Архив за 05.05.2019

RTL-SDR Discussion • No Device Found

Hi,

I have tested the following configuration several times:

1. I power up SDR using Type C PD out adopter, connect Micro USB to my Raspberry Pi 3 / B, I can see the LED white lite but no respond with rtl_test (device not found). I bought another Raspberry Pi 3 / B+, change a few cables but still receiving the same message (device not found),

2. I power up SDR using Type C PD out adopter, connect Micro USB to my notebook (Ubuntu), same problem as S/no 1 (device not found).

3. I have tested individual channel using sdrsharp-x86 on my WINDOWS desktop PC, all four channels are working (with FM radio).

Statistics: Posted by jackloh — Sun May 05, 2019 2:43 pm


KerberosSDR • Re: Some questions about KerberosSDR

kb3cs: I was merely theorizing that it should not matter how strong the received signal is (assuming it is within the receiver detectable boundaries) because all antennas would see the same power/signal increase and decrease relative to each other. And assuming antennas are identical then the reception should also be the same across all antennas. Whether or not this is the case in practice is a different matter, of course, but you have a point there.

Statistics: Posted by Airwind — Sun May 05, 2019 2:30 pm


KerberosSDR • Re: Some questions about KerberosSDR

But does it really matter what kind of reception antennas have when using identical antennas (assuming the reception is identical across all 4 antennas for any given frequency)?
are you certain that is a safe assumption to make? and are you certain higher gain (typically) as wavelength decreases creates a more useful reception pattern? the "gain" comes at the expense of less sensitivity in the rest of the pattern.

Statistics: Posted by kb3cs — Sun May 05, 2019 2:19 pm


Comment on RTL-SDR.COM Broadcast FM Band-Stop Filter (88-108 MHz Reject) Now for Sale + RTL-SDR V3 Dongle Availability by admin

Yes it’s safe to pass 80mA, and possibly up to 200mA.

KerberosSDR • Re: Some questions about KerberosSDR

rtlsdrblog wrote:
Sun May 05, 2019 11:15 am
You could update the code if you could do the math and figure out the algorithm for various arrangements,
I see, so it comes down to the algorithm then.
rtlsdrblog wrote:
Sun May 05, 2019 11:15 am
but i'm not sure why you would want to do that. Other types of arrangement would be suboptimal, you'd essentially be sacrificing an antenna.
Oh, how so? Assuming the algorithm works on the basis of time of arrival then the placement shouldn't really matter that much so long as all the antennas aren't placed on a straight line perpendicular to the direction of the signal (since all would sense the signal simultaneously). But then again I may be wrong since I'm not familiar with the algorithms used.
kb3cs wrote:
Sun May 05, 2019 1:03 pm
simple antennas have a varying reception pattern over a multi-octave frequency range such as the 24 to 1700 MHz range you mention. it's far more complicated than using a simple known antenna configuration for a (one) frequency of interest (plus or minus, say, 15% of center frequency).
But does it really matter what kind of reception antennas have when using identical antennas (assuming the reception is identical across all 4 antennas for any given frequency)?

Statistics: Posted by Airwind — Sun May 05, 2019 2:13 pm


KerberosSDR • Re: KerberosSDR as a simple RTL-SDR replacement tuner? Seriously.

You enjoy your rosey view of them, I will post and flog them relentless, and deservedly so.
you, sir, have drawn a conclusion without evidence.

obtaining a license and capability to encode/decode using DVSI technology is presently a simple matter of commerce. simple consumer commerce, as a matter of fact. no B2B and NDAs required.

the global effect of public (and private) entities deciding to use closed proprietary technology is another matter entirely, and one i did not touch upon. with this said, you may surmise our views to be more aligned than your aspersion assumes. and you would be correct.

Statistics: Posted by kb3cs — Sun May 05, 2019 1:14 pm


KerberosSDR • Re: Some questions about KerberosSDR

[*]Can this SDR be used for wideband scans with single antennas or do antennas need to be changed per frequency/band?


KerberosSDR is 4x RTL-SDRs with some circuitry to make it coherent. So even if you're not using the coherent features, you can still use it as 4 independent tuners. So you could use a splitter to connect a single antenna to all four ports. I'm not sure if many RTL-SDR scanning programs support using more than one tuner though. I believe there was one that does, but sorry I can't remember it of the top of my head.
i believe that would be "Unitrunker". one tuner for the (network) control channel, one tuner for talkgroup traffic.
Nah, I was asking whether the use of coherent feature (like for direction finding) needs to use different type of antennas for different frequencies or can 4 identical antennas (i.e. whip) be used across the entire supported frequency range (24 MHz to 1700MHz I think)?
Ah I see, yeah you could use the same antennas for the entire band. Of course if you want to optimize for best reception, you'd want tuned antennas. But for signals strong enough, any length of whip antenna would work.
simple antennas have a varying reception pattern over a multi-octave frequency range such as the 24 to 1700 MHz range you mention. it's far more complicated than using a simple known antenna configuration for a (one) frequency of interest (plus or minus, say, 15% of center frequency).

Statistics: Posted by kb3cs — Sun May 05, 2019 1:03 pm


Comment on Using a HackRF SDR to Withhold Treatment from an Insulin Pump by John Clere

Update, I’m so sorry. My doctor had me on sleep medicine and all of my first post is nuts. What I wrote was wrong and certainly not accurate. My vocation is in trucking not electronics or journalism. I don’t post on truck driver forums, it was not my normal behavior. It’s happened before with me in sleep texting family and friends. Admins, “My wish is that my comment could be deleted.” It’s hard to delete all of anything on the web and more like impossible!
Most of all on my mind is I want to say this. Thanks for the rebuke of my writtings in a decent, humane, respectable way. I’m owning this and it’s not the first time I’ve made a fool of myself. I hope it is the last time. So 9 months ago I sleep posted and found out that I did this by looking something up on Google. Again I’m shocked, sorry and grateful for everyone’s consideration. Hydrocodone, ibroprofen, flexaril, celexa, stress, long hours at work and a cellphone by the bed when sleeping is not a good combination. All the best to everyone.
Sincerely,
John Clere

KerberosSDR • Re: Setting the KerberosSDR EEPROM

suggest adding "-m RTL-SDR -p KerberosSDR" to each of the commands in the second set.

in this way, you can tell the RXs in the KSDR box apart from any other RTL-SDRs starting with a basic 'lsusb'.

Statistics: Posted by kb3cs — Sun May 05, 2019 12:51 pm


KerberosSDR • Re: Some questions about KerberosSDR

Nah, I was asking whether the use of coherent feature (like for direction finding) needs to use different type of antennas for different frequencies or can 4 identical antennas (i.e. whip) be used across the entire supported frequency range (24 MHz to 1700MHz I think)?
Ah I see, yeah you could use the same antennas for the entire band. Of course if you want to optimize for best reception, you'd want tuned antennas. But for signals strong enough, any length of whip antenna would work.
Is this a technical limitation or software limitation? Can other antenna placements (like the one I mentioned) be added by updating firmware?
You could update the code if you could do the math and figure out the algorithm for various arrangements, but i'm not sure why you would want to do that. Other types of arrangement would be suboptimal, you'd essentially be sacrificing an antenna.
Damn. I was hoping to use a static placement for multiple frequencies and not to have to bother with adjustment each time.
If the frequencies are close enough together, there's no need to update the spacing. Just change the spacing factor in software.

But you want to keep the spacing factor relatively close to the maximum (0.5 for linear, 0.35 for circular). Because the closer it is to the max, the better the resolution. Once you start taking the spacing factor down to 0.2 and less you loose resolution, and multipath signals could merge into the main graph peak, skewing the angle.

So if the frequencies are far apart in terms of wavelength, you'll want to use different physical spacings.

Statistics: Posted by rtlsdrblog — Sun May 05, 2019 11:15 am


Перевод
Рубрики
Архивы
Май 2019
Пн Вт Ср Чт Пт Сб Вс
« Апр   Июн »
 12345
6789101112
13141516171819
20212223242526
2728293031