No one signal on any freq...defective dongle?

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luc4sss
Posts: 19
Joined: Wed May 16, 2018 1:19 pm

No one signal on any freq...defective dongle?

Post by luc4sss » Wed May 16, 2018 1:34 pm

Hi,
first of all sorry for my poor English...

I've bought a RTL2832U based dongle, it is a classic "yellow-pcb" dongle...
My intention is to try to receive some NOAA image, so I have build a V-dipole antenna, and connected it to the dongle..
Now antenna and dongle are in the outside of the house, on the roof, but I'm unable to receive no one signal...even FM station...

The dongle is connected to a Raspberry Pi, and I'm using virualhere to get the usb dongle virtually connected to my PC in my room...
I'm able to connect it with Gqrx, and all works fine...but there is no one signal, no NOAA, no FM, no APRS...
I know that my antenna is not adequate to receive FM radio, but a FM relay is at 1km from my house, so i can aspect to find some station in Gqrx...in range 88 - 100 MHz...

I've also try to set Gqrx to 433MHz and "click" my car key near the antenna, i can only get a very very small signal in the monitor...

Could the RTL2832 dongle be defective?
Some screenshot attached

Here the rtl_test output:

Code: Select all

rtl_test -p
Found 1 device(s):
  0:  Realtek, RTL2838UHIDIR, SN: 00000183

Using device 0: Generic RTL2832U OEM
Detached kernel driver
Found Elonics E4000 tuner
Supported gain values (14): -1.0 1.5 4.0 6.5 9.0 11.5 14.0 16.5 19.0 21.5 24.0 29.0 34.0 42.0 
Sampling at 2048000 S/s.
Reporting PPM error measurement every 10 seconds...
Press ^C after a few minutes.
Reading samples in async mode...
lost at least 100 bytes
real sample rate: 2049493 current PPM: 729 cumulative PPM: 729
real sample rate: 2046117 current PPM: -919 cumulative PPM: -112
real sample rate: 2047852 current PPM: -72 cumulative PPM: -98
real sample rate: 2049313 current PPM: 641 cumulative PPM: 88
real sample rate: 2049351 current PPM: 660 cumulative PPM: 203
real sample rate: 2047816 current PPM: -90 cumulative PPM: 154
real sample rate: 2044462 current PPM: -1727 cumulative PPM: -116
real sample rate: 2047812 current PPM: -92 cumulative PPM: -113
real sample rate: 2049367 current PPM: 668 cumulative PPM: -26
real sample rate: 2046134 current PPM: -911 cumulative PPM: -115
real sample rate: 2048728 current PPM: 356 cumulative PPM: -72
real sample rate: 2048457 current PPM: 223 cumulative PPM: -47
real sample rate: 2049363 current PPM: 666 cumulative PPM: 8
Thanks
Attachments
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Schermata da 2018-05-16 15-28-37.png (1.86 MiB) Viewed 731 times
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Schermata da 2018-05-16 15-28-45.png (1.84 MiB) Viewed 731 times

rtlsdrblog
Site Admin
Posts: 1726
Joined: Mon Nov 19, 2012 11:54 pm

Re: No one signal on any freq...defective dongle?

Post by rtlsdrblog » Fri May 18, 2018 4:32 am

Something does seem wrong with that spectrum, it doesn't look right. It does look defective, i'd ask the seller for a replacement.

But first are you able to try connecting the dongle directly to your PC to rule out problems with VirtualHere? Even with the antenna inside, you should be able to receive broadcast FM at 88 - 108 MHz.

luc4sss
Posts: 19
Joined: Wed May 16, 2018 1:19 pm

Re: No one signal on any freq...defective dongle?

Post by luc4sss » Fri May 18, 2018 6:21 am

Same problem with the dongle connected directly to the PC...no FM...

I bought a new rtl-sdr dongle from rtl-sdr.com yesterday :)

rtlsdrblog
Site Admin
Posts: 1726
Joined: Mon Nov 19, 2012 11:54 pm

Re: No one signal on any freq...defective dongle?

Post by rtlsdrblog » Sun May 20, 2018 9:19 am

I just noticed that you have an E4000 dongle which explains the hump in the middle of the spectrum.

Do you have a link to the exact dongle that you bought?

Also have you ruled out defective coax, adapters, bad antenna etc?

luc4sss
Posts: 19
Joined: Wed May 16, 2018 1:19 pm

Re: No one signal on any freq...defective dongle?

Post by luc4sss » Sun May 20, 2018 11:54 am

Hi,
a photo of the dongle attached...
I've no more the link of the store, because i've bought this dongle some years ago...

I've already checked cable, connector and antenna, i got the same result with the "stock" antenna...
Today i've try with SDR# in Windows, and the result it's the same...
No signal, no FM broadcast...only the hump in the middle and the two "spike" at the left and at the right of the hump like in the 433MHz screenshot, same "spike" in the FM range...
Attachments
photo_2018-05-20_13-47-57.jpg
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rtlsdrblog
Site Admin
Posts: 1726
Joined: Mon Nov 19, 2012 11:54 pm

Re: No one signal on any freq...defective dongle?

Post by rtlsdrblog » Sun May 20, 2018 10:57 pm

I see no ESD protection diode on this unit, so it probably died from ESD long ago unfortunately. Many of the older generic units didn't come with ESD diodes.

luc4sss
Posts: 19
Joined: Wed May 16, 2018 1:19 pm

Re: No one signal on any freq...defective dongle?

Post by luc4sss » Tue May 22, 2018 7:14 pm

You are right, thanks man :)
I'll wait for the new dongle ;)

luc4sss
Posts: 19
Joined: Wed May 16, 2018 1:19 pm

Re: No one signal on any freq...defective dongle?

Post by luc4sss » Wed Jun 13, 2018 12:10 pm

With the yellow dongle no signal...
with the RTL-SDR.com dongle and a DIY V-dipole without LNA... :)
Attachments
NOAA1820180613-091620.color.png
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NOAA1520180613-084803.HVCT.png
NOAA1520180613-084803.HVCT.png (1.98 MiB) Viewed 407 times
NOAA1520180613-084803.color.png
NOAA1520180613-084803.color.png (1.84 MiB) Viewed 407 times

rtlsdrblog
Site Admin
Posts: 1726
Joined: Mon Nov 19, 2012 11:54 pm

Re: No one signal on any freq...defective dongle?

Post by rtlsdrblog » Thu Jun 14, 2018 12:17 am

Nice images!

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