Dont know how valid this is as I am not experiencing issues but W6KD thoughts??
Link to Blog
<<http://vk5rex.squarespace.com/blog/2013/2/6/important-information-for-dvap-dongle-and-g4klx-software-use.html>>
VK5REX D-Star Repeater
Blog
Important information for DVAP Dongle and G4KLX software users!
Wednesday, February 6, 2013 at 7:16PM
During the PapaSys Thursday night D-Star Round Table on 31st January 2013 (REF012 C), I heard something that immediately grabbed my attention.
Sean KK6BEB (and at least one other person during the evening) mentioned a post by Robin Cutshaw AA4RC on the DVAP Dongle Yahoo group.
groups.yahoo.com/group/DVAPDongle/message/2063As several people have experienced, there is a flaw in the 3rd party software
for the Raspberry Pi. The software wipes out the calibration data that is
programmed into the DVAP at the factory.
If you use the software, you will have to recalibrate using the DVAP Utility
software. It probably won't get you as close as factory settings but can bring
it back to usable.
73,
Robin
AA4RC
I found this message very interesting due to my recent experimentation with the DVAP Dongle and the G4KLX ircDDB Gateway & DVAP Node software. Personally I had not experienced any problems with my Raspberry Pi/DVAP Dongle/G4KLX Software combination. I have used both the Windows versions of Jonathan's software, and more recently the Linux versions. Hans DL5DI has made it very easy for amateurs to get the G4KLX software running on different Linux platforms. My Portable D-Star HotSpot works very well.
I had also recently had an email exchange with Jonathan KK7PW about getting the G4KLX software working on the Raspberry Pi and some strange "R2D2" that he has been experienced with his DVAP Dongle but only with his IC-91AD radio... maybe this was related??
I sent Robin an email about his message asking for more information and then started to look more into this. I downloaded the DVAP Dongle Technical Reference PDF, sat down and started to have a good read.
On page 28, (section 7.6.12.14) I started to put the pieces together...
7.6.12.14 DVAP Frequency Calibration
Purpose: Sets the reference frequency calibration of the DVAP.
Control Item Code: 0x0400
Control Item Parameter Format:
The first 4 parameter bytes are a 16 bit frequency offset value in little endian format.
The nominal crystal reference frequency is 19.6608MHz and this offset value is added to the nominal
reference crystal value when calculating the PLL output frequency.
The adjustment range is +/-2000Hz or about +-100ppm.
Example: Set the DVAP crystal reference frequency offset to -230Hz (0xFF1A):
The host sends:
[06][00] [00][04] [1A] [FF]
The Target responds with:
[06][00] [00][04] [1A] [FF]
This frequency calibration value is added to the reference crystal value to allow for component variations and to align the "dial" frequency with the actual transceiver frequency in the DVAP Dongle. This is not unusual, virtually all radios have a method of adjusting the reference crystal frequency. Adjustment can be done by various methods including a trimmer capacitor in series with the crystal & varicap diodes under manual or software control.
This DVAP Frequency Calibration value is set in "the factory" and should not need touching again. While I have only one DVAP Dongle, I would assume that this value is fairly unique for each unit.
I then started to look at the G4KLX DVAP Node software and configuration file. I recalled a setting in the dvapnode_1 config file called dvapOffset...and in my file this was set to 0 (zero). I never really paid attention to the this parameter or the value... as mentioned before I had not experienced any problems at all. I then started to think that setting this value to zero might be a problem.
I took my Portable D-Star HotSpot to work on the following Monday morning to do some further tests and observations on my IFR 500A AM/FM test set.
I downloaded Robin's dvaputil.exe software from the
www.dvapdongle.com website :-
www.dvapdongle.com/downloads/DvapUtil.zipWhen I started it up and pressed the "Connect" button, the first thing I noticed was that the Freq Calibration value was zero!
I connected the DVAP Dongle SMA antenna socket to my radio test set and checked the TX On box in DVAP Util. I was instantly able to see how off frequency my DVAP Dongle was with an offset value of zero!
My IFR 500A was on the 3K scale when the above photo was taken. The DVAP Dongle was around 1.35 kHz low with the DVAP Frequency Calibration value set to zero.
I found that the value needed to be around the -125 to -175 region to bring it back on frequency. I also noticed that the frequency seemed to drift a little the longer it transmitted. When the DVAP Dongle was "cold" a value of -125 was almost spot on, but after a minute or so of transmit the value needed to be decreased.
Having access to a radio test set or accurate frequency counter is essential to work out what Frequency Calibration value your DVAP Dongle requires.
If you don't have ready access to test equipment, in the short term I would recommend setting it in the -125 to -175 range and see how you go.
Also make sure you update your G4KLX Repeater software to version 20130203 (or later) or you will be undoing your recalibration work. Jonathan G4KLX has removed the dvapOffset "feature" from the DVAP Node software from this version. Both Windows and Linux versions are affected and need to be upgraded.
Through emails I have received from others, the ID-31A and ID-51A seemed to be affected more than older radios. I knew that amateurs using GMSK HotSpots with the newer radios needed to tweak the transmit deviation, too much deviation is bad! The receiver passband of the ID-31A and ID-51A is narrower than older radios. It's quite possible that if a DVAP Dongle is off frequency then the newer radios might have trouble decoding the transmissions.
If you aren't using a DVAP Dongle with the G4KLX software then there is no immediate need to update.
