconds (12000 ms) just to be sure.
7. Set the Start, Stop and power steps to desired value. Minimum power is +10dBm and max can be up to 32.5dBm, depending on region, model and power source. The power can be set to increment in as little as 0.25dB steps.
8. Click 'Data Capture' - ensure capture is set to 'On'.
9. Click 'Apply' - this will return you to the main screen.
10. Click 'Start Margin Test Run'.
Now MultiReader will start at the first power and sit there for 12 seconds hopping across all the frequencies before stepping to the next power and so on.
9. When finished, select 'File' from the menu at top left corner of MultiReader GUI and then 'Save Tag History'
10. Now you can choose a file name, notes and location for the test results spreadsheet.
11. If you use Excel to open the spreadsheet you can select the frequency column and select Data - Filter - Advanced Filter and select 'Unique records only'. This will filter out duplicate frequency reads and so you will see only the first time the tag was seen at any given frequency, the TX power and RSSI at that read.
For example, in the image below we see the data once the filter has been applied. The tag was read at +19dBm TX power at 37 frequencies/channels; the remaining 13 were read with a TX power of +20.
You can choose to not filter data and see the RSSI at various TX powers across all frequencies.