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Smart SDR iOS audio glitches

Andy M5ZAPAndy M5ZAP Member


I am using smart SDR iOS on both my iphone 6 Plus and my iPad Pro. I operate both over 4g via a VPN into my home network or over wifi from within my home network.

I understand that the amount of audio buffer is limited by the acceptable latency and occassional pops and minor short drop outs are tolerated when on 4g network with framerate etc turned down to work accepatably with my rather poor 1mb/sec upload speed.

However when operating on my home wifi I get larger audio glitches usually as a set of 3 I guess about 500ms long and 500 ms apart resulting in lost/very broken audio over a couple of seconds. It occurs every 5 mins or so. I am using higher bandwidth at home but I also have a fast wifi homenetwork but these longer ryhmic glitches dont occurr on 4g. It occurs on both 2.4 and 5 ghz networks.

I put it down to other network traffic so disabled everything else on network and the problem still persisted. If I go into the wifi setup menu the exact same glitch occurs as it searches/scans for available networks to populate the available wifi networks list 

I therefore presume that the iOS device must whatever you are doing on the device periodically check the available networks present,  which is how I presume it will move from one to another of my access points if it sees a stronger signal.

Has anybody else observed the same problem which can be tolerated unless your mid QSO and is there any way known to stop the iOS device periodically scanning the wiFi networks.

Many Thanks Andy M5ZAP


  • RiaRia Member ✭✭
    edited November 2019
    Hi Andy,

    I don't think it's strictly due to the wifi scanning. I experience it if I switch tasks so I am guessing that the iPhone SoC sometimes just can't keep up or the OS will pre-empt the foreground task to do other things. Writing iOS apps it's difficult to control these things because Apple gives you so little control (and rejects your apps for using undocumented APIs). 

  • Mike va3mwMike va3mw Member ✭✭
    edited February 2018
    Hi Andy As thi s occurs on both networks, it is going to be hard to diagnose. I am going to go down the path of the Wifi access point. What make and model are you using? Are you using 20Mhz wide channels or 40Mhz? Are you using any beam steering? If so, try changing that (on or off). Since it does not occur on 4G, then we have eliminated the core network as that works and is not related to your wifi. Sadly, Wifi is not created equal and there is no standard. Essentially, you have change things and see what makes it better. We really need to tune our APs to the same standards the gamers do. Personally, I don't see the same dropouts you are experiencing. I have found that older dual band routers work much better than new ones strange as that seems. Mike va3mw
  • edited January 2017
    FWIW - I get audio drop-outs using my iPad Pro but have NO drop-outs using my two year-old iPad Air. I wish I knew how to remedy this... - Cliff
  • Andy M5ZAPAndy M5ZAP Member
    edited February 11


    Thanks for both your replies.

    I run a pair of Apple airport expresses as access points. Generally I only use the 5Ghz network as I am the only person in my immediate area using 5 gig

    The problems occurs if I run on 2.4 or 5 ghz networks

    The problem also occurs if I only have one access point on the network and I sit next to it.

    I also forgot to put on the origianl post if i go onto the same network with a laptop running Smart SDR under windows with no limiting of framerate or waterfall and two panapters with 4 slices then all is ok with only a very small amount of audio break up.

    I have tried the obvious and closed all apps on the device.

    It doesnt stop me using the iOS devices more an annoyance.

  • Mike va3mwMike va3mw Member ✭✭
    edited February 2018
    Hi Andy I knew you were going to say that. :) Streaming to laptops seems to work better on most access points. If you had another AP that you could plug into the Airport Express, I bet you'll find the problem goes away. I have found the AE hard to deal with only because it is a close box and very difficult to tune. Your are not the first to tell me this and also had streaming issues. We are still looking for a common thread as to why some APs are good and some are not. I suspect (and I am guess), it has to do with buffer sizes. Mike
  • Andy M5ZAPAndy M5ZAP Member
    edited February 11

    Hi Mike

    I use the access points with a BT Homehub as the adsl modem, I however disable the wireless on the homehub as it is generally poor performance compared to Airport Express. I will test at the weekend with the Homehub only and see how I get on.

  • Mike va3mwMike va3mw Member ✭✭
    edited February 2018
    I think we have the same HomeHub here in Canada (Sagecom). The wifi on it was terrible. I turned it off.

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