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RSP2pro vs cheap RTL ?

Posted: Tue Jan 31, 2017 3:07 pm
by wireman
Hi all,
I Just got the RSP2pro £190, The thing is so far its not picking up any signal that my cheap 'full band rtl-sdr' £26 off ebay hasn't been able to do, most hf ham bands and sw, long wires with and without ununs and grounds, various dipoles vhf/uhf, pressing the filter buttons doesn't seem to have any effect,audibly or visibly unless its a subtlety i'm missing, both boxes have been ran side by side on the same antennas, the sd play does suffer a lot less ghost spikes though which is great, do i have a faulty unit i wonder, the plastic green terminal block does fall off quite easy but connects ok,for now until it wears out, also i cant seem to find the button for the 10mhz spread

Re: RSP2pro vs cheap RTL ?

Posted: Tue Jan 31, 2017 7:15 pm
by g1hbe
The SDRPlay receivers are head & shoulders abve the RTL-type dongles. I started off with a dongle, but the noise level was high and the dynamic range was poor. The RSP-1 pushed the noise level down and there was far less tendency to overload. Of course you will only see the benefit of the lower noise level if you have a low noise level in your neighbourhood. Then I moved on to the RSP-2 and it was even better, with extra filtering etc. I'm not sure about your difficulty with the green Hi-z connector, mine seems secure. Be aware that the two SMA connectors work best above 1.6 MHz, the green connector is much better below. I've found the green connector when wired correctly is generally the best for HF and the SMA's are great for VHF.
The IF filters do what they do on other receivers, and the difference is perfectly audible. It's worth spending some time reading the user manual and the Cookbook!
I'm assuming you are using SDRUno software? If so, make sure you have the latest version which will give you all the new feaures. You won't get them with HDSDR or SDR Sharp (not sure about Console). In SDRUno, the 10 MHz span is there with all the rest in the drop-down menu from the SR(MHz) button near the PLAY button. Select 10 MHz and DEC 1.

Re: RSP2pro vs cheap RTL ?

Posted: Tue Jan 31, 2017 10:38 pm
by hfaero
I'm going to jump in here and echo the findings of @wireman. I'm only talking here about HF frequencies but I found that the RSP2 yielded little if any difference to my sight or ears versus a v3 RTL-SDR. As an experienced HF listener dx'ing aero I've had a few receivers in my lifetime but nothing really compares to using an SDR over an analogue receiver. However, I have found that performance of the wideband SDR receivers like the RSP or RTL-SDR at HF frequencies to be just about indiscernible to me.

I do notice that there are less images with the higher priced RSP or Airspy+Spyverter but if I'm after good performance on HF then a dedicated HF only receiver is the only way to go.

I've parted with my RSP2 now and as a secondary backup SDR I'm back to a v3 dongle.

Re: RSP2pro vs cheap RTL ?

Posted: Tue Jan 31, 2017 10:47 pm
by 13dka
To expand on g1hbe's good point here:
g1hbe wrote: Of course you will only see the benefit of the lower noise level if you have a low noise level in your neighbourhood.
There are probably a few ways to make the RSPx appear less sensitive, like overloading it to the point it turns deaf, or not utilizing the available gain reserves properly (which is essential particularly on VHF+UHF, even more with passive antennas) , but one of the possibly most overlooked issues when comparing receivers is local QRM. If the local noise is above both receiver's noise floors, there will be no discernible difference in sensitivity between both. This is particularly true on the top shortwave bands below 10MHz where local and not so local QRM is pretty much always limiting the usable sensitivity of any receiver. This gets better with increasing frequency and on VHF/UHF you should see at least little improvements in sensitivity and SNR over your RTL-based receiver.

I take it you have one of the BA5SBA designed "direct sampling" variants of the RTL SDR that should employ a R820T2 tuner, which is surprisingly sensitive (better than my pricey but crappy DJ-X11!). It has been a while since I compared the sensitivity of the RSP1 (RSP2 is identical in this regard) vs. an RTL-stick but I think this screenshot proves there is (or should be) a difference:
InmarsatRTL_vs_RSP1.jpg (54.6 KiB) Viewed 10689 times
This is a little active log-periodic antenna delivering Inmarsat signals to both receivers, I could see the Inmarsat ACARS transponders on the RTL, but only the much better SNR of the RSP1 enabled me to actually decode something.

Since you seem to be well-equipped with antennas etc. - another source of noise is quite elusive and often misdiagnosed and confused - massive QRM from within your shack with its switching PSUs, plasma screens and computers, creeping along your coax/feeder line all the way up to your antenna and covering it with noise, no matter how far away your antenna actually is, or how quiet the environment actually was before you connected the feeder line. This can't be solved easily by grounding or random clip-on ferrites and requires properly dimensioned common mode chokes, sometimes several of them in a row.

Re: RSP2pro vs cheap RTL ?

Posted: Tue Feb 21, 2017 11:45 am
by wireman
Thanks guys for those replies, there does seem to be a lot more testing and comparing i have to do, If in uno the look of the scope line is given more shading and colour options and dynamic, i could see things that are going on straight away like in sdsharp, higher peaks and troughs etc, All the rest of it i like, buttons, s-meter etc, plus have labeling within the scope showing bands and favorites like sharp has, a basic scanning function but that may come in the future, the green scope looks great in uno, if i can get the notches to end up doing something somehow it will all be great