Pulsed signal even without antenna connected
Posted: Thu Aug 18, 2016 1:29 am
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
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