Measuring radio frequencies between 290MHz and 433MHz

[dw8000]

I was watching daves video below and wanted to know something that's been bothering me for a long time. In the US we have garage door openers, gate operators , etc. operated by radio transmitters that generally operate in the 290MHz to 433MHz range. Every once in a while I will have a customer that has transmission/reception issues. I haven't had one that I couldn't simply fix yet by relocating the antenna, shorting/lengthening the antenna, going up or down in frequency, changing batteries in the transmitter, etc. I know how to fix the problem without every really finding out what the problem was.

That's my question, if I want to measure RF at a particular frequency to see if there is noise, no signal present, etc. what do I need to verify what if anything is happening on that frequency? Oscope that goes that high, spectrum analyzer, etc. ?


This is a typical radio transmitter and receiver we use.

http://www.liftmaster.com/lmcv2/pages/productmodeldetail.aspx?modelId=8159

http://www.liftmaster.com/CatalogResourcesV3/en-us/shared/files/tucmanuals/114A4123.pdf


I use this on 318MHz and it helps to verify if there is noise, its getting the signal, etc.

http://www.linearcorp.com/product_detail.php?productId=989


daves video

[PA0PBZ]

A scanner would do all that and a lot more, as long as you don't want to take any absolute measurements.

[dw8000]

I never thought of that. So something like this:

http://www.radioshack.com/product/index.jsp?productId=2973252

[PA0PBZ]

That will do, although it is a bit overkill for what you want, you certainly don't need trunking and it would be easier to have a portable model.
I don't know where you live but a GRE PSR295 looks like something you could use. It does (amongst other frequencies) 216-512 MHz in both AM and FM for $100.

[olsenn]

Try this: http://www.seeedstudio.com/depot/rf-explorer-model-wsub1g-p-922.html?cPath=174

It's a cheap handheld spectrum analyzer. I wouldn't normally recommend it for people looking for a high end measurement tool, but for your purposes, it would be ideal!

[dw8000]

olsenn: This looks like it might work thanks for the suggestion. Has anyone used this?



http://micro.arocholl.com/

[Smokey]

I'm not sure how much hacking you are willing to do, but the RF-Explorer thing is just a https://www.sparkfun.com/products/10153
essentially.  Which is just a dev board of sorts for the SI4432.  It's funny how that Chinese company just changed the name and logo on the SI data sheet.  It's exactly the same.
There are RFM22 Arduino libraries for doing exactly what the RF-Explorer does on a PC.

Another option would be to get one of the RTL-SRD compatible USB Dongles. 
http://sdr.osmocom.org/trac/wiki/rtl-sdr
I'm pretty sure I saw a spectrum analyzer application someone did for those.  At the very least, you could tune it to the frequency you are looking for and check out the waterfall. 

Nothing too fancy or accurate, but it would give you a good idea of what's going on.

[dw8000]

Thanks smoke dogg

[kripton2035]

I also have an rf explorer with 2.4GHz and <1GHz modules and I can confirm it's a nice piece of tester...
I don't use it everyday, but it already saved me for finding bad wifi wds configurations ...
it would be ideal for what you want to measure...

if you want to play more, you can use an arduino and this arduino module :
http://altelectronics.co.uk/shop/arduino/arduino-rf-433-92-mhz-shield/prod_78.html
it's cheaper, but you have to program it...

[dw8000]

thanks Aurora

[dw8000]

kripton2035 i didnt see any specs that go down to 290MHz. thanks for the info


http://altelectronics.co.uk/shop/arduino/arduino-rf-433-92-mhz-shield/prod_78.html

[Fraser]

I just realised, I failed to make it clear that the WSub1G module (or complete <1GHz RF Explorer) covers 240MHz to 960MHZ CONTINUOUS, no gaps. My original description made it appear to be <1GHz ISM bands only. Oooops ! 

Fraser

[kripton2035]

kripton2035 i didnt see any specs that go down to 290MHz. thanks for the info


http://altelectronics.co.uk/shop/arduino/arduino-rf-433-92-mhz-shield/prod_78.html

oups sorry didnt see - it goes only down to 315MHz...

[dw8000]

I think I am going to get the rf explorer. i,ll touch base if i do

[G7PSK]

Here is a simple RF sniffer that will tell you if the transmitter works.

http://www.macgregor.co.uk/support/faq/gen-2.htm

[dw8000]

I might just have to try this