RCTIME to compare voltage ~2V
Hammer32
Posts: 5
My aim is to read the RSSI signal strength reading from parallax RF module into the Basic stamp. I don't want to use an A/D converter and I think I should be able to do this with RCTIME.
I don't want to get the exact voltage i just want to be able to compare it to know values. For example if I know the value for a Strong signal and the value for a weak signal I can make estimations in between.
I should be able to work out What voltage represents a strong signal (I think its around 2V) and what represents no signal.
Could I use RC time to measure this with a simple RC network?
I dot really need too much accuracy just enough to make maybe 3 or 4 levels of signal strength.
My main concern is that the stamp changes state at around 1.4 V
and I will only be measuring a max of 2V is this ok if i'm measuring the time it takes to get from 0 to 1.4?
Also does anyone know how the RSSI works on the parallax 433MX receiver?
To read the signal strength does the transmitter need to be sending out pulses or can it be read if the transmitter is just powered up?
Thanks for your help there is not much information about RSSI in the manual provided by parallax.
I don't want to get the exact voltage i just want to be able to compare it to know values. For example if I know the value for a Strong signal and the value for a weak signal I can make estimations in between.
I should be able to work out What voltage represents a strong signal (I think its around 2V) and what represents no signal.
Could I use RC time to measure this with a simple RC network?
I dot really need too much accuracy just enough to make maybe 3 or 4 levels of signal strength.
My main concern is that the stamp changes state at around 1.4 V
and I will only be measuring a max of 2V is this ok if i'm measuring the time it takes to get from 0 to 1.4?
Also does anyone know how the RSSI works on the parallax 433MX receiver?
To read the signal strength does the transmitter need to be sending out pulses or can it be read if the transmitter is just powered up?
Thanks for your help there is not much information about RSSI in the manual provided by parallax.
Comments
You could use an op-amp to raise the level of the signal prior to apply RCTIME, read the BASIC Stamp Editor's help for what relates the command RCTIME.
Hope to have somewhat clarified.
Regards
Stefano
P.s. The aim of amplification is to make the unkown voltage span adhere to the basic stamp span (0<>5 volt).
So if for your rf level you have a span of 0<>2 volt, you need an amplification of: 5(Basic Stamp span)/2(Rf span) = 2,5(amplification needed).
For what concern to known levels, you could decide several "areas" of values against wich compare the actual value.
Something similar to:
IF (ref > 0 AND ref < 100) THEN dothis
IF (ref > 101 AND ref < 150)THEN dothat
IF (ref > 151 AND ref < 255)THEN doelse
etc.
Post Edited (ellizard) : 5/27/2007 2:34:56 PM GMT
The highest voltage I have been able to get is 2.73.
When the transmitter is not turned on I typically get 1.64V but it has also been measured around 1.18V