Why only 4 DAX IQ Channels for 6700

  • 1
  • Question
  • Updated 2 years ago
  • Answered
With the ability to have up to 8 bands active at the same time on the 6700 why are the DAXIQ Channels limited to just 4 when there are 8  DAX Channels available?

I recently installed CW Skimmer but I can only monitor 4 bands at the same time with CW Skimmer due to the DAXIQ limitations even though my 6700 is monitoring 8 bands

Is this a hardware limitation or software limitation? If software are there any plans to expand to 8 DAXIQ in the future?
Photo of Pat N6PAT

Pat N6PAT

  • 846 Posts
  • 270 Reply Likes

Posted 2 years ago

  • 1
Photo of Ria - N2RJ

Ria - N2RJ, Elmer

  • 2314 Posts
  • 956 Reply Likes
That is a great question. I’ve also wondered that myself.
Photo of Mark WS7M

Mark WS7M

  • 505 Posts
  • 153 Reply Likes
I donno... Maybe the guys/gals that wrote the code only had a 6500?  :-)
Photo of Ria - N2RJ

Ria - N2RJ, Elmer

  • 2314 Posts
  • 956 Reply Likes
I doubt it since the 6700 was the first to be released I believe...

I think it's more of a question of available resources balanced with customer needs.

Ria
N2RJ
Photo of Pat N6PAT

Pat N6PAT

  • 845 Posts
  • 268 Reply Likes
Why hold a 6700 back to 4 bands when 8 are available? Isn't that the whole point of having (and paying a lot more $$ for) a 6700 rather than a 6500?

Well now with the array of Flex friendly intelligent third party apps , perhaps it's time to increase the IQ of the Flex - pun intended. I would like to use all of my wonderful Flex and not just a small slice of it - another bad pun.
Photo of Ria - N2RJ

Ria - N2RJ, Elmer

  • 2314 Posts
  • 956 Reply Likes
Negative... the 6700 has two SCUs whereas the 6500 has one. It also has a few premium features - OCXO, 2 meter support and a better preamp.
Photo of Pat N6PAT

Pat N6PAT

  • 845 Posts
  • 268 Reply Likes
And EIGHT available panadapters (as advertised) and I want to use all eight at the same time - again as advertised - but I cannot when using DAXIQ.
Photo of Mark - WS7M

Mark - WS7M

  • 1351 Posts
  • 503 Reply Likes
I was just making fun...  Another tells me the 6700 and 6500 were announced at the same time.

I have no idea why only 4 dax.  It doesn't make sense on a 6700
Photo of Pat N6PAT

Pat N6PAT

  • 845 Posts
  • 268 Reply Likes
Ria,

The major selling point of the 6700 was 8 panadapters. That's why I paid $3,000 more for it than the 6500 cost and I'm willing to bet that why most owners of the 6700 purchased it instead of the 6500.

I've been using 8 panadapters at a time via DAX and it's working great but now I'm using CW Skimmer and it works via DAXIQ and I want to continue to use all 8 panadapters.

It makes no sense to only have 4 available on the Flex flagship radio.
Photo of Ria - N2RJ

Ria - N2RJ, Elmer

  • 2314 Posts
  • 956 Reply Likes
The selling point of the 6700 over the 6500 is two SCUs. 8 slices yes, but the major differentiator is 2 SCUs. 
Photo of Pat N6PAT

Pat N6PAT

  • 845 Posts
  • 268 Reply Likes
The 6500 also has 4 DAXIQ so when they were upgrading all the features for the 6700 which cost an additional $3,000 why didn't they upgrade DAXIQ? If tthe 6500 can handle 4 DAXIQ with only 1 SCU why can't the 6700 handle 8 with 2 SCU's?
Photo of Mark WS7M

Mark WS7M

  • 505 Posts
  • 153 Reply Likes
Pat, you are a better op than I'll ever be.  I can't handle two pans!  LOL

Actually I've had 4 up but I have a tough time keeping up with everything going on, on 4 pans.  I cannot imagine 8.  I'd need a wall full of monitors!
Photo of Ria - N2RJ

Ria - N2RJ, Elmer

  • 2314 Posts
  • 956 Reply Likes
I think the processor is the same, or similar. 
Photo of Pat N6PAT

Pat N6PAT

  • 845 Posts
  • 268 Reply Likes
When I use all 8 at the same time I'm usually monitoring FT8 and using WSJT-X and WSJT-X-Alert which will notify me when a needed DX or State is identified.

For CW I've started using SDR Bridge along with DX Lab's DXKeeper and Spot Collector. SDR Bridge receives the data from the Flex and passes it on to DX Keeper and Spot Collector.

Spot Collector then has an option to display all or a filtered subset of active CW on the Flex. It even has an audio alarm to alert for needed DX and/or States.

You almost don't even have to pay attention to the panadapters as the apps are doing that for you. But they can only do that for the number of panadapters they can access and that is the problem as SDR Bridge uses DAXIQ and not DAX
Photo of David Salomon

David Salomon

  • 34 Posts
  • 3 Reply Likes
Now that someone mentioned DAX IQ, I have a question about this.  I'm using DAX Audio RX instead of DAX IQ for digital decoding.  It seems to work fine.  Is there is reason to use one vs the other?

73 - David, AG4F
Photo of Ken - NM9P

Ken - NM9P

  • 4239 Posts
  • 1351 Reply Likes
Dax IQ is only necessary for extremely wideband (as in, more than a slice bandwidth) decoders such as CW / RTTY Skimmers, etc.
Photo of Mark WS7M

Mark WS7M

  • 505 Posts
  • 153 Reply Likes
David,

I/Q would not be decodable by most of the digital programs.  It contains more than just audio data.  So no... it would take a special decoder to make use of it.

CW skimmer is an example of such a decoder.
Photo of David Salomon

David Salomon

  • 34 Posts
  • 3 Reply Likes
Ken and Mark -

Thanks for the info.  Oddly, I was using IQ at first and it decoded as well as the Audio RX.

73 - David, AG4F
Photo of Ria - N2RJ

Ria - N2RJ, Elmer

  • 2314 Posts
  • 956 Reply Likes
I/Q are in phase and quadrature components of the signal sent over a stereo audio channel. It’s the same as the older FLEX series radios used to send to your computer for decoding with PowerSDR. Quadrature is 90 degrees out of phase with the in-phase signal component. It’s also wideband up to the bandwidth of the sound card, up to 192kHz. Theoretically you can feed these signals into PowerSDR or HDSDR and use them or more commonly CW skimmer.

Good reading:
http://www.ni.com/tutorial/4805/en/#toc2

Better reading (ham radio related, written by Gerald):
https://sites.google.com/site/thesdri...
Photo of Ria - N2RJ

Ria - N2RJ, Elmer

  • 2314 Posts
  • 956 Reply Likes
The in phase component will decode...
Photo of Eric - KE5DTO

Eric - KE5DTO, Official Rep

  • 916 Posts
  • 344 Reply Likes
Official Response
Do the math on the data bandwidth at 192kHz (2 channels of 4 bytes per sample * 192000 = ~12.288Mb/s per DAXIQ channel).  This is in addition to the bandwidth for the displays, audio, metering, and command/control/status.
Photo of Pat N6PAT

Pat N6PAT

  • 846 Posts
  • 270 Reply Likes
Back to my original question:

Why are there only 4 DAXIQ for an 8 band radio?

If you are using an app such as CW Skimmer (or any other app using IQ) then it's really just a 4 band radio because that's all you access at the same time

What is the limiting factor? Hardware or software? And why are there not any more IQ Channels than the 6500 which cost $3,000 less?
Photo of Tim - W4TME

Tim - W4TME, Customer Experience Manager

  • 9198 Posts
  • 3558 Reply Likes
Official Response
It would consume too much of the FPGA resources to stream more than 4 192k of uncompressed IQ streams and it generates a lot of network traffic too.  The DAXIQ channel count and max bandwidth are sized to the radio hardware.
(Edited)
Photo of Pat N6PAT

Pat N6PAT

  • 846 Posts
  • 270 Reply Likes
If that's the case then shouldn't the band limits be a function of the total sample rates currently being selected as opposed to a hard and fast limit?

The DAX control panel allows us to change the IQ sample rate in steps from 24K to 192K. So if we choose lets say 96K then there should be enough resources to handle all 8 bands. right?

Also, if  IQ is sized to the hardware then shouldn't the 6700 have more robust hardware and therefore more IQ channels than the much cheaper 6500 or are you saying that the more expensive radio is using the same hardware as the cheaper one?
(Edited)
Photo of Varistor

Varistor

  • 334 Posts
  • 74 Reply Likes
This would make sense.

Also, for comparison, the 10x cheaper QS1R and Red Pitaya SDRs have no problem steaming 6 x 192 kHz @ 16 bits. This is what I use for my CW/RTTY skimmer node to monitor all 6 contesting bands 24 x 7.

This conversation is no longer open for comments or replies.