Almost deaf & mute bladeRF 115

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rickx
Posts: 1
Joined: Sat Jul 04, 2015 6:07 pm

Almost deaf & mute bladeRF 115

Post by rickx »

Hi,
On the weekend a friend brought over his brand new bladeRF to see if I could confirm his fears that it appeared to be quite deaf. I first ensured it had the latest firmware and bitstream installed and that the drivers on my Linux laptop were the latest available as part of the pybombs GNU radio install.
I have a couple of HACKRF, N210, B200 and an analogue devices fmcomms3 SDR development system so between us we are not strangers to SDR.
First we fired up the R&S FSH8 spectrum analyser in receive mode looking at 20MHz of spectrum centred on 460MHz where I know there are a large number of nearby P25 systems. Then we used GQRX talking to the bladeRF to look at the same part of the spectrum, took some screen shots and then substituted the HackRF. We are seeing about 15-20dB difference between the HackRF and the bladeRF. We tried all manner of gain settings and nothing would make the bladeRF hear any better. Many signals were not visible on the bladeRF.
I then tried the FRS application which comes with the bladeRF drivers library from github and with the FSH8 connected to a discone less than a metre away from the bladeRF - which had a 470MHz whip fitted to the TX port - the transmitted carriers were only about 10dB above the noise floor of the FSH (a $25000 test instrument).
Clearly there is something wrong here!
Does any of this sound like a common issue that some magic "fix" works for?
Unfortunately the device will have to be shipped back from Australia so it would be good to ensure it's not something that both of us have independently done wrong when testing the system.
Ideas?
Cheers,

Rick
jynik
Posts: 455
Joined: Thu Jun 06, 2013 8:15 pm

Re: Almost deaf & mute bladeRF 115

Post by jynik »

Hi Rick,

The only "common" issue we've really seen that sounds remotely similar to this is folks grabbing antennas from their WiFi equipment, not realizing that those have RP-SMA male, rather than SMA-male, connectors.

I suspect you've ruled out this possibility by using the antenna from one of the other devices you've listed?

If so, it sounds to me like an RMA is in order and we'll be in touch with your friend. We certainly would like to understand what's going on with this board, given that it shouldn't have made it past its initial calibration at the factory.

If you wanted to dig a little further for the time being, you could try a few different internal loopback modes using this flowgraph. If you're seeing reasonable amplitudes in the loopbacks mode, but not if you disable loobpack and then connect TX to RX through a 10-20 dB attenuator, that would indicate there may be some issue external to the LMS6002D.

Best regards,
Jon
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