Welcome to the new FlexRadio Community! Please review the new Community Rules and other important new Community information on the Message Board.
Need the latest SmartSDR, Power Genius, and Tuner Genius Software?
SmartSDR v3.7.4 and the SmartSDR v3.7.4 Release Notes | SmartSDR v2.12.1 and the SmartSDR v2.12.1 Release Notes
SmartSDR v1.12.1 and the SmartSDR v1.12.1 Release Notes
Power Genius XL Utility v3.8.8 and the Power Genius XL Release Notes v3.8.8
Tuner Genius XL Utility v1.1.20 and the Tuner Genius XL Release Notes v1.1.20
SmartSDR v3.7.4 and the SmartSDR v3.7.4 Release Notes | SmartSDR v2.12.1 and the SmartSDR v2.12.1 Release Notes
SmartSDR v1.12.1 and the SmartSDR v1.12.1 Release Notes
Power Genius XL Utility v3.8.8 and the Power Genius XL Release Notes v3.8.8
Tuner Genius XL Utility v1.1.20 and the Tuner Genius XL Release Notes v1.1.20
If you are having a problem, please refer to the product documentation or check the Help Center for known solutions.
Need technical support from FlexRadio? It's as simple as Creating a HelpDesk ticket.
Need technical support from FlexRadio? It's as simple as Creating a HelpDesk ticket.
Extreme DAX sample rate weirdness (low-level)
Andrew Rodland
Member ✭✭
So I'll begin by saying that I'm using my own implementation of the TCP API and DAX for Linux to talk to my 6400M (you can see more about that in my post history). I don't have a Windows or macOS machine in the house (although I can run a Windows 10 VM as required). I've had a few bumps along the road, including dealing with timebase skew to make sure that my audio buffers don't underrun or overrun... but I thought I had things reasonably well sorted out.
However, today, I absolutely could not the audio to quit stuttering. I tried rebooting the Flex, downgrading SmartSDR on the Flex, upgrading SmartSDR on the Flex, using a different PC, using a different version of my DAX driver, and connecting with the Windows version of SmartSDR in hopes that it would clear out some hidden setting I don't know about — all to no effect.
So I decided to fire up wireshark and do a packet dump of the incoming VITA49 packets. Everything looks neat, there are no gaps in the sequence numbers, the packets come at a predictable interval... only problem is that interval is about 5743 microseconds when it should be 5333. During a span of 100 seconds, I received 17,308 packets (should be 18,750). In other words, the Flex is giving me about 44.31 ksps instead of 48k!
Why in the world is this happening? My PCs are synchronized to NTP stratum-1 using Chrony, my Flex is locked to a ppb-accurate 10MHz reference, there's no tuning error whatsoever on the Flex, and the audio out of the Flex's speaker is fine.
However, today, I absolutely could not the audio to quit stuttering. I tried rebooting the Flex, downgrading SmartSDR on the Flex, upgrading SmartSDR on the Flex, using a different PC, using a different version of my DAX driver, and connecting with the Windows version of SmartSDR in hopes that it would clear out some hidden setting I don't know about — all to no effect.
So I decided to fire up wireshark and do a packet dump of the incoming VITA49 packets. Everything looks neat, there are no gaps in the sequence numbers, the packets come at a predictable interval... only problem is that interval is about 5743 microseconds when it should be 5333. During a span of 100 seconds, I received 17,308 packets (should be 18,750). In other words, the Flex is giving me about 44.31 ksps instead of 48k!
Why in the world is this happening? My PCs are synchronized to NTP stratum-1 using Chrony, my Flex is locked to a ppb-accurate 10MHz reference, there's no tuning error whatsoever on the Flex, and the audio out of the Flex's speaker is fine.
0
Comments
-
I can provide a PCAP dump file if that would help at all.0
Leave a Comment
Categories
- All Categories
- 244 Community Topics
- 2.1K New Ideas
- 481 The Flea Market
- 7.1K Software
- 5.9K SmartSDR for Windows
- 132 SmartSDR for Maestro and M models
- 331 SmartSDR for Mac
- 243 SmartSDR for iOS
- 222 SmartSDR CAT
- 162 DAX
- 348 SmartSDR API
- 8.5K Radios and Accessories
- 6.9K FLEX-6000 Signature Series
- 745 Maestro
- 41 FlexControl
- 836 FLEX Series (Legacy) Radios
- 720 Genius Products
- 387 Power Genius XL Amplifier
- 249 Tuner Genius XL
- 84 Antenna Genius
- 225 Shack Infrastructure
- 150 Networking
- 366 Remote Operation (SmartLink)
- 120 Contesting
- 580 Peripherals & Station Integration
- 114 Amateur Radio Interests
- 805 Third-Party Software