signal generator

Thread Starter

otpisani

Joined Feb 6, 2022
4
I want to made signal generator with whom I can play with RTL-SDR cards, testing digital modulation,. I have couple of questions regarding that I'm not skilled with soldering, but know basic of programming with GNU radio or arduino. What would be easisest but also efficient approach to manage that task, build something based on signal generator, connected and controlled over arduino, or with rtl-sdr cards like hackrf, hermes, pluto, lime.

1. Approach I don't know much about clock generators like Si5351a or AD9959, which is better, maybe something else that I connect to arduino, please something with already build libraries on github, etc.

2. Second approach, I have hackrf, but think that tx specs are pretty pure, not sure to invest in external tx amplifier or to buy better rtl-sdr card, speciffically for HF band, like Hermes lite plus, but again I don't even know if it's compatible with GNU radio, can't find block module on GNU radio, although on hermes site specs, they claim that it's full compatible with GNU radio.

Main goal is to made device for generating signals like FSK, PSK, but also that I play with replay attacks, just for testing purpose.
 

Ya’akov

Joined Jan 27, 2019
5,659
Welcome to AAC.

If you have a HackRF One, it can output 5-15dBm from 1 to ~2.7GHz and less above that, but all the way out to 6GHz.
Why would you need an amp? Why do you have to be concerned about HF, where it's specs are the best?

I am having trouble following what you are wanting to do.
 

Papabravo

Joined Feb 24, 2006
18,408
With an amplifier you might actually radiate enough energy to be detected, caught, and thrown in the jug, for unlicensed operation.
 

Thread Starter

otpisani

Joined Feb 6, 2022
4
Welcome to AAC.

If you have a HackRF One, it can output 5-15dBm from 1 to ~2.7GHz and less above that, but all the way out to 6GHz.
Why would you need an amp? Why do you have to be concerned about HF, where it's specs are the best?

I am having trouble following what you are wanting to do.
Hackrf is not good enough for band that I'm interesting 0-30 MHz, even rtl sdr v3 dongle leave better "footprint" in waterfall BUT with direct sampling (Q), must admit that I don't know how will that affect with Tx actually (hackrf), beacause I start playng with tx recently.
This is also reason why I choose forum to ask, also I don't have much experience with add on boards for arduino, and there are lots of them (price presume), so I ask for help, maybe someone try that before me, don't like to spend couple of thousands for NI gear (which I don't have ;-) ) , when you can get the same, for let say hundred bucks.
My question is the same, understand I will not purchase extra amp for hackrf, maybe investing in better sdr card which is better for that band, hermes or blade rf maybe, or if someone have experience with arduino and add on signal generator boards.

Thanks to all
 

sparky 1

Joined Nov 3, 2018
716
The NanoVNA can be a cheap RF signal source and has other functions for making filters, mixers.
The role of the mixer shifts the signal down with it's modulation. We can say the SDR signal has been down converted to a baseband.
The oscilloscope looks at modulation, Compatibility would favor USB interface (files and software compatibility) but is not absolutely necessary. A video shows a complex yet basic digital approach which let's you get some idea about the learning curve. A package already put together would be good choice.
 

Thread Starter

otpisani

Joined Feb 6, 2022
4
Looks like a job for a very fast DDS circuit so he can display arbitrary waveforms.

Would something like this be fast enough?
https://www.ebay.com/itm/284229559203?hash=item422d66e3a3:g:G-YAAOSwxYdgWbgr

Do you have any microcontroller programming skills? If so, which controllers?
Sorry, need to do little homework, I found on net test with AD9959, similar site like aac, don't like violate policy of use, if someone interested I will forward link over pm. Basically AD9959 is DDS add-on module/board for arduino, and you can operate/programming true arduino, also AD9959 is DYS kit for arduino, something that you recommend on ebay, but production line. It's actually something that I plan to use. Don't know if DDS support play from a file, raw data, for that presume you need also sdcard, emmc on board. In GNU radio that would be "file source module", don't know what is software support for AD9959, or production line DDS, do they support something like flow charts, which GNU radio and RedHawk are.

No, I don't have knowledge programming controllers, embedded system, etc, from scratch, like made java classes for example, but don't have problem adapt sources scripts, with google, manual, or compiling.
 

Thread Starter

otpisani

Joined Feb 6, 2022
4
The NanoVNA can be a cheap RF signal source and has other functions for making filters, mixers.
The role of the mixer shifts the signal down with it's modulation. We can say the SDR signal has been down converted to a baseband.
The oscilloscope looks at modulation, Compatibility would favor USB interface (files and software compatibility) but is not absolutely necessary. A video shows a complex yet basic digital approach which let's you get some idea about the learning curve. A package already put together would be good choice.
I'm using only sma terminator 50ohm for now ;-) , but will put nanoVNA in bookmark. I'm not good with soldering, if you mean that I build filter or mixer on my own, and after that calibrate filter or mixer with nano VNA,

I was looking for SDR mixer on net, but actually what you describe as mixer is filter which converts up/down signal, mixer would be something that join signals into one or signals, etc.
 

sparky 1

Joined Nov 3, 2018
716
Mr Bill gave a valid recommendation going with the feel tech. It will help to get through background study.
You are correct about the number of SMA connectors, what would a good setup look like using a scope ?
There are lots of mixers. Waves join naturally but getting the right waves to join in the right amounts so that modulation
happens in a controlled manner by using a mixer is the key. In modulation such as PSK or QPSK phase type we can see
one method how I and Q are balanced. Even though you may feel being proficient is far away getting the terminology and techniques has to start somewhere. We start off with baby steps and before long we can run. The video does have DIY soldered ade1-ask's and homemade modulator because soldering is a tradition with hams. You can buy them made. The Tektronix engineer and product development speaker takes time out from industry to share with amateur radio builders.


ZFMIQ-10M.pdf (minicircuits.com)
Mini-Circuits (minicircuits.com)
 
Last edited:
Top