Linksys/Cisco SPA3102 broken promises

My Linksys VOIP ATA was acting up, refusing to call one of my SIP services even though it claimed it was registered. I was on firmware 5.1.10 which has been the latest for a few years. Searching the internets for news of any update, I stumbled on the unfortunate tales of promises unfulfilled, as expressed in these threads:
right through to

and then ending up here

Basically, I’m facing the same problem as many. The ATA works fine until you make a call through your PSTN connection. This switches the SIP codec to G711u and locks it there. If you have a SIP service that demands something different (G711a in my case), you’re out of luck and the only option is to reboot the ATA. Any options you set are disregarded after the PSTN call.

I learnt from the discussions linked above that for three years, a group of dedicated owners have been chasing Cisco for a firmware fix. Support promised that the fix was in testing for years, continually pushing forward the release deadline. The last promise was US Summer 2011, and thats long gone now.

As someone who has worked for the last 22 years on many projects (including commercial simulation, realtime systems and satellite modems) with a release cycle measured in days or weeks, all I can say is that it was good to be made aware of this sorry 3 year saga before I upgraded the ATA with something new.

For now I’ve downgraded it to an earlier firmware version (5.1.7) which doesn’t have the annoying and stupid bug.

Stuttering Audio Fix for Asus EEE 1000HE

The not so new EEE PC was experiencing intermittently stuttery audio when playing a Flash based radio stream. This was strange as it coped fine with MP3 and WMV streams, even with video. It wasn’t a buffering issue. The audio had very short glitches – the kind of thing that happens when a device driver locks the bus too long (he says, having worked on a Linux audio driver a few years back).

The wireless drivers were up to date and the wireless hardware configured to use CAM mode (a problem that plagued the ION HTPC when I first installed XP on it). Power management settings were set for high performance.

I also determined it was no where near running out of CPU, sitting at only 10% when playing the stream. After updating drivers, firmware and minimising the configuration as much as I could, I started thinking it might be network related.

I set up a regular ping of length 8192 bytes from my workstation to the EEE so I could see what network performance was like. I was only half surprised to find that ping times were all over the place, with some peaks in the 100s of ms. With the audio streaming, the high peaks corresponded with glitches in the audio.

With it happening even when close to the WNDR3700 wireless AP, it wasn’t a signal level problem. It was connecting at 130mbit (N speed) on the 2.4GHz band.

I switched the router to limit 2.4GHz to 54mbit and the audio problem went away. Ping times to the EEE became a solid 4ms.

Looks like its a combination of crappy behaviour for the EEE’s wireless driver in “N” mode and the Flash Player using a very short audio buffer, making it easy to underrun audio playback. Fortunately I can handle the slower 2.4GHz network since I run a separate 5GHz network for the HTPC.

Samsung Galaxy Note / AM Radio Hack

I’ve discovered a unique hack with my Samsung Galaxy Note phone.

It was playing an audio podcast and sitting next to an AM/FM clock radio (in AM mode). I tried tuning the radio around just to see what the phones digital interference sounded like.

To my amazement I found I could tune in the audio playing on the phone, very clearly, in multiple places on the dial. Testing with a radio with a digital tuner,  I found 855KHz was a good spot.

It works best if the audio level on the phone is quite low and the screen is off. The AM radio makes a nifty audio power amp. Its not perfect, if the charger is plugged in things get really noisy … and when the phone polls the GSM network it makes the radio buzz, as you’d expect if you’ve ever left a digital phone next to a radio.

I’m guessing the phone uses a switchmode audio power amp which happens to make an effective very short range transmitter.