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

Hello
I have this question (and problem).
RTL2832u + R820T2 tuner,
Service:
Tablet [Android 4.2.2, SDR Touch]
Notebook [Windows 7, Zadig drivers, SDR # + libraries / SDR Console V2 + libraries]

In the three above-mentioned configurations on frequencies, e.g. CB, ie 27MHz, around 40-60MHz, I can hear radio stations operating in the 88-108MHz band. If I set a CB (any) channel, then when transmitting with a radio on this channel, you can clearly see the carrier, but instead of the voice you hear crackles (instead of words) (it's like trying to listen to FM with AM modulation).
The radio broadcasts in AM, in SDR programs, whether it is AM, NFM or WFM, it receives the radio in the same way. I have no problems with reception around 144MHZ, but again at 446MHz it seems to me that the received sound is very quiet (this is not the fault of the radio).
What could be the problem?
best regards

Buddy kriss51, I can feel a slight hint of irony.

It is possible that you have more knowledge and practice than I do, I will be happy to listen to your suggestions. With the rest, probably thanks to your posts, I paid attention to the matching of the Ne612 impedance to the rest of the circuit, which I did not pay so much attention to before.
I am in the habit of speaking on the forum when I want to ask about something myself or I want to help someone and I know that I am not wrong myself and I know what I am writing about.
I have had the topic of frequency conversion, converters in my "workshop" for some time and I made some observations and I want to share it.

I used NE612 in an unbalanced converter with transistor stage matching, but also what I am currently using in a symmetrical input system with 50/3000 transformer matching made on the ft37-43 core. I also played with the TA7358 chip and factory diode mixers (SRA, SBL, TUF). Currently, for listening to the KF I have a ADE-1 converter with a preamplifier plus switchable bandpass filters and it is connected to the LW 41m with matching by Un-Un which it also serves me to work in the ether.

What am I going to. By examining and comparing the listening experience of the converter with the active SA612 mixer and the passive diode mixer, browsing the signal spectrum and switching between different converters in different settings, I find what has already been stated a long time ago. Due to various parameters, including the mixing ratio IP3, even though the NE612 (Sa612) gives a higher signal level at the output because it does not bring any attenuation during the conversion but amplifies it, the signal-to-noise ratio and the amount of intermodulation waste are higher. Personally, I prefer to use a low noise amplifier and ADE-1 than the Ne612.
The differences are not dramatic but visible to the naked eye.

Buddy tuner22 As for winding transformers, the thickness of the wire is not critical. I personally wound 0.32 windings, you connect as shown in the picture. the end of one with the beginning of the other. If there will be problems, write to priv.
Personally, I used GD507 germanium diodes which I chose from 50 pieces, measuring each one separately and grouping. Then I read in the literature that in the mixer such pairing is not needed and it is enough that the LEDs will be of the same type. Pairing is used in modulators, that's where it is important.
Good diodes for mixers are 1n5711, but also ordinary 1n4148 or small-signal shots are also good.

Diode, circular mixer has one advantage. It can be assembled from the spout and works fine.

Buddy tuner22, you asked about the values of the elements at the quartz generator.
This is a guerrilla system assembled quickly. I think the potentiometer is 1k, which would, when measuring with an oscilloscope, break the signal from the oscillator going to the mixer.
If it is too big, various lines and additional mixing products appear in the spectrum. You can see it right away. A capacitor can be given e.g. 1nF.

Okay, that's it, because you give up on these arguments.
best regards :)

Added
Thunder6995, maybe someone more kumaty, for example Kriss51, will say, but from my own experience I know that these R820T and similar receivers are as thin as a ... snake.
They are terribly resistant to clipping with strong signals. Soul and silence in this sauce, producing various special effects while listening.
I would need to know what antenna you have and whether you are overdoing the gain sliders in the dongle settings. You may have a totally distorted receiver in there. If you have any strong broadcast stations nearby, it is even more likely. You can use a filter that cuts a fragment, e.g. 88-108MHz, but first check the gain if it is not too high.

Thank you very much for your answer.
I will pamper the amplifiers and the antenna (I'm just starting my adventure with SDR, so a lot of mistakes are waiting for me to commit )
I warmly greet you!

Hello
I made this converter for TA 7358AP, but because I did not have this system, I used AN 7205 and a 60MHz quartz generator, my surprise was that the receiver works great, especially WEFAX and RTTY, which I cared about the most, the rest was also good. Shift in SDR set to - 60 MHz and here the reception escapes a bit, I had to set - 59.997 MHz. What does it depend on ... I don't get it, but the most important thing is that it works. Thanks to everyone for your help.
What antenna amplifier can be used for the aviation band? because I have a little weak signal.
Do you also feel so hot this RTL2832U + R820T dongle? mine is warm after half an hour, is there any way to cool it down?
Regards Paweł

Why shouldn't it work? ? It works and is even quite sensitive because it gives amplification instead of loss on the transformation. The disadvantages are when compared with other receivers, mixers. The shift in frequency is the domain of the quartz oscillator in the dongles and / or the generator used in the mixer. Corrections should be made in the program settings. Mixer generator - shift, and if it's a dongiel, then you have it in the settings under the gain control, counted in "ppm". It is normal for the dongle to heat up. You can cool it or oil it. Many methods. Forget airband amplifiers. Mount the antenna that matches the band high. If the amplifier is only with a good antenna which is high and with an added filter for the air band. Otherwise, it will strengthen the nearby BTS or the RMF transmitter or zettes and completely plug the receiver which in the RTL donglu is very easy to override.
The best amplifier is a suitable antenna that is as high as possible. If it is low, it will not amplify the signal but noise. To strengthen you need to have something The most important thing is the ratio of the signal we want to receive to the noise and here we will only worsen the amplifier with a poor antenna, I guarantee.
Sorry for any typos. I go by bus and write from the phone

Hello, could someone describe and introduce the way of connecting the FP6L amplifier to the tuner so that everything works as it should. I am asking this question because I have no "green" idea about it, so please explain it in the simplest possible way. Can I use a ready plug with a power supply from a mesh antenna and how to connect it all into one working whole, i.e. what to attach a plug with power supply to a dongle or to an amplifier.

Buddy, I do not know this amplifier but I suspect that it is powered from the signal output side. I greased the scheme which will be 95% ok.
You need to separate the RF signal. going to the DVB-t tuner from the supply voltage and that's what the capacitor is for. There are ready-made power supplies with a separator for TV antennas with a boost. They would probably be good too.
As I wrote before, the basis is a correct antenna for a given frequency range. A bit of a boost to this amplifier. If you have a "silent radio" area and you want to strengthen something from the satellite or Airband, only the tuner gain slider in SDR # or other program that you use at a minimum can do.
There can be a massacre in a big city :D

I will ask here, directed by an admin from another department. Maybe someone has a solution to my problem. It's about SDRsharp installed on W7Home Premium. I installed the drivers, reinstalled the framework. The program does not start, I get information like this:
Description: Stopped working
Problem signature:
Problem event name: CLR20r3
Problem Signature 01: sdrsharp.exe
Problem signature: 02: 1.0.0.1337
Problem Signature 03: 55170078
Problem Signature 04: mscorlib
Problem signature 05: 2.0.0.0
Problem Signature 06: 5265d021
Problem Signature 07: a8c Problem Signature 08: 0
Problem Signature 09: System.IO.FileNotFoundException
OS version: 6.1.7601.2.1.0.768.3
Locale ID: 1045

Can you advise something?
Lech

Do you have NET Framework version 3.5 installed?

Stari PL wrote:

Do you have NET Framework version 3.5 installed?

I have 4.0.30319. On another W7 Starter laptop, I have version 4.5.50938 and it works.

Lechu77 wrote:

Stari PL wrote:

Czy masz zainstalowany NET Framework w wersji 3.5 ?

Mam 4.0

może nie wystarczyć:

Quote:

Failing to install the .NET Framework may result in an "Application failed to initialize properly (0xc0000135). Click OK to terminate." message when trying to run SDRSharp.exe. Another from Brian Gregory notes: "Go to Control panel, search for turn Windows Features on or off and enable Microsoft .NET Framework 3.5.1 (you do not need to enable the two sub features)". Although a report from Dick in The Netherlands says that on Win-7/64 with .NET 4.5, no installation of .NET 3.5 was required, it's possible that he had other software which had already enabled .NET 3.5. After enabling .NET, I would recommend running Windows Update, as the .NET stuff is frequently updated.

http://sdrsharp.pbworks.com/w/page/64706284/Installation

Stari PL wrote:

Lechu77 wrote:

Stari PL wrote:

Czy masz zainstalowany NET Framework w wersji 3.5 ?

Mam 4.0

może nie wystarczyć:

Quote:

Failing to install the .NET Framework may result in an "Application failed to initialize properly (0xc0000135). Click OK to terminate." message when trying to run SDRSharp.exe. Another from Brian Gregory notes: "Go to Control panel, search for turn Windows Features on or off and enable Microsoft .NET Framework 3.5.1 (you do not need to enable the two sub features)". Although a report from Dick in The Netherlands says that on Win-7/64 with .NET 4.5, no installation of .NET 3.5 was required, it's possible that he had other software which had already enabled .NET 3.5. After enabling .NET, I would recommend running Windows Update, as the .NET stuff is frequently updated.

http://sdrsharp.pbworks.com/w/page/64706284/Installation

Pomogło! Włączyłem obie funkcje dla Framework 3.5.1 i zrobiłem aktualizacje.

Dzięki za pomoc.

lysy1980 wrote:

There will be a post under the post, but I do not know if anyone mentioned modified drivers for receiving frequencies from 13MHz on tuners with the R820T chip?

For me, it goes even lower on this system. I can easily pick up stations in the 5Mhz range.

I'll try to make a better antenna and see if it goes lower. I would like to add that I catch the harmonics of the network so low on the slow bands (very weak, but still).

On the R820T, I was receiving 3.95MHz using the PA0RDT MiniWhip out of the window. On the R820T2 the signal was getting weaker below 14MHz but the 40m KF band could still be received (strongest stations). The best solution is to use a converter to receive KF, even the simplest one on a diode mixer made by yourself.

This SDR, however, has its drawbacks ...

Atena is a 10m wire hanging from the window.
The SDR saw some signals but they were too weak.

I started to add 2 LA1185 chip and a simple radio was created

Hello, I have a question, has anyone dealt with tuners like on this page?

http://janielectronics.com/index.php?route=product/category&path=18

According to the description, they work from 100KHz to 1500MHz. As you can see in the photos, their design is different to that of a traditional tuner. Maybe in China they also pat such tuners massively and you could get a little cheaper than for $ 130.

RTL2832U and R820T with built-in UpConverter
http://janielectronics.com/index.php?route=product/product&path=18&product_id=103
RTL2832U and R820T2 with built-in UpConverter
http://janielectronics.com/index.php?route=product/product&path=18&product_id=109

Changing the operating range (turning on / off UpConverterea micro-switch, therefore Attiny13 is on board)

You can see an additional double IC switch at the antenna socket and a generator with a mixer at the voltage regulator (the entire UpConverter is at the bottom of the PCB). On the back there is probably a preamplifier and diodes protecting by ESD.

I wrote to Realtek regarding the catalog notes of the RTL2832U chip, I took it up for a university project. Unfortunately, I didn't get any reply Anyone have any ideas? I wrote to several different addresses for them.

What do you need a catalog card for? There is a quartz generator, 4 8 bit converters and some power blocking elements.

The diagram can be downloaded perfidiously from the tuner and the possibilities can be taken from the drivers (and viewed in the SDR # code).

The tuner itself has its undeniable disadvantages, such as:
- low resolution (only 8 bit)
- limited dynamics to 60dB
- poor shielding

It also has advantages
- High frequencies (120MHz and 1.7GHz) can be received
- Super contactless frequency meter with perfect calibration (e.g. beacons)
- Bandwidth and custom modulation preview

That's it. It lacks the ability to output the generator signal from the R820T, some sensible shielding and the ability to work in both directions.


The whole thing can be quite neatly walked around!
We make the head for the R820T + immediately the second head, which tunes in the range of 0 - 30MHz (you can classically use an upconver). R820T outputs directly to the sound card and we get:

-Tuner which, with the integrated sound quart, already reaches 120dB (and with better 24bit, it's magic)
- Same possibilities as with donglu
- When you get a piece of the layout, you can overdo it
- Works normally with SDR #

And I would like to add that I sometimes use receivers for repair, often in cooperation with an upcoverter. You can easily and quickly locate the damage in a given block, all you need is a probe instead of an antenna.

All in all, I was hoping for a little more information with the catalog note. The system works well as a frequency meter, even when connected to a quartz (without connection to the power supply, it shows its vibrations on the graph). Unfortunately, the R820T system is very hot for me, so it is impossible to hold my finger (it's hard for me to judge how many degrees - I would have to measure it with a thermometer). I know it's normal, but it worries me a bit.

And also such a stupid question - I am looking at the chip note and I cannot understand its purpose in the tuner chip too much. As far as I understand how the SDR technology works and I know that this RTL2832 chip is an A / C converter, what is this R820T for? Strengthens the signal? Is he some kind of converter or what is it? I know that after releasing this system, you can easily listen to long waves. But what about the higher frequencies? Sorry for the stupid question that might be, but I don't get it.

R820T / fc0013 / e4k / ... - The easiest way; front-end, i.e. head, just like in a regular radio

So is there an amplifier and a down-converter there? My guess is that there is no tuning there because it would be different from SDR technology. Just some high-pass filter so that 50Hz is not full Do I get it right?

Everything is in datashit from these systems ... Not strictly SDR is RTL + softwere.

Good good. Well, from SDR there is mainly software that selects specific frequencies and demodulates them / with some type of modulation /. The RTL and SDR program works there the same as a sound card connected with a piece of wire and an SDR program. The card samples the signal and the program converts and demodulates it accordingly. Okay, but I still don't know what this tuner chip is for. The content of the note appeals to me on average.
best regards

Do you know how a classic radio works? I will explain to you peasant reason.

R820T (or other tuner system - in a classic radio HF head with a preamplifier, heterodyne, etc.) receives a given frequency, let's assume 1000Mhz and convert it to an intermediate frequency, let's assume 10.7MHz (no matter how, where, why and what for) . RTL2832U - let's assume the P.CZ. which receives the 10.7MHz, converts it into a digital form and sends it to the computer (from then on the computer becomes SDR) which it does for demodulators (AM, FM, SSB, and whoever came up with it) and for the loudspeaker as in a classic receiver. However, by entering the frequency, the computer only tunes the Front End via RTL (i.e. like in a classic receiver, it makes the tuning knob, the RFGAIN knob, etc.)

Of course, please correct me.

Thanks a lot lysy1980! So, as I suspected, this tuner circuit is a converter with an amplifier. So if I throw this system out of the tuner, I will get a radio for long, medium and short waves (but at the expense of high frequencies). However, if I do the other way, that is, connect this circuit to the sound card (as one of my colleagues suggested earlier), it won't do me a lot.
The operating frequency of the system (input) is 42 - 1002MHz (the R820T system, other versions have a wider range), but it will still convert this frequency to 10Mhz (which is beyond the card's operating range). I understand well?

Added after 8 [minutes]:

This is 10Mhz, of course, for example.

Yes and no, it depends on how you program the frequency of the R820T's internal PLL generator. If the conversion frequency is higher, then the band (frequency) that interests you will be placed lower, e.g. in the linear range of the ADC converter of the sound card. These circuits are more than just "converters", they are complete transformation paths, additionally digitally controlled.

So using the I2C bus and changing the frequency of the resonator in the circuit, I can change the frequency of the transformation - and also the operating range of the converter (or rather the output frequency). Cool thing :)

This is my last question. By changing the values of the quartz resonator, can I shift the operating range of this system up (for example, to listen to 2.4GHz) and down (so as to listen to hams) or is it rather not possible and will only lower the output frequency?

Thanks for answering my questions. best regards

In fact, with this IF at 10MHz, I did not notice it, but actually it is even better. For the R820T you have to throw SA612 with 10mhz quartz, duplicate the quartz frequency and amplify it on 2 transistors and give it to the R820T.
Behind the SA612 low-pass audio filter (cutting around 25kHz) and an audio amplifier if needed.

The system will work exactly the same as a ready tuner, with the difference that it will be difficult to overdrive (in the original FM hatch everywhere), low amplitude signals will be much more readable (currently 8 bit and in 16 or 24 tab), and better resistance to SLR and other crap.
This should be checked at KF.

Anyone mentioned something earlier that the R820T can be chased from 3MHz? This is confirmed? anyone have any description?

My tuner turns off below 25MHz