[Hackrf-dev] Amp On or Off

[Paul Jones]

In a future revision of Harkrf would it be possible to add an overload indicator for the rf frontend? Like a clipping indicator in audio equipment. That would be quite handy. I guess a quick utility that scans the entire usable frequency range, finds the peaks and gives a suggested max gain setting would be just as good.

Paul.

From: HackRF-dev [mailto:hackrf-dev-bounces at greatscottgadgets.com] On Behalf Of Paul Connolly
Sent: Wednesday, 1 July 2015 3:29 PM
To: hackrf-dev at greatscottgadgets.com
Subject: Re: [Hackrf-dev] Amp On or Off

If you set the sample rate to 20MSPS and decimate in your flowgraph down to a bandwidth of 1.25MHz (20000000/(2^4)) you will have increased the observed signal level by 12dB (3dB*4) with no possible damage to hardware. Provided at least one bit in the ADC sample is being tickled by the signal of interest, every time you decimate the bandwidth in half you will gain an extra 3dB of signal level. 12dB of extra signal, with no risk of damaging any hardware, provided what you are doing can function with 1.25MHz (or less) of bandwidth.

I leave the amp off at all times. The only time i would consider enabling it is if I was in a RF desert and I had scanned from DC to 6GHz and found no signals above -5dBm (see: https://github.com/mossmann/hackrf/wiki/HackRF-One#receive-power ).
On 01/07/2015 03:03, Tom wrote:

Just curious to what people do with the amp, do you run it most of the time

and not worry about frying it due to nearby transmitters? I'm in two minds

as in I would like to use it as much as I can because it makes a huge

difference, especially when driving and monitoring the ISM bands but at the

same time I worry that a strong transmitter nearby might damage it, I mean

is this really the case even though It might me few hundred mhz away from a

strong transmitting station.







I read one story where someone has destroyed the amp but that was because it

was connected to a satellite dish or something like that (can't remember the

full story) are there any other cases where someone has destroyed the amp?







Thanks



Tom
















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