Determine frequency of RF remote control

Hello!

I've got a Sharp LC-50CFE5101K, it uses an RF remote control (not IR), this means my Fire TV remote (IR) obviously can't control it.

I thought it might be possible to have an Arduino listening for the IR codes from the Fire remote, and transmit the equivalent RF signal to the TV so that the Fire remote would 'work'. I have successfully recorded the IR signals from the Fire remote but am now struggling to record the signals from the RF remote for replay.

I cannot find anywhere that tells me what frequency the remote is operating at so that I can buy the correct sensor to record and transmitter to replay the signals. Please could someone help me figure out what the frequency might be and how to proceed?

I attach photos of the inside of the remote and transmitter module. I've tried Googling these but not having a lot of luck.

Seems it's not 433MHz as the existing Arduino stuff I've got for 433MHz doesn't pick anything up when I press the buttons (and the remote does work, tested with the TV)

Thanks!


It may be easier and faster and there is no shame in…

… getting a second copy of the RF mystery remote and hijacking the buttons, that is to say place them under control of the Arduino which will receive the Firefest IR signals.

Lotsa ways to do the hijacking, none very hard.

a7

The writing on the crystal X1 might give a clue to the operating frequency.

Unfortunately it is not readable in your photo.

Can you tell us what it says ? or show us a better photo of it.

Maybe your TV remote can control the firestick through HDMI CEC (if enabled).
Leo..

Hi all, thanks so much for coming back so quickly

@alto777 I like that idea! We actually don't use the TV remote much, so could even just use that one. I'll look into some way of 'pressing' the buttons

@JohnLincoln - sorry for poor quality, it's my phone camera and I really struggled to get it in focus! The crystal has 'JHF 16.000' on it

@Wawa - thanks, this does work! However, I think perhaps due to the age of the TV it is quite slow to pass the commands over to the Fire stick, so it's not responsive enough for daily use (and you miss out on the 'extra' buttons provided by the Fire remote)

Don't suppose anyone had any further ideas on determining the frequency this remote operates at? Thanks :slight_smile:

RF spectrum analyser.

RF frequency meter.

Realtek SDR

Stupid question, but does your remote have a sticker on it (battery compartment maybe) or possibly some wording in the plastic of the rear casing that gives any regulatory information? That may give you a clue.

GET THE LOOK✨:original remote control for sharp LC-49CFE6031K LC-49CFE6032K LC-50CFE6131KLC-32CHE6131E LC-40CFE6131E LC-32CHE6132E led tv
PRODUCT PROPERTY::sparkles: Basic: Use is tv.Origin is cn(origin).
:sparkles: Hardware: Package is yes.Wireless communication is rf.Frequency is 433 mhz.Support app is no.Channel is 1.

https://www.aliexpress.com/i/4001215259152.html

@srnet Would something like this do the trick? I am concerned I wouldn't have any idea how to interpret it however..!

@markd833 - negative, no stickers!

@tom321 thanks for the link, although it says 433mhz on there I wasn't able to get anything to appear on my 433mhz receiver (which, granted, I might not have setup correctly - but it did receive data from the transmitter that came with it)

Thanks! :slight_smile:

A complete change of topic here - but bear with me and you should see where I'm going with this, but also note that I'm nowhere near as knowledgeable on this as I may sound!

I have a Ford car that has a Tire Pressure Monitoring System (TPMS). The vehicle can tell me that I have a low tyre pressure but not which tyre it is. I've got a cheap USB SDR (Software Defined Radio) dongle from Aliexpress that I am hoping to use to see if I can listen to the transmissions from the 4 sensors.

I think you can search for "RTL-SDR" to find it (or ones like it) - that seem to be used to detect radio transmissions from the 433MHz sensors in the tyres.

There are a few hits via Google if you search for "TPMS SDR". The websites give you details on how to do this and what software they used etc. Here's one that I remember reading:

You may be able to use the same sort of process to discover more about your RF remote.

Of course I could be talking complete c**p and I'm sure that @srnet will soon be along to correct me :grinning: :grinning: :grinning:

Is there an FCC ID number somewhere on the box

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That would work for you, but you would have to let air out of the tire to trigger the transmitter.

Edit: And I suspect it is like my VW, it only triggers ONCE! So you have to be ready to catch it!

You can use an SDR to check frequencies of stuff.

However its not ideal since the bandwidth of the receive window is not that wide, so there can be a bit of scanning up and down the frequncy bands before you hit the right spot.

But then SDRs are cheap.

There is also 403 on the pcb , 433 and 403 is very commonly used in RF remotes , cars and gate motors.

So being impatient I picked up one of these

It "works", as it shows 433 when pressing my car keys, but the TV remote doesn't show anything on the display (despite operating the TV). Quite possible is a sham product of course and doesn't really show 10-1000MHz, but any chance (do you think) that the remote is operating outside of this range?

RF TV remotes likely work in the 2.4Ghz band, like WiFi and Bluetooth does.
The fact that I need to pair my remote to my TV suggests BT.
"Pair" means two. I don't expect you ever can pair a third remote with your TV.
Leo..

Thanks @Wawa - sticking "2.4ghz" on to my Google search was enough to find this thread where someone is trying to do exactly the same thing...

@synthetikz - did you get any closer?!

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