Testing remote SDR systems

Testing remote SDR systems

Updated Feb 21, 2019, 9:53 PM  As many you do today i am also using a web SDR system. It stated around 4 year ago when global tuners were the main way of tuning to a remote HF system, and I’m sure that someone from you already tested one of them so far.     Here i will post some of my thoughts and reviews regarding these remote systems in draft due to medical parent reasons. that grab me more than 3/4s of my life. I’m uncertain if i will find the time to revise that. Please accept my apologies.  Yu may also comment below for amendments or anything other you think necessary  The first to notice here is the global tuners facility which unfortunately i don't remember so well. the only I can remember is the feeling of using a remote receiver that is controlled by a computer. Fortunately, these computers perform better than mine which is a full noise receiver. The radio is in between the computer tower and the 23" monitor and the times the PC does not operate (i.e. 95% the time) the secondary mains power splitter uses a switch to turn off all the connected equipment.  The router is over the PC and is connected to the main power splitter that also connects the receiver a LED lamp and the secondary mains power splitter.  MY tablet is also the same. This F&U tablet and its adaptor have also quite strong noise levels. The adaptor disconnected can also transmit some noise if a radio is very close to it. To add to the topic i spend too much time using the tablet then the PC. The PC is used only once or wice per week for just 3 hours max wehn the tablet can be used as long as ...12 hours per day. The reason is that I am jobless and my most time was spent in writing till my father's sickness problem.     Parentheses stops here with the noises caused by computers.    Glob tuners as idea was very good and was relatively easy thought the sole process was very time consuming if you want to monitor the band. IN contrast just working with preset frequencies is much better and faster. THis is one of its major drawbkacks. Dont forget, it is a netwirk of receivers connected into PC in contrast to the newer systems with PCB receivers or external interfaces.  Web SDR was the next option on around 15 or 16. I’m unsure on when they started. I used the Twente SDR since then which is the best among all others and the only one that uses the full band.  I have tested more than 10 spots across the globe but Twente is surely the best due to its full span that covers all the SW bands and still has the higher payload. I could prefer if at least 4-5 spots used the full frequency span so that i can make my own comparisons to several stations around the world that include my favs from Msia or any other useful SW stations.  Memories is its best feature something that Kiwi still lacks.  hurryingly waiting when they will add it  The web version is very simple self-explaining. Just the basics:  -Spectrum , freqs etc   -very few adjustments for waterfall with 3 speeds and 4 sizes .waterfall can be changed into spectrum.  -AM FM SSB and in several spots with AMSync  -recording facility with freq and time ID file. -keyboard usage of most operations.  -S-meter plots. for unknown reason the plots are not linear as i remember from the analog system of the 90s but a series of dotted lines that seem as a kind of chaos. Possibly faster tracking could help more in an operation i liked very much older times.   One great drawback: Once you visit the SDR centers you on the 14 MHz band then you have to change the frequency. I have never given a callsign to know if the radio can restart from an older session as with kiwi.    Kiwi Sdr iis now its main rival.I have used it around 17 adn then stuck with it adn its nice inetreface that seems more professional adn rich than its rival,and continuously  updated .if you dont know Kiwi SDR is a 'commercial' SDR  priced around 300USD and ofered via ebay and direct from their web page and connects into your router. Their philosophy was not to be a  one's SDr sut rather a shared system,. It uses a built  in microcomputer and the main radio card adn everytihng is made via a web browser  . Its interface and control panel are  better than the simplistic  of WebSDr  Too many featues are used  comparing to WebSDr as the decoders with I-Q except the FM.SSB, and AM that WebSDR (WSDR then ) uses . KIwi Sdr haa also the features below that Web SDr does not have:  -IQ demod does but seems a very funny demod to listen to a 'point that moves between the two earphones ' Actually it is used for providind raw signal  for external decoding programs as DREAM , MultiPSK etc. similar to other standalone SDRs of the market (RSP models , Airspy ec) -full Swband in all SDRs tested It is also nice to listen to the local MWs in all  sites . -More than 350 spots in 10 Dec  with less than 100 for narrow band or in  VHF etc . -seprate spectrum graph with amplitudes from the main consele  A newer version of the OS adss smoothing and max levels  -retune to the last station you visited the page. -adjustable bandwidth for all  decoding modes ,mouse controlled for both sidebands and 'memorized' if you return back later  -many adjustments for the waterfall including auto and 14 levels of  zoom. in the same tab.These parameters can clean the noise from the waterfall. Also some options  to change the colurs  -audio filters with NB and autonotch, decay and more from the audio tab of the consile  -separate tab to watch other users  and clik on other's basic reception parameters  -usage also with other SDrplay or specified card mounted into the motherboard  that costs around  100Eu (good price  same as RSP1) -various very useful extensions (plugins) that can be used to decode rtty fax sstv loran navtex and cw modes. However, if there is any unlisted FSK (RTTY) station from its database you need to adjust manually around 8 parameters for RTTY and never be assured. The fax mode is closed project but works fine. CW is not 100% sure and can’t be used for poor signals Navtex worked 80% well even if the signal was very good. There is a very interesting feature called TDoA that can be used as a radio direction finding mechanism of unknown signals  -There are several separate useful extensions as IQ   and S meter.  S meter can show a trace of the signal per the time as with the plot in WSDR but its traces are much more 'analog' than its rival. . I wish  this opration installed as a button  inside the console The IQ meter reminds me the use of oscilloscope to analyze the spatiality a stereo sound in 'orthogonal view'.  -easy programing from the URL for some options very similar to DOS  command line from the adress bar. .  -wish also later to include ISB decoding (3325RSG?itis bad that station closed  down two moths after  ) -and also a simplifid version for mobiles    Some draqwbaks of the Kiwi :  -recording doesnt  work in all kinds of tablets as tested with other than mine tablet.  -no memories as with WSDR  . This is  posibly the most forgoten thing  -up to 4 or 8 users max by design That lowers the usageof waterfall and other panel options WSDR can handle unlimited users. BUt you can  check what others monitor.I found a random frequency for pirate greek operators while i checked on a spot in Italy .   -a 'fake' chatbix  with someone via a userID.Thay happened  once with a radio pirate.WDSR has more capabilities between its users  -time limits  in most spots today. I dont know on how is defined ut the limits can be either for a given frequency (30 mins ) or by use (5 hours as one example ).  -easy to freeze temporarily  regardless of the operation system ie tablets or PC if you operate your broswer with more tabs  . Happeens also sometimes with  WSDR  -smartphones  are too small to use for Kiwi and the browser seems  to freeze or cant start the engine . In contrast tablets above 7' can be used well but most times freq change keyboard controlled  requires the tablet to turn laterally. WebSdr mobile can be used in smarthones and even in chrome as in my xiaomi witout any problem ecept rare cases of noise.    As for result i pefer the kiwi system in my tablet abd PC  that has much more useful operations then WSDR . WSDR is now used very rarely and only in the smartphone Both systems  hav good audio but sensitivity varies  depedent to the antenna used  There is a common problem for both systems: they very easily can break reception.  Thi can be hapened either by the abrupt stop of DSL coenction or if somethin happens to the "rig's" system be from computer or by the sdr card in case its  mother board 'freezes'  ..      Another  important problem comes from the reception system. I have tested  more han 40 spots and understood that: 1. not all systems have the optimal  configuration  so computer noises or other noises pass the system  2.most antennas have not fully tested to provide  noise rejection. Her are some spots that have more nose than signal ! 3. Also by the time evral clear systems degraded their noise deletion!  4. Supposedly also the sun increased ...its noise as read in a FC group    And another personal feeling here : One of my "wettest radio dreams" on 90s was the usage of a functionary  4D micro display or 'space hole' in which you could  look interactively to any point 'live'  in the world. This 4D display is determined by the  basic coordinates of the point that include  LAat/ Lon/ height /3-angle and zoom  Using a wire as antenna,  passed  it  thru the display or space hole  it is a perfect way to listen radio stations in all bands if not also for watching TV. And with crystal clear noise free sound    THis  idea is now relizal ble with both SDR systems for HF bands and with streaming radio as replacing the remote space hole reception.>However  there are stil man omissions fom my  perfect or ideal example as there are so many places in the wird that are not covered with Kiwi sdrs on South America or Africa and Oceania . A goo example si  Benin1566kHZ that can be head in my house occasionally when the local pirates are off but cant be heard in  any other  online system with better signal. Anyway the sense of listening to a very remote station that soul never be heard before is a marvelous experience!