Author Topic: 315Mhz (303.88) OOK radio modules?  (Read 116 times)

kalbanowski

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315Mhz (303.88) OOK radio modules?
« on: March 16, 2020, 12:21:16 PM »
Can anyone suggest a pre-built 315Mhz-band radio module, RFM69 or otherwise, suitable for OOK (ASK) transmission and reception at 303.88Mhz?

Do RFM* modules at 315Mhz actually exist, or just a persistent myth? I've been rummaging through the more obvious China sales sites and while the advertising suggests 315, no-one actually seems to have them in their store-front.

Felix, if you have a stash, I'd like to buy a couple. :)

I have found myself needing to interface a bunch of Arduino-style boards with a modern (you can buy it at Lowes, FCC ID and everything) home commercial remote-control thing (ceiling fan) that operates at 303.88Mhz for some strange reason -- and all of the tech I have available operates in 433Mhz-ISM and above. From what I've been able to tell, the radio front-end (antenna matching?) will be different between 315 and 433, so while I will give an RFM69-433 a try shortly, I shouldn't expect it to work. (I am not an RF expert, nor can I even do a good impression.)

The only other equipment I've found that purports to support 315Mhz are those cheapy digital AM transmitter/receiver pairs that don't have tunable transmitters, so that's unlikely to be useful, and Great Scott's YARD Stick One (based on the CC1111) which supposedly has a wide enough front-end to support 315Mhz just fine, unfortunately my own experience and that I've seen on-line is that these tend to operate completely inconsistently on modern Linux systems with USB continually getting stuck, and no obvious firmware fixes. Nonetheless, going in and writing some custom firmware for the CC1111 on it might be my simplest approach at the moment.

Any other suggestions? Maybe the receiver is wide-spectrum enough that a cheap digital transmitter at 315Mhz will work fine? An RFM69-433 will just work?

(I do have, and can more or less operate, some SDR equipment for sniffing the air, and can read FCC docs, so I have already looked at the signal I want to reproduce, it is definitely OOK at 303.88.)

Thanks all, and be well.
- Kenneth

Felix

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Re: 315Mhz (303.88) OOK radio modules?
« Reply #1 on: March 16, 2020, 12:51:31 PM »
I have found myself needing to interface a bunch of Arduino-style boards with a modern (you can buy it at Lowes, FCC ID and everything) home commercial remote-control thing (ceiling fan) that operates at 303.88Mhz for some strange reason -- and all of the tech I have available operates in 433Mhz-ISM and above. From what I've been able to tell, the radio front-end (antenna matching?) will be different between 315 and 433, so while I will give an RFM69-433 a try shortly, I shouldn't expect it to work. (I am not an RF expert, nor can I even do a good impression.)
I can bet they will work fine at your desired frequency, with the expected attenuation due to matching.
Although I haven't had a need for 315mhz, I could not find RFM69/315mhz either.