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

Nom, at the moment I have SDR on an Apollo tablet and it works without any problems that the processor does not work in it As for the modem, I use the ZTE MF637 and it works with my method without any problems other, for example, huawei also played and there is gitt.

What processor do you have there?
Most often I meet around 2x 1GHz and I wonder if it is enough.

Thunder6995 wrote:

What processor do you have there?
Most often I meet around 2x 1GHz and I wonder if it is enough.

I have a single-core 1GHz and it does not give much advice: / I mean when you turn on the "Spectrum" option in SDR Touch, it starts to cut the sound

The same for me on the ARM Cortex-A7 Dual Core 1.2 GHz. In addition, he can often break communication with the donkey. Initially, I thought it was a matter of RTL power supply, but unfortunately the same symptom on the external power supply.

zabex wrote:

The same for me on the ARM Cortex-A7 Dual Core 1.2 GHz. In addition, he can often break communication with the donkey. Initially, I thought it was a matter of RTL power supply, but unfortunately the same symptom on the external power supply.

As a curiosity, I will add that my tablet is on RK2826 and after changing the power supply of the dongle, the reception improved. And tell me if other devices connected to the tablet, e.g. flash drive, also break communication?

Only donglas do such numbers. I even bought a USB HUB with external power for testing and it changed nothing. The mouse, flash drive works great.
I don't know what's going on but on a phone with ARM A9 Dual Core 1.2GHZ it works great.

PS
"device is not responding, please replug the device"
Sometimes, right after turning on SDR Touch, and other times it can "even" work for a few minutes.
I also bought a mini dongle, hoping that something will change ... Let's not go into it Desperation knows no bounds

As for stuttering, maybe you have some background applications running that eat up CPU and RAM resources (since it cuts at 2x 1.2GHz ...)
Yes, I think that if OTG with flash drives works flawlessly, and the power issue has been eliminated, maybe the drivers are free / incompatible

I will quote my statement: I do not know what it is about but on a phone with ARM A9 Dual Core 1.2GHZ it works great.
I don't know about processors but isn't the architecture here (ARM7 ARM9)?
4.2.2 jelly bean systems.

PS Kol.Thunder6995 I eliminated the background of the application in the first place

I referred to the statement by Jezzman, who wrote that he has 1GHz and it is too little, because he is starting to break at the spectrum, but you (buddy zabex ) you replied the same on ARM Cortex-A7 Dual Core 1.2 GHz.
So either, as you correctly observed, the architecture has an impact on it, or the device that cuts you (and has 2x 1.2GHz) is still loaded with some processes, so SDR does not have at its disposal the computing power that it hypothetically has on the phone (which can not so burdened with other programs in the background).
Oh, those guesses ...

Thunder6995 wrote:

Oh, those guesses ...

Exactly.. The charms of a dongle

What am I wrongly positioned? SDRSharp goes up to 93Mhz, nice "bar" next to it there is noise I aim exactly and there is silence as if it was just a carrier without modulation.

Take a screenshot
Maybe you have the wrong modulation set or the squelch is twisted too much.

blur wrote:

What am I wrongly positioned? SDRSharp goes up to 93Mhz, nice "bar" next to it there is noise I aim exactly and there is silence as if it was just a carrier without modulation.

1kHz bandwidth on WFM is not enough, and fft and waterfall do not look promising.

Hello, I figured out how to receive AM stations, I soldered a piece of wire to the 1 pin of the RTL2832 processor and now I have a problem with setting the frequency because I mix FM and AM stations and you can not set higher frequencies and how to protect the tuner against burning because I also read that it can burn from the long antenna

darek89a wrote:

how to protect the tuner against burning because I also read that it can burn from a long antenna

It was about it. You can put two 1N ... diodes in anti-parallel, parallel to the input. But as there will be a lightning strike in the area, the induction current will damage the input. Do not connect the antenna during an impending storm or lightning.

Hello, maybe it's from a different barrel. The question is, has anyone tried to decode ed with SDR + Unitrunker ??
If so, I would need a little help.
So what do I have:
Installed everything you need to decode edk, i.e. SDR + Unitrunker, additionally Virtula cabel and all the rest.
I have the Control Chanel and Voice Chanel frequencies stored.
The problem is that you have to enter everything manually into Unitrunker.
Another thing is that I have no control over Voice Chanel, it is about "jumping" between
I have frequencies with voice modulation and only have bits of information.

If anyone did, I would ask for help in setting up the Unitrunker so that everything goes right

Regards, Krzych

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?

In the attachment, the SDR SHARP package is enough to replace the files and run the program.

Hello.
Screenshots of the work of a "bare" tuner on the R820T2 system with modified rudders. The antenna placed in the room is made of a coil that demagnetizes the cathode ray tube.
40, 41 and 80 meters in the drops.

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Well, but you check the R820T2 and these drivers were created for its prototype and they also work.

AVE! I read the whole topic and read about securing the input with a diode, but not how to do it, can someone explain to me? I would like to know how you can crack a small RF amplifier. Additionally.

Thank you greetings!

lysy1980 wrote:

Well, but you check the R820T2 and these drivers were created for its prototype and they also work.

This is exactly what users describe, I personally checked on the R820T2.

KamiJas wrote:

I read the whole topic and read about securing the input with a diode, but not how to do it, can someone explain to me?

Check if your system does not already have one.
My tuners are equipped with diodes:

I thought that the SMD transistor is not a diode. And there is some way to reduce the noise from the mesh antenna because the dvbt will not pick me up on it, but in gqrx it shows me a fairly strong signal on all dvbt frequencies from Tarnów. Radio stations can be listened to without any problems, I heard even conversations around ~ 430MHz

KamiJas wrote:

I thought that the SMD transistor is not a diode.

exactly two;
BAV99

Hello
I have a question whether a 60 MHz quartz generator can be used for this converter described here, because I have one
Regards Paweł

You can use any quartz generator or oscillator with a frequency that, when summed (or sometimes subtracted) in the mixer with the receiving frequency, will result in a frequency that will fall within the range received by the dvb-t dongle.
Any quartz generator from say 30-150Mhz can be used.

I would advise you to replace the input low-pass filter with a bandpass filter which is not a big problem to make, e.g. using standard cores.

Pay attention to the level of the signal coming from the generator to the mixer.
As far as I remember for NE602 (612) the signal should be in the range of 200-300mV.
A lot more goes from the quartz generator, which can cause a "garbage" on receipt but there is no tragedy because I checked.

If we use an output high-pass filter, it must be designed for the appropriate frequency depending on the quartz generator used.

tuner22 wrote:

Hello
I have a question whether a 60 MHz quartz generator can be used for this converter described here, because I have one
Regards Paweł

You can go ahead and apply one. The bandwidth of the output highpass filter should start at 60MHz.

welcome back
Thank you methyl and kriss51 I am starting to build this converter for the answer, but one thing bothers me is the coil. The description gives the parameters, i.e. diameter 2.5mm, and then for various coils, the number of coils and the size, but I do not know if I understand correctly, e.g.
L2: 15t 4mm, L3, L5: 9t 4mm, L4: 7t 4mm etc. and here I have a dilemma whether it is diameter or length. I attach a diagram and description on the 2nd page. Please help or explain how to wind these coils.
As for the settings in sdrsharp, you need to set shift to -60.000 with such a generator used in the converter
Instead of TA7358 I have AN7205
Regards Paweł

All coils are wound on a cotton swab-tube and are 2.5 mm in diameter. The other dimensions are the winding length.
In my opinion, a bad idea because it is very inaccurate and the "goodness" of these coils is also bad. But it sure works because it's not narrowband filters.

My advice, get 2 ferrite cores from antenna baluns or buy 1 PLN for example ft37-43 plus 4 some germanium diodes, but there can also be ordinary 1n4148 and some winding wire.

Out of boredom, I have just assembled a converter for HF.
Below is a photo of what it looks like and a screen shot of the 40m band listened to on this DVB-T converter and dongles. It is much nicer than the NE602 and the TA7358 not to mention. I know because I have a converter for NE612 (602) and I used to do it on TA7358.

tuner22 wrote:

but one thing bothers me, namely the coils.

The output filter inductances given to the diagram in the appendix are for a 50MHz generator, so to make everything correct, you should calculate the high-pass filter that will work from 60MHz up.

tuner22 wrote:

As for the settings in sdrsharp, you need to set shift to -60.000 with such a generator used in the converter

You have to set it up.

tuner22 wrote:

Instead of TA7358 I have AN7205

You can give AN7205

methyl wrote:

My advice, get 2 ferrite cores from antenna baluns or buy 1 PLN for example ft37-43 plus 4 some germanium diodes, but there can also be ordinary 1n4148 and some winding wire.

Ok, I have diodes, too, because I was buying today, but it is about the connections of these windings, I understand that the middle of the "secondary winding", the end and the beginning of the winding from the generator side to ground, and from the antenna side to the dongle, and the question of the quartz generator, I see in the photo that you have connected output via potentiometer and capacitor. What values are supposed to be. And with what wire to wind it is about wire diameters
Thanks

For such a mixer, all LEDs must be matched to their characteristics. They must all be the same. I would like to add that such a mixer has 5-7dB attenuation.

methyl wrote:

It is much nicer than the NE602

Did you connect the NE602 symmetrically and accurately matched its input (3K) to 50? using transformers so you say?