richandlea
Posts: 4
Joined: Mon Apr 22, 2019 9:24 am

RF receiver for 926.365 MHz

Mon Apr 22, 2019 9:53 am

HI,
Is it possible to buy rf receivers, or to make one that works with 926.365 MHZto work with raspberry pi, or via an arduino board? There are lots of info on 433 Mhz, but nothing I can really find to build to work with other frequencies? Any ideas on where to look for info or solutions. Thanks for any ideas.

User avatar
mahjongg
Forum Moderator
Forum Moderator
Posts: 12041
Joined: Sun Mar 11, 2012 12:19 am
Location: South Holland, The Netherlands

Re: RF receiver for 926.365 MHz

Mon Apr 22, 2019 10:11 am

433MHz is used Because its a legally free frequency, other frequenties are not.

Andyroo
Posts: 3850
Joined: Sat Jun 16, 2018 12:49 am
Location: Lincs U.K.

Re: RF receiver for 926.365 MHz

Mon Apr 22, 2019 10:22 am

That’s around the cordless phone frequencies - you will not find much readily available.

If you are looking for TX/RX via radio consider LoRa
Need Pi spray - these things are breeding in my house...

User avatar
Joel_Mckay
Posts: 289
Joined: Mon Nov 12, 2012 10:22 pm
Contact: Website

Re: RF receiver for 926.365 MHz

Mon Apr 22, 2019 12:34 pm

The RTL-SDR is a DTV receiver that had its driver enhanced to become a general purpose RF receiver.
A common ebay $10 USD 820T version can receive 24 MHz up to 1766 MHz with fairly good signal quality:
https://www.youtube.com/watch?v=bSAa2aOXpCc
https://www.rtl-sdr.com/about-rtl-sdr/

On a Pi3B+ one can decode mono SSB/FM/AM and so on... and building gnu Radio custom decoders is fairly easy.

In my part of ITU region 2, the 902 MHz to 928 MHz area is classed general purpose ISM like wifi, but 926.365 MHz overlaps Radio Astronomy specific uses. Since it is not primarily assigned for ham use, one is expected to avoid using this part of the spectrum if possible.

You can get a patched-up version of our local club raspbian image if you want to try a working RTL driver and radio receiver application like gqrx. https://sourceforge.net/projects/microm ... spberry-pi

Depending on your country, Broadcasting on the wrong channel without the proper license can get you fined and or a jail term.
I would highly recommend getting involved with your local community amateur radio group if you want to start building custom hardware, as they can help you understand what the local community expects from you (note a faulty transmitter is very easy to find if you know what you are doing.)

Ubiquiti Networks also makes inexpensive long-range networking hardware, and should have all the right licensing stamps if purchased locally.
;-)

Best regards,
J

User avatar
NGC6543
Posts: 75
Joined: Thu Feb 28, 2019 7:30 pm
Location: Lancashire, UK

Re: RF receiver for 926.365 MHz

Mon Apr 22, 2019 12:59 pm

What are you trying to receive? That's quite a specific frequency.

As said above me, and RTL-SDR dongle is an easy way to receive it. Although GNUradio supposedly runs on the Pi, I would run it on a PC and use a Pi as the remote connection to the RTL up near the antenna. Funnily enough, that's what I'm going to be setting up with an SDRPplay receiver some time soon.

Then just make yourself an antenna tuned for your frequency, and maybe a bandpass filter and LNA, depending on what the source is and your local noise level.

I'm still curious... what you want to receive?

richandlea
Posts: 4
Joined: Mon Apr 22, 2019 9:24 am

Re: RF receiver for 926.365 MHz

Tue Apr 23, 2019 11:53 am

Hi,
Thanks for all the replies.
I am wanting to monitor WiFi interconnected smoke detectors. If one detects smoke and alarms, it sends out a signal to the others that have been paired with it and the all alarm as well.
https://www.cavius.co.nz/wireless-family-smoke-alarm/
I was hoping I could monitor the frequency, sending alerts to my mobile if they alarm, including which unit was the trigger.
Thanks again.

User avatar
PeterO
Posts: 4882
Joined: Sun Jul 22, 2012 4:14 pm

Re: RF receiver for 926.365 MHz

Tue Apr 23, 2019 11:57 am

richandlea wrote:
Tue Apr 23, 2019 11:53 am
Hi,
Thanks for all the replies.
I am wanting to monitor WiFi interconnected smoke detectors.
They are "wireless" not "WiFi" !

PeterO
Discoverer of the PI2 XENON DEATH FLASH!
Interests: C,Python,PIC,Electronics,Ham Radio (G0DZB),1960s British Computers.
"The primary requirement (as we've always seen in your examples) is that the code is readable. " Dougie Lawson

User avatar
NGC6543
Posts: 75
Joined: Thu Feb 28, 2019 7:30 pm
Location: Lancashire, UK

Re: RF receiver for 926.365 MHz

Tue Apr 23, 2019 12:07 pm

A $10/£10 SDR dongle and GNUradio on the Pi is probably quite suited to that task. You might need to decode the data the units send when activated, or record it for comparison. GNUradio can help with that.

GNUradio looks really complicated at first, but it's actually not hard to use when you go through a few examples from the web.

richandlea
Posts: 4
Joined: Mon Apr 22, 2019 9:24 am

Re: RF receiver for 926.365 MHz

Tue Apr 23, 2019 5:05 pm

PeterO wrote:
Tue Apr 23, 2019 11:57 am

They are "wireless" not "WiFi" !

PeterO
Yes wireless, thanks for pointing out the typo.

richandlea
Posts: 4
Joined: Mon Apr 22, 2019 9:24 am

Re: RF receiver for 926.365 MHz

Tue Apr 23, 2019 5:09 pm

Hi.
Thanks for the info, very much appreciated. I'll look into GNUradio and see how it goes. Thanks.

bmernz
Posts: 1
Joined: Sun Jul 21, 2019 10:39 pm

Re: RF receiver for 926.365 MHz

Sun Jul 21, 2019 10:41 pm

Hi, I'm interested in doing the same thing, did you have any luck with this?

PhatFil
Posts: 1309
Joined: Thu Apr 13, 2017 3:55 pm
Location: Oxford UK

Re: RF receiver for 926.365 MHz

Mon Jul 22, 2019 1:28 am

bmernz wrote:
Sun Jul 21, 2019 10:41 pm
Hi, I'm interested in doing the same thing, did you have any luck with this?
if not there could be easier ways to detect alarm activity? if for example there is a led that lights or flashes when the alarm is triggered a simple LDR blutacked/glued over the led directly connected to your pi or some slave wireless dev board to signal when the led is activated.

Return to “Automation, sensing and robotics”