September 18, 2017

How to Analyze Why an NFC Payment Transaction Fails


The Challenge

Imagine your company produces contactless payment terminals (NFC) for banking and retail. Recently, you keep getting complains from the payment provider about failed payment transactions in a certain region. How to find the cause of the problem? It is much too costly to send out engineers that check all faulty terminals. Don’t worry, because COMPRION has the smart solution!


The COMPRION Solution

The new COMPRION TraceCase enables you to easily and inconspicuously trace NFC communication in the field! Send out anyone with a smartphone and a TraceCase and your experts will be able to analyze the problem soon after in the lab.


Step 1

After connecting your smartphone to the TraceCase Wi-Fi (and the antenna to TraceCase), start the TraceCase smartphone app.


Step 2

Tap “Start Tracing” and place the antenna onto the payment terminal.
Now, carry out a regular payment transaction using either credit card or smartphone.
When the transaction is finished, tap “Stop Tracing”.
That’s it! Now, the TraceCase app prompts you to enter the session details (terminal type, transaction status, etc.; GPS location data is added automatically!) You can even take photos of the trace situation and add the photos to the session.
Trace complete!


Step 3

Send the saved session data (including photos and comments) to the lab simply by using the smartphone’s share menu.


Step 4

In the lab, your experts open the session data with the included TraceCase Viewer on any PC to view and analyze the traced communication:

In this example, the digital channel view shows a number of errors (‘NFC Protocol Layer’ view lines 1 & 4, ‘Info’ view lines 4–7) and in the ‘Physical Layer’ view, you can see that the communication is corrupted.


Step 5

Get even more detailed information by opening the Analog Scope result:

Here, you can observe the following defects:

  • The envelope signal is distorted
  • The receiver cannot decode the signal, because the distortion causes faulty signal modulation (compare with following screenshot for an example of a correct NFC-A waveform):

The Conclusion

The payment transactions failed due to distorted signals. Most likely, another transmitter has been interfering with the RF signal. In this case, you’d have to physically examine the trace location in order to find the source of interference.

With only a few steps, you got to the bottom of NFC communication issues.

Mission accomplished!

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Kathleen Knievel

Corporate Marketing Manager

Phone +49 5251 6859 154

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