# aUaUaUaUaUaU and requested rx frequency not supported problem **URL:** \ **Category:** GNU Radio\ **Created:** [May 11, 2012, 7:09pm UTC](https://www.ruby-forum.com/t/auauauauauau-and-requested-rx-frequency-not-supported-problem/219690 "2012-05-11T19:09:24Z")\ **Posts on this page:** 2\ **Page:** 1
**Author:** ![Gurdipe\_D](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/g/b77776/32.png) [@Gurdipe\_D](https://www.ruby-forum.com/u/Gurdipe_D)\ **Post date:** [May 11, 2012, 7:09pm UTC](https://www.ruby-forum.com/t/auauauauauau-and-requested-rx-frequency-not-supported-problem/219690/1 "2012-05-11T19:09:24Z")
Hi Everybody, I am using USRP with daugherboard of range 1MHz to 250MHz. I am running the program with gnu-radio 3.6.0 on Ubuntu 11.10. I am trying to run the basic fm receiver program as shown in the video. Whenever I try to execute the code, I get following things on grc. I have double checked that the daughterboard works for the range. When I see the fft plot of the received signal I see that I have just noise all around. The hardware does not support the requested RX frequency: Target frequency: 100.000000 MHz Actual frequency: -28.000000 MHz aUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaU I have also tried to see if the antenna choices are correct. I checked it with uhd\_usrp\_probe The important part of the result was RX Subdev: AB | | | | Name: Basic RX (0x0001) - AB | | | | Antennas: | | | | Sensors: | | | | Freq range: -250.000 to 250.000 Mhz | | | | Gain Elements: None | | | | Connection Type: IQ | | | | Uses LO offset: No | | | \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ | | | / | | | | RX Subdev: BA | | | | Name: Basic RX (0x0001) - BA | | | | Antennas: | | | | Sensors: | | | | Freq range: -250.000 to 250.000 Mhz | | | | Gain Elements: None | | | | Connection Type: QI | | | | Uses LO offset: No So, when I try to work with uhd\_fft. I got same problem with following results uhd\_fft --spec B:AB linux; GNU C++ version 4.6.1; Boost\_104601; UHD\_003.004.001-39-unstable – Opening a USRP1 device… – Using FPGA clock rate of 64.000000MHz… Using Volk machine: ssse3\_64 UHD Warning: The hardware does not support the requested RX frequency: Target frequency: 100.000000 MHz Actual frequency: -28.000000 MHz Could you help me out here? Thanks in advance. – Pranav Sakulkar ---
**Author:** ![unknown](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/u/4bbf92/32.png) [@unknown](https://www.ruby-forum.com/u/unknown)\ **Post date:** [May 11, 2012, 7:36pm UTC](https://www.ruby-forum.com/t/auauauauauau-and-requested-rx-frequency-not-supported-problem/219690/2 "2012-05-11T19:36:02Z")
On Fri, 11 May 2012 19:08:38 +0200 (CEST), [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > Hi Everybody, > I am using USRP > with daugherboard of range 1MHz to 250MHz. I am running > the program > with gnu-radio 3.6.0 on Ubuntu 11.10. I am trying to run the > basic fm > receiver program as shown in the video. [http://www.youtube.com/watch?v=KWeY2yqwVA0](http://www.youtube.com/watch?v=KWeY2yqwVA0) [1] > Whenever I try to > execute the code, I get following things on grc. I have > double checked > that the daughterboard works for the range. When I see the > fft plot of > the received signal I see that I have just noise all around. > The > hardware does not support the requested RX frequency: > Target > frequency: 100.000000 MHz > Actual frequency: -28.000000 MHz aUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaU > > I have also tried to see if the antenna choices are correct. I > checked it > with uhd\_usrp\_probe > The important part of the result > was > RX Subdev: AB > | | | | Name: Basic RX (0x0001) - AB > | | | | > Antennas: > | | | | Sensors: > | | | | Freq range: -250.000 to 250.000 > Mhz > | | | | Gain Elements: None > | | | | Connection Type: IQ > | | | > | Uses LO offset: No > | | | * * * > | | | / > | | | > | RX Subdev: BA > | | | | Name: Basic RX (0x0001) - BA > | | | | > Antennas: > | | | | Sensors: > | | | | Freq range: -250.000 to 250.000 > Mhz > | | | | Gain Elements: None > | | | | Connection Type: QI > | | | > | Uses LO offset: No > > So, when I try to work with uhd\_fft. I got > same problem with following > results > uhd\_fft --spec B:AB > > linux; > GNU C++ version 4.6.1; Boost\_104601; UHD\_003.004.001-39-unstable > > – > Opening a USRP1 device… > – Using FPGA clock rate of > 64.000000MHz… > Using Volk machine: ssse3\_64 > > UHD Warning: > The > hardware does not support the requested RX frequency: > Target > frequency: 100.000000 MHz > Actual frequency: -28.000000 MHz > > Could > you help me out here? > Thanks in advance. > > – Pranav Sakulkar * * * > Discuss-gnuradio > mailing list > [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) [2] [Discuss-gnuradio Info Page](https://lists.gnu.org/mailman/listinfo/discuss-gnuradio) [3] The aU is because your audio subsystem is experiencing underruns, probably because you have a sample-rate issue in your flow-graph. The UHD warning is because the BASIC\_RX has no downconversion hardware at all, which means that any frequency above Nyquist (32Mhz for USRP1 and 50Mhz for N2XX) requires that the FPGA/ADCs sample the appropriate alias frequency, and UHD is warning you that’s what it’s doing. But without analog filtering in the front-end, you’ll end up with _unwanted_ aliases as well. The BASIC\_RX is very “BASIC”, and it’s really intended as an interface card to “proper” RF front-ends, with filtering, and probably downconversion to an IF. Links: