Hi RF link'ers
Does anyone have experience with using the 433MHz radio receiver H5V4D?
I need some very cheap 433MHz receivers and this module fits into the space I have available.
To evaluate the module for this project I bought only one, but now have a question about it's performance.
I hooked it up to a power supply and a small audio amplifier and I can hear local data transmissions so it is working.
However, when the 'band' is quiet, instead of the expected 'smooth' noise form the loudspeaker the volume seems to be cycling at about one hertz.
The noise goes up and down as though being amplitude modulated by a 1Hz sinewave. ( a continuous 'shhh, shhh, shhh. shhh')
I can only think it's an AGC issue as when I supply a weak continuous AM signal, the phenomenon is suppressed. (and under strong signal it is undetectable)
So my question is:-
Have you used a H5V4B and experienced the same behaviour, or do I have a faulty module?
This will be really annoying if it's a 'feature' of this receiver module and this could exclude the H5V4D from my project.
Please tell me your experiences with the H5V4D
Thanks in anticipation
All ook receivers do that - the agc is designed to adjusy sensitivity to get a 50% output duty cycle . It will adjust gain to achieve that whether there is a signal or not.. your software needs to be able to pick signal out of noise. they oilutput 50% duty cycle.
Thanks for the information about the AGC cycling effect that's interesting.
I have evaluated quite a few OOK receivers over the last year and not come across this effect before. It must be a feature of these tiny receiver IC's?
The receiver IC's in the ones I have tested were maybe more sophisticated (certainly larger).
I have tested ones such as the DL-RXC2015 from Dreamlink, RX-4MM5 from Aurel and several from Telecontrolli (RRQ5/4/2-XXX etc).
However they all have too large a form factor for my current application.
What RX IC's are these H5V4B type receivers using? I could do with a datasheet!
I am monitoring background noise in this project so this cycling AGC is an issue
Thanks for the replies.....
Beats the hell out of me - I never was happy with those models, I use the ones with the Synoxo chip - SYN470 or the 8-pin variant I think SYN480. Is the RXB-15 too large for your application? That one was pretty good.
In the case of that receiver, while t's not ideal that the receiver seems to be oscillating in the absence of a signal - I'm not surprised that it is. You should expect garbage whenever there is no valid signal and oscillatory behavior isn't particularly strange (Though . These are dirt cheap receivers, and not all of them are good (the synoxo chip beats the crap out of most of them, even the fancier looking ones that go for like $3-6, or it did during the maximum range testing I conducted a while back
Thanks, Isn't the RXB-15 an FM receiver though, I need that extra sensitivity of listening for an AM signal in the background noise.
I liked the size of the H5V4B as it was so compact, but was baffled by the 'motorboating' AGC.
Hence my asking for user experience here
(no specific endorsement of that seller, that's from some random aliexpress seller (which IS where you get the RXB-14 and RXB-12 but I don't claim that they are any more or less dubious that any other vendor on aliexpress that came up showing the right thing while I was googling RXB-(number in the mid teens) trying to figure out the model number).
I have no idea, whether it would do that in the sort of situation you're using it in. You're using it in a totally different way than I ever did.... I had them as inputs to microcontrollers, not connected to audio output device...
All I know is that a few years ago, is rthat the RXB12 (same chipset) beat the stuffing out of every one I did a side-by-side comparison with except one.. It came in a close second, beaten by likre 15% for range, by a US-mad unit that was a 1" x 1" x 3/8inch shielding covered brick with a $50 price tag. The next one behind it was an SRX772 or something like that, with like 30% less range, both of those crushed therogues gallery of other low cost receivers I tried.
Thanks for your comments, well they are so cheap I will just have to buy one and test it..LOL!
Yes I appreciate that when using it in a 'digital' environment you weren't concerned by the AGC as it would be suppressed by the digital stream. I am listening for single events spaced out with silence, so I don't need the background noise jumping around confusing the detector.
Watch this space