3dB, that is the noise figure of the internal LNA (MGA81563). The total
cascaded NF is much higher. It has been measured at 7dB. So, adding a
good (NF=1dB) external LNA will result in an 5dB improvement of
sensitivity. The additional cost of $30 ("LNA4ALL") may be well worth it.
However, please keep in mind:
- the transmitting path to the antenna will be blocked by the external
amplifier.
- the external amplifier can not be activated by the osmocom block under
grc.
- the internal LNA can not be deactivated by the osmocom source block.
It is always on.
John
Thanks,
SDR receiver noise figures seem to be in the 3 to 4db figure for
VHF/UHF. So you don't want to add too much more to that.
Stefan
On Sun, Nov 9, 2014 at 9:03 PM, Ariel Diaz
<[email protected]
<mailto:[email protected]>> wrote:
Thank you for your prompt reply. I couldn't find anything about
the NF on the hackrf but isn't it close to that figure? Or perhaps
too far from it?
Thanks,
AD
------------------------------------------------------------------------
*From:* Stefan Wagener <[email protected]
<mailto:[email protected]>>
*Sent:* Sunday, November 9, 2014 5:17 AM
*To:* Ariel Diaz
*Cc:* [email protected]
<mailto:[email protected]>
*Subject:* Re: [Hackrf-dev] LNA / Power Amplifier question.
Well,
According to the specs it will give you more than 25db in gain.
What is not so good (actually pretty bad) is the noise figure with
6db. Good preamps in VHF/UHF should have less than 1db noise added
to the signal.
my 2 cents,
Stefan
On Sun, Nov 9, 2014 at 6:53 AM, Ariel Diaz
<[email protected]
<mailto:[email protected]>> wrote:
Hello all,
While looking for a low noise amplifier for receiving, I got
mixed up with the model numbers from mini-circuits and ended
up getting what I thought it was a good deal on some
amplifiers ZHL-1042J+
<http://www.minicircuits.com/pdfs/ZHL-1042J.pdf>. Anyways,
question would be, will this amplifier provide any gain on the
Rx signal(since I already have it in hand) not interested in
Tx. Or should I sell this and buy something else. Any input
will be greatly appreciated.
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