Pulsed signal even without antenna connected

[wpats]

Hi,

I have been using the SDRPlay with different software packages including GNUradio. I ran the "osmocom_fft" program, that is distributed as part of gr-osmosdr, in scope mode (time domain plotting) using the following command line:

osmocom_fft --args="sdrplay" -s 10M -f 5M -S

The device is tuned to 5MHz center frequency with a sample rate of 10Msps. I observed an intermittent pulsed signal with width of around 50 micro-seconds. Note that this in "scope mode" i.e. time-domain display of I/Q data like an oscilloscope using the trigger feature. Since I could not pick up this signal with my other devices I tried disconnecting the antenna and observed that the signal remained. To rule out computer noise I tried this again using a laptop running on battery power and observed the signal again.

What could be causing this ? Is it noise being generated by the digital circuitry in the SDRplay itself (like the USB interface) ? Has anybody else observed this ? Or is this RFI in my environment being picked up internally by the device ?

Thanks for any info,

--Patrick

[BrodGasko]

Hi....as per my knowledge it can be the internal problem of SDR itself but it might not be. It can be the problem of Antenna also. Can you please share the specifications of all your hardware components, specially for Antenna? What type of Antenna you are using and what are its specifications?

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[wpats]

Hi BrodGasko,

I am using a Nagoya NA-774 telescopic antenna. However, as I mentioned the signal appears even without an antenna connected. I have reproduced the issue with the sdrplay connected to desktop and laptop both running Ubuntu Linux. Those are all the components of the system.

Thanks for any help,

--Patrick