RTL-SDR - an SDR receiver from a cheap DVB-T tuner on a USB connector

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#931 15881507 21 Aug 2016 12:17

matek189233 matek189233

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Post #931
15881507 21 Aug 2016 12:17

Hello, I'm new here, but please help pw if you can
I have:
http://g01.a.alicdn.com/kf/HTB1oshRJFXXXXXxXF...TL2832U-R820T2-with-120cm-Cable-MCX-Connector .jpg " target="_blank" rel="nofollow noopener ugc" class="postlink inline" title="" > http://g01.a.alicdn.com/kf/HTB1oshRJFXXXXXxXF...TL2832U-R820T2-with-120cm-Cable-MCX-Connector .jpg
and antenna:
Albrecht Allband
My point is that I can not cope with the configuration of SDR-Sharp and HDSDR programs, can anyone help me with e.g. TeamViewer?
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#932 15881780 21 Aug 2016 14:25

don_viking don_viking

Level 21

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Post #932
15881780 21 Aug 2016 14:25

sir_mendez wrote:
I recently came across the SDR slogan and I have these questions - there are several of them, but on one topic basically:
Does this RTL-SDR only receive the air signal? Inn. in words, is it suitable, for example, for the visual evaluation of the power of DVB-T TV channels in the antenna sockets in the rooms?
[I can see that the range is quite wide and it will probably also include: 470 - 790MHz (sheet 21 - 60), 790 - 862 MHZ (sheet 61 - 69), 174 - 230 MHz (sheet 6 - 12)]

What does SDR show at all when it is attached to a home satellite / DVB-T cable? Does it draw any graphs for the above channels? Power from the SAT socket will not burn something on USB in this mode?

Any info in this direction is welcome

Here you have a page where you can see the spectra of individual signals.

http://www.sigidwiki.com/wiki/Database

Not wanting to damage the tuner, connect such signals through the antenna separator.
#933 15884938 22 Aug 2016 21:05

Artur k. Artur k.

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Post #933
15884938 22 Aug 2016 21:05

Maybe I won't write anything new, but just out of curiosity, I compared two DVB-T receivers - typically Chinese, available at auctions for about PLN 40 in a black housing with the words DVB-T + DAB + FM with R820T tuner and blue LED and NOT LV5T Deluxe with the FC0013 tuner, which I recently bought for PLN 60.

I used RLT-SDR Scanner for Windows, scanned the 87-108MHz radio band

Black Chinese Tuner:

LV5T:

The effect speaks for itself, which is also audible and felt when using, for example, HDSDR.
If someone (like me) complains about poor results, poor sensitivity, etc., I suggest changing the tuner, and if someone is just going to buy, I suggest avoiding black Chinese inventions with a blue LED, it is better to add PLN 20 and not to tear your hair out of your head.
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#934 15888702 24 Aug 2016 15:30

don_viking don_viking

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Post #934
15888702 24 Aug 2016 15:30

I advise against the LV5TDLX tuner with the FC0013 chip for those who want to listen to signals above 800MHz because this tuner loses its sensitivity completely there. It drops to zero. The only option then is to turn on the Tuner AGC program and attach an external amplifier, due to the design it only works in LV5TDLX tuners and those that have generators instead of quartz. I had 4 such tuners and tested them in every way. Another drawback is that they are easily damaged by overvoltage at the antenna input. I recommend these tuners in the blue casing, they are short-circuit proof and have better sensitivity than all others and have the R820T2 chip.
#935 15888791 24 Aug 2016 16:18

Artur k. Artur k.

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Post #935
15888791 24 Aug 2016 16:18

don_viking wrote:
I recommend these tuners in the blue casing, they are short-circuit proof and have better sensitivity than all others and have the R820T2 chip

I just don't recommend them. Above you have a scan of the FM band, my tuner is black, but my colleague has the same blue, they both behave exactly the same. Anyway, worse sensitivity than the LV5 is audible when using HDSDR - stations that hum on this black noise, on the LV5 receive flawlessly.
With the factory firmware, it is exactly the same - using HD Blaze (software supplied with the black / blue tuner) in my apartment, the black tuner does not catch DAB, and on the LV5 it catches DAB.
Above 800MHz I did not check, because I am not interested in this band, while on VHF and lower UHF (500-600MHz) the LV5 is much better.
#936 15890410 25 Aug 2016 10:31

wbober wbober

Level 11

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Post #936
15890410 25 Aug 2016 10:31

Welcome back,
I made a collinear antenna according to http://projektpimalina.blogspot.com/2016/04/budowa-anteny-kolinearnej-colinear-1090.html
Almost the center of Krakow, RTL R820T2 and ADSB #.
I put on the balcony and the positive effects - a dozen or so airplanes, about 90 nm in the direction of "antenna visibility".
So I moved to the roof (single-family house) and here is a surprise
Everything has fallen, since many planes are not taking back position.
Of course, on the balcony the cable was about 3m, now the cable length is about 15m - old 50 ohm cable from CB.
Question: will replacing the cable with a more decent one help, or will the necessary linear amplifier?
kisses
bober
PS Oh, how should Confidence be set up in ADSB #?
#937 15890469 25 Aug 2016 10:59

lysy1980 lysy1980

Level 33

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Post #937
15890469 25 Aug 2016 10:59

The cable you need to use is at least H-155 - the RG58 that you are using now is not suitable for this purpose - it has cosmic attenuation - you have to change for a better one.
Anyway, with 15m of cable at this frequency, you will lose a lot even on the H-155.
The amplifiers also bring a lot of noise, the effect does not have to be positive.

It's best to buy a RAS-PI, put it on the roof in a hermetic box near the antenna, and power it via PoE.

As for placing the antenna in a PVC tube - you can also lose a lot, some tubes are not suitable for this purpose - proven in practice - I passed several DIY stores and bought tubes from several manufacturers. The only tube that did not introduce damping that I managed to get was HENSEL production - dug out somewhere from the old junk after the electrical installation, this tube is not white, but slightly cream. I don't think I have tested only NIBCO water pipes.

Transparent tubes from the knobs for adjusting the louvers are also perfect for closing the antenna, but the antenna must be made of a thin cable such as RG-174 or similar, eg RG316.
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#938 15891051 25 Aug 2016 15:38

wbober wbober

Level 11

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Post #938
15891051 25 Aug 2016 15:38

lysy1980 wrote:
The cable you need to use is at least H-155 - the RG58 that you are using now is not suitable for this purpose - it has cosmic attenuation - you have to change for a better one.
Anyway, with 15m of cable at this frequency, you will lose a lot even on the H-155.
The amplifiers also bring a lot of noise, the effect does not have to be positive ...

I exchanged for H-155 (they didn't have any better) and the difference is big (or even very big)
Conclusion: with ADSB, DO NOT WASTE TIME, MONEY AND NERVES ON RG58.
Regards and thanks for your help,
bober
#939 15891547 25 Aug 2016 19:47

Hajna Hajna

Level 24
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Post #939
15891547 25 Aug 2016 19:47

It is not for sdrsharper, but for sdrsharp it is a scanner. In the topic of 910 thanks for your help, I will say that sdrsharper would receive better than sdrsharp because in Zabrze I did not receive the GLC control box on sdrsharp at 150.375 MHz, and on sdrsharper I receive at 5, it is a pity that there is no scanner as a plugin in the program. And this is what the program looks like for me. Thanks don_viking.

Attachments:

Schowek01.jpg Download (320.63 KB)
#940 15893519 26 Aug 2016 18:02

sir_mendez sir_mendez

Level 10

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Post #940
15893519 26 Aug 2016 18:02

don_viking wrote:

sir_mendez wrote:
I recently came across the SDR slogan and I have these questions - there are several of them, but on one topic basically:
Does this RTL-SDR only receive the air signal? Inn. in words, is it suitable, for example, for the visual evaluation of the power of DVB-T TV channels in the antenna sockets in the rooms?
[I can see that the range is quite wide and it will probably also include: 470 - 790MHz (sheet 21 - 60), 790 - 862 MHZ (sheet 61 - 69), 174 - 230 MHz (sheet 6 - 12)]

What does SDR show at all when it is attached to a home satellite / DVB-T cable? Does it draw any graphs for the above channels? Power from the SAT socket will not burn something on USB in this mode?

Any info in this direction is welcome

Here you have a page where you can see the spectra of individual signals.

http://www.sigidwiki.com/wiki/Database

Not wanting to damage the tuner, connect such signals through the antenna separator.

Thanks ~ don_viking for the guidance ...

I used usb_820T2 + LinRAD (Linux64) and now dB preview of DVB-T channels like a fairy tale - fast. channel groups 34,41,48 actually in the shape of a brick lying of suitable height as shown at "sigidwiki.com/". :D

PS. Instead of the ant separator. you can also use SAT galvanic isolator (5-1000MHz) - it works for me and makes no difference.
#941 15918291 08 Sep 2016 01:09

roy883 roy883

Level 10

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Post #941
15918291 08 Sep 2016 01:09

Gentlemen ... One thing puzzles me ... What is the impedance issue on the line: self-made antenna -> cable -> tuner. 50 ohm or 75 ohm?
I made a dipole for the aviation band. I converted the 300/75 ohm impedance transformer by firing the core and used a typical 75 ohm cable and only picked up Okęcie with this noise (the block at the police station and their huge 3 masts that interfere with). There are plans to move the antenna outside the city.
Is it possible to use a balun for channels 1-12 or more precisely?
ANTENNA SYMMETRIZER 1-12 + VHF BADMOR without modifications and 75 ohm cable or this H155 with balun without core?
#942 15918400 08 Sep 2016 08:17

Artur k. Artur k.

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Post #942
15918400 08 Sep 2016 08:17

roy883 wrote:
One thing puzzles me ... What is the impedance issue on the line: self-made antenna -> cable -> tuner. 50 ohm or 75 ohm?

Purely theoretically, the standard 75R applies to TV antennas, and practically the Chinese could do as he liked, especially since the set includes an antenna. The Chinese tuner in a blue or black housing has an MCX connector. Typically, the MCX uses RG-174 and RG-178 cables, which are 50 ohm cables. However, what the Chinese did and whether he matched the tuner's input circuits to 50 ohms, nobody knows, and the Chinese himself probably does not know it either.

roy883 wrote:
I converted the 300/75 ohm impedance transformer by firing the core and used a typical 75 ohm cable and only picked up Okęcie with this noise (the block at the police station and their huge 3 masts that interfere with). There are plans to move the antenna outside the city.

If in Radom (this is what you say in the "city" field) you received a signal from Okecie, it must be admitted that this is a good result and I would rather not find the police command to be guilty in the fact that you have a noisy reception. The distance is considerable and the sensitivity of the TV tuner is unlikely to be overwhelming - this is the source of the problems, not the police station.

roy883 wrote:
Is it possible to use a balun for channels 1-12 or more precisely?
ANTENNA SYMMETRIZER 1-12 + VHF BADMOR without modifications and 75 ohm cable or this H155 with balun without core?

You can use it, but what will be the effect - you have to check. It will be difficult to predict mainly due to the unknown true wave impedance of the tuner input.
#943 15920211 08 Sep 2016 23:07

roy883 roy883

Level 10

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Post #943
15920211 08 Sep 2016 23:07

So:
-I used this impedance transformer for channels 1-12 to my antenna, I have access to various cables at work and I used approx. 4 meters of H155. I connected, set the air band, burying the sensitivity and gain in the SDR, I will say that it receives much better than the 75 ohm coax. Whether such an improvement lies with the cable or the balun itself, I do not know at the moment. A lot of noise during the first minutes, but I read that the tuner must warm up so that it "does not float in frequency". After about 20 minutes, much less noise.
Also the concept with a balun in a proprietary dipole improved the reception quality.
#944 15920463 09 Sep 2016 08:20

slu_1982 slu_1982

Level 26

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Post #944
15920463 09 Sep 2016 08:20

Artur k. wrote:
Maybe I won't write anything new, but just out of curiosity, I compared two DVB-T receivers - typically Chinese, available at auctions for about PLN 40 in a black housing with the words DVB-T + DAB + FM with R820T tuner and blue LED and NOT LV5T Deluxe with the FC0013 tuner, which I recently bought for PLN 60.

I used RLT-SDR Scanner for Windows, scanned the 87-108MHz radio band

Black Chinese Tuner:

LV5T:

The effect speaks for itself, which is also audible and felt when using, for example, HDSDR.
If someone (like me) complains about poor results, poor sensitivity, etc., I suggest changing the tuner, and if someone is just going to buy, I suggest avoiding black Chinese inventions with a blue LED, it is better to add PLN 20 and not to tear your hair out of your head.

Make a comparison with the same gain. I have a request for you. Wind the cable that you connect to the dongle 5-8 turns on e.g. a pen and check that the background noise does not drop. I reduced the noise by up to 20db, then experimentally added the core on which I wound it, the improvement is significant. It concerns inter alia interference received with the screen of coaxial cable. Could you compare both dongles on the same antenna on a segment of the band, e.g. 433Mhz and Airband? Maybe in the form of a screenshot from SDR #
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#945 15921487 09 Sep 2016 19:13

Artur k. Artur k.

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Post #945
15921487 09 Sep 2016 19:13

slu_1982 wrote:
Make a comparison with the same gain.

Here, the attenuation of 5.4dB is even better. Unfortunately, mi program automatically sets the level to -5.4dB for the LV5T tuner and I can't choose 0dB. For the Chinese, however, it is set to 0dB and I can't choose -5.4dB. Apparently this is due to the difference of the tuners themselves (R820T and FC0013)

slu_1982 wrote:
Could you compare both dongles on the same antenna on a segment of the band, e.g. 433Mhz and Airband?

Here you go, LV5T:

And the Chinese:

Here you can also see another drawback of the RLT Scanner - it automatically sets the scale of the Y axis, if I can turn it off, I don't know how to set the interval that interests me.

The antenna is the same in both cases - an ordinary car CB antenna set on the windowsill outside.
The included antennas are useless.
#946 15936126 17 Sep 2016 00:03

slu_1982 slu_1982

Level 26

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Post #946
15936126 17 Sep 2016 00:03

Good evening. On the same day when you presented your results I decided to buy notonly dvbt for comparison.
As the gain is differently set to not-only and differently in receivers called Chinese, I decided to set the best gain for both to compare what can actually be achieved. The antenna is the same for both receivers. I believe that the difference between them is not great with the correct configuration. In my opinion, a plus for blue dongles from RT820T2

Not only: and RT820T2:

And in the band where SATCOM satellites are present

Not only: and RT820T2:

I do not want to forcefully oppose the SQ5RM mark and having a radio license and common features of each mark holder according to the SP7PKI customs oblige to quarrels and insults :D

I believe that my assessment is not entirely objective, I will not give you the gain setting for the RT820T2, although it was very high, almost at the end. In my opinion, the most important parameter is SNR, i.e. the signal-to-noise ratio. I really couldn't get more out of the not-only because the noise increased more with the gain increase than the signal. I heard, somewhere I saw that you can add the appropriate drivers to the not-only ones that probably run one more amplifier, can someone write me about it?
In addition, I think that it is not only more sensitive to clipping, in the bandwidth with SATCOM you can see radio stations breaking through. In the RT820T2 input circuit, a choke up to + 12V is additionally added and several capacitors, including those separating the DC component, may detach a little. They certainly cut off some of the signal that reaches the tuner.

best regards
#947 15936219 17 Sep 2016 07:08

Artur k. Artur k.

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Post #947
15936219 17 Sep 2016 07:08

slu_1982 wrote:
Not only: and RT820T2:

What is this fringe showing NOT at 439.250MHz? In the case of the second tuner there is no such stripe, or at least not that high.
I have the impression that there is some automation in this NOT, which we do not fully influence.
Note that the noise floor is lower in the case of NOT - you have -55.5dB, and in Chinese it is -54.1dB. The bigger SNR came out because you pulled up the gain.
I borrowed one of the tuners to a friend, so I will not play for the moment. I think it can be checked quite easily - put the carrier on e.g. CB and see how both devices react.
If there is any automation, it will definitely try to reduce the gain.

slu_1982 wrote:
I do not want to forcefully oppose the SQ5RM mark and having a radio license and common features of each mark holder according to the SP7PKI customs oblige to quarrels and insults

It is evident that I am not fit to argue, because I have neither the sign nor the radio license. Once, I even wanted to own, but when I saw what it was blowing, I gave it up. Not to mention the fact that I might have failed the exam due to inaccuracies in the questions and answers.
#948 15936483 17 Sep 2016 11:12

don_viking don_viking

Level 21
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Post #948
15936483 17 Sep 2016 11:12

There is nothing to argue. Forum is to help yourself in solving problems. Each of the tuners has pros and cons. I am not an expert when it comes to testing the sensitivity, but I demonstrated the sensitivity of my tuners in pictures using the SDRSharper program. In the upper right corner you can see the s-meter and signal strength as well as the background color, which indicates the noise of the tuners' own. Regarding the gain setting, the relationship is such that in the R820T2 tuner the 7.7dB gain is comparable to the -5.8dB in the FC0013 tuner. Once upon a time, somewhere on some foreign forum, someone compared it.
R820T2 FC0013

As for the pros and cons, I will write it this way.

R820T2
After changing the drivers, the tuner works with a good antenna from about 2 MHz to 1500 MHz without any modifications and does not damage during surges at the antenna input. You do not need additional external amplifiers to receive the signal on 1090 MHz and INMARSAT satellites.

FC0013
The tuner works only from 24 MHz to 860 MHz above. If you want to receive any signal, you need to use an additional external amplifier at the antenna and turn on the Tuner AGC function in the settings. Then it is possible to receive the signal on 1090MHz, but not the INMARSAT satellites. The problem is also the possibility of damaging the tuner during a short circuit at the antenna input because the factory LV5TDLX tuners do not have a protective diode at the input and you need to solder it yourself. During the first attempts a few years ago, I damaged 3 tuners in this way. The choice of tuners is up to each of us depending on what they will be used for.
I also found an interesting file in the attachment, it is about the table on the second page.
Best regards and I wish you the right choice of tuners depending on your individual needs.

Attachments:

sdr.pdf Download (805.02 KB)
#949 15938014 17 Sep 2016 23:55

Artur k. Artur k.

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Post #949
15938014 17 Sep 2016 23:55

don_viking wrote:
The problem is also the possibility of damaging the tuner during a short circuit at the antenna input because the factory tuners LV5TDLX do not have a protective diode on the input and you need to solder it yourself.

In my life, I have not seen a device that can be damaged by a short circuit at the input. :)

I also heard opinions that the tuner with the FC0013 chip is worse than the R802T, but my experiments with the Chinese tuner brand DVB-T tuner model and the tuner as a reputable manufacturer indicate something else.
Maybe the R820T system itself is better, but it all depends on the entire structure and not only on the head system itself. This is the case in every area - you can use good quality elements and get the effect so-so, and someone else will use inferior elements and get a better effect.
It is clearly visible in audio devices, computers, cars, etc. I will not write about audio, because it is a wide topic and you have to feel it. It is easier to use an example from the field of computers - as you know, there are plenty of motherboard manufacturers and these boards have different performance, although their heart is the same chips.
Cars are also a great example, for example our Polonez with a Rover 1.4 16V engine reached 160 km / h and acceleration from 13.3 to a hundred. Meanwhile, the Rover with the same engine reached 182 km / h and accelerated to a hundred in 10.5 seconds.
So what if there was a Rover engine in the south? :)

PS Nobody's arguing here.
#950 15938076 18 Sep 2016 01:03

slu_1982 slu_1982

Level 26

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Post #950
15938076 18 Sep 2016 01:03

And I bought a dongle notonly in a currently known network that is slowly gnawing at mediamarts and others on k, where, after checking the inventory, I got it right away and now there is a protection diode at the entrance.
#951 15938175 18 Sep 2016 07:05

Artur k. Artur k.

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Post #951
15938175 18 Sep 2016 07:05

I think that LED was always there. Lack of a diode would be a cardinal design error.

I found an article from 2013:
http://majek.mamy.to/pl/rtlsdr-analyzer-from-dvb-t-tuner/
You can see that the duodiode is there.
It looks like the FC0012 version did not have LEDs:
http://web2.osb.hu/z/pic/FC0012.jpg
It is possible that the diodes are already built into the structure of the integrated circuit itself.
You would have to look for datasheets and compare.

At first glance, the arrangement of elements on the LV5T board is better from the point of view of interference than in the Chinese no name tuners.
#952 15938769 18 Sep 2016 13:35

don_viking don_viking

Level 21

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Post #952
15938769 18 Sep 2016 13:35

I had many of these tuners and none of them had this diode and I bought in various stores and described it in this post. https://www.elektroda.pl/rtvforum/topic2353101-510.html#14847822
I gave some of the burned tuners under warranty and the photos of those that remained to me are below. There is not even a trace of their assembly. Of course, these were tuners from 2013 to 2014, as you can see from the first digits of the serial number and stickers. Maybe the new versions have a diode, but the old ones mostly did not. The 2012 versions had the E4000 tuner and a different design.

Maybe other colleagues found tuners with a diode, but I have never had such a dongle.
Maybe there is also a question of defective tuners, which do not have a complete set of components and are sold, for example, in promotion or cheaper in large networks. Only I used to buy from various stores.
#953 15940310 19 Sep 2016 01:37

Artur k. Artur k.

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Post #953
15940310 19 Sep 2016 01:37

don_viking wrote:
Maybe there is also a question of defective tuners, which do not have a complete set of components and are sold, for example, in promotion or cheaper in large networks. Only I used to buy from various stores.

You obviously have missing copies. The photos clearly show that the diode (probably the BAV99 duodiode) has not been soldered, although there is a place for it on the PCB.
Most likely, the left batch appeared on the market, because I do not believe that the manufacturer would not consciously solder this element. Probably someone sensed an opportunity - brought in a container of production rejects and sold it on for a good price.
#954 15940746 19 Sep 2016 11:51

slu_1982 slu_1982

Level 26

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Post #954
15940746 19 Sep 2016 11:51

I am wondering what the tuner is actually installed on me ...

Turns out it's the same version 1.1 as don viking has. But I even have other markings on the tuner. Ps. A cool macro comes out of the phone after applying a 20x magnifier
#955 15941335 19 Sep 2016 17:27

Łukasz Gorzelski Łukasz Gorzelski

Level 15
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Post #955
15941335 19 Sep 2016 17:27

Hello. I started to "play" with the SDR technique for some time. Searching through different frequencies, I found a very interesting signal. Its sound reminds me of a visit to the hospital ward of OJOM. From what I can figure out, it may be a clock signal. However, when browsing the exact bandplans, the transmission of such signals does not fit in the frequency range I found. Maybe someone came across something like this?

The video is attached.

Attachments:

MOV 0387.mp4 Download (409.45 KB)
#956 15941482 19 Sep 2016 18:34

tygrysss tygrysss

Level 21

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Post #956
15941482 19 Sep 2016 18:34

Hello, as I have recently been interested in the subject of SDR, I have a few questions.
What is the best to buy now (I'm talking here at the tuner)? What antenna (I mean listening to aviation and local walkie-talkies) for this service, as long as the transmissions are not encrypted.
What program is best for a layman? I have followed the topic, but once that some coefficients (technical abbreviations) do not tell me anything, I do not know what to decide on.
Best regards.
#957 15941515 19 Sep 2016 18:50

Artur k. Artur k.

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Post #957
15941515 19 Sep 2016 18:50

I did not find anything the same, but with me, even on an ordinary analog scanner, I perceive similar things. These are either the interferences of two other frequencies on which the data is transmitted and they just make up such a sequence, or some local device. Sometimes such sounds can be sent over the air by a phone, tablet or laptop. Currently, the ether is very littered with digital signals and signals from home appliances.
#958 15942143 19 Sep 2016 22:19

Łukasz Gorzelski Łukasz Gorzelski

Level 15

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Post #958
15942143 19 Sep 2016 22:19

tygrysss wrote:
Hello, as I have recently been interested in the subject of SDR, I have a few questions.
What is the best to buy now (I'm talking here at the tuner)? What antenna (I mean listening to aviation and local walkie-talkies) for this service, as long as the transmissions are not encrypted.
What program is best for a layman? I have followed the topic, but once that some coefficients (technical abbreviations) do not tell me anything, I do not know what to decide on.
Best regards.

If we are talking about a tuner, the second version of the tuner with the RTL chip is enough.

rtl2832u-r820t2-sdr-ads (Type in google, search for you on the Allegro)

On this little device, you have half of Europe within reach. (With the right antenna, you can have the whole one.)

Personally, I use this tuner with my own made antennas. One per 1090 mHz aviation band. The second for service. I can pick up PSP, OSP, SM, P without any problems, even downloading from 80-100km distant units. The same applies to the aviation bands (I receive these from almost all of Poland and even from neighboring countries.)

The antennas I use are 1x kolinear 173cm, the other 148cm coiled (9x) for a lifeline.

I can easily receive signals from NOAA, METEOR and the aviation band on the collinear antenna. The second antenna copes with the services without any problems.

Local walkie-talkies transmit on PMR 446 (8 channels). To receive them, it is best to be close to them, as devices of this type have poor transmitting power. (In general, I live 8 km from the city and I receive different signals with a collinear antenna.)

Maybe my statement is not satisfactory, but I am still a layman in this field, I am learning and, as the saying goes, "I combine". So far, the effects are satisfactory.

ATTENTION ! You must have a permit for such practices.

Added after 2 [minutes]:

Artur k. wrote:
I did not find anything the same, but with me, even on an ordinary analog scanner, I perceive similar things. These are either the interferences of two other frequencies on which the data is transmitted and they just make up such a sequence, or some local device. Sometimes such sounds can be sent over the air by a phone, tablet or laptop. Currently, the ether is very littered with digital signals and signals from home appliances.

I will say this, I received the signal even when there was no power in my town. (SDR and Laptop on battery went.) Well, wi-fi, pc, electronics, household appliances are excluded.
#959 15942185 19 Sep 2016 22:27

Artur k. Artur k.

VIP Meritorious for electroda.pl

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Post #959
15942185 19 Sep 2016 22:27

Łukasz Gorzelski wrote:
ATTENTION ! You must have a permit for such practices.

For what internships?

Łukasz Gorzelski wrote:
I will say this, I received the signal even when there was no power in my town. (SDR and Laptop on battery went.) Well, wi-fi, pc, electronics, household appliances are excluded.

And did you rule out that the laptop and tuner itself could be the source of these signals? Besides, as I wrote - it can also be a smartphone or tablet.
#960 15945247 21 Sep 2016 13:17

tygrysss tygrysss

Level 21
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Post #960
15945247 21 Sep 2016 13:17

Łukasz Gorzelski wrote:

tygrysss wrote:
Hello, as I have recently been interested in the subject of SDR, I have a few questions.
What is the best to buy now (I'm talking here at the tuner)? What antenna (I mean listening to aviation and local walkie-talkies) for this service, as long as the transmissions are not encrypted.
What program is best for a layman? I have followed the topic, but once that some coefficients (technical abbreviations) do not tell me anything, I do not know what to decide on.
Best regards.

If we are talking about a tuner, the second version of the tuner with the RTL chip is enough.

rtl2832u-r820t2-sdr-ads (Type in google, search for you on the Allegro)

On this little device, you have half of Europe within reach. (With the right antenna, you can have the whole one.)

Personally, I use this tuner with my own made antennas. One per 1090 mHz aviation band. The second for service. I can pick up PSP, OSP, SM, P without any problems, even downloading from 80-100km distant units. The same applies to the aviation bands (I receive these from almost all of Poland and even from neighboring countries.)

The antennas I use are 1x kolinear 173cm, the other 148cm coiled (9x) for a lifeline.

I can easily receive signals from NOAA, METEOR and the aviation band on the collinear antenna. The second antenna copes with the services without any problems.

Local walkie-talkies transmit on PMR 446 (8 channels). To receive them, it is best to be close to them, as devices of this type have poor transmitting power. (In general, I live 8 km from the city and I receive different signals with a collinear antenna.)

Maybe my statement is not satisfactory, but I am still a layman in this field, I am learning and, as the saying goes, "I combine". So far, the effects are satisfactory.

ATTENTION ! You must have a permit for such practices.

Added after 2 [minutes]:

Artur k. wrote:
I did not find anything the same, but with me, even on an ordinary analog scanner, I perceive similar things. These are either the interferences of two other frequencies on which the data is transmitted and they just make up such a sequence, or some local device. Sometimes such sounds can be sent over the air by a phone, tablet or laptop. Currently, the ether is very littered with digital signals and signals from home appliances.

I will say this, I received the signal even when there was no power in my town. (SDR and Laptop on battery went.) Well, wi-fi, pc, electronics, household appliances are excluded.

Thanks for the answer. How is the R820T different from the R820T2? The price difference is about PLN 20. Is it worth paying extra?
I would like to pick up what is in Częstochowa (map) http://nadajniki.olo.ovh/

For example, will I receive something like that?

Code: text Expand Select all Copy to clipboard
Promień obszaru obsługi: 20 km Częstotliwości nadawcze: 152.97500 Częstotliwości odbiorcze: 152.97500 Szerokości kanałów nadawczych: 12.50 Szerokości kanałów odbiorczych: 12.50 Rodzaj stacji: FB Rodzaj sieci: A ERP: 10 Azymut: Elewacja: Polaryzacja: V Zysk anteny: 4.5 Wysokość umieszczenia anteny: 25 Wysokość terenu: 255 Charakterystyka promieniowania - poziom: 000ND00 Charakterystyka promieniowania - pion: 000ND00 Długość geograficzna: 19.129166666666666 Szerokość geograficzna: 50.824444444444445

I will be thinking quite high - 9th floor. What antenna do you recommend for this (self-made), unfortunately I can't put anything out of the window, no balcony and no facade.

best regards
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Topic summary

The discussion centers on using inexpensive DVB-T USB tuners, particularly those based on the RTL2832U chipset combined with various tuner modules like the R820T and E4000, as software-defined radio (SDR) receivers. These devices, originally intended for digital TV reception, can be repurposed for wideband SDR reception from approximately 25 MHz up to 1.7 GHz, covering amateur radio bands, FM broadcast, airband, ADS-B, and more. Modifications such as direct antenna connection to the RTL2832U chip pins enable reception of lower frequency bands (below 30 MHz), including shortwave, though precautions against electrostatic discharge and signal surges are necessary. Upconverter circuits based on chips like LA1186, LA1185, and TA7358AP are commonly used to extend reception down to HF and VLF bands by frequency shifting signals into the tuner's range. Various software solutions including SDR# (SDR Sharp), HDSDR, and dump1090 are recommended for Windows and Linux platforms, with driver installation often requiring tools like Zadig to replace default DVB-T drivers with RTL-SDR compatible ones. Users report challenges with driver installation, device recognition, and antenna selection, especially for frequencies outside the FM broadcast band. Amplifiers such as the FP6L and antennas like Discone or long wire are suggested to improve reception quality. Mobile and embedded platforms like Raspberry Pi and Android devices with USB OTG support are explored for portable SDR setups. The community shares detailed schematics, installation guides, and troubleshooting tips, emphasizing the cost-effectiveness and versatility of RTL-SDR dongles for radio experimentation and monitoring.
Summary generated by the language model.

FAQ

TL;DR: A US$13 RTL-SDR dongle with an R820T tuner covers 24-1762 MHz “Band 24-1762 MHz (no holes)” [Elektroda, zabex, post #12073526] and can be pushed to ≈100 kHz with a 50 MHz up-converter [Elektroda, sb8gapi, post #13074101]

Why it matters: One stick lets hobbyists scan HF, VHF, UHF and ADS-B without big radios.

Quick Facts

• R820T native span: 24–1762 MHz [Elektroda, zabex, post #12073526]
• Direct-Sampling mod: ≈0.1–28 MHz [Elektroda, methyl, post #13657048]
• Typical dongle cost: US$13–15 incl. whip [Elektroda, Ganjor86, post #12076142]
• PC spec: USB 2.0 + ≥1.2 GHz CPU [Elektroda, Serwis1, post #13206155]
• TA7358 up-converter parts ≈ PLN 15 [Elektroda, sb8gapi, post #13074101]

What frequencies can an un-modified RTL-SDR with R820T cover?

About 24 MHz to 1.76 GHz without gaps [Elektroda, zabex, post #12073526] That spans airband, AIS, ACARS, ADS-B, VHF FM, UHF trunked, LTE and more.

How do I install drivers on Windows XP?

Plug dongle, let Windows load Realtek driver.
Run Zadig v2.1 XP, Menu → Options → List All Devices, choose "Bulk-In Interface 0".
Click Install WINUSB driver. After 5 s SDR# sees “RTL-SDR/USB”. [Elektroda, lysy1980, post #13511327]

Why does SDR# show a spike at centre frequency?

That DC spike is the tuner’s zero-IF leakage. Enable “Correct IQ” to notch it [Elektroda, zabex, post #13333858]

I get no DVB-T after installing SDR drivers—normal?

Yes. WINUSB replaces Realtek’s TV driver. Switch USB port or reinstall OEM driver when you need DVB-T reception [Elektroda, lysy1980, post #13511327]

What’s the simplest way to receive 0–30 MHz?

Add a 50 MHz HF up-converter using TA7358 or LA1185. It mixes HF to 50–80 MHz, cost under PLN 15 and sensitivity beats direct sampling [Elektroda, sb8gapi, #13074101; Elektroda, zabex, #12073526].

Can overheating freeze the dongle?

Yes. R820T can reach >60 °C and USB disconnects appear. Resoldering the USB plug and adding small heatsinks stopped lock-ups [Elektroda, mkpl, post #13635115]

Which antenna works best for wideband scans?

An outdoor TV log-periodic or discone on 50 Ω feed covers 50–1300 MHz. For HF add Mini-Whip or 20 m long-wire plus the up-converter [Elektroda, methyl, post #13657048]

Edge case: why does FM broadcast appear at 30 MHz?

Strong local FM images alias into 26–40 MHz when the front-end overloads. Use 88–108 MHz notch or reduce RF gain [Elektroda, mkpl, post #13583266]

Can I scan automatically like a hardware scanner?

Yes. Install the ‘Frequency Manager Scanner’ plug-in for SDR#; it hops user lists at 20 channels /s and logs activity [SDRSharpPlugins].

Is spectrum-analysis possible?

RTL-SDR plus ‘RTL-Power’ or ‘Spektrum’ sweeps 24 MHz–1.7 GHz, 2 MHz steps, ~30 dB dynamic range—handy for EMC checks [majek, 2013].

Statistic: how much HF noise reduction after shielding?

Wrapping the PCB in copper foil cut spur floor by 6 dB [Elektroda, mkpl, post #13636615]

How do I add HF direct sampling without removing the tuner?

On R820T boards, wire a 1:10 transformer to RTL pins 4-5, select “Direct Sampling Q” in SDR#. This keeps VHF/UHF intact [Elektroda, BOOM i ZONK, #13914702].