Lag

I was up early and tuning the band and heard HL0NHQ on 40. It was perfect gray line time but the storm QRM kind of precluded my contact. I was able to hear him but he was dish water weak so I decided to make a blog entry

I got into a recent pissing contest over on EHAM with old Stan K9IUQ regarding the "lag" of the CW side tone. A fellow was interested in the F3K and wondered about the "lag". Stan is a bit of a misanthrope who likes to knock the F5K all the while claiming to be objective, so I decided true objectivity could be had by publishing an audio clip the demonstrated how the F5K actually sounds

The reason the Flex radio can do so many amazing thing is because after the signal hits the antenna there is a whole lot of computer processing going on before the audio hits your tympanic membrane and courses into your metenchephalon headed for your consciousness. In the old SDR-1000 days the lag was substantial. There was virtually no way you could use the sidetone in the radio to send code because what you heard in your headphones was "lagged" by at least the length of a dah. It was maddening. What I did to over come in in those days was to have the Flex audio mixed with the sidetone output of my keyer on a 3 channel stereo mixer so I could hear the radio and hear the sidetone from the keyer in the same headphones. That is basically all over, at least to my ear.

After all the kvetching from Stan I decided to make a recording of what my radio sounds like so people can listen for themselves and make a judgment. My keyer is set for 32 wpm

Sidetoneplus.mp3

What you hear is a mic recording of the sidetone of my keyer (the 500hz note) and the 350hz note of the side tone in my F5K I have my F5K set for



Audio buffers of 512 and panadapter bandwidth of 96K My DSP transmit buffers are set at 512 and my receive buffers at 4096


I have my transmit delay set to 60ms and you can hear the transmit relay clicking in the background as I send test. This gives you an idea of what hearing between words means, as you can hear the relay drop between words and letter sequences. With the relay set to this delay My rig is semi-breakin and I can hear between words in a normal 25+ wpm qso. The keyer is my USB winkey and I send the transmit signal into PSDR over a serial port into the computer. I do this so I can have 2 paddles attached to the radio, one to the keyer and one to the back of the radio. This has been my keying methodology since the SDR-1000 days.

So now you can put to rest all the opinions from the know it alls and make your own decision regarding the lag issue and the Flex line of radios I have no problem using the sidetone in the radio to send code up to 60 wpm which is the upper limit of my keyer not to mention my addled old brain and my creaky old joints. You can also hear that I have none of the so called "squelch tail" problem with these settings. The audio is clean with no pops added. I don't have a very fancy computer nor do I bother with worrying about latency. My computer is a shuttle core 2 quad and 3 gigs of memory

73

So where do we go from here

Sorry I haven been absent for the past 6 months. My professional life has been basically sucking the breath out of my hobby time and I haven't had much time or energy to devote to my ham radio and blogging duties. Hopefully things are slowing down to enough of a dull roar that I can allow my ADD to take over and start to populate this blog with some new information.

Since my last post Flex has released the F1500.


I don't have one yet but hope to obtain one in the near future. I got to play with a prototype at Orlando earlier this year, and if you are interested in learning something about SDR but don't want to invest a lot of money this is the way to go. For $649 you will have a fully functional SDR QRP rig with all the bells and whistles of PowerSDR. More to follow on this little beauty


They also have the UHF/VHF module for the F5K. Above is a picture of this transverter board installed inside the F5K. This module has a VHF UHF transverter of 60 watts each and allows full duplex and crossband operation in all modes supported including satellite, repeaters etc. PowerSDR is already fully complaint with all transverters. I used a TenTec transverter with my SDR-1000 set up and it worked great for SSB and CW

Here is a shot of the transverter set up screen in PSDR


In this shot I have highlighted 5 transverters. Note you can adjust virtually every parameter necessary to get a transverter working LO freq direction of VFO such that a LO that tunes from low to high or high to low will cause the readouts on PSDR to be correct. It controls any preamps and the IF gain of those as well as power output on a per band basis so you don't fry your transverter

Here is a shot of the normal PSDR band switch


Note the VHF+ button in the lower left Here is what you get when have set up the transverter form such as I did above and you tick this button


Pushbutton access to all of your transverters automatically configured.

Here is a shot of PSDR with the 2M button pressed


I do not have my 2 meter transverter hooked up at present so this is a bit of a mock up but as you can see all of the PSDR horsepower is ready to go.

On the other fronts, we continue to work on improving the SO2R nature of the radio and work out a few bugs. Steve K5FR is redesigning DDUTIL's contesting engine into a server client model which should substantially speed up things in the CAT channel and improve responsiveness. We are looking at designing a contest interface that mates specifically with PSDR so with a contest front end and a well honed DDUTIL back end things are getting interesting. More to follow as things progress

73