[creamers]

Great !! I'm curious! Sounds like you know what you're doing

[mercurio.]

@curlymo: just one question. how did you test the receivers? i mean if you speak about a receiver that generates a lot of noise, you mean hat if you connect it to the gpio pins and i.e. run the pilight-raw you get data even if you don't send?

the point is that it's an AM signal so if you have a sensitive receiver and no signal is sent it "hears" the noise that is in that channel (not generated by the receiver but by a lot of electromagnetic sources and also by mother nature).

for the aurel receiver you can determine the sensitivity by putting a resistor in between the test pin and ground. by doing so you reduce the noise but also the sensitivity (and thereby the area coverage).

i use a resistor of about 50k. so, when i don't send the output is zero for 99% of the time. when i send it shows an output. this also should help for the impulse senders. the point is that you have to choose a resistor depending on your environment (i.e. to set the level that's treated as noise) and that by doing so you also decrease the coverage.

i'm quite sure that we can have both, high sensitivity and high coverage by changing a few things.

the lpf should probably exchanged by a high speed fully differential i/o amp lpf circuit. this should give a filtering that really reduces the amount of work the software has to do.

then talking about the software. while changing some timing parameters to adapt it to my wall switch's timing i had a fast look at it. its really nice coded!! curlymo, your'e doing a great job there.
but i didn't find the time to read all of the code and fully understand the structure.

@curlymo some questions: how do you start listening for data? i mean which condition must be valid for you to start recording a dataset?
do you filter for the pulse length of the first bit? (i.e. wait till a bit with 200 - 300 us comes in) and then check if the header is valid before continuing with the processing?

then i had one idea, maybe it would be good due to the big variety of senders and receivers out there to add a "stupid" user learned protocol. i was thinking of something where the user can record a command by his remote and use this for receiving and sending.

well, it's gonna take me some time to get the filter running because i'm quite busy with my phd. but if someone else wants to play around with cheap homemade electronics i could give some hints how to proceed.

[curlymo]

@curlymo: just one question. how did you test the receivers? i mean if you speak about a receiver that generates a lot of noise, you mean hat if you connect it to the gpio pins and i.e. run the pilight-raw you get data even if you don't send?

Yes, and also check the CPU usage to see if the noise reduces.

@curlymo: just one question. how did you test the receivers? i mean if you speak about a receiver that generates a lot of noise, you mean hat if you connect it to the gpio pins and i.e. run the pilight-raw you get data even if you don't send?

I made a video that shows the output with and without a LPF:
https://www.youtube.com/watch?v=W87LOuC1FFM

the lpf should probably exchanged by a high speed fully differential i/o amp lpf circuit. this should give a filtering that really reduces the amount of work the software has to do.

@curlymo some questions: how do you start listening for data? i mean which condition must be valid for you to start recording a dataset?
do you filter for the pulse length of the first bit? (i.e. wait till a bit with 200 - 300 us comes in) and then check if the header is valid before continuing with the processing?

It start recording when a pulse > 4440 arrives. This pulse is then devided by 34 to retrieve the average pulse length. If the pulse length matches the one in the protocol, it calls the processing functions of that protocol.

then i had one idea, maybe it would be good due to the big variety of senders and receivers out there to add a "stupid" user learned protocol. i was thinking of something where the user can record a command by his remote and use this for receiving and sending.

That already exists and it's called "raw". Users can run pilight-debug to catch the raw code of their device and send it with the raw protocol.

One request. Can you also test the filter with the http://www.ebay.nl/itm/433MHz-Superheter...3a78a01065 receiver. That is the one i recommend because of it's coverage and price.

Maybe you can provide us with the LPF schematic till this far?

[creamers]

I think there are alot of people here that are willing to test things out if you don't have the time but most of them aren't that good in electronics. Sounds like you could be of much value for this project! Thx already!

[mercurio.]

so, here is a basic unipolar lpf. choose following values:

RA some hundred kOhm
RB some ten kOhm
RC some kOhm

CA some hundred nF
CB so that 1/(2*pi*RC*CB) is about 20000 (i.e. RC = 820, CB = 10nF)

this gives a basic 20kHz first order lpf. connected with a schmit trigger and the aural receiver with a resistor of about 50kOhm (you have to choose it basing on your em environment!!!) i have a perfect receiver for a range of about 10m. increasing the aural resistor strongly increases the range but also what you guys call noise and thus cpu load.

by perfect i mean if i don't press a button the raw output is null (less than one pulse per two seconds).

to get a really good data filtering you could try to build a lpf described here:
http://www.ti.com.cn/cn/lit/an/sloa063/sloa063.pdf

if i find the time i'm gonna build it and post some results

[curlymo]

by perfect i mean if i don't press a button the raw output is null (less than one pulse per two seconds).

Did you check my video? My LPF currently does no output when i don't press a button. And only output when i do. Range is still around 30m. However, doesn't work for pulses less then around 150us

Awaiting your test results and those by other users that already built your LPF.

[creamers]

Could it be possible to use one receiver from a set (3receivers 1remote) that you buy for 10euro in any store and modify that reciever to be used with a Pi and pilight?
If Impuls can receive it's own signals <200us than I assume it's a good filtered receiver ? The only question would be how to connect it properly...?

[curlymo]

Of course, that's how @BenPi from tweakers did it.

[BenPi]

  ImpulsIC-LP8029L4.pdf (Size: 269.5 KB / Downloads: 21)
Here a PDF sheet from LP8029 this is used as the IMPULS receiver IC.
It combines two IC's in one.
The first "in RF" is a 4069 with condensators and resistors is used as filter !!!!
The second is the decode IC. R8 is as selectable for own Brand .
Maybe the section "RF", page 2, is a good RF filter ??

[BenPi]

i will setup and test this filter with the 4069 asap
Ben