Starting with Horus Binary

[John Laidler]

About ten years ago I launched a HAB in the UK which had a successful flight using Dave Akerman's Raspberry Pi software. With my local radio club I now plan to launch another HAB but I am very out of date.  

From this Group it seems Horus Binary is now very popular but I cannot find any simple guides to setting up a tracker using an Arduino or RPi. I have found references to re-programmed RS41s but is this the only way it can be done?

I have found references to receiving Horus signals and we will need to be able to doi that but the first aim is to create a suitable payload.

Any help would be very gratefully received.

John

M0WIV

[Steve]

Overall I've found Horus Binary 4FSK very good - certainly an improvement over RTTY.

Horus Homebrew transmit - start here:   https://github.com/projecthorus/horusbinary_radiolib - an Ardiuno horus V2 4FSK example using RFM98W.

I got it working on the pi pico under Arduino pretty easily - and then changed to using  NTX2B and  LMT2 because of their frequency stability (although horus seems pretty capable of tracking frequency drift).

More recently I've used reprogrammed RS41 using https://github.com/mikaelnousiainen/RS41ng (which support horus V2)  and https://github.com/Nevvman18/rs41-nfw (which supports V3) - the nfw version is still a bit "beta" but it does seem to work.

Receive wise Ive used:

    https://github.com/projecthorus/horus-gui - I have V2 working on OSX and V3 working on Windows 10 laptop (as per recent posts) 

    and webhours   https://horus.sondehub.org/   - all you need is a chrome browser (works very well on windows and osx).

    Steve G8KHW

--
You received this message because you are subscribed to the Google Groups "UKHAS" group.
To unsubscribe from this group and stop receiving emails from it, send an email to ukhas+un...@googlegroups.com.
To view this discussion visit https://groups.google.com/d/msgid/ukhas/1e2b9d9b-a49d-4c69-bb60-af83ea71e3e2n%40googlegroups.com.

Virus-free.www.avg.com

[John Laidler]

Steve,

Many thanks, that's a very good steer. I was a bit overwhelmed by the amount of information and a potential warren of rabbit holes. 

John

M0WIV 

To view this discussion visit https://groups.google.com/d/msgid/ukhas/a39bcb74-11c0-4764-90c6-dcd1002a03d0%40randomaerospace.com.

[Ben Z en de rest]

I would also recommend to check for tbtracker on GitHub, it supports LoRa, Horus v3, on esp32 family https://github.com/RoelKroes/TBTracker-ESP32/tree/main

Op zo 22 feb 2026, 21:36 schreef John Laidler <rjohnl...@gmail.com>:

To view this discussion visit https://groups.google.com/d/msgid/ukhas/CAJn3SCqfQCKoSbCXG15P20%3Dex7dvJq-_tCKooEHnHw%3DuBCOK4Q%40mail.gmail.com.

[John Laidler]

Ben,

Thank you.  I had found that but at first sight it looks a bit complicated for me, I'm looking for an Idiot's Guide but I will have another careful look at it.  :-)

John

To view this discussion visit https://groups.google.com/d/msgid/ukhas/CACbGgOs%3D9L5%3D%2BjKYZWi2sC-%3DXcXZA8AfQWLP2q5%2BsBnm5OtiPw%40mail.gmail.com.

[John Laidler]

Steve,

I don't think I thanked you for this reply so apologies for the delay.  I've managed to get a receiver up and running and will be looking at the tracker next but I'm awaiting a few bits from AliExpress first.  I'm going to try a Heltec wireless tracker board first and if successful build something around a RPi Pico.

John

M0WIV

To view this discussion visit https://groups.google.com/d/msgid/ukhas/a39bcb74-11c0-4764-90c6-dcd1002a03d0%40randomaerospace.com.

[Nick McCloud]

The recent remote managed flight I did in NL was a XIAO SAMD, RA-02 (as they come on a handy mount PCB), a ATGM GNSS, an SD Card for data and a SEN66 I2C sensor.

All mounted on a huge piece of Vero that can go on a diet for the next flight. The SD Card was only to capture the SEN66 data, neither are needed for tracking. The SEN66 did in fact freeze, as in sensor data went AWOL but defrosted nicely, so Im still looking to make heat exchanger for the incoming air to get a full set of data. We also managed to capture a lot of particulate data down wind of a large town - someone there isn't being nice to the environment!

The TBTracker repro offers RTTY which I got to work exactly once and then never again and Mark said it was a known issue and to just concentrate on HB & LoRa.

As well as coming up with a generic version of the above, I'm fiddling with an ESP32-CAM so it can take pictures inflight and save to the built-in SD Card. Some hacking about will be needed to get to the I2C connections for sensors. Maybe transmit pictures in HabHub/DaveA/UKHAS/SSDV format at a later point.

Feel free to ask 'stuff'.

[John Laidler]

Nick,

Thank you, the XIAO and RA-02 look nice and compact. I'm going to try using a Heltec wireless tracker first, primarily just for convenience but I plan to build something lighter and your choice of components looks very good. The goal would be something solar powered which I could use under a "floater". 

I suspect I will need a "wiring diagram" when I come to building a tracker from scratch!

John

--

You received this message because you are subscribed to the Google Groups "UKHAS" group.
To unsubscribe from this group and stop receiving emails from it, send an email to ukhas+un...@googlegroups.com.

To view this discussion visit https://groups.google.com/d/msgid/ukhas/d163bcd9-293a-4035-b50e-353e5f8cc99cn%40googlegroups.com.

[Sasha Tim]

Nick,

When you used the RA-02 for 4FSK, did you notice any extra sidebands at about ~1KHz away from the main signal? I did some experiments with the SX1278 (which the RA-02 is based on) and always got nasty sidebands that took away much of the transmitted power

--Sasha VE3SVF

To view this discussion visit https://groups.google.com/d/msgid/ukhas/CAJn3SCo%3D83Whc7Pz0xdgD%3DAySC9k_hTUrmQc9AT4srM_APXgEg%40mail.gmail.com.

[Ross G6GVI]

I can see sidebands about 2kHz offset, but they are at least 16dB down on each side, so would amount to <5% of the output power:

That's from an Ra-02 operating at 144MHz.

It's pretty much the same on  LilyGo T-Beam operating on 70cm:

[Mark Jessop]

Yeah that doesn't look particularly nice. I guess it would look the same if transmitting RTTY too.

The demod *should* cope with that fine, as it'll be hunting for the strongest set of peaks.

73

Mark VK5QI

--
You received this message because you are subscribed to the Google Groups "UKHAS" group.
To unsubscribe from this group and stop receiving emails from it, send an email to ukhas+un...@googlegroups.com.

To view this discussion visit https://groups.google.com/d/msgid/ukhas/01b94104-f0e1-49b7-a307-43ee15624210n%40googlegroups.com.

[Ross G6GVI]

Yes indeed Mark, as those spurii lie either outside the SSB filter bandwidth or in the (suppressed) "image" sideband. 

In my recent tests, I regularly get decodes down to -6dB SNR.

I've not looked at a RTTY spectrum, but  similar spurs do appear when sending CW.

[Mark Jessop]

OK... so i guess what i'm curious about now is - are the spurs due to issues when changing frequency (so a result of the PLL retuning), or are they always there, even when just a continuous carrier is being transmitted?

73

Mark

--
You received this message because you are subscribed to the Google Groups "UKHAS" group.
To unsubscribe from this group and stop receiving emails from it, send an email to ukhas+un...@googlegroups.com.

To view this discussion visit https://groups.google.com/d/msgid/ukhas/93cb305d-f965-46b9-b527-29d43830672dn%40googlegroups.com.

[Sasha Tim]

Just tested this with some modules I have around - it appears that the sidebands always appear on the SX1278, even when transmitting a carrier. 

--Sasha 

[Mark Jessop]

Ahh right. so it's not just a modulation problem. That's a shame.

On Sun, Mar 1, 2026 at 9:42 AM Sasha Tim <sasha...@gmail.com> wrote:

Just tested this with some modules I have around - it appears that the sidebands always appear on the SX1278, even when transmitting a carrier. 

--Sasha 

--

You received this message because you are subscribed to the Google Groups "UKHAS" group.
To unsubscribe from this group and stop receiving emails from it, send an email to ukhas+un...@googlegroups.com.

To view this discussion visit https://groups.google.com/d/msgid/ukhas/CADS7kXUF-whXX_6Y9OUmjGDX-JELQ%2B9NNzqDQ_di_bz9K9xXPg%40mail.gmail.com.

[Steve]

Probably some form of PLL phase/frequency jitter as part of the fractional divide by N ?

    Steve

To view this discussion visit https://groups.google.com/d/msgid/ukhas/CABD2Lt1Htu%3DYUWJWNu%3DuyVFwa87osj5eO9b17keb466cVAbueg%40mail.gmail.com.

Virus-free.www.avg.com

[Nick McCloud]

Thank you to Ross for answering, I've all the kit and no idea (not strictly true, but you get the general idea) - and didn't think to look.

I/we used the RA-02 because they are relatively easy to get hold of and come pre-mounted on a 2.54mm pitch PCB. 

I can have a go with an SX1262 module when I'm doing some more on this project and see what comes up. 

Or more realistically, give Ross such a module as this sort of thing is his bag (baby).

[Ross G6GVI]

I've been using the SX1278 on 2m as it's specified down to 137MHz, whereas the 1262 only goes to 150MHz.

Of course I need to add an RF low-pass filter to operate there:

[Ross G6GVI]

Thanks to John G0WIV who's now got a Heltec board with SX1262 running and there are none of those close-in spurs on that:

On Monday, 2 March 2026 at 10:20:55 UTC Nick McCloud wrote:

[Ross G6GVI]

I've been playing with an E22-400MM22S LoRa module from Nick: this incorporates an  SX1268 core.

It shows none of those sideband spurs which we saw from the SX1278:

However I could hear a distinct drift LF during the course of each packet:

This can be mitigated somewhat by sending a couple of seconds idle tone before the FSK:

On Monday, 2 March 2026 at 10:20:55 UTC Nick McCloud wrote:

[Mark Jessop]

That's definitely not good drift. Too much and you'll start to impact demodulator performance.

Something you might be able to look into is if there's a mode where the radio isn't transmitting, but isn't completely in sleep with the oscillator shut down. It might help with turn-on stability.  Or it could be a thermal effect when more power is dissipated while transmitting, which is probably a bit harder to deal with.

Unfortunately these LoRa modules don't come with decent stability crystals or TCXOs...

73

Mark VK5QI

--

You received this message because you are subscribed to the Google Groups "UKHAS" group.
To unsubscribe from this group and stop receiving emails from it, send an email to ukhas+un...@googlegroups.com.

To view this discussion visit https://groups.google.com/d/msgid/ukhas/842d7018-43ab-4b3a-9d1c-cc0f11cc4686n%40googlegroups.com.

[Ross G6GVI]

Yes Mark, this  E22-400MM22S is a tiny self-contained package (just 10 x 10mm), so its ref crystal must be very close to the RF PA.

That's OK for LoRa, but bad news for narrowband signals.

This effect is not apparent with the larger Ra02 or RFM98 modules.

73 de Ross.