Tool to view/RX 6kHz GFSK modem datastream - Page 1
Forum section: electronics / rf-microwave

author: Psi
author_rank: Super Contributor
timestamp: January 03, 2023, 09:15:08 am
content: I have a GFSK 2.4ghz module with it's own internal library that's sending data at 6kHz and I would like to view the raw data it's sending.If someone can recommend a tool that I could buy to have a look at the datastream, ideally something that won't break the bank, that would be great!A devkit for some 2.4ghz transceiver that can do this mod/freq/datarate would be Ideal.I don't know a huge amount about RF transceiver IC programming but I guess it's time to startThanks.

author: Psi
author_rank: Super Contributor
timestamp: January 03, 2023, 08:59:08 pm
content: No one has any ideas?I've been searching for something myself but i'm not sure how data rates work with RF.Many 2.4ghz GFSK chipsets I find have a min data rate well above 6khz and i'm not sure if that's actually a problem or not.Can you configure a higher data rate and then analyze the data stream to remove blocks of the same samples to restore original slower data?

author: Gribo
author_rank: Frequent Contributor
timestamp: January 04, 2023, 04:15:12 pm
content: 6Kbps or 6KHz deviation from carrier? which transceiver?

author: Psi
author_rank: Super Contributor
timestamp: January 05, 2023, 08:36:43 am
content: 6Kbps data rate.Transceiver data sheethttps://www.emmicroelectronic.com/sites/default/files/products/datasheets/609014.pdf

author: JoeyG
author_rank: Regular Contributor
timestamp: January 05, 2023, 11:01:36 am
content: It's a fully integrated SoC module and there doesn't to be any raw data internal data signals coming out on the pins.

author: Psi
author_rank: Super Contributor
timestamp: January 05, 2023, 11:33:10 am
content: I'm investigating options to use an different transceiver and maintain backwards compatibility.but to do that it needs to transmit the same data in the same way.

author: PA0PBZ
author_rank: Super Contributor
timestamp: January 05, 2023, 11:51:41 am
content: If you're in for some fun buy a HackRF or clone and have a play with GNU radio.

author: radiogeek381
author_rank: Regular Contributor
timestamp: January 07, 2023, 11:25:51 pm
content: No two ways about it....If you want to get a "low cost" path to looking at the transmitter output from a 2.4 GHz module, download GNU Radio with GNU Radio Companion and buy a very inexpensive RTL dongle.An RTL-SDR dongle from Amazon can be had for $30 or so. This is a bargain, and it gets you a rudimentary software defined radio widget.The HackRF is a good choice, but a bit more expensive than the RTL-SDR (and a lot more capable).Getting in to SDR is much easier if you are motivated by a "pet project." But go slow, take it step by step. GnuRadio is a great start and there's lots of support on the web.(I've been "playing around" with SDR for a while now -- mostly USRPs, but I've got an RTL-SDR and a few other radios in between. )

author: PA0PBZ
author_rank: Super Contributor
timestamp: January 08, 2023, 12:07:12 pm
content: Quote from: radiogeek381 on January 07, 2023, 11:25:51 pmMind though that a standard RTL-SDR only goes up to 1.7 GHz so you'd need a converter too, that's why I mentioned the HackRF One, it goes up to 6 GHz and can also transmit.

author: MartinL
author_rank: Regular Contributor
timestamp: January 08, 2023, 01:07:14 pm
content: There's a good chance it can be demodulated by one of the CC24xx series parts with the right settings, but if you don't already know all the details of the modulation you're better off capturing it with an SDR receiver and having a look at the raw IQ. Useful software to help with this includes inspectrum, Universal Radio Hacker and GNU Radio as already mentioned.

author: radiolistener
author_rank: Super Contributor
timestamp: January 08, 2023, 04:01:50 pm
content: You can use RTLSDRv3 dongle as receiver or use any other SDR receiver with HDSDR software to receive the raw signal. Just select DIG mode as demodulator and setup desired bandwidth 6-8 kHz or what you want. In such way you can hear raw signal from your soundcard, record WAV file and analyze it in other software. Also you can setup audiooutput to a virtual sound cable (needs to install a driver) and redirect audio stream to another software which accept audio input to decode it in realtime.HDSDR provide you with a raw IQ stream to the audio output when DIG mode is selected.If you want more details on how to configure it, you can see manuals on how to configure HDSDR to receive DRM radio with using external decoder software Dream. Just use your software instead of Dream decoder to decode your specific stream.

author: Psi
author_rank: Super Contributor
timestamp: January 08, 2023, 10:07:31 pm
content: Quote from: MartinL on January 08, 2023, 01:07:14 pmyeah, probably best to SDR it first, but it would be really useful if a CC24xx can replace it.Can anyone recommend a good SDR for 2.4ghz ?Maybe RTLSDRv3 as radiolistener just described?I think i'd need a downconverter for that, correct?Looks like a ADL5350 and a ADF4351 is a good option. Just need to send it some known I2C commands to set 1ghz output to LO

author: Psi
author_rank: Super Contributor
timestamp: January 10, 2023, 06:35:24 am
content: Bump.Can anyone confirm the above is a good idea for RTLSDRv3 at 2.4ghz?

author: radiolistener
author_rank: Super Contributor
timestamp: January 10, 2023, 06:40:43 am
content: Quote from: Psi on January 08, 2023, 10:07:31 pmyes, with rtlsdr you will need downconverter, but also you can use other SDR receivers which already cover 2.4 GHz band in that way you can receive it with no need for additional equipment.For example ADALM Pluto coverage is from 325 MHz to 3.8 GHz, so you can use it.

author: Psi
author_rank: Super Contributor
timestamp: January 10, 2023, 06:52:53 am
content: Yep, ADALM Pluto is like $500 though.

author: PA0PBZ
author_rank: Super Contributor
timestamp: January 10, 2023, 08:40:00 am
content: The HackRF One can be bought for around €180 and you can also use it to recreate the signal, but I'll shut up now

author: Psi
author_rank: Super Contributor
timestamp: January 10, 2023, 10:14:43 am
content: Quote from: PA0PBZ on January 10, 2023, 08:40:00 amits sold out everywhere.But yeah, it is a nice tool at a great price.

author: PA0PBZ
author_rank: Super Contributor
timestamp: January 10, 2023, 10:33:38 am
content: https://www.aliexpress.us/item/2255800323502448.html

author: Psi
author_rank: Super Contributor
timestamp: January 10, 2023, 10:38:44 am
content: I'm not sure it's a good idea to get a finely tuned RF product as a china clone.

author: PA0PBZ
author_rank: Super Contributor
timestamp: January 10, 2023, 11:11:10 am
content: There's nothing 'tuned' in an SDRI have one from the same source and it's fine, but your choise of course.

author: Psi
author_rank: Super Contributor
timestamp: February 11, 2023, 09:07:41 am
content: It's been a few months, but I bought a HackRF one and it arrived.I was looking for a windows install of the SDR app and tried PothosSDR package however the latest version is from 2021 so i'm probably way behind the latest version of CubicSDR.Anyway, I am able to see modem transmit some data! See pic below.Where I should go to learn about how to set this up the best way possible for capture of FSK data?The version I installed has a few modulations AM/FM/CW/LSB etc.. but not FSK?Secondly, is using the hackRF one in linux a better option for a wider selection of tools/software?Id rather use windows but i can setup a linux PC if that is worthwhile.Is there a good windows install package for using the HackRF one ?Thanks

author: Kean
author_rank: Unknown
timestamp: February 11, 2023, 10:22:23 am
content: I haven't used my HackRFs in quite some time (>5 years) so I can't give very much advice, but have you looked at the radioconda application which seems to be a more recent Windows port of gnuradiohttps://github.com/ryanvolz/radiocondaIn Michael Ossmann’s SDR course he covers FSK demodulation using gnuradio in section 9https://greatscottgadgets.com/sdr/and although this is kind of old, I think he explains the process wellAnother option to look at is AirSpy SDRsharp/SDR# which is what I think I was using in the pasthttps://airspy.com/download/SIGMIRA also supports a bunch of demodulators including FSK - never tried this one myselfhttp://www.saharlow.com/technology/sigmira/

author: PA0PBZ
author_rank: Super Contributor
timestamp: February 11, 2023, 11:06:44 am
content: For what you want to do there's no problem using windows, but I doubt that you can find a windows app that does exactly what you want. I highly recommend that you have a look at GNU radio and learn how to build your own FSK demodulator. There are some fine tutorials around, but to make a start have a look here:https://wiki.gnuradio.org/index.php/WindowsInstall

author: Psi
author_rank: Super Contributor
timestamp: February 11, 2023, 12:33:14 pm
content: Thanks, ill have a look