are these any good? - Page 1
Forum section: electronics / rf-microwave

author: silly sausage
author_rank: Regular Contributor
timestamp: January 20, 2025, 10:45:55 pm
content: just got one of these sdr things,are they any good,ive got it going using sdruno but the interface is a horrid mess, Are there any better programs to use these, sdr uno seems bloody aufull.

author: shabaz
author_rank: Frequent Contributor
timestamp: January 20, 2025, 11:24:58 pm
content: (changed subject heading from "are these any good?" to make it relevant).

author: pienari
author_rank: Regular Contributor
timestamp: January 24, 2025, 10:53:40 am
content: Im using SDRuno & RSP1A and it works really good vs. SDR sharp & chinese R820T2 / RTL2832U systems.I donno what mess you have made?.More advanced setting makes it just better but sw is not all what makes sdr shine.I can use high gain antennas without terrible harmonics.But.. what frequency range and bw you would need?

author: pienari
author_rank: Regular Contributor
timestamp: January 24, 2025, 11:01:17 am
content: Here is list for sdr receiver comparison.https://rssl.lk/2023/07/18/popular-sdrs/

author: radiolistener
author_rank: Super Contributor
timestamp: January 24, 2025, 03:00:10 pm
content: Quote from: silly sausage on January 20, 2025, 10:45:55 pmThis is MSi chip based device, the same as RSP1. I evaluate it as a piece of crap. If you don't want to listen strange noises, to see spurs and to fight with strange behaviors and bugs, just buy RTLSDRv3 or RTLSDRv4 - it has good performance and plain and simple controls with good and stable software/drivers. It's just works as expected and you will never notice all these bugs and issues, like it happens with MSi based devices.Quote from: pienari on January 24, 2025, 10:53:40 amThis is not true, from dynamic range and spurious performance point of view, all MSi based devices are significantly worse than RTLSDR based devices (820T* / RTL2832). There is very aggressive marketing pushing MSi based devices to the less knowledgeable ham radio community. Just don't listen to all this marketing bullshit, but look at the real technical specifications and usability.Software and drivers for MSi devices also very buggy and full of multi-threading issues and bugs. And it is not open source.RTLSDRv4 is the best what you can at 200 USD price range, it has the best dynamic range, sensitivity and frequency coverage.I have RTLSDRv3, RTLSDRv4, RSP1 and FPGA based SDR receivers with dedicated high speed ADC and can compare their performance. I never use RSP1 due to their spurs, noise and frequency gaps issues, it's just lying on the shelf. Usually I'm using RTLSDRv3.While RTLSDRv4 has better performance I'm using it to listen short wave, where it shine. The rest of the time I'm using RTLSDRv3, it is connected to antenna 24/7, so in such way it reduces probability to burn out RTLSDRv4 input from static/lightning electricity.The only pros of MSi based devices is 9 MHz bandwidth and a little bit higher upper limit of frequency coverage. However, the benefits of a wide bandwidth are offset by the abundance of spurts and noise. If you really need so wide bandwidth, it's better to use devices which utilize dedicated high speed ADC with FPGA processing. But this is not required at all if you planning to use it as a usual SW/VHF/UHF receiver.If you're needs wide bandwidth for spectrum analysis, it's better to buy tinySA.The main cons of MSi based devices are too many spurs, frequency gaps at short wave, low sensitivity at VHF and very annoying issues with noise and gain control. In addition there are a lot of bugs in drivers.Quote from: pienari on January 24, 2025, 11:01:17 amThis is marketing bullshit. It says that RSP1 has 14-bit ADC, this is false. You will never get the same performance on it as with fair 14-bit ADC. The root of their lie is that these 14-bit is just due to processing gain, which you get on any SDR receiver. The same you can say that RTLSDR has 14 bit ADC: (8×6.02+10×log(3200000÷500))÷6.02 = 14.3 bitAs you can see, the table from your link don't have dynamic range and sensitivity specification at all. It just manipulate with marketing numbers, "bits" and "MHz" in order to create the illusion of advantages for illiterate radio amateursYou can also notice another manipulation on this table it says that RTLSDR has sampleRate=3.2 MS/s. This is false information. RTLSDR ADC works at sampleRate=28.8 MS/s. While 3.2 MHz is bandwidth after applying DSP low pass filter and decimation. While MSi chip ADC works max at 10 MS/s.If you understand DSP and what is Nyquist border, it explains you why MSi devices have so bad spurious performance in comparison with RTLSDR devices.

author: pienari
author_rank: Regular Contributor
timestamp: January 24, 2025, 04:24:13 pm
content: I want to see who have get 3.2MHz bw working with RTL2832+820t2 combination?.Maybe 2.8MHz stable.I know this RSP1A sucs but in my case it works much better then RTL sdr.Good example is receive ATIS 135.450MHz 20km from my qth.Aerial dipole antenna 9m from the ground.RTL based sdr i get really bad rx.Old SDRsharp was better then new airspy version in this case.SDRplay RSP1A i get much better rx without strange noisefloor.Gree Air heat pump 7m away from antenna.I know my GREE Air heat pump is making me nuts because it is making so much rf noise and in house electric system.Watch this.https://youtu.be/c9EYSO5l0RMIn 4m band i get really good results with RSP1A and 6el quad antenna.I like to listen 4m band and RHA68 in Finland 67.500-72.325MHz.

author: tooki
author_rank: Super Contributor
timestamp: January 24, 2025, 04:35:28 pm
content: Quote from: shabaz on January 20, 2025, 11:24:58 pmNo, you didn’t. You only changed it in your reply, which does not apply to any other posts, including the original post. The OP or a moderator needs to go back and edit the original post itself.

author: radiolistener
author_rank: Super Contributor
timestamp: January 24, 2025, 04:47:46 pm
content: Quote from: pienari on January 24, 2025, 04:24:13 pmIf you cannot get better SNR and spurs with RTLSDR, it just means that you use it in the wrong way. The usual mistake of newbies is enabled AGC or don't adjusting gain for better SNR.My RTLSDRv3 can receive very weak stations on VHF and air band, which is even don't visible in noise floor on MSi chip.Also you need to use good RTL dongle, like RTLSDRv3 or RTLSDRv4, because the market is full of cheap clones which may suffers from PCB layout and schematic issues. For example, USB RF-choke filter may be missing on some cheap clones and it may lead to high interference.Also consider that the cable, computer radiation and radiation in the room where you use the device have a strong effect on the noise level, so it is important to pay attention to this issue. If you use cheap devices with missing a filter for USB, this can have an extremely negative effect on the noise level and as result you will be unable to receive very weak stations.And I must point out that the effect of the cable and interference from the computer and in the room is very significant, which many people neglect.Quote from: pienari on January 24, 2025, 04:24:13 pmIf you use Windows, I recommendHDSDR, it is much better than SDRsharp or SDRplay. I didn't seen better software for SDR RX on Windows, it has pretty good filters dynamic rage and low CPU usage.On linux you can use SDR++, but it has some issues with spectrum gain and filters dynamic range is not so good as on HDSDR.I fixed spectrum unity gain in my mod:https://github.com/qrp73/SDRPPIt also has fix for spectrum zoom, mouse wheel support and other things, like file source which supports more WAV formats and has playback position slider. Also it has custom HPSDR module for HPSDR protocol devices, you can use it with Radioberry for example.Also I replaced SNR meter with level meter which also shows both - peak level and SNR as numbers. And added red triangles to show LO frequency on frequency ruler (see screenshot below for details).By the way, Radioberry with its 12-bit ADC has significantly better performance than RSP1, just try it and you will notice that it has better dynamic range, almost no spurs and pretty high sensitivity. I recommend to use it with Radioberry Juice board.Quote from: pienari on January 24, 2025, 04:24:13 pmRegarding to "strange noisefloor", it just confirms that you don't understand how to control the gain and how it affect the noise floor.Strange and unstable noise floor is the main issue of MSi based devices, but not RTLSDR.RTLSDR has very stable and predictable noise floor.When you set gain too high, it leads to ADC overload and as result you get a lot of non-linear distortions due to signal clipping, it increase noise floor. So, it's important to keep gain high enough to get good sensitivity, but at the same time low enough to not get ADC overload.When you know this, it's not so hard to learn on how to properly adjust the gain to get good sensitivity and SNR. Unfortunately there is no way for simple and plain gain setup with no side effects on MSi devices, so I recommend to learn it on RTLSDR where it works simple and predictable.Here is example of RTLSDRv4 reception on Medium Wave band:On short wave:Notice the difference between station peaks and noise floor. This is dynamic range. You can see station SNR level below peak level value on level meter (SNR 54 dB and 62 dB). On MSi it is much worse and unstable (very depends on LO and gain settings in non-linear and non-predictable way).I also should mention that MSi devices have very bad and unstable DC offset noise. You can easily detect it, because DC offset peak on RTLSDR can be easily and completely removed with reject filter with 1 Hz bandwidth, this shows that RTLSDR DC offset is very stable and can be easily removed.While on MSi devices you will be unable to remove DC offset even using reject filter with 500 Hz bandwidth. This is a clear indication that MSi devices have very poor DC noise with wide bandwidth. As result it affects overall noise floor and spurious performance. And you will be unable to receive weak low SNR stations which can be received with RTLSDR.

author: pienari
author_rank: Regular Contributor
timestamp: January 24, 2025, 08:25:23 pm
content: You are totally right, i have used SDR about. 10 years now and used it wrong all time but i try to learn every day.But im not noob with SDR technicue, at my work i was repairing and testing 2.5yrs military SDR radios so i know something about them.Here is too much manmade noise to rx anything under 8MHz so i have antennas only 27Mhz to 450MHz.Im really curious what is the noisefloor with your RTLsdr v4 at 70MHz?.With. RSP1A @ 6el quad 4m band (10.5db gain) feeded with 1/2" coax.-124 to 120dbm FM 10khz (depending on my neighbor's rfi noise level)RSP1A receive better then my 4m radio.Im pretty sure my last RTL v3 was expensive genuine one.Edit.My next SDR will be tx/rx .. maybe Adalm Pluto +.

author: radiolistener
author_rank: Super Contributor
timestamp: January 24, 2025, 10:04:29 pm
content: Quote from: pienari on January 24, 2025, 08:25:23 pmIf you don't know something, it doesn't mean you're a noob. It's impossible to know every detail about everything, and that's perfectly normal.For example, I have an in-depth understanding of DSP mathematics. I know how it works, I am familiar with the algorithms, and I have developed SDR receivers both in software and on FPGA. Yet, I still don’t know everything about it.I firmly believe that it is impossible to know everything because the more you learn, the more you realize how much there is yet to discover.Quote from: pienari on January 24, 2025, 08:25:23 pmI'm not sure that I have precise signal source to test it.Just tested it with signal generator with 70 MHz, 55 mVpk=-15.2 dBm output and 120 dB combined attenuators (40 dB+30 dB+20 dB+10 dB+20 dB) connected with coax cable to RTLSDR.In theory it should be about -135 dBm, but there is possible some parasite leakage.RMS noise floor is measured with HDSDR calibrated at -135 dBm for carrier. It shows -155 dBm at 500 Hz bandwidth.It looks a little bit below thermal noise floor, so I think there is some signal leakage and real power is a little bit higher than -135 dBm.Here is how it looks on RTLSDRv3:And here is RTLSDRv4, with the same 40 dB gain, noise floor is about 5 dB better:Technically at 70 MHz, 10 dB SNR sensitivity appears to be about -145 dBm @ 500 Hz.But as I said, I suspect, there is some signal leakage through attenuators, so the real signal probably a little bit higher and sensitivity probably is a little bit worse.Unfortunately I don't have more precise signal source for so weak power.Quote from: pienari on January 24, 2025, 08:25:23 pmYes, here is also too many noise. The picture was taken during power outage of entire city (2 million population)...