[Discuss-gnuradio] what's the actual freq. when input freq. is wrong

[Weixian Zhou]

I use two USRP N210 (daughter boards are XCVR2450 supports freq range in 2.4GHz - 2.5GHz) to experiment with tunnel.py in gr-digital/example/narrowband. I followed the instructions of README and varied the parameters.

When I set freq in 2.4GHz to 2.5GHz:

./tunnel.py -f 2.42G -c 50

It didn't work, both the transmitter and the receiver only showed TX without RX and it didn't response when I ping.

But when I set the freq to 300M (which is not supported by daughter boards)

./tunnel.py -f 300M -c 50

It worked and both the transmitter and receiver showed TX and RX and response when I ping. And it also gave the following warning:

UHD Warning:

    The hardware does not support the requested RX frequency:

    Target frequency: 300.0000000 MHz

    Actual frequency: 2400.0000000 MHz

UHD Warning:

    The hardware does not support the requested TX frequency:

    Target frequency: 300.0000000 MHz

    Actual frequency: 4500.0000000 MHz

Clearly the 4500MHz is not the real TX frequency. What is that?

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Regards,

Weixian Zhou