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confused: spectrum analizer and sdr

Posted: Mon Apr 29, 2019 5:57 pm
by alidav
Hi, I am a sound technician and need a fast tool to make an rf scan quite wide, 430 -830 Mhz, to set properly all my radio mic systems avoiding any intermodulation issues.
I bought an SDR smart dongle, Nooelec, and downloaded some app on Mac and on a smartphone, but I have only a view of 2 Mhz.

I noticed that many colleagues use "Rfexplorer" standalone hardware,
my question is can I get the same result with this dongle?

Re: confused: spectrum analizer and sdr

Posted: Mon Apr 29, 2019 6:48 pm
by alanzfq
About 2MHz is all you get in real time. There are programs that build up a spectrum in slices but that would take a long time to do 400MHz even if any actually is capable of such a scan.
I guess the RF Explorer uses a much higher sample rate.
Alan

Re: confused: spectrum analizer and sdr

Posted: Mon Apr 29, 2019 7:33 pm
by snn47
I am confused if they are your PMSE why would you need to measure the frequencies you operate on?
Furthermore I doubt you have sufficient dynamic range with a rtl-sdr stick to measure in presence of much much stronger BC, TV or cell phone equipment. Even a SA like the R&S FSW13 with 512 MHz bandwith has Intermodulation problems i presence of strong transmitter.
As I said befor since you should know the frequencies of your PMSE equipment just calculate the necessary frequency offset necessary to avoid Tx-IM, I remember Sennheiser US has a tool for it.

Re: confused: spectrum analizer and sdr

Posted: Mon Apr 29, 2019 7:40 pm
by alidav
I hope in a displayed immediately help to set up all mic correctly, the main problem is the chaos of frequencies in many cities in Italy in big towns close the sea, tv stations and many illegal devices everywhere, very often is impossible to work with radio mics because of interferences and drops.

Re: confused: spectrum analizer and sdr

Posted: Tue Apr 30, 2019 6:53 pm
by dlritter
Yes.
Touchstone Pro from Nutsaboutnets.com is intended for use with the RFExplorer, it does support an RTL-sdr device and
the app defaults to the UHF Wireless Audio chunk from 470-600

I don't find my RTL at the moment to cert my statement as all I find at my desk is my Airspy mini and RSP1.
oh yes and my RFE.
However, they have the RF Viewer.. which is an RTL-SDR object.

But if your in the business, what you really want is ClearWaves.
good luck

Re: confused: spectrum analizer and sdr

Posted: Wed May 01, 2019 2:54 pm
by dlritter
Found my RTL.. Yes Touchstone Pro opens and address an RTL device without issue.

Re: confused: spectrum analizer and sdr

Posted: Thu May 02, 2019 10:17 pm
by Kenn
I use a netbook running Linux Mint and Pavel's Spektrum:

https://www.rtl-sdr.com/spektrum-new-rt ... -software/


It'll scan 430-830 just fine. Using 'Relative Mode' is key. With a rubber duck antenna connected directly to the RTL dongle on a short USB cable I can turn the gain down and use it to pinpoint noise sources. For example, in one location I found a dimmer that was generating a LOT of RFI in the VHF-Hi band that was blanking out a wireless audio link.



-K

Re: confused: spectrum analizer and sdr

Posted: Sat May 04, 2019 10:06 am
by snn47
I thought that you should also keep Receiver Intermodulation (Rx-IM) in mind, meaning that not necessarily all signals that you receive may exist in the RF-Envrionment, but can be generated in your receiver. Since I just answered to another post in detail on the effects of Receiver-Intermodulation in presence of may strong signal viewtopic.php?f=4&t=4656#p11054. I thought it might be usefull for you to get yourself also a variable attenuator and/or filter to ensure that you are not identifying signals that do not exist.