RE: Connection dropouts

[Bob M. <rvm@CBORD.com>]

> From: Greg - ZL3IX
> 
> Hi, I'm using TightVNC to access the PC at a remote amateur radio
> station that I run.  The remote server PC is running Win 7 and is
> connected via 3G, while the local client is running Win XP, and is
> connected using ADSL2.
> 
> The remote PC is running a software defined radio application, which has
> a continuously changing spectrum display.
> 
> I can always make the initial connection, but it always drops out after
> a few seconds or minutes.  The time varies, but it is seldom longer than
> 5 minutes.  Sometimes the spectrum display freezes, but I still have
> control of the remote radio.  Sometimes I lose control as well.
> Sometimes I get a notice that the connection has been lost, but usually
> there is no warning message.
> 
> Does anyone have any ideas why this may be happening?
> 
> I haven't found a help file for setting up TVNC.  There are quite a lot
> of parameters that can be set, which I have left at their default
> value.  Is there a help file or manual available anywhere?

The most likely causes are CPU overload on the server or bandwidth limitations between the units. TightVNC was never meant to pass real-time video, and your spectrum display is the equivalent of watching a video in a small window. It takes a lot of CPU horsepower to encode that ever changing image to send it to the remote viewer, and that produces a lot of data to be transferred.

You might try reducing the sampling frequency on the server so it only takes an occasional snapshot of the display. That is set using the polling cycle option in the server properties. Try changing that to 3000 ms or more.

Bob McConnell (N2SPP)