Re: [Freetel-codec2] Comparison between digital voice and analog narrowband FM on weak signals with interference

As long as you look after an overload or an intermodulation condition, I don't see a problem with the RTL-SDR. The phase noise wont matter for low density modulation types like QPSK... But as Helmut says, looking after the overload or intermod , SFDR condition will be very important 8 bit is

Re: [Freetel-codec2] Comparison between digital voice and analog narrowband FM on weak signals with interference

well, 2.4 GHz (compared to 70-500 MHz), a short delay profile will be what you are working with, but with a high likelihood of 0dB echos. The echoes tend to get quite strong due to the large reflective surface performance. But there tends to be alot of them, rather than 1 or two dominant echos .

Re: [Freetel-codec2] Comparison between digital voice and analog narrowband FM on weak signals with interference

Hi Adrian, everything better than the 8 Bit RTL-SDR improves the chance for meaningful test results. I think all available 12 bit SDRs like Ettus B200/210, but also your LimeSDR-Myriad (LMS7002M) or a configuration using the AD 9364 would be a better choice. 73, Helmut

Re: [Freetel-codec2] Comparison between digital voice and analog narrowband FM on weak signals with interference

Hi Glen, On 9/18/17, glen english wrote: > > It would not improve the performance in a low local multipath dominant > two tap local delay scenario like rural/farmland. > I would be very curious about the dB levels vs. frequency. From my knowledge, above 400 MHz is highly

Re: [Freetel-codec2] Comparison between digital voice and analog narrowband FM on weak signals with interference

Hi, Do you have a particular device in mind? Anything that is supported by Osmosdr can be tested, but I only have AD9364 and Lime Micro devices available. 73, Adrian On 9/18/17, Helmut Oeller wrote: > Hi, > > IMO objective and severe comparison in presence of interference can

Re: [Freetel-codec2] Comparison between digital voice and analog narrowband FM on weak signals with interference

Hi Greg True diversity (2 x omni) receiver wont fix the long echo scenario it is likely in that scenario both diversity branches will cop the same (bad) delay profile . However it would likely improve the performance if there was a very high level of local multipath, as such decorrelating

Re: [Freetel-codec2] Comparison between digital voice and analog narrowband FM on weak signals with interference

Hi, IMO objective and severe comparison in presence of interference can only succeed using appropriate SDR hardware. These USB sticks are not developed for narrow bandwidths due to very low SFDR, phase noise of LO etc. 73, Helmut -Ursprüngliche Nachricht- Von: Adrian Musceac

Re: [Freetel-codec2] Comparison between digital voice and analog narrowband FM on weak signals with interference

Hi Alex so the ETSI HTx 6.2.2.4 propagation profile is specified as : two taps, ratio 8.6dB tap delay : 1/4 TETRA symbol (12.5uS) In my opinion, this is completely insufficient. Any arse can pass that. A more realistic test would be two taps 0dB, and 25uS delay. That's reality Their EQx

Re: [Freetel-codec2] Comparison between digital voice and analog narrowband FM on weak signals with interference

On Mon, Sep 18, 2017 at 9:14 AM, glen english wrote: > The only real fix is slowing down the symbol rate. A true diversity receiver is also a real fix. -- Check out the vibrant tech community on

Re: [Freetel-codec2] Comparison between digital voice and analog narrowband FM on weak signals with interference

Hi ALex well ETSI can say what they like, but unless the system is long delay multipath tolerant, it will be a poor performer with respect to analog if a hill gets in the way with another hill behind it... This is not a rayleigh flat fading scenario, this is a frequency selective fast fading

Re: [Freetel-codec2] Comparison between digital voice and analog narrowband FM on weak signals with interference

Hi, Helmut, for me RTL-SDR support is required. I will not be testing with another SDR hardware for reception as my application is meant to work with the USB stick (small dynamic range or not). Glen, have a look at http://www.etsi.org/deliver/etsi_etr/300_399/30001/01_60/etr_30001e01p.pdf

Re: [Freetel-codec2] Comparison between digital voice and analog narrowband FM on weak signals with interference

HI Adrian good stuff! OK, now try the analog versus the digital, with a copy of the TX signal at 30uS delay and -10dB with respect to the wanted signal (a common multipath ) , and also 30uS delay and 0dB. Let me know... On 15/09/2017 9:10 PM, Adrian Musceac wrote: > Hi, > > I present a