My issue is regards to viewing the FM spectrum using USRP N210 & GNU Radio. I did try to use several blocks of GNU Radio to view an FFT plot of the FM band using the USRP N210 device. My blocks and results are as below,
I used my mobile phone to listen to 90.5MHz FM channel and confirm that there was indeed a working FM channel at that. Actually, there has to be multiple channels in this band.
In many FM radio examples, it is possible to observe multiple bands of FM channels. Unfortunately for me, I cannot see a single one. I feel that there is something wrong with my setting in GNU radio. I post the settings I have applied to each box below.
As Marcus Müller has requested I ran the command to find the daughter board I am using. My output is stated below.
user@userpc:~$ uhd_usrp_probe
linux; GNU C++ version 5.3.1 20151219; Boost_105800; UHD_003.009.002-0-unknown
-- Opening a USRP2/N-Series device...
-- Current recv frame size: 1472 bytes
-- Current send frame size: 1472 bytes
UHD Warning:
Unable to set the thread priority. Performance may be negatively affected.
Please see the general application notes in the manual for instructions.
EnvironmentError: OSError: error in pthread_setschedparam
_____________________________________________________
/
| Device: USRP2 / N-Series Device
| _____________________________________________________
| /
| | Mboard: N210r4
| | hardware: 2577
| | mac-addr: 00:80:2f:0a:d5:64
| | ip-addr: 192.168.10.2
| | subnet: 255.255.255.255
| | gateway: 255.255.255.255
| | gpsdo: none
| | serial: F384DA
| | FW Version: 12.4
| | FPGA Version: 11.1
| |
| | Time sources: none, external, _external_, mimo
| | Clock sources: internal, external, mimo
| | Sensors: mimo_locked, ref_locked
| | _____________________________________________________
| | /
| | | RX DSP: 0
| | | Freq range: -50.000 to 50.000 MHz
| | _____________________________________________________
| | /
| | | RX DSP: 1
| | | Freq range: -50.000 to 50.000 MHz
| | _____________________________________________________
| | /
| | | RX Dboard: A
| | | _____________________________________________________
| | | /
| | | | RX Frontend: 0
| | | | Name: Unknown (0xffff) - 0
| | | | Antennas:
| | | | Sensors:
| | | | Freq range: 0.000 to 0.000 MHz
| | | | Gain Elements: None
| | | | Bandwidth range: 0.0 to 0.0 step 0.0 Hz
| | | | Connection Type: IQ
| | | | Uses LO offset: No
| | | _____________________________________________________
| | | /
| | | | RX Codec: A
| | | | Name: ads62p44
| | | | Gain range digital: 0.0 to 6.0 step 0.5 dB
| | | | Gain range fine: 0.0 to 0.5 step 0.1 dB
| | _____________________________________________________
| | /
| | | TX DSP: 0
| | | Freq range: -50.000 to 50.000 MHz
| | _____________________________________________________
| | /
| | | TX Dboard: A
| | | _____________________________________________________
| | | /
| | | | TX Frontend: 0
| | | | Name: Unknown (0xffff) - 0
| | | | Antennas:
| | | | Sensors:
| | | | Freq range: 0.000 to 0.000 MHz
| | | | Gain Elements: None
| | | | Bandwidth range: 0.0 to 0.0 step 0.0 Hz
| | | | Connection Type: IQ
| | | | Uses LO offset: No
| | | _____________________________________________________
| | | /
| | | | TX Codec: A
| | | | Name: ad9777
| | | | Gain Elements: None
user@userpc:~$
To support Marcus's second answer, I post an image of the inside of my USRP N210 below.
It would be really great if my mistake can be spotted.
uhd_usrp_probe
) $\endgroup$