> Found an interesting program RTLSDR-Airband > https://github.com/microtony/RTLSDR-Airband > > Which allows up to 8 channels to monitored and fed to Icecast > servers...
Oh looks nice! I will investigate, hopefully this is easier than manually clicking around trying to listen to active channels as you visually spot a transmission. > The setup requires a center frequency to be used and then the > channels monitored need to be withing some "bandwidth" of the SDR > device used... > > *BUT* > > What is this max bandwidth allowed??? Depends on what you set it to. As you'll see one of the first specs listed for any SDR device is the maximum bandwidth possible, and for RTL2832 devices it's generally around 2MHz, but you can go over 3MHz if you don't mind the odd bit of signal loss here and there. This means you can decode say 2MHz of the RF spectrum at a time. Where is up to you - you could choose to decode from 120MHz to 122MHz, or from 121MHz to 123MHz, and so on. But two of the channels you list (120.65 and 124.5) are more than 2MHz apart, so you wouldn't be able to listen to these two at the same time. The centre frequency is just the middle of the two extremes, so tuning to 120MHz with a bandwidth of 2MHz will get you 119.0 through to 121.0. Note that an actual broadcast at 119.0 will go below 119.0 a little, so you should consider any channel at the extreme of the range unavailable for decoding. > Is this within in the "Max Bandwidth" of these E4K and RTL283U > devicess??? As above, generally you will have to stick to 2-3MHz so not all of those channels are within range. You will need a second device, or a different device with larger bandwidth, to receive them all at the same time. > The README never seems to outline what this, how I would find it, > etc... Don't take this the wrong way, but it's such a basic specification when you select your SDR device that it's taken for granted you know what it means :-) > Is this within the bandwidth of these SDR units??? Or something > narrower??? And thus 2-3 dongles are needed??? I could narrow this > down... a little more to: > > 121.500 > 124.500 > 122.950 > 121.400 This spread is 3.1MHz which is so close to the upper limit of 3.2MHz you may just be able to scrape through, but you will definitely experience some packet loss. > But the prime two targets 124.500 and 121.4 with their ~ 3MHz > separation I see being a problem.. Yes, you might just be able to get these two but you will likely get some interruptions as USB packets are dropped due to limitations of the RTL2832 chip. You might be better off getting a second device. Cheers, Adam.
