HackRF power output
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Aurelien Picart
Dec 21, 2015, 3:54:16 PM12/21/15
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hi everybody,
i just baught a 1,5W amplifier for extand a little bit the coverage of my HackRF One, i know it's better with a USRP but it's just for test before buy it someday.
This little amplifier accept 0dBm input, but i don't have any spectrum analyser for analyse the output of the hackrRF...
Somebody can help me in this way? ever try to test the hackrf output and amplify it?
the link of the power module: http://www.ebay.com/itm/1MHz-500MHZ-1-5W-New-HF-FM-VHF-UHF-RF-Power-Amplifier-For-Ham-Radio-Heatsink-/181695318352
Regards,
Aurélien.
Matthias Brändli
Dec 21, 2015, 3:59:36 PM12/21/15
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On 21. 12. 15 21:54, Aurelien Picart wrote:
> i don't have any spectrum analyser for analyse the output of the hackrRF...
you are walking on thin ice. Be careful with what you transmit !
> i don't have any spectrum analyser for analyse the output of the hackrRF...
About the PA: very strange that the marking on the chip has been made
unreadable...
mpb
Jan de Vries
Dec 22, 2015, 3:05:28 AM12/22/15
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For amplifying digital signals, without distorsion and maintaining at least 40 db shoulder, you always have to use a class A amplifier.
Here they are using MMIC types op amplifiers, that most likely are class AB types.
The Hack Rf makes about - 25 dbm rf, that means for getting 1mW you have to amplify 25 db ! in class A, thats a hell of a job !
This amplifier can amplify your signal a bit, but degradation of shoulder and constellation will occur !
jhansen1
Dec 22, 2015, 10:22:25 AM12/22/15
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Sergiy pointed me in the direction of this:
Could this be a better option?
Jan de Vries
Dec 22, 2015, 11:56:52 AM12/22/15
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Yep is a good alternative, keeping distorsion in mind, you should make no more than max 5 or 6 watts, because this module was made for amplification of FM signals , but when you set the current rather high, some linearity is there in the lower power range, and can be used for DAB signals.
But still keep in mind , you need a license for broadcast ! And most likely a mask filter to keep acp within range, and maintain the 40 db shoulder.
But still keep in mind , you need a license for broadcast ! And most likely a mask filter to keep acp within range, and maintain the 40 db shoulder.
jhansen1
Dec 22, 2015, 12:00:04 PM12/22/15
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tirsdag 22. desember 2015 17.56.52 UTC+1 skrev Jan de Vries følgende:
Yep is a good alternative, keeping distorsion in mind, you should make no more than max 5 or 6 watts, because this module was made for amplification of FM signals , but when you set the current rather high, some linearity is there in the lower power range, and can be used for DAB signals.
But still keep in mind , you need a license for broadcast ! And most likely a mask filter to keep acp within range, and maintain the 40 db shoulder.
What is the consequence if acp isnt within range and the 40 db shoulder isnt maintained?
Jan de Vries
Dec 22, 2015, 1:50:23 PM12/22/15
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As there is more ajacent power in the neighbour channel, and consequently less shoulder performance, means that you have intermodulation in your hf signal, resulting in more receiving errors.
This you can see/messure at your constallation, the dots are going wilde.
Good shoulder performance give stabil constellation, you can check this on a analiser or on sdr-j .
For instance 0.1 watt with 40 db shoulder gives better receiving results than 5 watt on 20 db shoulder !!
You can enhance the shoulder by using a mask filter, e.g. a bandpass filter , just wide enough to let the 1.75 mhz signal pass.
Still its way better to use amplifiers who are lineair in amplification, so use the amp way below the 1db cp !
Aurelien Picart
Dec 23, 2015, 10:25:19 AM12/23/15
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Thanks for your comments,
i have connect the power amplifier and it's work great!
the coverage with a external aerial was 50m before and now close to 500m.
Jan de Vries
Dec 23, 2015, 4:48:12 PM12/23/15
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and checked your shoulder steepness ? just out of interest.
If the amp does what it says, 32 db, then you should now have some 7dbm > 5 mw. ( -25 + 32 )
If the amp does what it says, 32 db, then you should now have some 7dbm > 5 mw. ( -25 + 32 )
That is when you have your amplification in the hackrf call = 31
jhansen1
Jan 1, 2016, 8:43:41 PM1/1/16
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What kind of aerial are you using?
Aurelien Picart
Jan 6, 2016, 5:00:12 PM1/6/16
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Hi! So happy new year for everybody ;)
i try with SDR# and SDR RTL2832U receiver for few analyse of the spectrum.
What kind of aerial are you using?
I'm using a classical VHF BIII antenna with 5 elements on my roof, connect with a 75ohms cable. I usually use it for receive DAB signal from Belgium.
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